MACO / BRUTE Seventy-Five

[238]

The resistor going to the tubes are carbon. seeing as they are hard to get + expensive, what kind do use? 238

 

[nomadradio]

Nothing magic about carbon resistors. The more-modern carbon-film resistors made on a ceramic body will work just fine.

73

 

[238]

Thanks. Jim/238

 

[238]

The caps on 3 & 11 show no ohms. The one on 12, the filament shows a small number of ohms. All the pin sockets check out ok. 238

 

[nomadradio]

The reading on pins 3 and 11 should be an open circuit. The path from those pins to ground goes through a zener diode. The meter will read it as an open circuit.

Seems to me they ran a jumper wire under each socket between pins 3 and 11.

I would check for continuity from pin 3 on the tube that gets hot to pin 3 on the tube that doesn't.

Likeliest thing to make the tube overheat would be loss of the negative bias voltage on pins 3 and 11 of one tube, but not on the other.

73

 

[238]

Chris I think i have got you confused. I am working on a Brute 75 with 1 M2057. Recon has the 75 with 2 tubes. 238

 

[nomadradio]

DOH!

One thread, two amplifiers...

73

 

[238]

Sorry about that. I had posted a pic of my Super75 so he could compare the two. I was not sure if the caps were pf or uf. Thanks 238

 

[238]

Recon needs to put a good picture of the inside of his amp so you can see how it is done. His looks odd as compared to mine. 238