Home Entertainment & Technology Resource

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Problems with Panasonic DMR-E85H

Discussion in 'Blu-ray & DVD Recorders' started by tamick25, Mar 14, 2006.

  1. ianba

    ianba Member

    Joined:
    Dec 29, 2006
    Messages:
    13
    Trophy Points:
    1
    Ratings:
    +0
    I had a DMR-E85H with the same problem - it began when it was around two years old, when it would power off when completing an HD -> DVD dub. It steadily got worse, to the point where it wouldn't even power on without going through several self-test/power off cycles.

    I contacted Panasonic, who told me to take it to their authorised repair centre and get a repair report prepared. This came back saying it needed a new PSU (no surprises there!). However, after a bit of arm twisting - and despite the fact hat by now the machine was approaching its third birthday - Panasonic agreed to provide the new PSU free of charge, so I only paid the labour charge for fitting it.

    OK, so even that came to £50 + VAT, but it might be an option if you'd like a bit more use out of your recorder and don't want to risk destroying it with a botched DIY repair.
  2. smokin

    smokin Guest

    Ratings:
    +0
    Well, it paid off. I sent my E85 for the second time to Circuit City for repairs under my $109 five year warranty, just before Christmas. It was slowly refusing to read any new disc I put in, and the ones it did record on were similarly refused as often as not the second third and fourth time inserted. I was beginning to be trained to not record until I had four hours of something to put on at one time. Then it started to fail finalizing. Grrrrr......

    I received it two weeks ago with a note that the hard drive had been replaced. I coudn't get it to read a single disc when I got home with it, but I did get a new error message. Back to CC I go and yesterday they tell me they're replacing it under the lemon policy, three major failures in two years. Since two years was up 2/14....er....14/2 I feel blessed to be the owner of a brand new, slightly less capable, DMR EH75V.

    FIrst time I've ever purchaed an extended warranty and it paid off. I got a three year on the new one ;)

    By my rough count, my DMR-E85h recorded some 5500 hours in the 23.5 months I owned it. It lived like a hot flame.
  3. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    In reply to "Moschops" who wanted to know if the PSU could be purchased, you could try searching for "ETXMM507E4F" which is described by one Parts Supplier website as the "Power Supply PCB" for the DMRE85H . I assume that it would have all the components already installed onto it ... but I could be wrong there.
    • Thanks Thanks x 1
  4. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    I replaced the STR-G6353 in one of my E85s recently. My other E85 is not exhibiting any symptoms as yet. As has already been said, the 6353 is a conventional package, not surface mount. It's like a TO-220 package, but it's all plastic, including the tab. So the thermal resistance of the package must be quite a bit higher than a TO-220 with a metal tab, and I doubt if the moulded plastic surface makes very good contact with the heat sink. There was no thermal pad and no sign of any thermal compound.

    I'm not totally convinced that the problem is just overheating. I've never known a power device to die gradually before. It's normal for power transistors and regulators to work at elevated internal (junction) temperatures. Provided they are used within their ratings and safe operating area they should continue to work. But exceed their ratings or safe operating area and they can fail in a fraction of a second, usually by going short circuit. This hasn't happened to the E85s in this thread. They have continued to work, but gradually less reliably. The symptoms I was getting were consistent with a regulator current limit gradually getting lower until it was being tripped by normal peak currents during power up and DVD burning. I can't help wondering if it's a device problem - that some 6353s are gradually deteriorating during normal operation. Perhaps impurities are migrating within the devices.

    Anyway, be that as it may, I played safe by using a very thin smear of thermal compound when I replaced the 6353. (If you do the same, be careful not to get the compound anywhere near the pins or on the PCB, especially if it's a metallic type.)

    If you're experienced at repairing PCBs you should have no difficulty replacing the 6353. The 5 pins are single in line as they come out of the package, but pins 2 and 4 are preformed to make a DIL arrangement. I used a solder sucker once on each pin, moved the device gently, moved a couple of pins gently, and it came out cleanly. The pins weren't a tight fit, and I don't think the holes were PTH (but this is from memory, and I don't remember specifically checking), so there was no need to cut the pins.

