Hello forum people. Noob here,
Recently I bought a slightly working Naim CD3 cd player from eBay. When playing a CD from DIN to RCA output, the right output worked fine. The left output was all static with some music peaking through, but only at higher volumes. Next test, per Lucasz Fikus, bypass the entire filter section by soldering a coupling capacitor to RCA from the first set of op-amp inputs. There wasn't any change. Perhaps this is caused by a faulty voltage regulator, DAC chip, or SAA filtering chip?
Now here's where things get drastically worse... Due to some sloppy voltage regulator testing, I slipped and shorted two legs. The LED that displays the track number went blank, the play button doesn't respond. So I turned off the unit for a while. First lessons learned, when testing voltage regulators, wrap the multimeter probe with electrical tape so only a small amount of the probe's tip is showing.
If that wasn't enough, when turning it on again, the cd spins CCW at some ridiculous speed.
Any thoughts on where to start troubleshooting?
Any help would be appreciated.
Recently I bought a slightly working Naim CD3 cd player from eBay. When playing a CD from DIN to RCA output, the right output worked fine. The left output was all static with some music peaking through, but only at higher volumes. Next test, per Lucasz Fikus, bypass the entire filter section by soldering a coupling capacitor to RCA from the first set of op-amp inputs. There wasn't any change. Perhaps this is caused by a faulty voltage regulator, DAC chip, or SAA filtering chip?
Now here's where things get drastically worse... Due to some sloppy voltage regulator testing, I slipped and shorted two legs. The LED that displays the track number went blank, the play button doesn't respond. So I turned off the unit for a while. First lessons learned, when testing voltage regulators, wrap the multimeter probe with electrical tape so only a small amount of the probe's tip is showing.
If that wasn't enough, when turning it on again, the cd spins CCW at some ridiculous speed.
Any thoughts on where to start troubleshooting?
Any help would be appreciated.
Well, you already know the voltage rails are affected. I suggest you start tracing the fault back towards the bridge rectifiers and secondary windings' PCB terminations. You may be lucky - Naim may have included the fusible resistors/fusses...
The CD spins because the oscillator lost its voltage rail (3.3 / 5V DC)
The CD spins because the oscillator lost its voltage rail (3.3 / 5V DC)
There are iirc four LM317s in the CD3.
You've certainly 'lost' the clock, which means you've lost the supply to the SAA7220B, teh digital filter that also generates the clock, or the SAA73xx servo chip which controls the disc transport.
If you were exceptionally unlucky, and shorted the Vin pint to Vout, you will have killed the chip - the raw voltage supply rails run c +21Vdc. Check what regulated rails you now see on Vout very, very carefully.
NB the original fault is a classic problem of the TDA1541A dac cooking with age - one or both channels goes noisy, first after a while warming-up; eventually, that's all it will do. Source a late-production (taiwan-made TDA1541A to replace it. You won;t find an honest 'S1' grade anymore, but the pate production Taiwan made ones seem to be about as good-as from comparisons made between self and a friend with a range of both to compare about 5 yrs ago. (NB the 'S1 / S2' designations came about from production line selction on test -i.e. its purely a selection-on-test made from the one production chip, not a 'better'/different /higher-quality production run. Avoid TDA1541A 'R' grades though - they are 'binned' in the opposite direction - less accurate than nominal)
You've certainly 'lost' the clock, which means you've lost the supply to the SAA7220B, teh digital filter that also generates the clock, or the SAA73xx servo chip which controls the disc transport.
If you were exceptionally unlucky, and shorted the Vin pint to Vout, you will have killed the chip - the raw voltage supply rails run c +21Vdc. Check what regulated rails you now see on Vout very, very carefully.
NB the original fault is a classic problem of the TDA1541A dac cooking with age - one or both channels goes noisy, first after a while warming-up; eventually, that's all it will do. Source a late-production (taiwan-made TDA1541A to replace it. You won;t find an honest 'S1' grade anymore, but the pate production Taiwan made ones seem to be about as good-as from comparisons made between self and a friend with a range of both to compare about 5 yrs ago. (NB the 'S1 / S2' designations came about from production line selction on test -i.e. its purely a selection-on-test made from the one production chip, not a 'better'/different /higher-quality production run. Avoid TDA1541A 'R' grades though - they are 'binned' in the opposite direction - less accurate than nominal)
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SUPERB!!!!
MC!!!
Aye, ... 'ow ya' doin', Guv!!!!!!.
In all me years, I ain'ts eva 'ear o' da 1541 "cookin'" with age.
'ad ova 2 dozen 1541-based players roll in and outs me livin' room.
