Panasonic DMR-EX75/85 U81 Error Repaired / Solved

macklij

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I managed to repair my Panasonic DMR-EX85 which developed the U81 error after being restarted.

In a couple of replies I promised to write up the experience, so here goes. Read on over the next few posts...
 
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The U81 error came immediately following after a power off, which gave a strong hint that there was a semiconductor involved. A close look at the circuit board revealed a swollen C1530 (a 100uF, 25V electrolytic capacitor) which gave me a clue about the area involved. A look at the schematic in page 48 the service manual (I got this from ftp://wolf170571.dyndns.org/C%EF%F0...Panasonic/Panasonic_DMR-EX75EG,EX85EG_dvd.pdf) gave me a clue that the IC1508 voltage converter may be the culprit.

img3m.jpg


IC1508 converts the 12v rail voltage to 1.8V. The 1.8V output should be present on Pin 7 of connector P7413. It wasn't - only about 0.1V was present. 3.3V on pin 8 and 11.6V on pin 10 were present though, which told me that the 12V supply rail shared by all the voltage converters/regulators was OK.

I therefore decided to replace IC1508 and the swollen C1530. It also seemed a good idea to change C1533, which causes the 'no Freeview' fault.

Of course, it may be possible that the U81 error is caused by something else, so if you have the problem it's worth checking the voltages on connector P7413. The following pictures show where the connector is.

img1geb.jpg


img2wb.jpg
 
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I bought C1530 (100u 25v 105C) and C1533 (680uf 6.3v 1.5C) from eBay without any problems. Had I thought more about it, I could have got them from the supplier of IC1508.

IC1508 is an MD5001T voltage converter/regulator. It can be obtained from https://www.chsinteractive.co.uk/electrical-components/misc/dmrex75-md5001-ic-panasonic.htm or Panasonic MD5001 IC C0DBAJG00011 | Products | Spared Parts

I chose CHS because Spared Parts were on holiday at the time! The component can be sourced much more cheaply from the Far East if you are buying several (I wonder if that is what the eBay chap does?).
 
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WARNING
Usual precautions apply:

a. You need to understand what you are doing.

b. You need to take anti-static precautions because there are static sensitive devices around.

c. There may be mains voltages lurking.

d. I'm not liable for your ability or inability to carry out this repair, or for any inaccuracies in my well-intended posts.
 
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This repair is complicated by two main factors:

1. It involves removing the main PCB out because IC1508 located on the underside of the board.

2. IC1508 is a surface mount component (an SMD).

Disassembly
In reality, removing the main PCB isn't too bad. The service guide gives details, but in summary:

1a. Remove the top cover (three screws on the rear, one on each side).

1b. Remove the front panel (two plastic tabs at the side and three underneath. Careful you don't break them!)

1c. Remove the HDMI output board. The ribbon cable goes into the digital PC on a simple push fit connector. Gentle pulling removes it (when replacing ensure it is parallel).

img4fy.jpg


1d. Remove the SD card board. Two screws and another ribbon cable.

img5c.jpg


1e. Remove the rear panel (5 self tapping screws, including the one already removed for the HDMI board, plus two smaller machine screws). Leave the fan screws in place and instead disconnect the fan cable from the power PCB. There are two metal lugs holding the rear panel in place - one on each side.

1f. Remove the power PCB. Gently pull the power rail connector (it's quite stiff) from the power PCB and remove the 3 screws. Remember, there may be some nasty voltages still lurking!

img6qc.jpg


1g. Remove the hard disc drive (HDD). Detach the HDD power cable from the main PCB and remove the four mounting screws that go through the main PCB.

img7ov.jpg


1h. Remove the Digital board (that's the main green board to the left of the HDD). I didn't remove it completely. I detached the ribbon cable that goes to the HDD, removed the screws (mine only had three out of four present). I then pulled it up very gently from the rear (it has two multiway connectors on the underside). When free, I gently flipped it over onto the DVD drive so I didn't have to remove the other three ribbon cables.

