VintageKustom.com: Repairing Kustom Amps

Fri, 15 January 2016 16:07

Shaun_Musings
Messages: 323
Registered: April 2009
Location: Reading, MA

Senior Member

Okay, so I replaced the NTE129, discovered a blown TO-3 (2N3055) on the floor of the chassis, replaced that with an old one (I know they need to be matched, but I want to make sure another one won't blow., and booted it up. Getting 6-7 VDC from the output jack. I plugged the speaker in, and there is a loud hum, but no crackling and popping. Loud enough to be annoying, but not loud enough to blow my ear drums out.

I tested the furthest 2N3055 to see if the collector and base or emitter and base would show a short. The yellow wire back there (not sure if it is B or E) beeped, signaling a short. I pulled off the black connector (which broke in half. What is a replacement?) and found that the yellow wire beeps a short with the chassis even though it is disconnected. This is either the - DC PCB or the + DC PCB, not sure. What could be causing this?

So, just a few questions:

1. Why am I still getting 6-7 VDC at the output? I have ordered replacement 5 watt resistors (to replace the Memcor ones). Someone in an earlier post stated those 5-watt resistors should be replaced with either 7 or 10-watts (still 1 ohm).

2. Why am I still getting a short (it is a quick beep, never continuous) between the yellow wire and the grounded chassis?

3. Why does it seem the two input boards are not connected?

Born on the Baaaaayou (Ok, in Massachusetts)

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