Troubleshooting Crate G40C amp

[mandomaniac]

Hello forum folks,
Newbie here, so please bear with me. I am seeking guidance on steps to take to repair a Crate G40C amp.
The beast will power up (indicator lights come on for power and channel selected), but NO sound. No sound through headphones either.
I did manage to obtain a schematic from Mackie.com (a big THANK YOU to Chrys in Tech Support). However, a basic stepwise approach to diagnosing the problem is needed.
I realise this might be simple stuff to most of you...but almost Greek to me! However..... I am trainable!
Any assistance with figuring this out would be greatly appreciated.
Thanks!


BTW.....if this post is in the wrong place, please accept my apologies and relocate it as needed.

[Ronsmusicrepair]

I don't know what type of repair instruments you have, but I ususlly check the power supply voltages first. My schematics only go back to 1999 and that was made in the late 1990's. If all the voltages are good, I then check the amp, which is a stereo amp in this cabinet. Can you hear any hiss out of the speakers at all? Check for any cracked solder joints at the input jacks and controls. The Crate amps have had a bad problem with the line out and amp in jacks on the back panel. If these have a dirty connection the amp goes mute. Besides that you would have to trace the signal with an oscilloscope to see where the signal is and isn't. I hope this helps.

[mandomaniac]

Thanks for the reply!
I will follow your suggestions and see what I come up with.
No oscilloscope...but might be able to borrow one. Multimeter is best I can do now.
No noise at all out of speakers.
I do have schematics from Mackie.com but I needed basic knowledge to start searching this out.

Maybe I will get lucky and it be something simple.

Any other helpful thoughts would certainly be most welcome!
Thanks again.

[vangelis]

Originally posted by mandomaniac
Thanks for the reply!

I do have schematics from Mackie.com but I needed basic knowledge to start searching this out.

Please, attach the schematic if it's in electronic form (pdf). Maybe others of us can help you...

Did you smell any smoke anytime in your amp? Is your amp stop working at once, when you play it, or after long pause?

In any case, don't worry. I'm sure you can repair the beast with help of some of us.

[digitaltoast]

Hey mando, could you please email me a copy of the schematics? I happen to have one open here, in front of me, that craps out on loud transients...likely capacitors, but it would be nice to have a copy of the schematic.

As for your troubleshooting... Do you have any output at the line out jacks on back?

my email is toastmiami2 at yahoo ... thanks

[lnr241]

This is the schematic from Mackie, if anyone still needs it.

[digitaltoast]

Hey lnr241, could you email me a copy of that schematic?

toastmiami2 at yahoo.com

It didn't seem to post on the forum, and unfortunitly my privliges don't yet allow me to email you directly ... so hopefully you have email notification ON.

thanks in advance,
dan

[lnr241]

Sorry guys, for some reason the schematic didn't attach. I'll try again here, but if it still doesn't work, feel free to email me at; lnr241@yahoo.com

[lnr241]

Sorry guys, the file was to large. For some reason it didn't tell me that the first time I tried to post it. Anyways if you need the schematic, feel free to email me at;
lnr241@yahoo.com

[sixstringfling]

Hello,Ive got a G40C with a problem.It seems that someone took the first input socket out.Also, the amp powers up and sounds good,but,fades out after 5 seconds.Any ideas?