Hello everyone
I have a polytone IV latest version.
the toroidal transformer make hum.
This happen without any cable connected .How can I solve this problem?
I have a polytone IV latest version.
the toroidal transformer make hum.
This happen without any cable connected .How can I solve this problem?
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Dont know if it is toroid style transformer or EI transformer
Toroid more susceptible to physical humming.
Can check mounting hardware a tighten if needed
EI core, you can check same thing if mounting hardware is loose
or if any bolts for end bells are loose
Can also try another electrical wall outlet on different breaker.
If any appliance / fan control / dimmer is putting DC on the AC line
transformer will hum.
That is for physical transformer hum/ vibration.
If there is hum in signal
Be usual candidates rectifier / rectifier diodes
or older power supply capacitors.
Since its seems as if no input or no speaker connection
their is physical humming of transformer.
Can be DC on AC line, or old transformer
and possible loose hardware
Toroid more susceptible to physical humming.
Can check mounting hardware a tighten if needed
EI core, you can check same thing if mounting hardware is loose
or if any bolts for end bells are loose
Can also try another electrical wall outlet on different breaker.
If any appliance / fan control / dimmer is putting DC on the AC line
transformer will hum.
That is for physical transformer hum/ vibration.
If there is hum in signal
Be usual candidates rectifier / rectifier diodes
or older power supply capacitors.
Since its seems as if no input or no speaker connection
their is physical humming of transformer.
Can be DC on AC line, or old transformer
and possible loose hardware
it’s toroidal.
the amp is new, I don’t think the caps are involved. The hum is audible even when the speaker is disconnected.
the amp is new, I don’t think the caps are involved. The hum is audible even when the speaker is disconnected.
Try it at a different house, in case you have DC on your power line.
If it still hums there, it must be internal to the amp.
If it still hums there, it must be internal to the amp.
If amp is new and under warranty take it back to shop and have them deal with it.
If it implies getting a new power transformer from warranty, so be it.
By your description, it´s mechanical laminations buzzing, or loose windings, which are annoying and you can´t solve.
Tell them as-is amp is unplayable, specially you can not record with it or play in a quiet room.
Ok, then you can try re-impregnating it with varnish.
IF possible, try to find (transformer manufacturer ...electric motor manufacturer-rewinder) somebody with a vacuum chamber, that guarantees varnish getting everywhere, even remotest places.
You can kludge one yourself, but BIG mess if varnish bucket gets kicked, so ....
https://audiokarma.org/forums/index...mpregnation-yes-you-can-do-it-at-home.859083/
IF possible, try to find (transformer manufacturer ...electric motor manufacturer-rewinder) somebody with a vacuum chamber, that guarantees varnish getting everywhere, even remotest places.
You can kludge one yourself, but BIG mess if varnish bucket gets kicked, so ....
https://audiokarma.org/forums/index...mpregnation-yes-you-can-do-it-at-home.859083/
There is a varnish specially made for transformer and electric motor impregnation, so first search for it, but if hard to find or you must import it, good quality regular home use wood varnish is fine, only it will take longer to dry and stink for a couple days.
Oil/synthetic based only, do not use "green" types because they are water based and you do NOT want water inside a transformer.
Simplest is to place transformer in a Tuppperware or similar container, coverit with varnish and wait until no more bubbles exit, even overnight, regular varnish solvents do NOT harm insulation.
Then you pull it out by the wires or a loop of wire through it and tie it to a broomstick between 2 chairs, so excess varnish drops back into the container.
Remove and cover container or even better pour remaining varnish back into its can, it can be used for furniture later, transformer will actually "absorb" very little.
Let it air dry for 1 day and you can re mount it on amp.
"Pro" varnish does exactly the same, only it has an additive which makes it fully air dry in 1 hour, or 10 minutes in an oven, good in a Factory, no BIG advantage at home.
Vacuum impregnation is the same, only it pulls out all bubbles in 2 minutes.
edit:
Same instructions, but I suggest you remove the black rectangular stamped cover(s) , by removing 4 bolts , pass a wire through one bolt hole, and use it as a handle to put transformer inside/pull it out of the impregnation pot.
Oil/synthetic based only, do not use "green" types because they are water based and you do NOT want water inside a transformer.
Simplest is to place transformer in a Tuppperware or similar container, coverit with varnish and wait until no more bubbles exit, even overnight, regular varnish solvents do NOT harm insulation.
Then you pull it out by the wires or a loop of wire through it and tie it to a broomstick between 2 chairs, so excess varnish drops back into the container.
Remove and cover container or even better pour remaining varnish back into its can, it can be used for furniture later, transformer will actually "absorb" very little.
Let it air dry for 1 day and you can re mount it on amp.
"Pro" varnish does exactly the same, only it has an additive which makes it fully air dry in 1 hour, or 10 minutes in an oven, good in a Factory, no BIG advantage at home.
Vacuum impregnation is the same, only it pulls out all bubbles in 2 minutes.
edit:
That is NOT a toroidal but a conventional EI type 🙂
Same instructions, but I suggest you remove the black rectangular stamped cover(s) , by removing 4 bolts , pass a wire through one bolt hole, and use it as a handle to put transformer inside/pull it out of the impregnation pot.
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If Polytone closed in 2013, the amplifier is obviously not new, is it? If you mean that you bought the amp. only recently and in used condition, you have been swindled! If you have owned the amp for some time but it only recently started humming and you don't want to fix the transformer, it will need a replacement transformer, preferably salvaged from another amp of the same or similar model.
Otherwise, if you bought it recently, demand your money back or negotiate a lesser amount to cover the transformer replacement or repair cost. Before doing anything drastic though, have you checked that the mains power is the same as your local supply and the wiring hasn't been messed with, just to get it working? Be warned that guitar amps often also use a particular type of transformer construction that affects the sound when used at max. power and you won't get the same sound from standard (e.g. hobby grade) replacement transformers when using your amp. on stage and turned up loud.
Otherwise, if you bought it recently, demand your money back or negotiate a lesser amount to cover the transformer replacement or repair cost. Before doing anything drastic though, have you checked that the mains power is the same as your local supply and the wiring hasn't been messed with, just to get it working? Be warned that guitar amps often also use a particular type of transformer construction that affects the sound when used at max. power and you won't get the same sound from standard (e.g. hobby grade) replacement transformers when using your amp. on stage and turned up loud.
None of the information given makes sense so far.
Not even a toroid transformer and no where close to being a new amp.
for all we know the amp was abused.
or the the mounting hardware is loose.
who knows.
Most the models I have seen were usually hundred watt combos.
Its likely a cheap 200 to 260 Volt amp transformer.
I almost bought a few EI core transformer on a buyout from Ampeg a few
years ago. same thing, cheap transformers for a older " 100 watt" combo.
Seen plenty of them on ebay.
Not even a toroid transformer and no where close to being a new amp.
for all we know the amp was abused.
or the the mounting hardware is loose.
who knows.
Most the models I have seen were usually hundred watt combos.
Its likely a cheap 200 to 260 Volt amp transformer.
I almost bought a few EI core transformer on a buyout from Ampeg a few
years ago. same thing, cheap transformers for a older " 100 watt" combo.
Seen plenty of them on ebay.
Call a few electric motor repair/rewinding shops, asking them: "I have a buzzing power amplifier transformer, can you vacuum impregnate it for me?"
Consider Switzerland and Italy.
https://www.google.com/search?q=ele...BCDAuMTUuNC4ymAEAoAEByAEIwAEB&sclient=gws-wiz