Hi all. I picked up a Victor Stereo Sound System - (Japan Victor Company) console that was beat up but had the amp in it with tubes intact. I have stripped out the amplifier and it works. That said, it had a lot of pops and crackles and hiss. So, I replaced several coupling capacitors with orange drops of the right value and the popping and crackling is gone but the hiss remains in one channel.
This set had the speakers separate from the amp and the output transformers are connected via an 24" four-pin connector wire to the amp and then to the speakers. I noticed that the hiss follows one transformer. I have tried switching wires and speakers and wherever the transformer is in the chain the hiss follows. I have switched the power tubes side to side and the hiss still follows the transformer. I have read that output transformers usually do not fail and they either work or they don't.
The hiss is significant and constant though the music plays through it well.
The other speaker is clear and clean and when I switch sides the new side is as well.
Do output transformers ever have symptoms like this?
Thanks,
James
This set had the speakers separate from the amp and the output transformers are connected via an 24" four-pin connector wire to the amp and then to the speakers. I noticed that the hiss follows one transformer. I have tried switching wires and speakers and wherever the transformer is in the chain the hiss follows. I have switched the power tubes side to side and the hiss still follows the transformer. I have read that output transformers usually do not fail and they either work or they don't.
The hiss is significant and constant though the music plays through it well.
The other speaker is clear and clean and when I switch sides the new side is as well.
Do output transformers ever have symptoms like this?
Thanks,
James
Sounds like there may be a partial insulation breakdown in the transformer.
That is often the end result of an amp running at high levels and losing speaker connection.
If that is the case, then sadly it is not going to get better without a new transformer.
Gary
That is often the end result of an amp running at high levels and losing speaker connection.
If that is the case, then sadly it is not going to get better without a new transformer.
Gary
Hiss usually indicates a resistor. Check the cathode and plate resistors in that channel. This is especially true for carbon comp resistors. I have run across this problem and it was the cathode resistor on the input tube.
He clearly wrote that the symptom follows the transformer. So this is not an option. Transformer is messy, I'd say.
Best regards!
Thanks for the responses folks.
Rotaspec - the hiss is more than a preamp hiss with the volume up and more like the sound a faucet makes when you are running water into the sink - a little deeper and substantial and volume level changes make no difference.
DF96 - Does parasitic oscillation sound like I described above? Google here I come.
DocOct - the hiss changes to whatever side I put the transformer on and the opposite side sounds fine. Transformer on left? Hiss on left and right sounds good. Transformer on right? Hiss on right and left sounds good.
Last question. I have checked the connectors themselves - little four-prong jobs that plug into the amp and run to the transformer and they seem fine. I have reflowed the solder connections to the transformer. Should I reflow again or peel back a little of the transformer wire to look for a weak spot?
Thanks all for your help on this interesting puzzle.
Rotaspec - the hiss is more than a preamp hiss with the volume up and more like the sound a faucet makes when you are running water into the sink - a little deeper and substantial and volume level changes make no difference.
DF96 - Does parasitic oscillation sound like I described above? Google here I come.
DocOct - the hiss changes to whatever side I put the transformer on and the opposite side sounds fine. Transformer on left? Hiss on left and right sounds good. Transformer on right? Hiss on right and left sounds good.
Last question. I have checked the connectors themselves - little four-prong jobs that plug into the amp and run to the transformer and they seem fine. I have reflowed the solder connections to the transformer. Should I reflow again or peel back a little of the transformer wire to look for a weak spot?
Thanks all for your help on this interesting puzzle.
I'm thinking this might be a form of "corona discharge" noise due to insulation breakdown (varnished paper carbonized by arcing at some point to create a path to gnd?) in the transformer and the resulting leakage current flowing to either the core, or if you are really lucky in the lead termination layer on the outside of the transformer primary windings.
You might want to consider inexpensive replacements from Edcor unless it is very obvious where the problem lies and you are able to fix it.
You might want to consider inexpensive replacements from Edcor unless it is very obvious where the problem lies and you are able to fix it.
It is rare, because in such a case,a classic ozone or paper burning odor must be feeling and some kind of smoke, and an acoustic noise from the trafo.
I insist in checking the amp for ultrasound oscillation.
Solved
Hi,
Thanks to all on this little mystery. It was a combination of things.
During additional troubleshooting I noticed that when I touched the speaker wire going from the amp between it and the transformer there was noise. Hmmmmmm.. I wiggled it some more and more noise. One of the wires was actually moving inside the pin. The wire soldered into the inside of the pin was loose. I resoldered it and the noise was much lower but still there.
I went ahead and replaced the rest of the smaller coupling capacitors with orange drops. And I resoldered the transformer too just for good measure.
Now, it is quiet at rest and sounds really good at play.
Thanks all for your help and wisdom
James
Hi,
Thanks to all on this little mystery. It was a combination of things.
During additional troubleshooting I noticed that when I touched the speaker wire going from the amp between it and the transformer there was noise. Hmmmmmm.. I wiggled it some more and more noise. One of the wires was actually moving inside the pin. The wire soldered into the inside of the pin was loose. I resoldered it and the noise was much lower but still there.
I went ahead and replaced the rest of the smaller coupling capacitors with orange drops. And I resoldered the transformer too just for good measure.
Now, it is quiet at rest and sounds really good at play.
Thanks all for your help and wisdom
James
Problem solved now, but for future reference parasitic oscillation can cause some or all of the following:jmcanna said:
- distortion
- noise (could be hiss, rumbles, whistles - almost anything strange)
- 'plops' or clicks
- shifts in DC conditions - especially when something moves
- interference in nearby radios
- hum
- overheating
- Status
- Not open for further replies.