#52: EICO 667: Initial testing

This video looks more closely at the circuitry of the EICO 667 and goes through an initial test. We identify some needed resistor replacements, which must take place before attempting to calibrate the unit in a future video.
* A nice summary of the model 667 tester, diyaudioproject...

[@wa4aos]

FYI, some carbon R's do drift over time from current past degrading the C substrate. However, slightly used vintage C resistors and even NOS C resistors drift up in tolerance. Presumably since the C substrate is somewhat hygroscopic and absorbs moisture. A test, take your out of spec, slightly used R's measure them with an accurate DMM. Then bake them at 140F for an hour or leave them in the sun for most of a day and remeasure. In all most every case, the value will go back to normal or well in the value provided by its tolerance band. To go further, test them again in a year or two and they will still be in tolerance. Apparently, the drifting up in value takes years to occur. So, in your case, if you had left the unit outside bottom up for most of a day, I suspect, strongly, your R's would be back in spec.

[@jameslucas6589]

Just watched it again, and really like your presentation. Give us more vintage restores please!!!! I find those to be the most interesting and educational of all. Great job!

[@johncunningham5435]

A good in depth interpretation of the EICO 667 tube tester, "well done".

[@larryrichards1795]

Further Comment on R8 and R19. I found a 1964 schematic on BAMA that shows both resistors at 270K. All other resistor values the same as my 1973-4 schematic, except some of the power ratings. There probably are a number of units out there that have the 270K resistors. I’m surmising that when the schematic was changed, the two resistor values were switched. My thinking is the schematic is in error, not the factory installation of the resistors that seem to have been switched in this video. (far more unlikely)?? See my other post that brings me to this conclusion. Can anyone verify any of this?

[@jimdawes7261]

I have one of these also and think it's a beautiful machine as well, now I must look under the hood and check the resistors.

[@robbyxp1]

Again, great video, good camera work. thanks

[@larryrichards1795]

I just received a 1973-74 Eico 667. It is a kit assembly, no roll chart. The interesting point is the problem you looked at in this video of the resistors R8 and R19. You surmised that the factory had switched them in error per the schematic. I thought that was pretty astute until I looked at the operating manual with my newly acquired unit. The long time kit builder had made a notation on the schematic that switches the locations of R8 and R19. Interesting! Perhaps the schematic is in error and the factory resistor install was correct? If so your unit is not measuring correctly? Perhaps there was an 1973 addendum that corrected the mistake on the schematic, since this builder in 1973-4 had penciled the change on his schematic. And since the factory install did it according to his schematic notation change, it is now more likely to me that the factory did NOT make a mistake.

[@adriannicol8529]

Thanks, clear and informative and helpful as I am restoring a 667 right now, albeit an earlier version to the one you show - and way more beat-up! I am slightly confused as to why you thought the apparent reversal of the two resistors would explain the reported 'low' readings unless you attempted a calibration (it takes approx 40 seconds to do) and had it fail? Each was only 30K adrift from the nominal shown on the schematic and each is in series with a 100K pot wired as a variable resistor so the thing may well have been capable of calibration even though the pots may end up towards one end of their travel. It is the total of the R6 & R7 and the R18 & R19 combination that matters, the proportion of which is fixed or variable is irrelevant to the operation of the instrument? Just FYI my earlier version has them both the same at 270K + 100K pots.

[@mikem5043]

My 667 has the roll chart and there are definitely some different value resistors

[@W1ZY]

38:02 *You need to remove the tube before changing the levers.*

[@jeffreyhaynes5774]

Do you have a listing for 6BQ5 in your manual for this tube tester?.

[@Tysman909]

Those resistors should be fine it's the brown ones you should worry about there carbon comp which drift up with heat and moisture

[@radiotvrepair1059]

Thanks for this vedio.I am a technician of old TV radios I want to know if a tube is working well or not working. To test the short circuit, leakage and emission.

[@SandersAmps]

I was lucky to buy an almost mint 667 off ebay yesterday. I replaced the 10uF caps and calibrated - it didn't need much. But it reads good 12ax7 tubes in the red when I know they're new and work well. Is that poor calibration on my part, or perhaps an error on the roll settings?

[@Tysman909]

Interesting that you have to depress a leakage switch to do a merit test

[@2tallB]

“I cleaned up the blades of the power cord to make sure there was no oxidation on the blades. And that worked out well…” I didn’t see the rest of the video because at that point I slit my wrists and died. Sorry.

[@peteleoni9665]

Here's an hour and a half. Now you can watch 60 minutes. 😂

[@jameslucas6589]

Good eye for detail. Really clean factory build. But I surmise this might have been built. In the 1970s That era was fraught with really poor craftsmanship. I noticed from autos to plumbing, people were absent in moral and ethical work habits. People took great pride in mediocrity and mistake making.. So went the jobs and products and people's livelihood. I share your issue with color. Very very frustrating when attempting resistor and bumble bee checkout.