galaxiex 5/9/2018 7:30 PM
My new toy :)
Moderators, I didn't see a section for test gear so I thought I'd put this here since I will be using it to test caps for guitar amps.
Please move if this is not the appropriate place for this.
Thanks!

So my new toy is in very nice physical condition, but I may have to do some work before plugging it in.

Those caps look positively ancient!

The seller already powered it up to show that the magic eye tube works, but I still think I'd better check out those caps first.
 
The Dude 5/9/2018 7:58 PM
Now you need to buy a cap tester to test the caps in your cap tester.
 
galaxiex 5/9/2018 8:26 PM
Ha ha
Yes, the irony was not lost on me.
 
Enzo 5/9/2018 9:34 PM
My favorite piece of gear. I had an old Eico 950B which is very similar. It puts real world voltages on caps, so you really can test a cap at 400v for leakage. And leakage is what matters. It really doesn't matter much if your coupling cap is 0.019 rather than 0.022, but it does matter if it leaks like a screen door at anything over 200v.

Good, clean looking unit.
 
galaxiex 5/9/2018 10:29 PM
Thanks Enzo.

That's why I bought it, for testing leakage.

I knew it could be done, (and I have the feeling I've changed quite a few caps that didn't need changing) but no modern testers do that.

So I came across this website...

http://www.angelfire.com/electronic/...at_I_need.html

... and he recommended the Heath IT-11 or IT-28.
A couple came up on ebay but out of my price range.

Then my search found this Heath C3 that looked really nice and I could afford.
Not quite as fancy as the other two but should suffice.
 
Enzo 5/10/2018 6:15 AM
Yep, those two are more the prize, but nothing wrong with what you got. The recommended ones are just a little more featurely.
 
mozz 5/10/2018 2:12 PM
The Sencore LC models are very nice, if you happen to have a extra $1000.
 
galaxiex 5/10/2018 5:56 PM
Quote Originally Posted by mozz View Post
The Sencore LC models are very nice, if you happen to have a extra $1000.
I'm sure they are nice, but for that much... ain't gonna happen.
 
R ski 5/15/2018 3:52 AM
Deja Vu

My dads television work bench had a similar tester, I thought the indicator eye in the upper left corner was cool. By the early 70's I was into solid state electronics. Ironically by the late 90's tube guitar amps were on my bench.
 
galaxiex 5/19/2018 7:16 PM
Work has been progressing on the cap checker.

Still waiting for the 8uf supply caps.

I rewired it with colored stranded wire.
Originally it was wired with solid core and all the same (green) color.
Replaced all parts (caps and R's) that were quite far out of tolerance.
Some of the originals were still good.

Found a nice manual for it.
Drat, tried to upload it but the pdf is too big.
Here's a different one, not as nice but has the essentials.

Edit; here's a link to the nice manual download if anyone wants it.

https://archive.org/details/Heathkit...rCheckermanual

I installed a 3 wire grounded power cord.
Should I leave out the line to chassis .05uf cap?
 
jmaf 5/19/2018 8:01 PM
Nice toy OP.

But my cap tester is something RG posted here years ago: a resistor in series with a cap under full voltage. If there's voltage on that resistor, the cap leaks. Sometimes I'll rig this up on a protoboard and test 10's of caps and then dismantle it.

But seeing the result on a cat eye tube is a higher level of tubromance no doubt about it.
 
galaxiex 5/22/2018 4:40 PM
Final parts came today so I got to finish up this project.

Was waiting for the two 8uf filter caps.

The 2 dark ones bottom center.

[ATTACH=CONFIG]48926[/ATTACH]

Top side guts final.

[ATTACH=CONFIG]48927[/ATTACH]

200K calibrating resistor, pretty close.

[ATTACH=CONFIG]48928[/ATTACH]

Had to test all the caps that got replaced in this unit.
All are leaky and some don't read *any* value at all.

[ATTACH=CONFIG]48929[/ATTACH]

These are from the 1970 Traynor Guitar Mate I've been working on.
All blue caps are leaky (no surprise) values test ok.

All yellow caps test good for value and leakage.

[ATTACH=CONFIG]48930[/ATTACH]

And finally the main filters from the 1970 Traynor.
I was really questioning these whether I had to replace them or not.
Amp "seemed" to work ok with them.
These are the originals with 1970 date code.
They leak.
With the new caps the amp is punchy and LOUD!

[ATTACH=CONFIG]48931[/ATTACH]
 
g1 5/22/2018 5:59 PM
Out of curiosity, did you happen to test the new caps for the amp before installation? Always good to check for comparison.
 
galaxiex 5/22/2018 6:45 PM
Quote Originally Posted by g1 View Post
Out of curiosity, did you happen to test the new caps for the amp before installation? Always good to check for comparison.
Unfortunately, no.
I had replaced those caps some time ago and only got this tester up and running today.
The amp is all back together... but I spose I could pull the chassis and check them... maybe later....

FWIW the old caps tested spot on for value, just leaky.
 
g1 5/22/2018 6:53 PM
Quote Originally Posted by galaxiex View Post
FWIW the old caps tested spot on for value, just leaky.
That's what kind of made me wonder how the leakage is calibrated and how leaky the new caps would check out to be. Good to have a reference from some new caps.
 
galaxiex 5/22/2018 7:23 PM
Quote Originally Posted by g1 View Post
That's what kind of made me wonder how the leakage is calibrated and how leaky the new caps would check out to be. Good to have a reference from some new caps.

Agree, the next time I get an amp for a cap job I will certainly compare the old and new.