I am very new to amp design and construction, so I need some advice. I have an older amp that I made some modifications on and now the transformer overheats as soon as the amp is turned on. I believe that the transformer would meltdown if I did not intervene.
Here are the changes -
Removed power cord and installed a IEC Mains Filter AC Chassis socket.
Removed a 230 or 250 volt mains voltage selector swith and wired to 230 Volts on which I have been using it on.
Added a ferrite filter ring on the mains wiring inside the chassis.
Replaced a combination on-off and speaker A, B, A & B, and headphones selector switch with a simple toggle on - off switch. Removed the wiring for speakers B and head phones and wired "A" speakers directly to the output jacks.
A few notes on the transformer -
3 Primary wires -
White - which I assume is the neutral, or negative wire.
Brown - which appeared to be used for the 250 Volt windings
Orange - which appeared to be used for the 230 Volt windings
(As near as I could tell these wires were not in series or paralleled by the voltage selector switch, but used seperately to determie the input voltage.)
5 Secondary wires -
Red x 2 - each of which are wired into a diodeand then they both are wired on the positve side of the main power supply cap.
Blue x 2 - both of which are wired directly to the negative side of the power supply cap. One wire did have a small light bulb in line before the cap to light an indicator lamp on the front panel. I removed that lamp.(could that be the problem.)
1 Black - which soldered to the Star ground of the chassis.
Interestly the amp works fine and plays music as well as it ever did if not better since I eliminated quite a few switches and etc. by wiring the outputs direct instead of the signal going through a selector switch. But I have not been able leave the amp on for very long as within 5- 7 minutes of cold start it is way too hot to touch.
Any suggestions, I may try to sketch a wiring diagram and post it.
Surf, Sun & Sound
I just remembered that there was this little green thing that crossed the mains before the transformer, I did solder it back on between the positive and negative wires after the switch and the fuse but before the transformer. I could not tell that it was directional, sice with a continutiy tester I could get a reading either way. It is lime green about 1/4" by 3/8" with the following markings - ARCO 1.06 3300 / 20 630 V - .
Here are the changes -
Removed power cord and installed a IEC Mains Filter AC Chassis socket.
Removed a 230 or 250 volt mains voltage selector swith and wired to 230 Volts on which I have been using it on.
Added a ferrite filter ring on the mains wiring inside the chassis.
Replaced a combination on-off and speaker A, B, A & B, and headphones selector switch with a simple toggle on - off switch. Removed the wiring for speakers B and head phones and wired "A" speakers directly to the output jacks.
A few notes on the transformer -
3 Primary wires -
White - which I assume is the neutral, or negative wire.
Brown - which appeared to be used for the 250 Volt windings
Orange - which appeared to be used for the 230 Volt windings
(As near as I could tell these wires were not in series or paralleled by the voltage selector switch, but used seperately to determie the input voltage.)
5 Secondary wires -
Red x 2 - each of which are wired into a diodeand then they both are wired on the positve side of the main power supply cap.
Blue x 2 - both of which are wired directly to the negative side of the power supply cap. One wire did have a small light bulb in line before the cap to light an indicator lamp on the front panel. I removed that lamp.(could that be the problem.)
1 Black - which soldered to the Star ground of the chassis.
Interestly the amp works fine and plays music as well as it ever did if not better since I eliminated quite a few switches and etc. by wiring the outputs direct instead of the signal going through a selector switch. But I have not been able leave the amp on for very long as within 5- 7 minutes of cold start it is way too hot to touch.
Any suggestions, I may try to sketch a wiring diagram and post it.
Surf, Sun & Sound
I just remembered that there was this little green thing that crossed the mains before the transformer, I did solder it back on between the positive and negative wires after the switch and the fuse but before the transformer. I could not tell that it was directional, sice with a continutiy tester I could get a reading either way. It is lime green about 1/4" by 3/8" with the following markings - ARCO 1.06 3300 / 20 630 V - .