Hi all,
I hope you can help me with this one...
I have an old pioneer stereo amplifier from the 70's.
The model is SA-6500 II.
It's working ok, and it sounds extremly good, but there is
one problem: when I turn it on I have a big thumb for a second
or two...like big mmmmmm, so I always turn it on with the speakers' switch in off position, waits few seconds, and then turn the switch back on....
I think it's a dc offset problem, or maybe bias problem,
anyone has a clue on how to fix it? or anyone knows
where can I find the schematic?
Thanks in advance,
Udi.
I hope you can help me with this one...
I have an old pioneer stereo amplifier from the 70's.
The model is SA-6500 II.
It's working ok, and it sounds extremly good, but there is
one problem: when I turn it on I have a big thumb for a second
or two...like big mmmmmm, so I always turn it on with the speakers' switch in off position, waits few seconds, and then turn the switch back on....
I think it's a dc offset problem, or maybe bias problem,
anyone has a clue on how to fix it? or anyone knows
where can I find the schematic?
Thanks in advance,
Udi.
There's a good change the electrolytic caps on that have dried up. They may need replacing. DC offset does not cause "MMMMM" for a sec or two... neither does bias... they usually cause it for a long time of out of whack.
Try replacing the samller caps around the input stages, seems like the input bias circuit has a defective capacitor.
Try replacing the samller caps around the input stages, seems like the input bias circuit has a defective capacitor.
Hi K-amps,
Thanks for the reply...
In fact, I have this problem for a few years now, and last year
I replaced all the electrolitic capacitors in the amp
(except for the power supply capacitors), and it didn't help,
and in fact the sound got worse , but I guess this
is because I used cheap capacitors.
You think maybe it's the power supply capacitors?
Udi.
Thanks for the reply...
In fact, I have this problem for a few years now, and last year
I replaced all the electrolitic capacitors in the amp
(except for the power supply capacitors), and it didn't help,
and in fact the sound got worse , but I guess this
is because I used cheap capacitors.
You think maybe it's the power supply capacitors?
Udi.
Hello udip,
do You solve that problem about bad sounds through switching amp on?
I received Pioneer SA-8500 with similar problem (left channel only), but here at me it works fine, I should wait until it sounds would appear!
I think the problems lying in some active component (diode or transistor), amp is very old and semiconductors change their characteristics.
Let us find it!!!
Regards, Munja
do You solve that problem about bad sounds through switching amp on?
I received Pioneer SA-8500 with similar problem (left channel only), but here at me it works fine, I should wait until it sounds would appear!
I think the problems lying in some active component (diode or transistor), amp is very old and semiconductors change their characteristics.
Let us find it!!!
Regards, Munja
Help
I have a 1974 Pionner SA-6500 II amp that was givin to me 12 yrs ago and it has worked fine all these years but a few years back a friend of mine fliped it on and i guess was listing to rap and roasted the speakers to the point of setting them on fire the board isnt burnt any where i have been able to find but it still will not put out any sound on a loud buzzing noise any one that help me i would be greatfull
I have a 1974 Pionner SA-6500 II amp that was givin to me 12 yrs ago and it has worked fine all these years but a few years back a friend of mine fliped it on and i guess was listing to rap and roasted the speakers to the point of setting them on fire the board isnt burnt any where i have been able to find but it still will not put out any sound on a loud buzzing noise any one that help me i would be greatfull
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