Cliping in crate gx65

ihu98 · 22nd April 2004, 01:33 PM

I have a crate Gx-65w guitar amp.I have replaced the cooked o/p transistors but the amp clips at low volume reguardless of which channel is selected.A C.R.O shows the o/p of I.C.3(an NE5532p) forming a square wave when the gain pot is only moderately cranked. Ihave checked most components and found no reason for this behavior.Any ideas would be great.Thanks

Centauri · 23rd April 2004, 12:18 PM

Very unusual... Check transistors Q10 & Q11 for short circuit C-E (these are the overcurrent shunts) and R73 & R74 .33ohm 5W resistors for open circuit.

With no signal, there should be 10mV DC across R74 - this can be adjusted with trimmer AP1.

Unusual circuit.

Cheers

ihu98 · 27th April 2004, 07:26 AM

Thanks to Centuri,I have a fully operational amp now.I replaced Q10 and D11(both shorted) I also replaced R74 (open) The amp is working as normal now.Thank you for your (correct) sugestion.
Cheers IHU98

22nd April 2004, 01:33 PM	#1
ihu98 diyAudio Member Join Date: Apr 2004 Location: melbourne	Cliping in crate gx65 I have a crate Gx-65w guitar amp.I have replaced the cooked o/p transistors but the amp clips at low volume reguardless of which channel is selected.A C.R.O shows the o/p of I.C.3(an NE5532p) forming a square wave when the gain pot is only moderately cranked. Ihave checked most components and found no reason for this behavior.Any ideas would be great.Thanks

27th April 2004, 07:26 AM	#3
ihu98 diyAudio Member Join Date: Apr 2004 Location: melbourne	Solution to crate GX-65 problem Thanks to Centuri,I have a fully operational amp now.I replaced Q10 and D11(both shorted) I also replaced R74 (open) The amp is working as normal now.Thank you for your (correct) sugestion. Cheers IHU98

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23rd April 2004, 12:18 PM	#2
Centauri diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Very unusual... Check transistors Q10 & Q11 for short circuit C-E (these are the overcurrent shunts) and R73 & R74 .33ohm 5W resistors for open circuit. With no signal, there should be 10mV DC across R74 - this can be adjusted with trimmer AP1. Unusual circuit. Cheers