Problem with Pioneer c-355 stereo amp.

[fezder]

Hi,
i got this amplifier/mini system from a friend, as he didnt needed anymore it and didnt have room for it at his apartment. The problem is pretty ''simple'' really, no sound from speakers, and stereo jack is busted.....it turns on fine, motors check-in at startup etc. DMM shows 0.01 VDC from speaker outputs, so ampplifier ic should be fine? any advice what to check next? could the busted stereo jack be the problem, as if i read schematics correctly, its switched-type jack
there are no burns, blown caps or anything visual that suggests electricial damage.
and, all fuses all intact
i'm not sure do i brake any law, sorry if i do but here is service manual

**broken link removed**

and, little afterwords, sorry if this thread/topic is already in use, please move me to correct direction

 

[alec_t]

DMM shows 0.01 VDC from speaker outputs, so ampplifier ic should be fine?

How do you reach that conclusion? There could be other causes for that reading.

any advice what to check next?

Check if there is audio output from the headphone socket whenthere is a known good audio source (e.g. CD playing).

 

[fezder]

well last time i had problems with an amp, DMM showed reading of about 40 VDC, which was said to be because of burned/shorted amp, but yes you are right, there could be some other cause, i just dont know that much of amps.

i checked what i could from stereo jack, and yes, there is signal from headphones, but not from speakers even if headphones are not plugged in.

 

[alec_t]

If the audio gets to the headphones then the headhone amp is ok at least; so the fault lies somewhere between the headhone amp input and the speakers. I'd bet the main amp IC is faulty.

Edit: Is the fault in both channels or just one?

 

[Nigel Goodwin]

How do you reach that conclusion? There could be other causes for that reading.

Actually it's a pretty good indication the output IC is OK, unless there's a broken headphone socket between amp and speakers, or a protection relay.

 

[fezder]

If the audio gets to the headphones then the headhone amp is ok at least; so the fault lies somewhere between the headhone amp input and the speakers. I'd bet the main amp IC is faulty.

Edit: Is the fault in both channels or just one?

yes, both channels are ''dead''

 

[diy didi]

Do hear the speaker relays click on after a couple of seconds??

 

[KJ6EAD]

That broken jack could be the only problem and should be replaced before continuing with other troubleshooting.

 

[fezder]

That broken jack could be the only problem and should be replaced before continuing with other troubleshooting.

will any switched stereo jack do, or must it be PCB mounted?

 

[fezder]

Do hear the speaker relays click on after a couple of seconds??

there's no sound at all from speakers if thats what you mean? only thing that clicks is power relay located right next to mains transformer.

 

[KJ6EAD]

Will any switched stereo jack do, or must it be PCB mounted?

It would be best to replace it with a same or similar PCB mount type.

 

[fezder]

little update for this problem: i couldn't find suitable jack anywhere, and even local repair service would have to buy total new fronboard, where this jack was located, no separate jack as replacement was an option. oh well, gonna take this apart for replacement parts.....thanks for your help all!

edit: it was afterall PHILIPS, not pioneer....silly me

 

[tvtech]

little update for this problem: i couldn't find suitable jack anywhere, and even local repair service would have to buy total new fronboard, where this jack was located, no separate jack as replacement was an option. oh well, gonna take this apart for replacement parts.....thanks for your help all!

edit: it was afterall PHILIPS, not pioneer....silly me

Hey Fez

I would give anything to be you right now.....discovering Electronics and how wonderful it is. Heck, stay here and make me interested again in the best hobby ever. Once the bug bites...you will will probably want to do it forever..

Electronics is like "magic" for some. For others a necessary evil.

For me, an absolute "magic" trip. Still learning here @ 50 years old...and loving it every step of the way. In spite of my accumulated knowledge

Especially when a dude like you comes along and want's to learn and has passion for Electronic stuff....waay beyond cool. Another Rep for you. Stay well. And keep learning and posting and stay interested in Electronics....

Regards,
tvtech

 

[tvtech]

Duplicated post. So deleted.

 

[fezder]

Hey Fez

I would give anything to be you right now.....discovering Electronics and how wonderful it is. Heck, stay here and make me interested again in the best hobby ever. Once the bug bites...you will will probably want to do it forever..

Electronics is like "magic" for some. For others a necessary evil.

For me, an absolute "magic" trip. Still learning here @ 50 years old...and loving it every step of the way. In spite of my accumulated knowledge

Especially when a dude like you comes along and want's to learn and has passion for Electronic stuff....waay beyond cool. Another Rep for you. Stay well. And keep learning and posting and stay interested in Electronics....

Regards,
tvtech

thanks mate for nice reply. I was once that side of coin, for who the electronics was evil, or at least darn hard to understand! Now it starts seem to be that ''magic'', hard to explain for who doesn't understand, and it teaches daily! I was indeed bitten by E-fly....

 

[HiTech]

Hey Fez

I would give anything to be you right now.....discovering Electronics and how wonderful it is.... For me, an absolute "magic" trip. Still learning here @ 50 years old...and loving it every step of the way. Regards,
tvtech

Well then, you're invited to my lab so you can take a magic trip down Grief Lane to repair my Leader NTSC sync Generator. I've narrowed the problem down to a pcb that has approx. 130 ICs

 

[tvtech]

Hi HiTech

130 is quite a lot of IC's

Fortunately (for me), I am strictly an Analogue guy. Digital Electronics and I don't really play well together even though we are seeing more and more CRT sets using Digital control and the I.C's (Jungle and Micro) in one package. And then it's surface mount too. So I am learning as I go along and writing down everything I discover so I don't forget. So far so good. Generally found Micronas little surface mount Jungle and Micro chips very reliable...

Unlike their older Philips TDA series cousins.

But........ TV digital control is nowhere near what you are dealing with. I wish I could help you. I am afraid I would not know my ar*se from my elbow. And just confuse the issue more. I know my limitations

All the best,
tvtech

 

[unclejed613]

most receivers use the switch inside the headphone jack to control the speaker relays. i've seen quite a few headphone jacks get the switch contacts shorted by tin whiskers. when that happens, the speaker relays won't turn on. disconnecting the cable from the jack switch usually will make the relays work.

 

[fezder]

hmm, never knew that tin whiskers are also in such places. thanks for the tip, for future repairs!