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...
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...
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.
If in doubt go round all the joints with fresh solder. It doesn't take long.
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.
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)...
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.
An externally hosted image should be here but it was not working when we last tested it.
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)...
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.
) 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.
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!
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!
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.
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.
And yes, this was indeed the case...a very strange and seemingly complicated fault had an incredibly simple cause...Mooly said:
I was just in another room when I heard white noise coming from the living room and I thought "OH NO, NOT AGAIN!" 
, but then I heard the white noise fade out and music fade in...
I am listening to the album "All Things Must Pass" from George Harrison (2001 rerelease). Track 12 of the 2nd disc ("I Remember Jeep") starts with a white noise sound effect that was not unlike (bit whiter, though) what the D20 used to do when it went bad.
Geez, that had me jump up for a second...
, but then I heard the white noise fade out and music fade in...I am listening to the album "All Things Must Pass" from George Harrison (2001 rerelease). Track 12 of the 2nd disc ("I Remember Jeep") starts with a white noise sound effect that was not unlike (bit whiter, though) what the D20 used to do when it went bad.
Geez, that had me jump up for a second...
I'm sad to report that the white noise problem has reappeared. Perhaps I was looking in the wrong direction all this time, but maybe I found the actual cause by chance today. Maybe... http://www.diyaudio.com/forums/ever...-potential-chassis-cd-player.html#post2364084
This white noise problem keeps me puzzled. After connecting the CD-player to PE the problem went away...for a while. It came back big time today and kept reappearing a short time after each of several resets.
In the past the analogue output would just start to make white noise, but now it's accompanied by a buzzing sound which has a lot in common with that of an electric arc sound-effect in many a Hollywood production... It cuts in and out when the analogue output is producing white noise (presumably and upset DAC).
Now that this buzzing keeps cutting in and out more often and for longer periods have I finally something to trace...
There's definitely an intermittent failure going on here that seems to progress, albeit very slowly (just have a look at when I started this thread). Now that it keeps reoccurring rather rapidly can I hook up a scope to the PSUs of the analogue pcb and wait. Perhaps a bridge rectifier is failing...
In the past the analogue output would just start to make white noise, but now it's accompanied by a buzzing sound which has a lot in common with that of an electric arc sound-effect in many a Hollywood production... It cuts in and out when the analogue output is producing white noise (presumably and upset DAC).
Now that this buzzing keeps cutting in and out more often and for longer periods have I finally something to trace...
There's definitely an intermittent failure going on here that seems to progress, albeit very slowly (just have a look at when I started this thread). Now that it keeps reoccurring rather rapidly can I hook up a scope to the PSUs of the analogue pcb and wait. Perhaps a bridge rectifier is failing...
Finally found something.
The DAC-board is powered by four voltage regulators. An LM317/LM337 combo for the analogue circuits and two LM317s for the DAC (one for digital and the other for the analogue section).
It's the PSU for the analogue section of the DAC that seems to go wrong intermittently.
The LM317 is fed through a 22R0 resistor (just like the other one). Across it is 1.075 V, so I calculated a current of 49 mA. When the fault occurs, Vin of the LM317 drops below 8 V (it's set to 5 V Vout). It drops to ca. 7.6 V, and that's probably not enough to keep it in regulation. I assume this leads to an unstable 5 V which upsets the DAC.
It only lasts a short time before the fault somehow corrects itself, but this time it was long enough to see Vin drop far below the normal 8.1 - 8.2 V. I wasn't able to measure the voltage drop across the 22R0 resistor in time to see if the drop was caused by an increased current draw. Neither had I time to measure if the voltage on the other side of the resistor remained steady.
Now I know why the DAC gets upset, it's time to trace the real cause. In other words, up- or downstream the LM317. I'll replace the LM317 tomorrow to rule that out. I must do that at work as it's an SO8 we're talking about, and I don't have desoldering equipment for SMD at home.
The DAC-board is powered by four voltage regulators. An LM317/LM337 combo for the analogue circuits and two LM317s for the DAC (one for digital and the other for the analogue section).
It's the PSU for the analogue section of the DAC that seems to go wrong intermittently.
The LM317 is fed through a 22R0 resistor (just like the other one). Across it is 1.075 V, so I calculated a current of 49 mA. When the fault occurs, Vin of the LM317 drops below 8 V (it's set to 5 V Vout). It drops to ca. 7.6 V, and that's probably not enough to keep it in regulation. I assume this leads to an unstable 5 V which upsets the DAC.
It only lasts a short time before the fault somehow corrects itself, but this time it was long enough to see Vin drop far below the normal 8.1 - 8.2 V. I wasn't able to measure the voltage drop across the 22R0 resistor in time to see if the drop was caused by an increased current draw. Neither had I time to measure if the voltage on the other side of the resistor remained steady.
