Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jan Sat 16, 2021 3:40 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 28 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Eico 666 Puzzle!
PostPosted: Oct Fri 29, 2004 8:11 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1982
Location: Oswego, NY, USA
Tom, On most testers, if some of the filament voltages are a little low, and some are a little high, it means that you need to live with it and just make slight "line adj." changes as you test various tubes. Many of the filament transformers weren't wound perfectly or were possibly wound for a little different line voltage. Some transformers are better than others in this regard. If some of the voltages are out by more than a few tenths volt, then some windings might be bad; time for transformer replacement. Some Ebay testers get sold with damaged transformers & burned resistors, etc. I think that it's difficult to find an affordable replacement Eico666/667 transformer unless one purchases a "parts only" complete unit; then it's a gamble if that transformer was fried. The applied filament voltage doesn't have to be perfect, as long as you are in the range and are consistent.<BR>Fred <P>------------------<BR>


Top
 Profile  
 
 Post subject: Eico 666 Puzzle!
PostPosted: Oct Fri 29, 2004 8:27 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 25381
Location: Pocasset, Cape Cod, MA
They'll be high with no load; try measuring with a tube connected. But it may be normal. I have a Sencore Mighty Mite that puts more than 7 volts on the 6-volt tubes.<P>------------------<BR>


Top
 Profile  
 
 Post subject: Eico 666 Puzzle!
PostPosted: Nov Thu 04, 2004 10:35 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1982
Location: Oswego, NY, USA
My "as-is" Ebay Eico 666 tube tester arrived (2 yrs. ago) with a burned out meter armature. Last night I finally installed a good meter taken from a Sargent-Welch Analytrol spectrometer (obsolete) that is the exact same meter except that the Eico meter armature is ~1000 Ohms@200ua (200mvfs) & the Sargent meter is 468 Ohms@200ua (96mvfs). The replacement meter calibrated fine with the "Line Adj." & "Leakage Cal" steps in the Eico manual, but all of the "merit/value" readings read extremely high beyond full scale. I then installed a small wirewound 1K trimpot in series with the meter & set it to 530 Ohms (for a total of 1000 Ohms in the meter circuit) which then provided the correct merit readings, compared to my Eico 667. So, the "value" readings are also greatly dependent on the meter circuit resistance/meter mV sensitivity. I reset the Line & Lkg pots. but they hadn't changed much. Ink stamp date in my 666 is Dec. 31, 1958; the two diodes are original/ancient but work fine.<BR>Fred <P>------------------<BR>


Top
 Profile  
 
 Post subject: Eico 666 Puzzle!
PostPosted: Nov Fri 05, 2004 10:14 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1982
Location: Oswego, NY, USA
Tom, <BR>My post from yesterday was merely to show that the panel meter resistance helps determine the final tube value/merit reading on the Eico 666/667/Simpson1000, and it could be used as a way to fine-adjust the overall merit/value readings if they are too high or too low; as long as everything else is OK. With your tester, the transformer is probably alright. As Mr. Douglas mentioned, be sure to take the line readings with a typical tube (for that filament voltage) inserted. Then make a mental or written note of these slight differences of the "Line Adj." meter reading so you can easily dial up the correct fil/heater V. with other batches of tubes. All nine of my testers (various brands) have some degree of the problem you've described; it's a matter of temporarily hanging an ACVmeter and recording these differences. On tubes that pull alot of Fil. Amps (extra voltage drop), it can help to check with the voltmeter again. <BR>Fred <P>------------------<BR>


Top
 Profile  
 
Post New Topic Post Reply  [ 28 posts ]  Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: frustro, mrrstrat, Sid47, Willitwork and 17 guests



Search for:
Jump to:  


































Privacy Policy :: Powered by phpBB