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Old 7th December 2008, 08:16 AM   #21
Mooly is online now Mooly  United Kingdom
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Maybe try the freezer, in an attempt to see if you can stop the fault happening. Just tiny drips. Interesting fault.
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Old 8th December 2008, 09:26 AM   #22
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Trying to stop the fault from occurring with FS might be easier said than done. The problem is that the white noise occurs randomly, or so it seems. It can take 5 mins after swithcing on or 5 hours, or anything in between. It's not a question of "if" but of "when".

But... I'm beginning to think it might be PSU related. The D20 just did something I hadn't noticed before. While I was listening to music I suddenly heard a strange sound followed by white noise. Then, a second later I heard it again clearly on top of the white noise and it went away again after a second or so. It's probably like you wrote: once upset, the digital part of the player won't correct itself unless a reset is performed (i.e. me switching the player off and on again).

Now you're probably wondering about the strange sound, the best description I can come up with is the following:
In shots of neon signs in films, they usually put a sound effect in the soundtrack that sounds a bit like arcing. Think electric welder, but not as loud and with a bit more hum. That's more or less the sound I just heard.

I'm thinking intermittent failure of a rectifier, power cap or regulator now. Could this be a logical assumption?

I think I'll apply some heat (or would FS be better?) to certain PSU components and try to force the problem to appear...
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Old 8th December 2008, 11:49 AM   #23
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It's quite possible it's PSU and it's usually things that get hot. It's surprising how many components can look well soldered but are not. Hitachi TV's were the worst for this !! several years ago, the solder just would not take at all to the parts due to oxidation.
If in doubt go round all the joints with fresh solder. It doesn't take long.
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Old 8th December 2008, 12:37 PM   #24
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In order to exclude a bad contact in a via I was going over all of them with the iron when I noticed I had overlooked a near DJ on a capacitor. It's close to the digital decoding IC. It looked like there was hardly any solder on the pad.
I took it off to see if the white noise problem would appear. That didnt happen but the transport would no longer read discs.

I also applied heat to about every component and did some more pressing, I still can't force the white noise to appear.

Click the image to open in full size.
Main PCB without transport obscuring everything.

Apart from the four bridge rectifiers for the PSU of the digital circuitry, and the vias, I didn't solder anything else yet, on purpose. I first would like find out if somehow the badly soldered capacitor between transport and digital decoding IC had any inlfuence on the problem. So, I'll have to wait (again)...

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Old 8th December 2008, 12:51 PM   #25
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It's always best to ( and nice ) to find any fault like this scientifically but sometimes that just doesn't happen.
If you do resolder all the joints -- and I mean all -- and the fault recurs at least that possibility has been removed.
We use to do this with whole TV chassis/tuner IF's etc at times. It sounds a poor way to repair something but when time is money sometimes you just have to go down that route.
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Old 8th December 2008, 01:26 PM   #26
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I don't necessarily regard it as a poor thing to do when it gets the job done. I'd probably do the same if time was money.

Repairing the D20 is, of course, the primary purpose , but learning something in the process is also a welcome thing. I'm not fed up (yet) with trying things...

BTW, unexpectedly, resoldering the capacitor seems to have been somehow beneficial to the sound quality of the CD-player. Its musical character has become even more noticeable!
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Old 12th December 2008, 02:29 PM   #27
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I'm beginning to think that, this time, I fixed my Primare D20 for good! Another week of good behaviour and I will pronounce it "repaired"!
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Old 12th December 2008, 04:35 PM   #28
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That's sounding promising then
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Old 19th December 2008, 11:28 PM   #29
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Default problem fixed!

A week later and the Primare D20 is still playing very well! I'm confident the cause of the white noise has been fixed!

Recap: while going over the vias (and SMD fuses) with an iron to exclude dry joints I stumbled upon a capacitor that was soldered well only on one side. (C19 main board, approx. 2n2 if I measured correctly).The other side made sufficient contact with the pad for the first few years not to give problems. Over time the very weak joint must have cracked leading to intermittent failure. At least, that's the most likely explanation I can come up with.

Quote:
Originally posted by Mooly
When you do find it you will kick yourself, the evidence will have been there all along.
And yes, this was indeed the case...a very strange and seemingly complicated fault had an incredibly simple cause...
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Old 20th December 2008, 07:42 AM   #30
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Quite often strange faults have simple causes. Badly soldered joints are not always obvious either, sometimes threatning them with the iron is the only way as you are then really looking at each connection in turn.
Anyway it's good to hear you have it sorted
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