Now I know why the DAC gets upset, it's time to trace the real cause. In other words, up- or downstream the LM317. I'll replace the LM317 tomorrow to rule that out. I must do that at work as it's an SO8 we're talking about, and I don't have desoldering equipment for SMD at home.
Found it?
Believe it or not, but after several years of chasing ghosts, I might finally have found the cause of the white noise problem!
When it happened again, I saw the voltage drop on Vin while at the same time the voltage across the 22R0 resistors stayed the same. In other words: no change in load but in voltage supplied to the VRs.
It seems that one of the pins of the pcb-transformer for the analogue circuits isn't making contact with the windings properly. It's a 4x 7.5 V transformer of which 1x 7.5 V is used seperately for the DAC and the remaining three in series for the analogue power supply. Repair of the transformer itself is impossible, it is a pcb-type which is sealed with resin.
It's the winding that feeds both VRs for the DAC that seems to make intermittent contact. I found out by chance when I touched the wires (transformers were originally pcb-mounted, see earlier in this thread). Then I measured the several windings and found that one of them varied with pressure applied to the pins. This most likely also happened when in normal use as a result of expanding/shrinking due to heating/cooling. When that voltage dropped below the threshold of the VRs min Vin, that would have led to no regulation and as a result a DAC that would start spit out white noise until a reset.
To make absolutely sure, I will supply power the DAC from an external PSU and see what happens...
Believe it or not, but after several years of chasing ghosts, I might finally have found the cause of the white noise problem!
When it happened again, I saw the voltage drop on Vin while at the same time the voltage across the 22R0 resistors stayed the same. In other words: no change in load but in voltage supplied to the VRs.
It seems that one of the pins of the pcb-transformer for the analogue circuits isn't making contact with the windings properly. It's a 4x 7.5 V transformer of which 1x 7.5 V is used seperately for the DAC and the remaining three in series for the analogue power supply. Repair of the transformer itself is impossible, it is a pcb-type which is sealed with resin.
It's the winding that feeds both VRs for the DAC that seems to make intermittent contact. I found out by chance when I touched the wires (transformers were originally pcb-mounted, see earlier in this thread). Then I measured the several windings and found that one of them varied with pressure applied to the pins. This most likely also happened when in normal use as a result of expanding/shrinking due to heating/cooling. When that voltage dropped below the threshold of the VRs min Vin, that would have led to no regulation and as a result a DAC that would start spit out white noise until a reset.
To make absolutely sure, I will supply power the DAC from an external PSU and see what happens...
FINALLY FIXED!
I finally fixed the D20 by adding a transformer from a scrapped pcb I took home from work.
After a night on the lab PSU it kept working flawlessly, so I decided to finalize the repair. Going through the scrapped pcbs I was lucky to find one with suitable voltage. The somewhat higher voltage of this transfo meant upgrading one elco on the analogue pcb to a higher voltage (was 10 V). Luckily I had one of the same capacity and lead spacing of 35 V lying around.
I quoted Mooly's first reply as the combination of logic lockup caused by a faulty power supply was indeed the case (albeit caused by a somewhat less common fault). Finally fixed...
Sounds like a logic "lockup" to me. It's the sort of symptom you can create by shorting out random IC pins etc ( not something you should do unless you are extremely bored and don't mind the possible consequencies ) and the unit stays locked up until you switch off. Bit like a computer not responding etc.
As to a specific cause it could be anything !! Anything that gets hot, such as a regulator developing dry joints and "spiking" the logic is a possible, it really could be anything though. You may well have found the cause with the socket - time will tell
I finally fixed the D20 by adding a transformer from a scrapped pcb I took home from work.
After a night on the lab PSU it kept working flawlessly, so I decided to finalize the repair. Going through the scrapped pcbs I was lucky to find one with suitable voltage. The somewhat higher voltage of this transfo meant upgrading one elco on the analogue pcb to a higher voltage (was 10 V). Luckily I had one of the same capacity and lead spacing of 35 V lying around.
I quoted Mooly's first reply as the combination of logic lockup caused by a faulty power supply was indeed the case (albeit caused by a somewhat less common fault). Finally fixed...
Attachments
Another very strange fault
By both a CD-100 from Thule Audio and a D20 from Primare I observe, that the tray goes several times in and out and then only in one direction without stop.
Therefore I have start a new thread:
http://www.diyaudio.com/forums/digi...d20-thule-cd-100-both-mk-1-a.html#post3270416
By both a CD-100 from Thule Audio and a D20 from Primare I observe, that the tray goes several times in and out and then only in one direction without stop.
Therefore I have start a new thread:
http://www.diyaudio.com/forums/digi...d20-thule-cd-100-both-mk-1-a.html#post3270416
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