Got it ---thanks---ill report back when i get one
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Fender FM 65
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Ok , what is the acceptable temp range on these transistors ?? Somethings still not right (i think? )
Amp is powered up--no bulb limiter , no output load .
Just replaced Q17 / 6 /8 .
The temp is creeping up to over 95 before i shut it off on Q 11 , Q 15/17/18/19 .
Everything else is at 66-70 degrees . There is no Dc at the speaker out . The bulb is dark now if i use the limiter even with a load on output
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Originally posted by Valvehead View PostThe temp is creeping up to over 95 before i shut it off on Q 11 , Q 15/17/18/19 .
95°C would be excessive. 95 degree Fahrenheit corresponds to 35°C and should be no problem. Semiconductor temperature tends to get critical, when it's too hot to touch (above 50°C to 60°C).
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Are all transistors bolted to heatsink and all heatsinks completely assembled to chassis? What are your DC voltages across R103 and across R105 ?Originally posted by EnzoI have a sign in my shop that says, "Never think up reasons not to check something."
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Originally posted by g1 View PostAre all transistors bolted to heatsink and all heatsinks completely assembled to chassis? What are your DC voltages across R103 and across R105 ?
r103 / r105 , 4mv and 10mv to gnd
Edit----good call G1 , amp is back together and everything looks stable now....will try it tonight
Last edited by Valvehead; 04-21-2021, 04:48 AM.
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