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Needed: helpful DIY suggestions to get my Naim CD3 working again…

How good are your camera skills?

Lots of light, pop the camera into macro mode if it has one as its will help it focus much closer and see how you get on.

Good luck!
Sam
 
Uploaded snaps here.

I'm disappointed that the consensus isn't that it's the PS caps, as, contrary to expectation, they ARE big and obvious! They also look like the kind of thing I could replace: why are they above suspicion?

I've homed in on a couple of small caps (photo P1000469) which look dodgy to me, but what do I know?

Other than that, I can't see anything blindingly obvious, so I might have to resort to an expert after all...
 
get your dvm and measure the voltages on all the local regulators.

the lm317 and lm337 three pin devices and let us know what your findings are.
 
Er, I have identified the local regulators (screwed to the back plate), 2x 337s and 4x 317s, but am not sure across which pins to measure.

I got 22V across the left pin and centre pin of the left hand 337, but nothing meaningful when I tried across the right pin and centre pin. All I can do is follow instructions, because I haven't a clue about electronics...

Sorry!
 
Ok, thanks for that. Had a look through the linked PDF, so I've learnt that one is V in, one is V out, and one is ADJ, but I'm at the level of "I've got a black probe and a red probe, and the black is negative/earth/common, and the red positive". How this very limited knowledge on my part translates into V in, V out, ADJ, I don't know!
 
Note of caution when measuring voltages on 3pin regs: take great care not to let a DVM probe slip and accidentally short any two of the legs together (which is easy when you are trying to reach pins in situ)

A momentarily slip usually results in feeding the raw input voltage straight to the supplied circuit and in the CD3 this could mean sending 21-22v to integrated circuits like the TDA1541AS1 dac, the servo (SAA7020) the digital filter (SAA7220) - which will probably not survive.
 
F*ck! Got this message just after doing that, or something like it...

I measured the V between centre and right pins on the left-hand 337, got 20 or so V, then moved on to a 317, and a CD I was playing at the time suddenly speeded up frantically, the display went off, and opening the CD tray did not stop it whizzing really fast...

Turning the CD3 off and on again did not help, as soon as the power is on, the CD transport whizzes round like a loon.

B*ll*cks! I shall close it up and save up until I can get a proper repairer to fix it: whatever was wrong with it is now a lot worse.

Thanks for the attempts to help, chaps, but I'm just not savvy or skillful enough to do this.
 
:(
Too late now, but for future reference the hook probes are best.. Turn everything off, hook the probe onto what you want to measure, double check its not contacting anything then turn on.

Sam
 
Oh bugger.

The CD running-away means you've either lost the system clock (SAA7220 dead), or the servo IC (SAA702 or 7030, can't remember which it is here ) is not happy; replacement should effect complete repair (these things can still be found with a bit of hunting).

Given your location why not give Mark at Witch Hat a call? He's 'MJS' on this forum and knows this equipment inside-out.
 
Crikey! It didn't even occur to me that these chips (?) might not even be available anymore...

The CD3 was an eBay bargain (£225, IIRC) so I'm reluctant to spend that amount again on getting it fixed. As I mentioned in my OP, I was aware of Witch Hat, but hoped I could do it via PFM for next-to-nothing.

Who's sorry now?

...I'm now going off to have a little cry.
 
It will most likely have just taken out the regulator

The regs I wanted you to test are the ones in your picture next to the output stage not the ones with adequate heatsinking

Setbacks like this are part and parcel of the learning curve you are currently enjoying

Don't give up!

Get yourself a replacement regulator and a soldering iron..
 
"On picture 478 is that heat sink shorting out one of the resistors below? cant see that well but you could take of the heat sink and have a close look.

for info on the LM317 the back metal part of the reg is connected to the volts out live centre pin so to measure the output just clip on to a local ground connection and touch the back of the case with the positive probe you should get the output without trying to touch the pins. The 337 is not the same and the case is not the output one of the outer pins is the volts out so I try to find the component that is connected to the output pin usually a 120ohm resistor or 1uf cap and use a shrouded clip as Sam said.

Excellent photos BTW what camera / flash arrangement did you use to take them?, I always have problems photographing circuit boards:(

Alan"
 
Alan
Thanks for the suggestion, I'll have a look at the heatsink and see if it's shorting out a resistor, but it's not going to sort out the CD3 now.

Snaps taken with a Panasonic Lumix TZ10, macro mode, some with flash, some not: great little camera, really pleased with it (just got it, used, from eBay via Santa!)

The real irony with my blowing whatever I've blown (incidentally, the madly whirring CD transport when the power is on is independent of the tray position, it whizzes at full speed even if the tray is open) is that the CD3 was just beginning to play music: both channels, very distorted, but loud (like it was when I first got it). I'll never know if that problem might have gone on to resolve itself, as it had previously on first powering up.

Sob.
 
Don't give up Johnny, these little mishaps (!) are part and parcel of learning DIY Hi-Fi electronics. I've often wanted to give up & buy an off-the-shelf unit but there's a great pleasure to be had in sorting this stuff out for yourself (with the great and copious help you'll get from the pfm folks).

Keep calm & carry on!
 
Thanks, for the gee-up, chaps, but I'm not sure how to proceed. I can't even be certain which of the regs I was testing when the CD transport went berserk. I don't know how to test them to find out (and I'm not doing it with the power on again!). And, even if I manage to get that sorted, I haven't a clue as to how to check ICs further down the line that I've probably fried.

So, you see, I'm right out of my depth here...
 
Unplug the transport so no uncontrolled spinning

Then get the meter out again and measure wrt earth so you only have one probe to worry about

The broken reg once replaced will most probably return you to where you were
 
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