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Pignose 30/60 repair. help!

Started by AllThorUp, August 30, 2016, 01:54:18 PM

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AllThorUp

Hi so I found this forum while google searching about this amp I am trying to fix.  ive been following an old thread as my instructional guide to fix my 30/60.  Ive gotten as far as replacing the transistors and turning it on using the light bulb limiter, which is where the old thread ends because for the OP his started working at this point. Well, as far as mine goes, lets say im not so lucky. So, it no longer immediately blows the breaker when i switch it on but the bulb limiter still glows brightly and im getting what i believe is DC hum from the speaker.  any advice on where to go from here would really be greatly appreciated!!

On a side note it appears someone mucked around with this amp sometime before i got ahold of it, because the 2 most notable things were that LED 1 and 2 which i assume to be a clipping section, have been replaced with a pair of diodes, and the other is that the 2955 transistor was replaced with a different one (whos numbers i cant recall at the moment, and took a bit of searching to find what it was) but the 3055 was there still. Dunno if those alterations could have contributed to it landing in its current state of non op, but figured it was worth the mention.

phatt

Likely DC on speaker ,,so disconnect that speaker before in burns out. :'(
Now set your meter to DC Volts and read the voltage at output terminals.
It should be very close to Zero Volts (100mV either way is normal).

Meantime maybe hunt down the schematic for your amplifier. :tu:
Phil.

blackcorvo

#2
No need to hunt down the schematic, I already did:
http://bmamps.com/Schematics/Pignose/Pignose%207-3060.pdf

Sending it as an attachment as well, just in case.  :dbtu:

It has the voltages on it, so I'd make a comparison between your amp's and the schematic's and make sure everything checks out.