Crate Powerblock smokes......fixed it!

[RussB]

I should open up the dead powerblock I have buried in the spare room and try to fix it as well...

[teemuk]

there is a reason that these were discontinued based on all I've read (my own is a refurb, meaning it sh!t the bed once itself before being repaired)....

What's with the "products are discontinued because they are unreliable" -myth? Plenty of classic Vox, Marshall and Fender amps were discontinued too, you know...

More likely the sales didn't really meet the production costs or executives saw fit to pave way for new products.

[teemuk]

On topic, though... what's the purpose of the circuit around Q2 & Q3 etc. Seems somewhat detached of rest of the stuff. Is it some sort of brute voltage limiter in case those 25V rails start peaking above the Zener values?

[Tone_Terrific]

Originally Posted by teemuk

On topic, though... what's the purpose of the circuit around Q2 & Q3 etc. Seems somewhat detached of rest of the stuff. Is it some sort of brute voltage limiter in case those 25V rails start peaking above the Zener values?

The schematic outlines those parts and says 'These parts used on 01 assy only'....whatever that means.
Possibly they were a limiting circuit that proved unnecessary and were dropped from later builds(?)