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Sorry, no schematic, posted a request in that forum, no responses.
So, powered speaker was getting HOT
While testing output blew.
Basic power amp, two 150watt transistors one npn, one pnp.
Each has a TO220 sized driver of it's polarity and each side has two smaller current driver transistors, everything else surface mount.
I replaced the blown drivers and anything else suspect and amp works, drives a load, signal looks great, but it's drawing too much current
Bypass light bulb limiter and POOF! There go the output transistors
It's got to be biased too hot.
Looked for what looks like the bias string, found a 330 ohm resistor, shorted it with tweezers and bulb barely lights.
Lowered it to ten ohms, amp works, signal looks great, drives a load and bulb barely lights
It's pulling about 200 milliamps at idle, that sound right?
Only thing left to do is plug it in without the limiter
Or should I try and get idle current lower?
I'm afraid to try it without the limiter
Thanks
So, powered speaker was getting HOT
While testing output blew.
Basic power amp, two 150watt transistors one npn, one pnp.
Each has a TO220 sized driver of it's polarity and each side has two smaller current driver transistors, everything else surface mount.
I replaced the blown drivers and anything else suspect and amp works, drives a load, signal looks great, but it's drawing too much current
Bypass light bulb limiter and POOF! There go the output transistors
It's got to be biased too hot.
Looked for what looks like the bias string, found a 330 ohm resistor, shorted it with tweezers and bulb barely lights.
Lowered it to ten ohms, amp works, signal looks great, drives a load and bulb barely lights
It's pulling about 200 milliamps at idle, that sound right?
Only thing left to do is plug it in without the limiter
Or should I try and get idle current lower?
I'm afraid to try it without the limiter
Thanks