Hello , I just purchased an Amber series 70 power amplifier . It sound very good but has a transformer hum audible from 3 ft away . No speaker noise , just mechanical . A friend audiophile says his Parasound has the same issue , a tech friend wrapped the transformer in mortite insulation tape . Noise now inaudible . He suggests this for my amp . Seems to me like a recipe for an overheating transformer . Any ideas on this anyone. thanks in advance
The hum may have other sources too. This is a 25 years old amplifier. In some cases, recap the main filter cap and the driver PCB power input cap may be necessary. If it does not work, re-flow the solder joints of all output power transistors may be necessary.
Yes, tighten the transformer mounting is the first thing to try. Overheated transformer is a sure source of hum and an indication of under designed power supply, which may be a less likely source for the Amber, which is quite heavy.
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Take a screwdriver, hold the point onto the transformer and your ear to the hilt and listen, The screwdriver acts as a stethoscope and mechanical noise will be amplified for you to confirm mechanical noise.
Many transformers where loosely wound and causes it to buzz. Remove the transformer and take it to a transformer manufacturer and ask him to vacuum impregnate it. If you don't have the facility, use a thick outdoor varnish preferably water based and dunk the transformer into it for a while, then remove it and let the excess varnish drip off then bake it in the over for between 70 and 90 degrees centigrade for about an hour or until it is not sticky anymore.
Many transformers where loosely wound and causes it to buzz. Remove the transformer and take it to a transformer manufacturer and ask him to vacuum impregnate it. If you don't have the facility, use a thick outdoor varnish preferably water based and dunk the transformer into it for a while, then remove it and let the excess varnish drip off then bake it in the over for between 70 and 90 degrees centigrade for about an hour or until it is not sticky anymore.
Agree with dunking in varnish except on the water based part.
Please don´t.
All transformer manufacturers use solvent based varnish.
This is not the place to go "green"
In fact, you must first dry your transformer, BEFORE impregnating, so as not to trap any humidity inside.
To boot, the warm transformer will make varnish more fluid and will impregnate better.
Wait until no bubbles exit for at least minutes.
For pre-drying you can put it for an hour inside your oven at minimum heat, with the door slightly open, of if available, 1 or 2 hours under noon bright Sun.
Please don´t.
All transformer manufacturers use solvent based varnish.
This is not the place to go "green"
In fact, you must first dry your transformer, BEFORE impregnating, so as not to trap any humidity inside.
To boot, the warm transformer will make varnish more fluid and will impregnate better.
Wait until no bubbles exit for at least minutes.
For pre-drying you can put it for an hour inside your oven at minimum heat, with the door slightly open, of if available, 1 or 2 hours under noon bright Sun.
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