Panasonic DMR-EX75 No Freeview Fault

Thanks for your reply, but i don't want to change all capacitors in that region.
What i found (worthy speculative) is the power for the tuner is following this way:

C1611 (47uF/10V) for X_SW_5R8V (TU) to IC7802 (5V regulator), then to

C7809 (47uF/6,3V) for VIF_5V (TU) and C7811 (47uF/6,3V) for TUNER_5V (TU).

So i will get these three capacitors C1611,C7809 and C7811 and change it, then i will report back.
(Sorry about my english, hopefully you understand, what i mean).
 
Regrettably I don't have experience of DMR-EX83 however a weakness in these systems is that if the voltage is allowed to become too great for the back-end board it is will be damaged.
Correcting the voltage to the back board deals with the supply issue but the back-end board will still be unserviceable.
You will need to check the voltages at the two back-end board connectors are correct according to the service manual.
Steve, who trades as agoodmorning on eBay.co.uk may well be worth contacting, undertakes repairs at a good price and undertakes work internationally via carrier service.
Any report that he gives to you may benefit everyone.
 
@Absolutely: Thanks for your comment. The thing is, that the -ex75 (and -ex85) has a back-end-board, but the newer system of the -ex83 has no back-end-board at all. I think, that function is realized in that high integrated chip (IC7301) near the tuner (TU7801) for the K-Version of the -ex83 (= DMR-EX83EG-K).
I have the service manual of the -EX75 too and know, what you mean. I would go further and look for the power supply of the IC7301.

Correction at 28.06.2016: The -EX3 has no separate back-end-board, but a back-end-section at the digital-pcb. I have to pay attention of this...
 
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Hi,

Just wondering whether anyone has any thoughts on a tuner problem on an EX95?

A few months ago I fixed my Dad's machine which had the classic 'No Freeview' problem by changing the requisite capacitors. Now he is reporting that with only the aerial 'input' cable plugged in, he gets a relatively low level, but still usable signal. However, when the loop-through to the TV is then also plugged in, the signal on the Panny drops off and is unusable, as if it is being loaded somehow.

He lives away, but is coming for a visit soon, bringing the machine with him, so I'll only have a few hours to look at it, and wanted to be fore-armed with as much knowledge as I can glean up-front!

Thanks.
 
Now he is reporting that with only the aerial 'input' cable plugged in, he gets a relatively low level, but still usable signal. However, when the loop-through to the TV is then also plugged in, the signal on the Panny drops off and is unusable, as if it is being loaded somehow.

He lives away, but is coming for a visit soon, bringing the machine with him, so I'll only have a few hours to look at it

Before he brings it to you ask...if it's connected by an HDMI lead ask him to temporarily disconnect it at both ends and connect a scart lead from it to the Tv.
Also if there is any other equipment connected to the Tv by HDMI also unplug those at each end.
If the signal then returns that suggests a faulty HDMI lead, these are known to radiate spurious RF knocking out some Freeview channels and sometimes whole MUX's.
 
Thanks. He actually brought it along yesterday unexpectedly, so no chance to try what you suggested. However, no fault was found when plugged into my aerial, so I'm guessing that he has a borderline Freeview signal (part of the distribution system in a block of flats). He's going to check it out, and I've loaned him a couple of amplifiers to try out.
 
Hello all. Pleased to find this forum with the chance of fixing my DMR- EX75. On plugging it in the clock was flashing 00.00 and after resetting it, no tv stations were found and in 'Set up' the 'Signal' was greyed out - no problem with the tv. The clock time would not hold if the power was switched off. Trawling through these pages, this appears to be a common fault which may be fixed by replacing the 680uf capacitor (C1533) on the main board below the green ic board in the centre. All the capacitors appeared to be OK with just a slight doming on the C1533.

I replaced C1533 by snipping off the legs on it, reducing the legs on the new one to about 10mm and poking them down the holes against the existing legs, before soldering and bending it slightly to clear the underside of the green board. Fairly easy to do - the ribbon cables on the green board are easily pulled out with the strips fixed to them, so no need to tug at the ribbon itself. Much to my dismay, this 'fix' did not work and the fault is still there.

Looking through your posts, C1530, 1502 and 1508 are mentioned, but I do not appear to have these on my board and the nearest I have are C1516 and 1518. I am thinking that perhaps the fault is due to a 'dry joint' on one of the legs on the main board and by soldering the new capacitor on, it has done nothing to improve it? Before going to the trouble of removing the main board, I would very much appreciate the advice of anyone with more knowledge than myself- which is very little!
 