1i. Remove the digital input board (one screw).

img8sz.jpg


1j. Remove the digital board support frame. This is a bit fiddly. One of the screws is shared with the DVD drive and when this is screw is removed, the frame has to be pulled gently from beneath the DVD drive holder.

img9oe.jpg


1k. Remove the power button PCB. This long thin PCB is attached to the main PCB by a soldered wire (don't unsolder it). Carefully remove the screw and slide the PCB on the metal lugs to free it. See picture at step 1i.

1l. I left the other components (the tuner module etc) attached to the main board. The main board is removed by undoing the remaining screws (there is a 'hidden' screw running horizontally just under the front panel phono sockets - see pic below).

img12qs.jpg


1m. Remove the PCB and gently turn over onto a suitable surface (I used an antistatic mat).
 
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This picture shows the old IC1508 - note the slight damage (arrow) caused during failure.

img15o.jpg


Replacing IC1508: Removing SMD devices can be very tricky. This one isn't too bad because it only has 8 pins and they aren't too close together. Nevertherless, be very careful not to damage the solder pads on the PCB. I found it easiest to snip the leads and then just individually unsolder each remaining lead. YMMV!

There are plenty of guides about removing and soldering SMDs on the Internet. This picture of the old chip should give you an idea of its size.

img10xz.jpg


When soldering in the new chip be sure to get its orientation correct. The chip has a small indented circle by pin 1. See the following picture of my clumsy soldering! I also double checked that there weren't any solder 'bridges'.

img11l.jpg


Replacement of C1530 and C1533: Observe polarity! I completely unsoldered them from the PCB and replaced (if IC1508 had not needed replacing I would have used the in-situ method shown in other threads).

Replacement of C1533 was not required, but I did anyway, in an attempt to avoid encountering the 'no Freeview' fault in future.

img14c.jpg
 
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Reassembly
Reassembly is the reverse of disassembly. The main, digital and power PCBs have 'notches' that fit into special 'lugs' in the case to ensure positioning is absolute.

The whole job took me just over half an hour. I would expect it to take less than 15 minutes the second time around.

Comments
I think Panasonic must be running these components close to their tolerance to result in so many failures. Just how many users have suffered either U81 or the 'no Freeview' fault?

There is someone on eBay offering what I believe to be this repair for £32 including postage. Given the disassembly and the surface mount device (SMD) replacement that pretty good value, especially if you are inexperienced with electronics repair. I only did this myself because I enjoy a challenge!

Thanks for reading - and I hope it is of some use.
 
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Thanks for the comprehensive report.

A satisfying job - I have no doubt.

Now - How would you feel about replacing the other common failure IC3001
[ 100 pin SMD ] :D

Well done.
 
Thanks Gavtech - I'm still editing away!

As for the 100 pin chip - I'd ask the guy of eBay! :)
 
Hi,

Thank you for your very clear and documented post.

I also have troubles with my DMR EX85 with an U81 message.

As you suggested, I checked the voltage between Pin11 and Pin7 of connector P7413: I measured 2.5 V (not the expected 1.8V).

My knowledge in electronics is old and limited.

Do you think that the IC1508 may be faulty and should be replaced ? or I should look for another diagnostic of the U81 message ?
 
Hmmm... How do the voltages on the other pins mentioned above read?

If they read OK then the rail voltage from the power supply is probably OK in which case I would think that the regulator IC1508 is blown, or possibly one of he capacitors around it is to blame. There is a resistor/capacitor arrangement that determines the voltage that IC1508 delivers.

As a first step, I would check the capacitors mentioned in this and other threads for signs of overheating or damage.

Looking forward to hearing how you get on!
 
Here are the voltages I measured on the pins of connector P7413:
- Pin11: Ground
- Pin10: 11.82 V
- Pin9: 0.0 V
- Pin8: 3.34 V
- Pin7: 0.31 V
- Pin6: 2.53 V
- Pin5: 3.06 V
- Pin4: 3.27 V
- Pin3: 1.92 V
- Pin2: 3.92 V
- Pin1: 3.31 V

I think that in my previous post I must have measured the pin6 thinking about the pin7.