    If you're not experienced at soldering but want to have a go, here's how, using a solder sucker (others may advise using wick). Remove the screw securing the 6353 to the heat sink. It's easier to remove cut pins than the intact device, so cut the 6353's pins on the component side of the board using a small pair of side cutters. You can either cut them short and suck the pins out with the solder, or cut them long and pull them out from the component side. Use a temperature controlled iron if you can. Wait till it's up to temperature. Clean the tip of the bit by applying a little solder and wiping the bit on a damp sponge. Prime the solder sucker and hold the tip of the sucker close to the first pin. Then apply the tip of the soldering iron bit to the solder fillet, rather than the pin or the pad. As soon as the solder fillet melts (it should almost immediately), pull the bit away, move the sucker tip against or over the pin and trigger the sucker, all in one quick smooth move. If you time it right, the sucker should remove almost all the solder and possibly the pin, leaving a clean undamaged pad. If the pin is still in the hole there will probably be a tiny bridge of solder between the pin and the edge of the hole. (If you don't get it right, it may be easier to apply some fresh solder to the joint then let it cool before trying again.) Repeat for the other pins. Apply just enough heat to free any pins that are still in the holes in turn and pull them out using fine pliers. Check there are no solder splashes or fine strings of solder between the pads. If you've got some PCB cleaner, now is a good time to apply some to the area you've been working on and scrub it with a fibreglass brush or a tooth brush.

    Be careful not to apply too much heat with the soldering iron, or too much force when trying to remove the pins, or you might lift the pads from the PCB. There are some surface mount devices on adjoining tracks quite close to some of the pads. In these cases apply the bit to the solder fillet on the side of the pin furthest from the surface mount device.

    Fit the new 6353 and screw it to the heat sink. Then solder each pin in turn. Apply the bit so the tip is touching the pad and the side is touching the pin. At the same time feed some solder onto the bit so it runs onto the pin and the pad. As soon as the solder has formed a conical fillet right round the pin, remove the solder and the iron and let the joint cool. The solder fillet should have a shiny appearance. Finally check there are no solder splashes or fine strings of solder between the pads. As before, if you've got some PCB cleaner, apply some to the area you've been working on and scrub it with a brush.

    Some other comments:

    You don't have to remove the top and bottom brackets from the hard disk (though it does no harm). You can remove the hard disk with the brackets still attached. Remove one screw securing the flexible printed cable and the four screws holding the hard disk assembly and the PSU board. Remove the hard disk connectors (forwards) and lift out the assembly.

    Some screws are fitted beyond the reach of your fingers. A slightly magnetised screwdriver helps when reassembling.

    The cooling is directed through the PSU by plastic baffles. The fan sucks (rather than blows). Cold air enters via ventillation holes in the sides of the case near the front and warm air exits via the fan in the rear panel. The case remains fairly cool. In my opinion there should be no problem with stacked units. They look like they are designed to be stacked. But it is important to ensure that the ventilation holes in the sides of the case are not blocked in any way. I would allow at least one inch clearance between the sides and any other objects.

    Many thanks to Leslie Rushforth for the original repair information.
    • Thanks Thanks x 2
  5. Ian01

    Ian01 Guest

    Ratings:
    +0
    Thanks to everyone for the advice! I had the same problem with my DMR E85H, read the posts, but didn't fancy doing the soldering in case I broke something else. Took it to local TV/Video repair shop and mentioned the thread on this forum.... after 6 weeks and several phone calls(!) the shop eventually said it was a laser fault and not economic to repair.

    Now having nothing to lose, I ordered and fitted the voltage regulator (which was easier than I'd expected), now the machine works fine again!
  6. keenannz

    keenannz Guest

    Ratings:
    +0
    hello everyone,Im from New Zealand. Unfortunately I have the same problem with my DMR E85H,continuosly going throught the self check cycle. So I decided to order the part from panasonic NZ at a total cost of $42.00. I have taken the recorder apart and found the ic that needs replacing. I took the recorder into one of our local TV repair shops who did not want to do the repair! I have ordered the part myself and am waiting for it to arrive. I think I will have to use Next Electronics, anyway will let the forum know how I get on once the repair is done. Thanks once again to the forum as this is the way I found out about the problem.
  7. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    I think most reputable TV repair shops would refuse to do a just "parts replacement" job. It isn't worth their while in relation to how it affects their "reputation" if the repair doesn't work or doesn't last. They'd rather you leave it with them to do the fault finding and repair work....and they'd rather replace the whole Power Supply board than to waste their time checking out individual components.