A "dry solder joint" would be obvious. You'd be able to pull the capacitor wire out of it with very little force.

Replacing a bulging capacitor, as you did, was the logical thing to do. Hopefully you replaced it with a true "low ESR" capacitor for longevity.

Look for any other capacitors that are not perfectly flat on top. If nothing is visible, then you must resort to proper capacitor testing with an ESR meter. These are becoming increasingly cheap from China via eBay.

(My original ESR meter from America set me back £220 ! You can resell the meter on eBay at little or no loss because people prefer "next day UK delivery" rather than "some time next month" from China.)

Failing that, a qualified repair technician will have the knowledge and equipment to trace the fault cause and it should be a lot cheaper than an equivalent replacement unit. You could ask Michael at DigifixLtd.co.uk
 
Hello all. Pleased to find this forum with the chance of fixing my DMR- EX75. On plugging it in the clock was flashing 00.00 and after resetting it, no tv stations were found and in 'Set up' the 'Signal' was greyed out - no problem with the tv. The clock time would not hold if the power was switched off. Trawling through these pages, this appears to be a common fault which may be fixed by replacing the 680uf capacitor (C1533) on the main board below the green ic board in the centre. All the capacitors appeared to be OK with just a slight doming on the C1533.

I replaced C1533 by snipping off the legs on it, reducing the legs on the new one to about 10mm and poking them down the holes against the existing legs, before soldering and bending it slightly to clear the underside of the green board. Fairly easy to do - the ribbon cables on the green board are easily pulled out with the strips fixed to them, so no need to tug at the ribbon itself. Much to my dismay, this 'fix' did not work and the fault is still there.

Looking through your posts, C1530, 1502 and 1508 are mentioned, but I do not appear to have these on my board and the nearest I have are C1516 and 1518. I am thinking that perhaps the fault is due to a 'dry joint' on one of the legs on the main board and by soldering the new capacitor on, it has done nothing to improve it? Before going to the trouble of removing the main board, I would very much appreciate the advice of anyone with more knowledge than myself- which is very little!
Welcome to the forum.

You need to take out the central so called digital board to find C1530.
It is underneath it.

I think you must be mistaken about C 1502 and 1508 numbers.

There is no C1502 in this machine ... and C 1508 is a chip capacitor.
 
Thanks Martin. The Cap. was from Farnell and made by Rubycon, so should have been good enough to fix any problem even if it only lasted a few years - not that educated to ESR (equivalent series resistance?). By the way, since last buying from Farnell, a handling charge of almost £5. has been introduced on small orders, so might look to Maplins if I need any more.

As far I can see, all the other capacitors look perfectly normal, so I will have a look at the ESR meters as you suggest.
 
Welcome to the forum.

You need to take out the central so called digital board to find C1530.
It is underneath it.

I think you must be mistaken about C 1502 and 1508 numbers.

There is no C1502 in this machine ... and C 1508 is a chip capacitor.

Thanks for the welcome. The C1502 and 1508 are just parts noted while trawling through the 600 odd posts and perhaps are for different models. If not, I have got it wrong. The C1516 and 1518 are close to the replaced C1533 in the EX75 but I will have another look under the green board for the C1530 and get back to you. Thanks.
 
Yes, it is there. Smaller than I was looking for and it appears to be 100uf at 25v? I have posted a picture for anyone coming 'new' to this problem. C1530 is about 20 mm away from the replaced C1533 which is leaning towards 3-0 clock, making the C1530 position, 8-0 clock - I recommend taking out the SD board first by removing the 4 screws -2 very small and 2 large - then remove the ribbon cables followed by the 3 or 4 screws fixing down the green board. Lift the green board at the end furthest away from the SD slot by about 20mm and it should pull away from the SD - there are two sockets below the green board into which it plugs.

I will replace C1533, keep my fingers crossed and let you know if it is successful. Thanks again for your help.
 

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Another 'busted flush'! I have now changed C1530 and 1533 but the problem remains. Wondering if anyone knows of another component that might cause the same problems? - unable to find any stations and the clock not holding the time. I checked out the ESR meters on ebay as Martin suggested, but not sure if they are all suitable. Most seem to have sockets for the components to plug into, but will they also test in-situ? Any guidance appreciated.

PS Just tried connecting a VHS player to the EX75 via a co-ax cable. It will find the signal and records it. Does not mean much to me, but to those who know about these things, I wondered if it indicates that the tuner is OK?
 
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