Panasonic DMR-EX75 No Freeview Fault

rusp191

Novice Member
Just thought I'd post to indicate how I repaired my DMR-EX75 which would not find any freeview channels. Other than no freeview analog TV and all other functions were ok.

On removing cover there is a Green circuit board between the DVD and Hard Drives fed by ribbon cables which needs to be removed.

Under the centre of this board on the main circuit is a 6.3volt 680uf capacitor. Replacing this cured my fault.
I was able to see that the capacitor top had blown.
 

ROYOLD

Novice Member
Thanks for that information.

The Freeview channels failed on one of my DMR-EZ45VEB machines but I suspected the tuner. Will check sometime to see if any electrolytic caps blown.

Not an urgent job as the dvd drive is also defective.
 

Gavtech

Administrator
Just thought I'd post to indicate how I repaired my DMR-EX75 which would not find any freeview channels. Other than no freeview analog TV and all other functions were ok.

On removing cover there is a Green circuit board between the DVD and Hard Drives fed by ribbon cables which needs to be removed.

Under the centre of this board on the main circuit is a 6.3volt 680uf capacitor. Replacing this cured my fault.
I was able to see that the capacitor top had blown.
Welcome to the forum.

Many thanks for posting that information.

Did you happen to notice what circuit designation number was given to this capacitor? It is usually printed on the board nearby.
 

rusp191

Novice Member
Sorry was keen to put it back together and test.
Although it's very easy to see as there are not many caps of that size in the area.
 

bigmin

Novice Member
Hi Gavtech,

Sorry to hijack.
Do you remember my “no freeview on rescan” problem on my DMR ES20? I wonder if it is this same capacitor at fault?

bigmin
 

Gavtech

Administrator
Hi Gavtech,

Sorry to hijack.
Do you remember my “no freeview on rescan” problem on my DMR ES20? I wonder if it is this same capacitor at fault?

bigmin
Indeed I do. It was my intention to post about this elsewhere to bring it to your attention.

Although not the same model, not surprisingly these units all have similar overall structures as regards the circuitry. So such a capacitor could well be implicated.
As yet I do not have detail of the function of this cap.
If I knew its circuit designation I could deduce it... Unfortunately circuit analysis down to this level virtually does not happen any more in servicing such that I was shocked to discover yesterday, when I looked into this particular capacitor, that Panasonic do not even provide component values in the service manual [ EX75 - I don't have the manual for the ES20 ]... so I could not find the responsible component.

Up to now I've had a working hypothesis of what may be going wrong:
As far as I can tell users have reported that their units apparently scan and find channels as normal - but none are stored, so none are present when the user tries to use a channel.
As far as I know, channel placeholder information is held in an eeprom... which requires significantly more current to overwrite the information stored in it than in normal routine read operations.
It would be just such a moment that would find a weakness in a supply due to a dodgy smoothing or decoupling cap. I'm guessing that, as the cap cited here is moderately large and is located away from the general PSU area, that it is performing as a decoupling device.

In other words, the information is available, but does not get stored.
There is a flaw in this hypothesis: Why does the old information get erased?

The problem here is I don't have enough information to be certain of the functional operation of this system - so I'm clutching at straws.

The tuner itself has a number of supplies associated with it and this cap could be implicated in any of those... albeit it is a long way from either the tuner or PSU section.

Suffice to say that overstressed caps are just about the commonest cause of failures so it is a strong contender.

It may be that there were software issues also. As I recall you seemed reasonably certain that the scanning problem with your machine with the problem software would always fail on first scan and always succeed on second scan.
If it was truly that reliably predictable, it does call the software into question.
 
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rusp191

Novice Member
The fault I had is that it would do a scan for freeview channels, none would be found. It then goes on to scan for analog channels and finds them and assigns them as channels 1 to 5 which would have prviously been digital.

I think I may be right in saying that the ES20 is the sam machine without the hard drive. Good chance it will be the same capacitor.
 

ROYOLD

Novice Member
The fault I had is that it would do a scan for freeview channels, none would be found. It then goes on to scan for analog channels and finds them and assigns them as channels 1 to 5 which would have prviously been digital.
Exactly the same as my DMR-EZ45VEB does.

My ES20D and EH60D are both working fine.
 
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StormCrow

Novice Member
Sorry was keen to put it back together and test.
Although it's very easy to see as there are not many caps of that size in the area.
My EX75 has developed the same fault so I've had a go with the screwdriver and look at what I found. Seems to be the same capacitor. I've ordered one from e-bay so once that arrives I'll get to see if I can remember how to solder!!!!!

 

Gavtech

Administrator
Thanks for posting a picture.

That nails it.


C1533 680µF 6.3V


Replacements should preferably be 105 degree types.

Can you identify which part of the board this is in please?


De-soldering is probably more of a problem than resoldering.

You may find it easier to cut out the component then remove the wires when de-soldering.

Keep everything clean and tinned and don't linger with the soldering iron and you should be fine.

Good luck.
 

StormCrow

Novice Member
Thanks for posting a picture.

That nails it.


C1533 680µF 6.3V


Replacements should preferably be 105 degree types.

Can you identify which part of the board this is in please?

Hopefully this will do as its the only photo I took and I've put it all back together now as I'm off to Glastonbury next week so it will be a while before I can attempt to repair this.
The position is as the original posted stated, ie underneath the green circuit board that lies between the hard drive and dvd drive. you must remove this board to get access to the capacitor.

 

Gavtech

Administrator
I've just noticed - on the bigger picture ... evidence of board heating around the W72 link ... close-ish to the faulty cap.
 

