Crate G40C schem?

[bobsamps]

Crate Schem

Is this what you're looking for? Not the best quality, but beats the snot out of nothing!

Thanks! Cool old sheets. I'll have to take a new look at it now.

[mhd720]

I have the G40CXL and the two x '50Ω 10W' resistors (see pics) are almost too hot to touch when clean volume is > half.

I measured voltage across them and it was only about 7.8V each. Assuming they're still 50Ω, then that means about 0.16 mA through each one, which should not be enough to make them > 60 degrees C, right?

Will replacing the resistors be enough? and should I replace with ones with higher power rating?

[Dano]

Crate G40 etc

In regards to the turn-on thump, after going through a Crate G40, trying to find the cause, (we are talking weeks of hours, sometimes I get too obsessed with things) I finally called SLM which used to be the old Crate Factory.

The tech said the thump is normal and there is no turn-on muting circuitry.

Got to know this amp pretty well.

[mhd720]

I have replaced the 50ohm resistors, but they still get warm. Now I'm wondering if maybe I need to replace the large 3300uF caps next to the transformer. my multimeter has a CAP function but it definitely isn't going up into the hundreds or thousands of microFarads...

[Enzo]

They are dissip[ating over a watt. That is enough to make them hot. it is normal for dropping resistors to get hot.

[dobrota]

Resistors in G40

I have the G40CXL and the two x '50Ω 10W' resistors (see pics) are almost too hot to touch when clean volume is > half.

I measured voltage across them and it was only about 7.8V each. Assuming they're still 50Ω, then that means about 0.16 mA through each one, which should not be enough to make them > 60 degrees C, right?

Will replacing the resistors be enough? and should I replace with ones with higher power rating?

No, 7.8V/50Ω is 0.156A !! current through each one and about 1.2W heat on each one, so they're too hot to touch.
It's normal, "hot" resistors before zener diode for decrease high voltage for power amp to get lower voltage for preamp section. It seems from 35V to 20V in (worst quality) schematics and so about 4.5W heat on each one - 10W rating is for longer resistors life time

[mhd720]

What output should I expect from the transformer? I get 28v AC on each side so I assume it is center-tapped, hence the two red wires and one green wire....

[dobrota]

What output should I expect from the transformer? I get 28v AC on each side so I assume it is center-tapped, hence the two red wires and one green wire....

There's 35V DC after bridge rectifier in the schematics, so about 28V AC is OK.
But only two wires - pin J21, J22 on secondary wiring, no center tap.