    Well, I managed to overheat some adjacent component (probably a Surface Mount component) when using desolder wick. So in retrospect I think I should have used a Vacuum Pump Solder Sucker or I should have been more careful with how long I persisted with heating the desolder wick. The machine now powers up and just "cycles" but doesn't "SELF CHECK". But all is not lost. I may get to replace one or more SM components after all. (I also considered replacing the whole Power Supply board but the Spare Parts Supplier emailed me that the part is no longer available from Panasonic ... perhaps Panasonic only supplies them to their Authorised Service Agents?)

    By the way, I may be overly cautious but I would avoid touching the BIG electrolytic capacitors to give them enough time to discharge after powering off (exactly how long I've no idea ... at least 10 mins?). Actually the correct thing to do is to discharge them through a big resistor but that means rigging up some sort of "probe" to do that.... most of the time they should quickly discharge soon after powering off but you can never be certain.
  8. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    Are you sure? If not - if you're just assuming you must have - I would check a few other things first. As you say, all may not be lost.

    Examine the your soldering carefully:
    - Look at each joint. The solder should look smooth and shiny. Is it dull grey? Are there any holes in the solder? The solder fillet should be reasonably conical with the base of the cone just covering the pad. Look at the contact angle. If it's rounded the solder may not have wetted the pad or the component lead, leaving you with a bad joint.
    - Look at the area round each joint. Is it clean and solder free? Have you bridged two of the pads with solder? Thin strands of solder can be so thin they are difficult to spot. Use a magnifying glass if you've got one.
    - Look at the tracks where they join each pad. Can you see any cracks?

    Do some continuity checks with a multimeter.
    - Check the continuity of each lead from the component side to the track side of the board.
    - Trace the track from each pad to the another component. Check the continuity of the track.

    If you find a bad joint, suck all the solder off and resolder the joint.

    If you find a cracked track, bridge it with some fine equipment wire. It is possible to scrape the green resist off the track and solder a small bridge directly to the track, but it's safer to trace the track carefully to another pad and solder both ends of the wire to pads. Form the wire neatly, avoiding any protruding component leads that might puncture the insulation.

    When soldering, use a temperature controlled iron if possible. Wait for it to reach working temperature, which should only take a minute or two if it's temperature controlled. My iron clicks as the temperature cycles. If the iron isn't hot enough, or is too light, it will take too long to melt the solder. The aim should be to only apply the iron for a very few seconds. I haven't timed it, but I would say around one to two seconds is typical for desoldering or soldering a joint. If it doesn't work, let the board cool down before trying again so heat doesn't build up in the board. One danger of too much heat is lifting a pad. If a pad starts moving you can get a hairline crack between the pad and the track which can be difficult to spot.

    Keep the bit clean by wiping it frequently on a damp sponge. Solder stations have a sponge on top for this purpose. If old solder won't melt easily, apply some fresh solder to get it going.

    I only ever use a solder sucker, and I described how in my previous post. I know some people advocate solder wick, but I'm used to using a sucker. Wick has to be fresh. Check the suction of a sucker by blocking the tip of the nozzle with your thumb while you release the sucker, then remove your thumb. Clear the sucker frequently by operating it several times over a sheet of paper or a waste bin. Remove the nozzle to clean it if it gets bad.

    If you haven't soldered before, practise on something that doesn't matter - an old transistor radio for example.

    Good luck.

    It's good to be cautious but they should be safe by the time you have dismantled the unit. The big electrolytics will probably only have low voltages on them, but they can produce a healthy spark if you short them out when they are charged. Any filtering capacitors on the mains input will probably have discharge resistors across them.
  9. ROYOLD

    ROYOLD Active Member

    Joined:
    Jul 5, 2005
    Messages:
    3,898
    Trophy Points:
    103
    Ratings:
    +354
    ....and the large, low voltage, electrolytic capacitors were also a major source of failure. This was 20 years ago when I was dealing with radar repairs - perhaps there has been an improvement in reliability in the intervening years.
  10. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Hi Maldonian and Royold. Thanks for the detailed advice. So far, I've done continuity checks of the solder joints using a multimeter. All of them seem OK and there don't appear to be any unwanted solder bridges between tracks. Anyway I'll do a more thorough examination of the solder joints before I replace anything.

