I've tried looking for info on this forum about it but nothing useful has come up so here I am with a new thread. I'm only sort of experienced with repairs but know enough to fix some things.
Anyway, I got this from my dad and I have been looking to make it work again. The problem is theres no sound leaving the phones/ speaker terminals. The power comes on, it lights up, the mainboard has 2 LEDs that come on, so i suspect the power supply is good, but theres something common to both channels thats stopping any noise from getting to the output.
I've traced the signal lines and found everything checks out before going into the power amp area.
I tried replacing the output relay (the previous owner mumbled about the wife cleaning it or something 🙄 ); that didn't work.
I suspect that maybe theres a problem with this odd little circuit (EQ maybe?) that sits between the volume control and the tone/ balance controls. I've wondered about bypassing all of this with the direct signal button or just soldering a test wire from the input jack to the volume pot. The volume pot is kinda strange (to me), its a 4 pin double gang pot, 2 lefts enter 1 left leaves, thems the rules of thunder dome, same goes for the right.
I guess I can try replacing those fuses, but they looked fine so maybe I was just being naive. Nothing looks burnt out anywhere, its just, auuggghh where is the signal stopping for a vacation and not gettn' to business!
I can't find a service manual so I don't know if the LEDS being on are a good thing. I assumed it was to let you know there was power on each channel, might be wrong.
Since this thing is pretty damn old and replacement parts can be tricky I'm not willing to invest too much into repairing it, just wanted to see what it was like (for driving woofers)
If anyone has a manual or knows about this model or just anything in general, I'd love to hear it.
Anyway, I got this from my dad and I have been looking to make it work again. The problem is theres no sound leaving the phones/ speaker terminals. The power comes on, it lights up, the mainboard has 2 LEDs that come on, so i suspect the power supply is good, but theres something common to both channels thats stopping any noise from getting to the output.
I've traced the signal lines and found everything checks out before going into the power amp area.
I tried replacing the output relay (the previous owner mumbled about the wife cleaning it or something 🙄 ); that didn't work.
I suspect that maybe theres a problem with this odd little circuit (EQ maybe?) that sits between the volume control and the tone/ balance controls. I've wondered about bypassing all of this with the direct signal button or just soldering a test wire from the input jack to the volume pot. The volume pot is kinda strange (to me), its a 4 pin double gang pot, 2 lefts enter 1 left leaves, thems the rules of thunder dome, same goes for the right.
I guess I can try replacing those fuses, but they looked fine so maybe I was just being naive. Nothing looks burnt out anywhere, its just, auuggghh where is the signal stopping for a vacation and not gettn' to business!
I can't find a service manual so I don't know if the LEDS being on are a good thing. I assumed it was to let you know there was power on each channel, might be wrong.
Since this thing is pretty damn old and replacement parts can be tricky I'm not willing to invest too much into repairing it, just wanted to see what it was like (for driving woofers)
If anyone has a manual or knows about this model or just anything in general, I'd love to hear it.
basic tests will solve the problem
basic tests is something like that....
make shure all your switches and pots are clean
( good quality conatct spray is a start )
then check voltages all arround
beyond the main psu that feeds your power amp there is also secondary psu that feeds aux circuits like tone control and so
depending on the age of the device a quick look about the solderings all arround is a must
pick up any small capacitor from the circuit ,,,,,, measure it to see if it is with in specs if more or less that is an indication that your amp ( depending on the age ) needs total recaping
given the oportunity if caps are needed to be replaced its a wise idea to upgarde to something either biger or better ....
finally i have composed a "vintage amplifier upgrade and repair manual " which i will be more than happy to email to you since its quiet big to place here
regards sakis ( with sexy avatar )
basic tests is something like that....
make shure all your switches and pots are clean
( good quality conatct spray is a start )
then check voltages all arround
beyond the main psu that feeds your power amp there is also secondary psu that feeds aux circuits like tone control and so
depending on the age of the device a quick look about the solderings all arround is a must
pick up any small capacitor from the circuit ,,,,,, measure it to see if it is with in specs if more or less that is an indication that your amp ( depending on the age ) needs total recaping
given the oportunity if caps are needed to be replaced its a wise idea to upgarde to something either biger or better ....
finally i have composed a "vintage amplifier upgrade and repair manual " which i will be more than happy to email to you since its quiet big to place here
regards sakis ( with sexy avatar )
That would be great if you could email that, would be useful in the future.
I'm not so interested in this amp to replace all the caps in it, but I have taken the time to resolder several joints that looked suspicious. Theres simply way too much stuff to check and I don't have the equipment to do it all so I might just say forget it to repairing the thing.
Maybe I'll find something in your guide
I'm not so interested in this amp to replace all the caps in it, but I have taken the time to resolder several joints that looked suspicious. Theres simply way too much stuff to check and I don't have the equipment to do it all so I might just say forget it to repairing the thing.
Maybe I'll find something in your guide
you will not ....
i will send you the manual
but this how you have to work ..... also upgarding an amp like that might have a lot of ineterest and also mazing results
many happy regrads sakis ( with sexy avatar )
i will send you the manual
but this how you have to work ..... also upgarding an amp like that might have a lot of ineterest and also mazing results
many happy regrads sakis ( with sexy avatar )
Thanks for the manual.
I know haha hard work, but I only have a multimeter and so much time, thanks for the help though.
I know haha hard work, but I only have a multimeter and so much time, thanks for the help though.
- Status
- Not open for further replies.