Thanks, there are some thin little clear shims covered in thermal paste, I think made of plastic, maybe to electrically isolate the transistors from the heatsink, do I need to refit those prior to testing?
I think I should run the tests with the amp still attached to the plate and the woofer disconnected right?
Would running the amp through my variac be a good idea, for safety, if I did use it I'm guessing that that will lower the voltages across the board?
I think I should run the tests with the amp still attached to the plate and the woofer disconnected right?
Would running the amp through my variac be a good idea, for safety, if I did use it I'm guessing that that will lower the voltages across the board?
TO247 devices come in various versions with different insulation needs for heatsinking.
Some only require insulation washers on there screws, and/or insulation wafers right under their back side. Some TO247 doesn't need anything insulating them at all from the heatsink. Anything with metal tabs necessitates insulation. The case usually is connected to the collector which typically goes to one of the power supply rails.
Some only require insulation washers on there screws, and/or insulation wafers right under their back side. Some TO247 doesn't need anything insulating them at all from the heatsink. Anything with metal tabs necessitates insulation. The case usually is connected to the collector which typically goes to one of the power supply rails.
TO-247 used for amplifiers require a mica washer or sil-pad, unless it’s a topology that uses grounded collectors/drains. QSC likes to do that. The hole on a TO-247 is insulated - if it’s not, it’s not a TO-247 but something else. Nobody is making TO-218 (SOT-93) anymore. The last hold-out was ST, and they dropped it a decade ago. ON just before that.
I’ve seen TO-247’s without the hole at all, and some with isolated back sides - but not on semiconductors that one would use building audio amps. IGBTS and thyristors. And the package goes by a different designation. Maybe in the power supply, but not the audio portion (even class D prefers mosfet, which would have drain to backside).
I’ve seen TO-247’s without the hole at all, and some with isolated back sides - but not on semiconductors that one would use building audio amps. IGBTS and thyristors. And the package goes by a different designation. Maybe in the power supply, but not the audio portion (even class D prefers mosfet, which would have drain to backside).
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If the Japs are doing that, it’s probably not called a TO-247. They have their own designations for their packages.
It’s not the best way to make a transistor either. The only really high thermal conductivity solutions are not going to be RoHS compatible. So if they are “green” they are going to suck. BeO has been around a while, and they’re trying to get rid of it.
It’s not the best way to make a transistor either. The only really high thermal conductivity solutions are not going to be RoHS compatible. So if they are “green” they are going to suck. BeO has been around a while, and they’re trying to get rid of it.
Thanks ProFiGuy for the tip on Speaker Power- made in America. 700W @ $599 sounds reasonable. . . and reliable. Nuff said.