Now, me 'spose if y'all 'ad a Servicin' Shoppe, ya' mightta run into da rare over-used unit, left on 24/7 fer 'ears n' 'ears. But dem dare 1541 were built like tanks.
And especially in high-end units like Naim -- with ultra clean PSUs -- those 1541 will last fo-eva. Sorry .... I ain'ts buyin' the cookin' theory.
MC!!!
Aye, ... 'ow ya' doin', Guv!!!!!!.
WHA??????
In all me years, I ain'ts eva 'ear o' da 1541 "cookin'" with age.
'ad ova 2 dozen 1541-based players roll in and outs me livin' room.
Now, me 'spose if y'all 'ad a Servicin' Shoppe, ya' mightta run into da rare over-used unit, left on 24/7 fer 'ears n' 'ears. But dem dare 1541 were built like tanks.
And especially in high-end units like Naim -- with ultra clean PSUs -- those 1541 will last fo-eva. Sorry .... I ain'ts buyin' the cookin' theory.
Hey all, thanks for all the support. This last week has been busy, so most likely I'll start testing tonight.
As Extreme_boky said, start from the transformer, rectifier, and through to the (very carefully) voltage regulator pins. I'm hoping this will shed some light on where the fault had propagated. And I hope none of the chips are fried. If so, I'll take your advice @martin Clark to buy an aftermarket-potentially-lower-quality-Taiwan-made TDA1541 chip.
Thanks,
Jeff
As Extreme_boky said, start from the transformer, rectifier, and through to the (very carefully) voltage regulator pins. I'm hoping this will shed some light on where the fault had propagated. And I hope none of the chips are fried. If so, I'll take your advice @martin Clark to buy an aftermarket-potentially-lower-quality-Taiwan-made TDA1541 chip.
Thanks,
Jeff
I've had several 1541A's start to become noisy after warm-up and eventually noisy completely, even from cold.
Most often in ARCAM Players but in others too.
I can possibly see your point about it not being a ''classic'' symptom as there must be an awful lot of these chips out there, but, I have definitely experienced this exact fault on much more than one occasion.
P.
+1 to that. It's not at all unknown in the Naim CD3.
It's got nothing to so with how good the voltage supplies might be, but perhaps something to do with how much heatsinking on the pcb (copper area off the DAC pins) there is. This chip has to dissipate c 0.85w - conduction via the pins helps a lot, since no-one ever fitted a heatsink to it.
Naim's CDS, CDi, CD2 - the original big, one box playersseem to suffer much less than the CD3 as a result. They've superbly-well laid-out internals, and were high-budget items.
NB the Arcam Alpha 5 is an excellent source of spares for the Naim CD2 & 3..if you find a working one. And as above, they also tend to bake-out (rather quicker - again: look at the pcb - dac is packed-in tight on small traces.)
But the heat-death of the TDA1541A is not unique to these - it was widely reported in the various philips, marantz/magnavox... myriad other makes using it. Go read a little further 1z2A...
It's got nothing to so with how good the voltage supplies might be, but perhaps something to do with how much heatsinking on the pcb (copper area off the DAC pins) there is. This chip has to dissipate c 0.85w - conduction via the pins helps a lot, since no-one ever fitted a heatsink to it.
Naim's CDS, CDi, CD2 - the original big, one box playersseem to suffer much less than the CD3 as a result. They've superbly-well laid-out internals, and were high-budget items.
NB the Arcam Alpha 5 is an excellent source of spares for the Naim CD2 & 3..if you find a working one. And as above, they also tend to bake-out (rather quicker - again: look at the pcb - dac is packed-in tight on small traces.)
But the heat-death of the TDA1541A is not unique to these - it was widely reported in the various philips, marantz/magnavox... myriad other makes using it. Go read a little further 1z2A...
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Without knowing the history of use of the device in which the 1541a was used you can't really come to any realistic conclusions on the issue.
That said, I have a double crown 1541a (Taiwan), purchased "new", that was used in a much-modded cd650. And after about 1/2 hr, the sound of the 650 would "lose steam" (no audible distortion, but sounds as if muscle and energy had been removed from the music.).
I put the SAME double crown 1541a in another Philips CDP, this one with fewer mods, and I have no issues, but it doesn't sound as nice as the 650 (< 1/2 hr into use).
That said, I have a double crown 1541a (Taiwan), purchased "new", that was used in a much-modded cd650. And after about 1/2 hr, the sound of the 650 would "lose steam" (no audible distortion, but sounds as if muscle and energy had been removed from the music.).
I put the SAME double crown 1541a in another Philips CDP, this one with fewer mods, and I have no issues, but it doesn't sound as nice as the 650 (< 1/2 hr into use).