Thank you for your help and sorry about the bad measure.
 
It sounds like you have the same problem I and others have had - IC1508. I would recommend you change the capacitors as well.

There is someone on eBay who repairs this recorder for just over £30. Given that it will cost more than £5 to get the chip without the capacitors, it does seem a good deal, especially if you don't have the soldering equipment.

Do report back...
 
It seems to be a very good deal for £30 !

However, seen from France, I already have troubles to source the spare parts for a reasonable price (I think about buying in UK).

I will have a look on ebay to check if the offer can be concluded with a shipping from France.

Otherwise, I will have to do it myself but changing the IC1508 does not seems as easy as my prévious intervention (replacing C1533).

I keep you informed.
 
Thankyou very much, macklij. A most helpful and detailed explanation of the repair procedure.
 
I bought C1530 (100u 25v 105C) and C1533 (680uf 6.3v 1.5C) from eBay without any problems. Had I thought more about it, I could have got them from the supplier of IC1508.

IC1508 is an MD5001T voltage converter/regulator. It can be obtained from https://www.chsinteractive.co.uk/electrical-components/misc/dmrex75-md5001-ic-panasonic.htm or Panasonic MD5001 IC C0DBAJG00011 | Products | Spared Parts

I chose CHS because Spared Parts were on holiday at the time! The component can be sourced much more cheaply from the Far East if you are buying several (I wonder if that is what the eBay chap does?).


Thanks macklij for all your great effort in producing this repair guide.

My Panny DMR EZ25 DVD recorder without HDD has shown exactly the same U81 error after a power off period.

Although a different model from yours, it appears to be almost identical inside minus an HDD.

I carried out the Cap check and the C 1530 had certainly a domed top end cap.

Also all the voltage checks were good except pin 7 at 0.13v

I aim to get the IC and Cap as per your post but I am not 100% sure if they will be the same as DMR EX75. as I am struggling to get into the website for the Service Manual.

Can you please help with a link to the DMR EZ25 service manual

Thanks

Jon
 
Hi Jon

I did a quick web search but couldn't find a manual. You may end up doing an educated guess on the basis of having nothing to lose. Or perhaps try the eBay based repairer?

Macklij
 
Thank you for that detailed breakdown of repair.
As title says E-Bay repair for the U81 error message still available £32.00.
A repair kit with 2 types of Capacitors and chip with solder and earth strip E-Bay available £6.50.
I purchased the repair kit, and when it arrived the points of soldering are very tiny, so you must be really good at soldering these tiny connections.
 
It's not too bad. I used a fine tipped soldering iron, fine solder and a magnifying glass. If you are quick and don't overheat, then he gap between the solder pads resists solder.

Solder wick and/or a solder sucker help too.

Good luck!
 
Hi all

Thanks for all the info in this thread, I thought my panny was a gonner till I find this!

Not having the time or particularly the inclination to attempt the repair myself (I can solder just fine) I made contact with Steve (agoodmorning) on ebay.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220897944956

He was both reassuringly communicative and professional and so I sent off my panny with a degree of confidence.

I was in no hurry and he'd explained that he was busy so it really didn't matter that it was 6 days from sending to receiving back, including a weekend.

My panny has been serviced, upgraded (firmware), cleaned and repaired and I'm well happy!

I thoroughly recommend him and the service he provides.

Cheers, Steve
 
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Hi Macklij,

Many thanks for the report on your Pany repair, I have ordered the parts and will let you know how I get on.

Cheers

P
 
@sabre2. I tried to reply to your private message, but the system told me you can't receive messages!
 
Well that's odd - you couldn't just have one more try? I can't see any reason at my end.

Many thanks

John
 
I cannot see any reason either.

Please do try again and report back should it fail.
 
The PM has worked this time. Not sure what was happening. What's odd now is that sabre2's original post with the question seems to have disappeared. Or am I going mad?

What was the comment/question?
 

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