What guitar amp is this?

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What guitar amp is this?

Postby the19thbear » Sat Oct 17, 2015 9:16 am

Hi. On a flea market I found an old tube guitar amp.
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It looks profesionally built inside, but the case is homemade. Its not really working, but it would be fun to get it working.

On the front it has this:
3 inputs (?!?!?!?)
Treble pot
Bass pot
Volume pot
? Pot (maybe for reverb. THere is a reverb tank, but no reverb sound
Tremolo depth
Tremolo speed
A 3 way switch with an lightbulb on each side. One green one red. None of them work.
In the middle position i a really low sound, with lots of distortion on it. Which maybe could sound way cool, but its just way low.
In any other position i get sound.

It has these tubes:
2x 12ax7
1x 12au7
1x 6av6
2x 7189a

Im not even sure that the right tubes are in the unit, but since i have some sound, it cant be way off.
There are no labels to tell me what tubes should go where.

I swapped the 2 12ax7s around, but no improvement. I even did the same with the 12au7 and swapped that around, but no improvement.
Maybe the tubes arent even in the right places. Who knows.

What is the difference on the two ouput jacks? One seems to have huge green capacitors (maybe) the other output doesnt have any.

Would love a schematic, but first i have to find out what kind it is:)

Thanks!



This is the amp part only. I dont have a speaker, but plugged in a set of crappy headphones to the speaker output jack and kept the volume WAY low.
Last edited by the19thbear on Sun Oct 18, 2015 3:05 am, edited 3 times in total.
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Re: What guitar amp is this?

Postby Geek » Sat Oct 17, 2015 1:21 pm

We need a pic ;)
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Re: What guitar amp is this?

Postby the19thbear » Sun Oct 18, 2015 2:51 am

Done:)
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Re: What guitar amp is this?

Postby Geek » Sun Oct 18, 2015 5:07 am

That's either an advanced home-brew or a kit amp. Unlikely a commercial build, unless a "one-off-out-the-back-door" for a friend.

First thing I'd do is recap it... all the caps. You can use Orange Drop from Antique Electronics Supply for the coupling caps and some F/T from the same place for the electrolytics. Personally I avoid the cheaper Illinois Caps in any amp because of their high ESR, which can cause instability (motorboating) through the power supply line.

Look for out-of-spec resistors in there, too.

Cheers!
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Re: What guitar amp is this?

Postby the19thbear » Sun Oct 18, 2015 9:50 am

Hi and Thanks :) the thing is that I won't really be able to find an out of spec resistor when I don't have the schematics. Or maybe I'm misunderst something:)
Thanks for taking the time
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Re: What guitar amp is this?

Postby battradio » Sun Oct 18, 2015 10:54 am

To find out of spec resistors all you need is an ohm meter , the color code or writing on them will tell you the original value .Most all resistors a stock values so out of spec is easy to determine .

It is made with mostly Japanese parts , . it was a home brew or made from a magazine article .
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Re: What guitar amp is this?

Postby TomMcNally » Sun Oct 18, 2015 2:02 pm

It's obviously not American, probably Japanese, judging by the components used in the construction. I'd say late 60's ... that might help in googling around.

found it .... 1966 Teisco Del Rey Checkmate 20

https://reverb.com/item/1118215-1966-teisco-del-rey-checkmate-20-amplifier

There is a schematic at that link !
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Re: What guitar amp is this?

Postby the19thbear » Sun Oct 18, 2015 3:17 pm

YOU ARE FREAKING AMAZING!!!!! Thanks!:)
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Re: What guitar amp is this?

Postby Geek » Sun Oct 18, 2015 4:28 pm

TomMcNally wrote:found it .... 1966 Teisco Del Rey Checkmate 20


I had one in the shop a couple weeks ago that looked quite different (the amp, the cab was the same). How many revisions were made????
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Re: What guitar amp is this?

Postby TomMcNally » Sun Oct 18, 2015 4:43 pm

I never heard of it until a few hours ago. Just like to google ... haha "Japanese 60s guitar amps" I grew up with Lafayette stuff, it's all built like that !
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Re: What guitar amp is this?

Postby the19thbear » Tue Oct 20, 2015 6:10 am

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