    I did have problems removing one particular pin where the solder wouldn't melt through the wick (probably my iron wasn't hot enough to melt the solder with the wick in place...or the flux in the wick wasn't "fresh" even though the wick was recently purchased... next time I'll try your suggestion of melting fresh solder onto the joint). Consequently I accidentally lifted the pad off the board when I wiggled the lead of the component that I tried to remove and there was still some solder holding the pin onto the pad. I tried repairing this by scraping the "resist" off the region near the damaged pad hole to uncover the copper track and then putting in a tiny solder bridge between the pin of the replacement component and the copper track. From memory I don't recall seeing any unoccupied pads on the same track as the damaged pad. So putting in a jumper lead to connect the pin to a "good" pad would involve desoldering a component that currently occupies a "good" pad on the track...something I'm reluctant to do unless it's absolutely neccessary.

    Yes, you are right that the Capacitor voltages are probably low.
  11. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    Too much heat weakens the track adhesion. You need to apply the heat for as short a time as possible. But it's very easy to lift a pad on a single sided board, even experienced technicians can do it occasionally. If the component lead is still attached to part of the pad after desoldering you can sometimes free it by moving it slightly, but you risk lifting the pad. If a slight movement doesn't free it and further desoldering is unlikely to help, you need to melt the tiny amount of solder that's still holding the lead. Either (a) gently push the component lead towards the centre of the hole using the tip of the bit until the solder melts, or (b) stand the board on edge so you can hold the component on one side while you apply the iron to the lead (not the pad) on the other side until the solder melts and you can move the lead or pull it through.

    Avoid using just solder to bridge a gap. Instead, take an unused small resistor and form the tip of one of its leads into a small U shape using a small pair of long nose pliers. Hook this around the pin, and lay the straight part of the lead across your scraped section of track. Solder the lead to the pin. Shape the lead so it touches the scraped track without springing away. Cut off the excess lead together with the resistor. Carefully solder the lead to the track.

    I didn't mean you should look for an unoccupied pad, there probably isn't one anyway. Solder the other end of the wire to another occupied pad on the same track. There's no need to desolder. Bare the end of the wire, wet it with solder, and solder it to the existing solder joint on the pad. Perhaps I didn't make it clear I was suggesting running the wire across the track side of the board, not the component side. There are ways you can add wiring on the component side, but it's much simpler to add it on the track side.
  12. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Yes...it's a good suggestion. Another website also recommended doing this as it gives a stronger bond than just solder by itself.

    Yes...I thought about running a wire between the component and another "good" PAD on the same track as the damaged PAD (on the track side of the Board) but I wasn't sure of what Gauge of wire to use. eg. I have some "HDD power lead" wire but I wasn't sure if this could carry the current load in that part of the Board.
  13. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    We haven't got the data sheet for the STR-G6353. Typical current ratings for TO220 cased voltage regulators are 0.5A, 1A and 2A. With these sorts of currents you don't need to worry too much about which wire to use. There are TO220 regulators with higher ratings than this, but the TO220 package with a metal tab must be capable of handling higher powers than the all-plastic 6353 case, so it seems unlikely that the 6353 would have a high current rating (though it doesn't necessarily follow).

    You can also judge what the working current might be, to a certain extent, by the width of the copper track you want to bypass with wire. We don't know the actual copper thickness or the maximum temperature rise the designers worked to, but for typical 1oz copper and the common recommendation of a 10 deg C rise, here's a list of roughly equivalent track widths and equipment wire gauges:

    0.02" track = 1/0.6 or 7/0.2 wire (1.5A)
    0.05" track = 16/0.2 wire (3A)
    0.10" track = 24/0.2 wire (6A)

    Solid (single strand) wire can be dressed neatly either point to point, or parallel to the board edges with one or two right angle bends, or following the original track. Multistrand wire is more flexible, doesn't retain a shape as well and can droop, so it's best to go point to point.

