petehall347
the brandy coffee man
could i suggest removing the outputs for safe keeping and use 1k resistors in place of them from B to E connections on the board for testing purposes ?
Agree..could i suggest removing the outputs for safe keeping and use 1k resistors in place of them from B to E connections on the board for testing purposes ?
What wattage should I use for those?could i suggest removing the outputs for safe keeping and use 1k resistors in place of them from B to E connections on the board for testing purposes ?
good question .. avionic will know best . i have used 1/4w in some amps no problem but never done this with this one .What wattage should I use for those?
1/2 watt should do.What wattage should I use for those?
Was going to say 1/4-1/2w. If a 1/4w smokes go with 1/2. Technically there should only be around 600mv on the base of the outputs.good question .. avionic will know best . i have used 1/4w in some amps no problem but never done this with this one .
Also, just to make sure, (since I'm assuming you've seen these Yamahas before), what would happin if the transistors we're put in the wrong way (as in the paint were reversed, not the pins)Was going to 1/4-1/2w. If a 1/4w smokes go with 1/2.
Blow a fuse for sure.Possible destroy the transistor as well. Depends on how long it takes for the fuses to blow.what would happin if the transistors we're put in the wrong way (as in the paint were reversed, not the pins)
well yes there is a chance of smoke either way but better than trashing obsolete outputs . i do see others that go straight for 1/2w though .. i can never do the maths to work out the current . i know ideally they will see about 600mv .Was going to 1/4-1/2w. If a 1/4w smokes go with 1/2.
Let google do it for you.i can never do the maths to work out the current .
So, TR-721 is showing a dead short as well (pulled it to test) could he have been the reason that resistor popped?Let google do it for you.
Just plug in the two knowns..1KΩ and .6v then press "calculate"
http://www.ohmslawcalculator.com/ohms-law-calculator
1/4w should be fine.
I was thinking he would be why it popped even with good ouput transistors there.hard to say what transistor went first .
Could have. Is this the same channel as the other two shorted transistors?So, TR-721 is showing a dead short as well (pulled it to test) could he have been the reason that resistor popped?
Yes, he's on the same side I was seeing rail voltage before.Could have. Is this the same channel as the other two shorted transistors?
Keep checking transistors and diodes further upstream on that left channel.Yes, he's on the same side I was seeing rail voltage before.
Everything else checked out alright, fingers crossed that was the underlying cause. This is becoming a money pit.Keep checking transistors and diodes further upstream on that left channel.
You haven't seen nothing until you T-shoot and repair and M-60/65,M-80/85 or a B-6 that has "Chernobyl'd"This is becoming a money pit.
Oh god, on another note, I've got an M-40 at home I got from a goodwill for $10, is there any preventative maintenance I should do, or just leave it since it works great?You haven't seen nothing until you T-shoot and repair and M-60/65,M-80/85 or a B-6 that has "Chernobyl'd"