Tube tester Precision model 612 advice needed!

[jelle]

Hi,

I'm considering buying a tube tester Precision model 612 to test stuff like 6L6, EL34, 6550 and the 12 series preamp tubes for my amps.

Is this a good tester for this application?

Since I will be picking up the tester, is there a way of finding out if it is still working? It will be my first tube testing experience...

Thanks,

Jelle

[ampdoc1]

Take a tube with you and try it! There is really no other way. If you buy it let me know. I have (I think) the same model I bought a couple of years ago that had no tube chart. I'd pay to get a copy!

ampdoc

[jelle]

The seller better have a tube chart....

OTOH, I have seen a website where charts can be bought for 10-15$...

Keep ya updated!

Thanks,
Jelle

[Sonny ReVerb]

Try this:

http://www.nostalgiaair.org/References/Manuals/

[jelle]

Thanks for the advice!

I bought it and it has a tube chart!

Please email me at jwelagen (at) hotmail.com.

I have replaced the 100nF cap with a OD715 100nF 600V. The resistors are a bit off value...

BTW I'm a total newbie at this tube testing....I've tested a bunch of 12ax7's and they measure between 60 and 80% but what am I measuring here, slope, gm? Also some of my 12at7's have drifting (decreasing) measurements. What does this mean? Can I use this thing to select balanced phase inverter tubes?

For the power tubes...can I use this tester to match tubes?

I have a lot to learn....

Jelle

[ampgeek]

Hey Jelle,
I always return to this site whenever I have basic tube tester questions:

http://www.tone-lizard.com/Tube_Testers.html

Very informative and, often, quite humorous in a quirky sort of way.

Check out his other pages for similar, primer type info delivered in the same spirit.

Good luck,
Dave O.

[tonelab2]

Hello jelle,
On any old tester I would change out all caps ( unless they're good film caps) electrolytics, wax, ect. Next, I would get rid of any CCs in the circuit. CCs can add mojo to audio but really suck in test gear as they
get warm /hot the value drifts causing sag ect. Replace all resistors that have drifted in value.

[Sonny ReVerb]

The Antique Radio Forum 'test equipment' section has some knowledgeable folks concerning tube testers. They helped me out when I restored my Sencore MU140.

http://antiqueradios.com/forums/viewforum.php?f=8

[jelle]

Cool! I'll try that. Thanks,

Jelle

[skyboltone]

Hello jelle,
On any old tester I would change out all caps ( unless they're good film caps) electrolytics, wax, ect. Next, I would get rid of any CCs in the circuit. CCs can add mojo to audio but really suck in test gear as they
get warm /hot the value drifts causing sag ect. Replace all resistors that have drifted in value.

Well, ah, hmmmm. That would be all of them in most cases. They were custom made and have specific high preceision values not always replaceable. In my Hickok they would number in the hundreds I think. Still, have a look see and get an idea of the ones that have drifted terribly and have replacements.

My tester doesn't do well on 6EA8s. Known new stock tubes always fail. That's a tip off that somethings amiss but I've never sought to chase it down. Good advice on the power supply though. Don't be tempted to go solid state here. The tests are based on specific voltage values and a SS recto will through everything off.

[skyboltone]

Here's the one I want when I grow up:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... BS:US:1123