CD32 lasted an hour...crackly audio/ 1 Paula channel very low

[ImmortalA1000]

I took out a CD32 the other day to play some games, not used it for ages but it has been stored in a clean dry environment and in the box.

I turned it on this morning to try out a few more of my games I found and now there is like a static noise like an old vinyl record being played, like a bad earth on a phono cable, on both audio outputs. So I thought it might be the phono to SCART adaptor but it does exactly the same when connected to the TV with RF. The TV is fine....works great with my 1982 Silver label C64 so it's not a SCART port or RF lead issue.

I noticed on Roadkill the audio for the engine sound is low, and on Project X one of the Paula channels is very low, in both cases the other 3 Paula channels are fine?

Duff Paula? Is it actually a stock Paula chip inside the CD32? if it is the same chip is it socketed or soldered to the board? Any other ideas like caps/resistors around that area? If it wasn't for the low volume on 1 of the 4 sound channels (it sounds about 75% lower volume than the other 3 being played) I might start looking for dry joints but it is happening on every output port (I don't have any headphones to hand to check).

PS I don't have a multimeter OR a soldering iron etc
PPS Let's hope the internet keeps working so I can read any suggestions.

[Jope]

Was the machine ever recapped?

[ImmortalA1000]

Nah but it worked fine 24 hours earlier, no problems at all. It was also tested before purchase and it worked fine before being stored in a cool dry area of the house.

It could be C305 cap I think after reading some stuff but very little info for crackle on all outputs and only 1 of 4 Paula channels is very low volume with other 3/4 Paula channels sounding fine.

Crackling does go away if you leave it on for a while (an hour?) but the low volume on one of the channels is always there.

[r.cade]

CD32's are really bad about failing caps. It needs recapped, cleaned up, and probably repaired now.

If you sniff a little, you will probably smell the "fishy" smell around it.

Unfortunately, things usually work fine right up until they break.

[Nobby_UK]

Especially the 2 larger Caps by the power switch
which are often reversed as is the silk screen.

[ Show youtube player ]
3:08 and 7:42

[ImmortalA1000]

Me recapping the whole surface mount board might not be enough to make up for however this thing was stored by various people since 1993, there are other things that fail before/same time as caps as well and I will cause more damage trying to replace SMT resistors and whatnot without the correct tools and years of experience (and a giant illuminated magnifying glass!). Mistakes are very unforgiving on these SMT boards and best to fix what is wrong with it for now. I couldn't find the "C65" PSU from my other [dead] CD32 to check the -12v supply problem but it is only 1 channel that is affected. If it was a C64 I would say SID is duff, not so sure about how Commodore wires in Paula and what all the pins actually do. Maybe there is some corrosion as well, have to open it up and have a look.

People with similar isolated channel problems seem to point towards C305/C306 so I can try changing those some point in the future if they are not microscopic SMT components. Beyond that it's a dead end unless it's actually a faulty Paula chip on the board, I have a dead CD32 I can pull things like that from but we'll start with the obvious cap's that Google is pointing me towards first.....for the foreseeable future no CD32 gaming.

Thanks for the advice everybody.

[Daedalus]

Paula outputs just left and right, so the two sample channels associated with each side are already mixed within Paula. If there's an analogue issue that really only affects one of the 4 sample channels, it can only be within Paula. You'd really need to be sure of your test setup to call that diagnosis though... Paula failures like that are pretty rare, though not impossible.

Failing capacitors can have interesting effects like affecting different frequencies in different ways, so if a mod sounds like it's playing back without a channel, it could be down to the particular samples that make it sound like just one channel is dropping out.

SMT work can be tricky, but with the right tools and experience, capacitors are fairly routine. Capacitors are an order of magnitude easier than replacing a SMT Paula chip - don't go pulling chips off boards until you're 100% sure it's the chip, and you know you can do it without causing further damage.

[ImmortalA1000]

Only the engine noise is low on Roadkill and only 1 channel in the title music for Project X is low (the rave siren type instrument). There is however the full on vinyl record playback crackle going on for both channels so it could be two faults at the same time, need to do a proper test though using the AV inputs and trying one audio port at a time (my portable TV and Commodore 1702 both only had one audio input).

Hmmm, this looks like a job I can't fix and CD32's are not worth the money they go for now for the games you get to play on them so I guess that's that as I have no idea if the Paula chip in the dead CD32 is still working so it's not going to prove anything if replacing it doesn't cure the problem.

If my A4000 is still working I suppose I could play CD32 games via a simple IDE CD drive fitted to it, I think I only have DVD drives though.

I don't want to pull the Paula out of my only A600 (if it still works) as I have 2mb in that so it makes a good WHDload machine for OCS games.

This is the bad side of having a huge retro collection. Who's to say when an ebay seller claims it has already been recapped it actually has been, dead end but thanks for the help to everyone. Will just have to unpack a different Amiga now, the white Trinitron goes well with the A1000

[SurfFerret]

I had the crackle on my CD32 before recapping. Used it for a few hours total after I unboxed it from my parents’ loft after 23 years, and got to the first sub level in Bubble and Squeak. The first time I heard it I thought I knocked the volume slider - second time, I shut it off and sent it in for a recap pronto.

After recapping it’s been on for a good 50+ hours (of varying session length) and no problems whatsoever. I’m not saying it’s definitely caps for you but it’s probably caps.

[Daedalus]

Just send it to someone for recap and repair. It'll cost far less than a new machine, and you could well find that it didn't need anything major other than the recap. You're right to not attempt to do it yourself though if you don't have the right gear and experience. There are a number of guys in the UK who do such repairs - I have a list of some of them here.

[jaycee1980]

Why are you even assuming that Paula MUST be faulty ? There's plenty of things that can cause audio faults in a CD32 besides Paula.

In a CD32 often I've had weak distorted audio that has been down to the muting FETs having been leaked on by the capacitors, and they become partial shorts. I've also had 4066 multiplexer IC's go bad which have caused similar audio issues.

A recap wont "fix it" but assuming that a custom chip must be dead is silly

[ImmortalA1000]

Again thanks to everyone for their responses.

I am not assuming anything Jaycee, just guessing at the sort of problems causing these symptoms based on experience with other machines and google searches specific to this problem.

I suspect there are two faults going on, one is causing audio crackle on left and right output (which does seem to calm down after machine warmed up for an hour during my second time using it) and the other is about 80% lower volume for just one channel out of four which could be Paula or some other issue but as I was told Paula outputs two audio channels on a single pin (2 pins 4 audio channels) and I only have a problem with low volume on 1 of 2 channels on that particular phono socket so it's is not going to be caused by anything other than a custom chip issue I am guessing.

Clearly there are other things going on too so it probably has multiple issues, needs more than a full recap. I didn't open it up, it's back in the box for now. When I have a workshop built I will look at it physically, could be partly due to corrosion not component failure and the black screening motherboard of spare CD32 might be an easier fix than this thing for all I know, need to inspect motherboards next step.

I am not buying another CD32, same reason I never bought an Atari Jaguar