Hi everyone, usually I'd take this kind of thing to an electronics repairmen but I've been tinker with my own gear more and more these days.
I've opened this old 70s spring and there's not much in it, could someone point me in the right direction in terms of how to diagnose where the problem in the power section is. Info on how to not electrocute myself would also be nice. I can post photos if thats helpful? Just though this might be an easy repair for me to learn on. I have a multimeter and solder station etc. . .
Thanks
I've opened this old 70s spring and there's not much in it, could someone point me in the right direction in terms of how to diagnose where the problem in the power section is. Info on how to not electrocute myself would also be nice. I can post photos if thats helpful? Just though this might be an easy repair for me to learn on. I have a multimeter and solder station etc. . .
Thanks
Hi drrats,
Determine whether the power supply operates direct from the mains or not. Is there a power transformer? If so, proceed. If not, set it aside and don't touch it.
Step one is to make sure the power supply is working properly. A good meter will be required, an Oscilloscope would be a definite asset too.
As John asked, what is the problem with it? Observations only please.
-Chris
Determine whether the power supply operates direct from the mains or not. Is there a power transformer? If so, proceed. If not, set it aside and don't touch it.
Step one is to make sure the power supply is working properly. A good meter will be required, an Oscilloscope would be a definite asset too.
As John asked, what is the problem with it? Observations only please.
-Chris
The schematic is available at Pioneer SR-202W Manual - Reverberation Amplifier - HiFi Engine
Not much to it, Just make sure that you have about 35V on the collector of Q205 and about 25 or more on the emitter.
Not much to it, Just make sure that you have about 35V on the collector of Q205 and about 25 or more on the emitter.
Hi John,
You must have been unconscious throughout the 70's and 80's then. They didn't choose capacitors that went open on purpose, but they happened to get that feature by spending less than other manufacturers. But then, I suppose that Pioneer is mystified and shocked that their power supplies in most receivers cook to death. The fact that those are mounted upside-down against the chassis has nothing to do with it. A completely unforeseen problem I guess.
Most techs around here are very familiar with Pioneer receivers going mute due to coupling caps. That couldn't possibly happen to the reverb unit - could it? We don't have that problem to near the extent that Pioneer product does with other brands. So yes, as those capacitors age, more and more of all brands will suffer from the same issue. I never said capacitors don't age in everything else.
Don't tempt me to tell you about the stunned design I just fixed in another Pioneer piece of <non-optimized shoddy design>. The money went to advertising and a pretty face, that's all.
-Chris
You must have been unconscious throughout the 70's and 80's then. They didn't choose capacitors that went open on purpose, but they happened to get that feature by spending less than other manufacturers. But then, I suppose that Pioneer is mystified and shocked that their power supplies in most receivers cook to death. The fact that those are mounted upside-down against the chassis has nothing to do with it. A completely unforeseen problem I guess.
Most techs around here are very familiar with Pioneer receivers going mute due to coupling caps. That couldn't possibly happen to the reverb unit - could it? We don't have that problem to near the extent that Pioneer product does with other brands. So yes, as those capacitors age, more and more of all brands will suffer from the same issue. I never said capacitors don't age in everything else.
Don't tempt me to tell you about the stunned design I just fixed in another Pioneer piece of <non-optimized shoddy design>. The money went to advertising and a pretty face, that's all.
-Chris
Sorry I know this seems basic but what will this test for? Could you please break this down for me? I know it seems basic but my electronics knowledge is pretty limited. I'm alright at fixing things because I'm not afraid at having a go but this stuff is new to me.
I can replace the caps but perhaps I should be check the power transformer first? I know that's the big thing wrapped with copper wire
Great I've found Q205 but where is the emitter? I realise this is probably a silly question
When I measure these with my multimeter what setting should I use?
From what I gather emitters are part of transistor based designs, do you know anywhere I could read up on this to understand better?
Thanks
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