    There's a readable article about track widths and clearances here.
  14. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Thanks again for the useful info about the wire current ratings. Sounds like 2 Amp or 3 Amp wire (22 AWG or 20 AWG) wire should be OK to use. However, for now, I'll stick with using a "lead wire" bridge between the STRG6353 pin and the broken track since I prefer not to "disturb" another "good solder joint" by soldering a wire onto it.

    I just downloaded the Service Manual from one of the Google Sponsor sites (in my case www.service-manuals.net)... mainly to find out more info about the PCB tracks running from the STRG6353 and the components on these tracks. It would have been useful for the PCB map to be in colour...even at 400x magnification it's difficult to identify some track sections. Eventually I was able to identify everything by matching things up with the corresponding Schematic diagram (a very slow process !). Surprisingly the manual doesn't have any "Trouble Shooting" guide (what to do when such and such a condition happens.....or doesn't happen). About the closest thing it has is a table of Expected Voltage readings at different circuit points when the machine is in different conditions (doing different operations) and some Oscilloscope Waveforms. It also has Assembly/Disassembly instructions, PCB maps and Schematics and a list of Parts (there's a warning that you should order Part Numbers from the Parts List and not from the Schematics since the Part Numbers on the Schematics may be out-of-date).

    One interesting thing. The manual says that Panasonic uses "lead free" solder and that it has a higher melting point (370 deg Celsius) than standard "tin/lead" solder. I think this would probably only affect people using "temperature controlled" irons to desolder components. So crank up your irons but only use them for a couple of seconds at a time. Anyway, hopefully everyone who tries the STRG6353 repair will be more careful than I was so you won't need this sort of info.
  15. Gavtech

    Gavtech Administrator

    Joined:
    Oct 25, 2005
    Messages:
    18,892
    Trophy Points:
    166
    Ratings:
    +4,262
    Unfortunately that link doesnt work because of the bracket being part of it - [ removed in the quote ] .. but even when I get there, it's been hacked by 'Turkish Hacker' with a political message.
  16. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Hi Gavtech. Sorry about that. The correct website address is http://www.service-manual.net/ashop/catalogue.php (ie. I pluralised "manual" by mistake). You then need to search on "panasonic dmr" and then locate your particular DMRE85H model on the Results returned (eg. the Australian model happens to be DMR-E85HGN. I don't know what the UK model would be).

    The website is American and the prices are in US dollars ($11.99 USD for each manual). There are other websites but this was the cheapest I could find at short notice. I can't vouch for the manual's "legitimacy", eg. the PCB maps should really have been in colour to more easily identify neighbouring PCB tracks. So it may very well be a B/W Photocopy of the Panasonic manual. But this is just my own speculation...they could very well be an authorised outlet.

    Also I was a bit uncomfortable with the way their website redirected me to Paypal. I prefer to type in the Paypal website address explicitly so I know that I'm not being redirected to a "fake Paypal" website.

    The downloaded manual is in Adobe pdf format and is about 16 Mb.

    Gary
  17. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    Lead solder was banned by the EU last year for new equipment sold in Europe. Most major Japanese manufacturers have been using lead free solder for green reasons for several years. My experience pre-dates lead-free solder so I don't know what it's like to use. This Wikipedia article indicates there are lots of different types.

    You can mix tin lead solder with lead free when repairing though it's best to use the same type of solder if you can identify what was used. My iron is a Weller that's still going strong after many years. The temperature is controlled by the interchangeable tip. The tip I normally use sets it to 700 deg F. I had no difficulty using it on the E85 PCB, the existing solder seemed quite normal. I used a reel of multicore solder I've had for years.

    I'm tempted to, but I haven't done it yet. Armed with a circuit diagram and expected voltages you stand a good chance of finding your fault. Be careful, there are mains voltages on part of the board. Powering up with the HDD disconnected may cause the HDD to be formatted after you reconnect it. I'm not sure, I haven't tried, it may only happen if you reconnect a different drive. If you extend the short power lead (use a splitter lead) you might be able to lift the drive out of the way with it still connected.

    I agree. Let us know if the payment goes through ok.

    That's the first time I've seen a hacked site. I must live a sheltered life.
  18. Annie_M

    Annie_M Member

    Joined:
    Jan 5, 2007
    Messages:
    26
    Trophy Points:
    6
    Ratings:
    +2
    YAAAAAAAAAAAAY...

