Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: stingray_65 on March 20, 2010, 11:37:22 pm
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WOW!
I was knocking around my fathers shop today and my cousin happened by, At the time I had an old Pontiac AM radio in my hands from the early 50's and she asked if old tubes were good for anything.
as fate would have it she was cleaning out her grandmothers house and she found her grandpa's stash of old tubes and a box with a bunch of levers.
I had an Eico model 666 15 minutes later.
This thing looks absolutly brand new the charts roll perfectly and the cord is still supple. There are reciepts dating back to 1958 and an original sales reciept for the Eico for $112.
the manual is pefect with the excepton that the center page has been pulled thru the staples. This page is also the schematic and parts list.
This Eico has no tubes inside it.
That said,should I bring this unit up on a variac? you know to "reform" the caps?
If so how would one go about doing that?
The latest recipt in it was from 1972 and likely the last time it was used.
Thanks
Ray
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One cardinal rule with Eico testers: DON'T TRUST THE ROLL CHARTS!
They are full of errors even in updated form.
More info: http://www.tone-lizard.com/Eico666.html
Download and use the latest - 1978 - Coletronics tube charts. There are still a few mistakes but AFAICT all really silly ones have been ironed out.
http://bama.edebris.com/download/eico/666/charts-1978/666-%20coletronics-1978.pdf
Re. maintenance, I would change the two 10µF elcos as well as their associated selenium diodes, check pots and internal wiring. You may also consider adding a 3-pronged cord and earthing the chassis.
More details: http://www.tone-lizard.com/Eico667_troubleshooting.htm
(The 667 is nearly identical, no more evil name, no more 4- and 5-pin sockets and a front panel fuse added)
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Evil tester---RUN AWAY!!!! :evil4: :wink:
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So, just fire it up?
If the caps go POP replace them?
OK i just re-read every thing and I have the stuff to change them out before I use it.
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Mine found a hot-short. Paid for itself right there.
The main "test" function is IMHO hardly useful. The charts are wrong. Even when they are right, it is just a conductance test, and often brutal to the tube (why tube-vendors hate these things). I ran through a bunch of used tubes and decided that whatever a 667 said, good or bad, was usually wrong.
Set the settings and *verify* you get the right heater voltage in the right holes. Insert tube; does it light? Run through the short-test, but don't trust a "bad" reading until you compare the pinout. Let it heat for 5 minutes and short-test again. Then TAP the test button; if the meter moves at all, call it "good?", good enough to put in an amplifier for further study.
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You can access a current discussion on 2 sites through this link;
http://www.tdpri.com/forum/amp-central-station/203024-eico-667-tube-tester-best-way-determine-correct-settings.html#post2403722
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Thanks guys!
I never knew a simple tube tester could be so complicated or controversial.
It seems my first tube tester is the best so far, but limited in scope of the types of tubes I can test (model 5F2-A)
I do lke the way there are so many ways to set a tube up to check it. it's no hi dollar hickock, but its mine!