Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: EDWARDEFFECT1 on October 15, 2011, 05:21:12 AM

Title: shorted kustom 400 watt bass head
Post by: EDWARDEFFECT1 on October 15, 2011, 05:21:12 AM
i have a kustom 400 watt bass amp one of the newer china amps.it blew the 8amp fuse and a npn output chip.i replaced the bridge rectifier also.i replaced the parts and plugged it in with a homeade current limiter with a 100 watt bulb.the bulb is staying bright so i have a short in the amp. what is the best way to find it.if it is with an ohmeter what readings should i look for.are there any other ways to test for a short.variac? oscilloscope ect.how do you do it .....thanks...ed
Title: Re: shorted kustom 400 watt bass head
Post by: J M Fahey on October 15, 2011, 04:24:41 PM
1) get the schematic, ask Kustom.
2) you probably have more shorted transistors, the one driving the one you replaced is probably bad too.
Title: Re: shorted kustom 400 watt bass head
Post by: joecool85 on October 17, 2011, 02:18:25 PM
Quote from: J M Fahey on October 15, 2011, 04:24:41 PM
1) get the schematic, ask Kustom.
2) you probably have more shorted transistors, the one driving the one you replaced is probably bad too.

Also, check that your speaker isn't fried and/or a short in the output wires.
Title: Re: shorted kustom 400 watt bass head
Post by: Enzo on October 17, 2011, 07:57:12 PM
And make sure that all the resistors that are involved with those transistors are intact.  When transistors go shorted, they often burn resistors open.