    My recorder is now a happy bunny. So am I, as it's better than the Phillips replacement we bought.

    Firstly let me give a big hug to the person who identified the solution to this problem.

    Secondly, I must say I'm very impressed with the response from Nikko (Dalbani in the UK). The chip was ordered last monday afternoon and was delivered Tuesday morning!!

    Now. The Masters Method to fix this fault.

    I felt that simply replacing the chip was just delaying the same problem later on, so I decided to re-mount the chip in a better location. After removing the dead one and the heatsink, i made up a length of reasonably robust ribbon cable (about 10cm) & soldered one end into the pcb where the chip was originally. As previously stated, there are a few surface mount components very close to the regulator. Extreme care is needed not to overheat them during (de)soldering.

    The heatsink fits neatly at the rear of the board in front of the fan next to the mains socket. Unbend the solder lugs so they stick out horizontally from the heatsink, then mark the board underneath the lugs for drilling (about 5mm in just where the green printing is on the top surface). Ensure it's not too far in as the mains fuse is right behind the new position! At one end, the drilled hole will go into the ground rail next to the pcb mounting hole and can be soldered to fix it (the regulator is fully insulated so this won't cause any trouble). At the other end you will need two holes close together. I looped and soldered some thick wire round the lugs (1.5mm mains copper wire) to go through the holes. The end that can't be soldered needs to loop under the board to stick back up the second hole in order to give it some support.

    Next, I used two old TO220 heatsinks with fairly long fins to assist the original. One of these holds the regulator on the right end (as viewed from the 'front' of the board) this makes the length of the ribbon as short as possible. The other goes at the left hand end. There are 4 pre-drilled and threaded holes in the original heatsink. Solder the ribbon to the legs of the new chip. BE AWARE the chip is now the other way round to it's original position so the ribbon will need a twist to make the connections correct.

    Re-assemble the psu into the machine & put the hard drive back in. Again be very careful with the black data cable on the top of the hard drive. You will need to trim the plastic baffle attached to the drive, as it will foul on the fins of the extra heatsinks.

    This entire process took about 2 hours, including the 'How Do I Do This' stage.

    I was a little concerned that extending the wires to the chip would possibly cause some instability or noise, but it seems fine. I dubbed half a dozen films to dvd and the regulator barely got warm.

    Hope this is of some use to someone.

    Annie.:thumbsup: :smashin: :clap:
  19. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Hi Maldonian. Yes...the payment went through OK. (so far so good ... but I'll watch out for any unauthorised charges to my Paypal account just in case).

    Hi Annie_M. "cool" idea of yours to move the Voltage Regulator closer to the fan.
  20. smokin

    smokin Guest

    Ratings:
    +0
    ...was a failure out of the box. :suicide: Panasonic customer service tried for 40 minutes to make it work and then told me to take it in for service. I returned it to Circuit City, got a store credit for $500 (which was against the normal rules) and bought a $130 LG with no HD. So I'm out fo the Panasonic game, for good I hope.

    Just thought I would let you know the outcome, if anyone is interested. Good luck with all your DVD recorders. Thanks for the help and advice :) :hiya:
  21. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Hi Smokin. Good luck with the LG :thumbsup:

    Hi Annie_M. Another good thing about moving the Voltage Regulator closer to the fan is that it is farther away from the Power Transformer which is always ON when the machine is in Standby mode. I suspect that the Transformer may contribute some heat to slowly "cooking" the Regulator. So Fred Smith's idea of running the fan all the time is a good one....or perhaps switching off the power at the Power Point would also work as well (when you don't want to schedule a Timer Record). :thumbsup:

    As for my own little machine, it looks like I must have cooked one or more of the Surface Mount capacitors and perhaps one of the Surface Mount Zener diodes in the "Feedback path" that eventually supplies 3.3V and 1.8V to sections of the main board (the 12V and 5V supply paths are unaffected). The Zener diode and a capacitor are in parallel and my multimeter shows a current flow (and low voltage) in both forward and reverse directions (the multimeter diode test should only show a current flow in the Forward direction). I would have to remove one of these from the circuit to determine which is faulty but doing this will probably destroy the component. In any case, it may be academic if I can't obtain replacement components (my Spare Parts supplier doesn't keep these in stock. Hopefully they'll still be able to order them from Panasonic).

