Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Make it loud here.
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tribi9
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Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sat Jan 02, 2021 1:27 pm

Bought it from some "tech" douchebag expat that lives in Japan.. Supposedly serviced..

Came to me with a ground cord, barely attached to the chassis, sounds horrible after a half hour of playing.. A big loud grumble happens.

Im going to recap, put some new tubes and retest...

Nothing looks burned inside. So that might take care of things..

I have cleaned the stinky tolex, I did get rid of the smell mostly, now I just want the tolex to look less beat up.. I sprayed contact cleaner on the tolex and got rid of some of the crud.


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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by countertext » Sat Jan 02, 2021 2:33 pm

β€œIt worked the last time I turned it on...” ;)

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sat Jan 02, 2021 2:52 pm

Give me my money back....!

Debating whether to order 6P3SE tubes for it.. Or some JJs.. Something entry level.. Bills need to get paid, so gotta cut some corners.

All the resistor values check out. Solder joints look good. Waiting on caps..

I think some stand offs might not be q bad idea for the circuit board.. πŸ€”


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Last edited by tribi9 on Sun Jan 03, 2021 1:09 pm, edited 1 time in total.

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sun Jan 03, 2021 12:44 pm

The tolex looks great, doesn't feel sticky but time will tell if using electronic contact cleaner was the right call.

Also, the loud fucking grumbling that usually happens after the 30 minute mark seems to be gone.. I replaced the three 100k plate resistors that were in there. Got the dog bone resistors the fuck outta there... I had to get creative, as i only had one 100k, but had four 220k on hand, so I piggy backed two and two, of the 220k.

Two 220k piggy backed give you 110k give or take. Depending on what the resistors measure originally.. I really should check the bias but haven't yet.. :fp:

It still sounds like it could use new caps, but like I said, i think that rumble is gone. It was so bad, i pretty much had to turn it off on the spot every time it got there. It almost sounded like it was about to blow up..

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Last edited by tribi9 on Sun Jan 03, 2021 4:24 pm, edited 2 times in total.

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by terminalvertigo » Sun Jan 03, 2021 1:50 pm

nice work bud!
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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sun Jan 03, 2021 3:08 pm

terminalvertigo wrote: ↑
Sun Jan 03, 2021 1:50 pm
nice work bud!
Thank boss. The amp sounds fucking awesome. Once i recap it, i can bolt it back and rock it for another 15 years or so relatively trouble free..

I put in two vintage 12AX7s from my stash. I don't even think I need to recap it anymore.. Sounds really good.... But I will because i can't cancel the order fuuuck πŸ€”

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by terminalvertigo » Sun Jan 03, 2021 8:05 pm

might as well do it and knows it done right, ease of mind and whatnot :)
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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sun Jan 03, 2021 8:24 pm

True, but I start college tomorrow, so funds are going to be tight for two years, and it really could wait.

Ive had this amp for two years, and today is the first time ive gotten to play it longer than a half hour.. Like ive been playing it all day non stop hahaa...

Is like I got a new amp today. 😎

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by HNB » Sun Jan 03, 2021 8:48 pm

I had some sound issues and noise that was fixed with new tubes. It is smart to update the caps just to know it is done. Especially since you ordered them anyways. :)
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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Sun Jan 03, 2021 8:52 pm

The old tubes that were in there sound good too. I guess I'm glad the resistors were the only part I had handy.. Cause I would have probably tried that last.. :fp:

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Mon Jan 04, 2021 12:43 pm

The owner of the Tube Store was cool cancelling the order. Im zipping this up and rocking it til further notice.. 😎

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by terminalvertigo » Mon Jan 04, 2021 1:52 pm

what ya taking in college?
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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Mon Jan 04, 2021 2:11 pm

Fast tracking in 2 years a 3 year diploma. Network Systems Administrator.. I took computer programming back in the day, fresh out of high school but didn't finish. Im going to give'r this time. This is my last chance.

Just got my timetable today, meeting the faculty online tomorrow. Classes start Wednesday.

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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by terminalvertigo » Mon Jan 04, 2021 5:12 pm

:)
I did a 3 year networking diploma
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Re: Servicing a Guyatone GA-940 that sounds like shit after a 1/2 hour of playing...

Post by tribi9 » Mon Jan 04, 2021 5:39 pm

Sweet, hoping I can join your team then. Maybe, i'll even get to own some cool guitars like you then... ;D :D

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