Gavtech

Administrator
I've just noticed - on the bigger picture ... evidence of board heating around the W72 link ... close-ish to the faulty cap.
Further analysis:

Under the board at that point is IC1508 and is probably the cause of the heating discolouration. [ albeit L1502, the large cylindrical inductor may be adding to it as it is in the line output of IC1508 ]

IC1508 is a 1.8V regulator feeding one of three voltages [ provided by other regulators] to the 'Back End Panel' which is the vertical panel immediately to the right of the hard drive on the wider view picture above.

The faulty capacitor and the L1502 inductor are the smoothing network for the IC1508 regulator output.

There are no circuitry details available for the 'Back End board' as it is regarded as unserviceable down to component level, so analysis can go no further in that regard... but the 'back end board' takes the IF output from the tuner... and loss of this 1.8V supply must effectively produce this ' no digital tuner output' effect.
 

Gavtech

Administrator
My EX75 has developed the same fault so I've had a go with the screwdriver and look at what I found. Seems to be the same capacitor. I've ordered one from e-bay so once that arrives I'll get to see if I can remember how to solder!!!!!
One more point - Remember to observe polarity when fitting the new cap.
 

ROYOLD

Novice Member
Hi Gavtech,

Sorry to hijack.
Do you remember my “no freeview on rescan” problem on my DMR ES20? I wonder if it is this same capacitor at fault?

bigmin
I did a rescan on my ES20D machine yesterday and it found ten analogue channels from various areas (Granada, Wales, Midlands) but NO freeview channels. Tried this again with similar results.

Left the machine switched off at mains for over 30 minutes, restarted machine and did another rescan with same results - only the ten analogue channels found.

Thought about this for a while then from FUNCTIONS menu selected "Add New DVB Service" The tuning bar started searching at channel 21 all the way through the band and loaded 96 digital channels - about the norm for this area. Puzzling!
 

StormCrow

Novice Member
One more point - Remember to observe polarity when fitting the new cap.
Thanks, back from glastonbury now and after a couple of days sleeping I've only just got round to replacing the capacitor today and it now appears to be working ok.
Wonder how many of these have been thrown out that could have been so easily repaired?
 

Gavtech

Administrator
Thanks, back from glastonbury now and after a couple of days sleeping I've only just got round to replacing the capacitor today and it now appears to be working ok.
Wonder how many of these have been thrown out that could have been so easily repaired?
Plenty I don't doubt.

Good luck with the machine.
 

Gavtech

Administrator
I also have this fault.
Can anyone tell me where I can get the right replacement part?
This component is an awkward size / value for standard components.

If you can find one try to use a 105 degree type rather than the standard 85 degree types.

Try Seme-Nedis. The Panasonic part number is F2A0J681A550

Other places to try: CPC, Farnell, Grandata, maybe even Maplin.

(2012 Edit - Ebay is a good source for these capacitors)
 

Rufus McDufus

Novice Member
One question - the Panasonic part# F2A0J681A550 - does this refer to the 105 centigrade product? I can't find a description of this part anywhere :(
 

Gavtech

Administrator
One question - the Panasonic part# F2A0J681A550 - does this refer to the 105 centigrade product? I can't find a description of this part anywhere :(
That part number will apply to the original part which will be a standard 85° type capacitor. [ EDIT - Correction - It isn't. Its a 105 deg.]

Replacing it with that type will work of course ... but I recommend fitting a 105 degree type, if it can be sourced, because the part has shown itself to be vulnerable in this location, almost certainly due to the local heat as detailed elsewhere.

I don't have one of these machines to hand so I cannot tell how critical the component size is - or how much clearance there is between it and the digital board that mounts above it.... because it is also possible to use capacitors with a slightly higher voltage rating [ not too high] and often a value either side of the specified value.
The rating here may be critical - I don't know. But the problem of using other capacitors may be one of physical size.

Judging by the pix - it may be possible to mount a cap sideways if it is physically larger .... provided one can be sure it is physically secure.
 

Rufus McDufus

Novice Member
Thanks! There is a bit of leeway regarding component size, and it's clear all around so could be put on its side.
I went for the original part so mine will be the 85 degree version - but I ordered 2 so that should keep me going for a few years hopefully, or until I'm tempted enough to go for a Panny blu-ray recorder/hdd instead.
 

Gavtech

Administrator
Thanks! There is a bit of leeway regarding component size, and it's clear all around so could be put on its side.
I went for the original part so mine will be the 85 degree version - but I ordered 2 so that should keep me going for a few years hopefully, or until I'm tempted enough to go for a Panny blu-ray recorder/hdd instead.
Yes - Hope so.

Good luck.

Where did you source from eventually?
 

Gavtech

Administrator
Eccellente !
 

Gavtech

Administrator
For anyone else trying to source, here is a high temperature type that is probably suitable.

It is rated at 10V and is 16 mm high... I don't know the size of the original.

( Edit October 2014 - I have found this ebay supplier to be a good and quick source.)
 
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13eastie

Standard Member
For anyone else trying to source, here is a high temperature type that is probably suitable.

It is rated at 10V and is 16 mm high... I don't know the size of the original.
I went for this from Farnell.

They charged me only 20p (INCLUDING P&P!) and the cap arrived the next day.

Took only a minute or too to fit, new cap is a fair bit bigger, but no problem with size.

Tuner works 100%.
 

Gavtech

Administrator
I went for this from Farnell.

They charged me only 20p (INCLUDING P&P!) and the cap arrived the next day.

Took only a minute or too to fit, new cap is a fair bit bigger, but no problem with size.

Tuner works 100%.
Great stuff... and a real bargain.
 

13eastie

Standard Member
Great stuff... and a real bargain.
Thanks very much for your help, Gav.

I was moments away from another trip to Richer sounds.

As well as costing me £150 I'm guessing it would have automatically invited the imbeciles at TV Licensing to resume their monthly, baseless threats and unnannounced visits!

I owe you a pint...

Cheers!
 

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