    Oh, I eventually found some Trouble Shooting info in the Service Manual however it only deals with Error situations that occur AFTER the machine powers up properly.
  22. Annie_M

    Annie_M Member

    Joined:
    Jan 5, 2007
    Messages:
    26
    Trophy Points:
    6
    Ratings:
    +2
    Hi Gary. Although I haven't had a meter or oscilloscsope to my machine, my suspicion is that the offending article is used as a mains chopper switch, and the transformer is a HF type as:

    A) it doesn't seem big enough (at 50Hz) to cater for the demands of all the gizmology that it supplies.

    B) an awful lot attention has been paid to filtration on the mains side (inductors of all shapes and sizes), which makes even more sense than usual if there is a lot of HF noise being produced.

    Anyway, the bottom line being that the STRG6353 may be powered and running even when the machine is off! If this is the case, the chip may well get at least as warm when the machine is on standby (and without the benefit of any airflow) as it does when under full load. Therefore powering the whole thing off when not in use could be a very wise move!!

    Of course, I could be completely wrong - it's not unusual.

    As for fried SMC's. You really will need a full service manual to ascertain the component types and values (as I remember there were a couple of resistors, capacitors, a zener and an ordinary diode) - but I don't see any reason why they can't be replaced by equivalent standard profile comps with a little care and ingenuity, as there's a good bit of room under the board.

    Good luck.. Annie
  23. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    3.3V and 1.8V sound like processor i/o and core voltages, but perhaps it's just a coincidence. I should think the regulator for the processor is on the processor board. The zener diodes could be providing reference voltages or level shifting. They could be part of a circuit that senses overvoltage and shuts down the supply if it occurs. Zeners look like normal diodes if you check them with a low voltage multimeter (though I don't think I've ever checked a 1.8V zener - that's pretty low), but in situ there will probably be other current paths in parallel.

    As Annie says, you can replace a damaged discrete surface mount component with an equivalent normal non-SMC type. Apart from mounting these on the track side, other techniques can include (1) drilling small holes very close to or just touching each track you want to attach the component to and fitting the component on the legend side of the board with the component leads through the holes, bent over and soldered to the track, (2) drilling small holes just touching each track, fitting tubular or Vero pins and soldering them to the tracks, wrapping the component leads round the pins on the legend side and soldering them, and (3) using existing holes - empty holes or through holes or by lifting other components and mounting them on pins. You may need to sleeve the component leads, depending on how long they are and what they lie close to.

    It would be interesting to put a temperature probe on the heatsink.
  24. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Hi Annie_M. From my circuit diagram and the multimeter readings that I took at the multi-wire cable that links the Power Supply with the Mainboard, there's always power to the STRG6353 even in STANDBY mode, however, the STRG6353 only feeds some paths in STANDBY mode (ie. the 13v and 5.8v paths) but not others (ie. it doesn't feed any power to the 12v, 3.3v and 1.8v paths until you Power ON). So you could say that the STRG6353 is being "slowly simmered" during STANDBY even if you were to relocate it away from the power transformer.

    Yes I have the component types and values from my Service Manual (for now just one zener diode and one capacitor that I know are definitely faulty), however, the authorised Panasonic Spare Parts supplier doesn't have them in stock and needs to get them from Panasonic (Matsupoopa). So I'm waiting for them to reply.

    There's usually a good reason why Panasonic uses Surface Mount components instead of Discrete components (apart from cost and heat dissipation). eg. Surface mount capacitors are used to eliminate "noise" generated by Power transistors and ICs such as the STRG6353 and to do this they need to have very short leads (I guess the leads must generate some noise as if they were tiny radio antennae) and they need to be located as close as possible to specific pins on the IC (the source of the noise ?). This noise disrupts the output of the other pins of the STRG6353 that eventually feed a "photo coupled" power transistor that feeds the 3.3v and 1.8v paths. (hey, I'm just reading this stuff from the Service manual...I don't know what a photo coupled transistor is). In any case, the Service manual warns against component substitutions.

    Hi Maldonia.
    From datasheets, the MA8051 zener diode has a Zener voltage of 5.1V. Even though the STRG6353 eventually feeds the 3.3V and 1.8V paths there's a few Power Stages between it and them. Anyway, as you say the zener diode should act like a normal diode under a multimeter diode test, ie. there shouldn't be any current flow in the reverse direction when the Reverse voltage is less than 5.1 V (depending on what else is in parallel with the diode....in this case it's basically a Surface Mount capacitor that leads to Ground). The zener diode is part of a feedback path from the Mainboard that leads back to the STRG6353. I guess it tells the Voltage Regulator to "fine tune" its output voltage for those paths which require a more "regulated" supply from the STRG6353.
  25. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    I suspect that the capacitor (and not the zener diode) has "shorted out" when I desoldered my STRG6353 for too long and this is why the diode test shows a reverse current flow however I can't check this without taking the capacitor out of the circuit.

    I think the zener diode is supposed to tie the voltage at pin 5 of the STRG6353 to the zener voltage of 5.1v whenever the voltage in the Feedback Path (pin 2) gets too large, however, because of the fault, the voltage at both pin 5 and pin 2 is ALWAYS low regardless of the feedback signal sent back by the Mainboard. Having thought about it, the STRG6353 doesn't actually feed power directly to the later Power stages. It's more like it indirectly controls (or regulates) the power that the Power Transformer feeds these Power Stages (via the photo coupler transistor). So it's like a high speed switch that has to withstand Mains level voltages (the capacitors in that part of the circuit are rated at 25v or 50v).
  26. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    My Spare Parts supplier replied that they can sell me a generic 470pf, 50V Surface Mount capacitor but I need to give them a Series Number which apparently indicates the size that I want. So I may try using a generic SM capacitor rather than a non SMC capacitor once I find out about "Series Number". The Generic Part only costs about 50 cents (20 pence ?).

    If it doesn't work out, I can always try a non SMC capacitor.
  27. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    I just discovered another reason why my machine won't power up properly...a hairline crack on the board near the screw hole eyelet which is closest to the Right Hand side of the Front Panel. It's the eyelet that doesn't have any metal reinforcement (all the others do). So be very careful not to overtighten any screws when you reinstall your boards.Anyway, I'll try running a lead to bypass the crack (see Maldonian's earlier posts on how to repair/bypass a crack).

    Finding a generic replacement Surface Mount capacitor is proving a bit more complicated for me than just measuring its size. a) some suppliers only sell them in packs of 50 (I just want 1 or 2), b)there are different classes of capacitors depending on whether you want a wider operating temperature range (accepting some variation in capacitance as the voltage varies) or if you want stable capacitance as the voltage varies over a narrower temperature range. In my case, I think the original capacitor falls into the second category (ie. it's an NPO or COG type).
  28. maldonian

    maldonian Member

    Joined:
    Nov 25, 2004
    Messages:
    919
    Trophy Points:
    43
    Ratings:
    +120
    Hi Gary

    I suggest you try replacing the 470pF SMC with a leaded ceramic capacitor. They are tiny and they are available in a wide range of values (including 470pF). They are also cheap (around 10p each in the UK) and they are excellent for decoupling. The leads are usually 0.1" or 0.2" spacing. You can easily solder them onto the track side of the board.

    The large value disc types (Z5U dielectric) have a large non-linear temperature coefficient, which doesn't matter if they are being used to decouple rails. Medium values (X7R dielectric) don't vary as much with temperature. The NPO/COG types have stable values.

    Ian
  29. garyleeoz

    garyleeoz Member

    Joined:
    Jan 1, 2007
    Messages:
    40
    Trophy Points:
    8
    Ratings:
    +1
    Yes... it'll probably work. I just realised that if Annie_M can move the STRG6353 as far away from the Surface Mount capacitor and zener diode as she did without any side-effects then a few millimetres of component lead aren't going to cause any noise problems.

    Actually cost really isn't an issue. I found a supplier who can sell me a 25 pack of ceramic SMT NPO capacitors for about 18 cents each (7 pence each). But it seems like a waste to buy so many of them. Still it gives me 25 chances to do the job properly.
  30. ROYOLD

    ROYOLD Active Member

    Joined:
    Jul 5, 2005
    Messages:
    3,898
    Trophy Points:
    103
    Ratings:
    +354

Share This Page