Engineer
October 13th 06, 04:09 AM
François Yves Le Gal wrote:
> I've just got a near-mint Eico 667 (late production, ca. '75) in need of the
> usual TLC - I'll replace ASAP the original selenium diodes CR1 and CR2 as
> well as the C1 and C2 electrolytics and the calibration potentiometers R7
> and R18. Does any RAT have other suggestions re. restoring this tester to
> it's full glory?
>
> OTOH the 667 has no sockets for oddball tubes such as the 807 or 2A3, so
> I'll need to find - not very easy - or build - more probably - a 615
> adapter. I've searched for it's schemo but haven't found it. Has anyone got
> a copy he'd share? Or should I go the simplest way : build it my own way and
> wire it pin 1 on the adapter to pin 1 on the tester, etc.?
I restored a simple Heathklit TC-2 the same way, replacing the selenium
rectifie with a Si diode, but I had to recalibrate it due to the
different diode voltage drop. It was a while back and I don't recall
all the details but I used a helipot to adjust the DC.
Also, I found al the fixed resistors (carbon) were way off - up to 25%
or so - replaced all with metal film 1% types to factory values.
Cheers,
Roger
> I've just got a near-mint Eico 667 (late production, ca. '75) in need of the
> usual TLC - I'll replace ASAP the original selenium diodes CR1 and CR2 as
> well as the C1 and C2 electrolytics and the calibration potentiometers R7
> and R18. Does any RAT have other suggestions re. restoring this tester to
> it's full glory?
>
> OTOH the 667 has no sockets for oddball tubes such as the 807 or 2A3, so
> I'll need to find - not very easy - or build - more probably - a 615
> adapter. I've searched for it's schemo but haven't found it. Has anyone got
> a copy he'd share? Or should I go the simplest way : build it my own way and
> wire it pin 1 on the adapter to pin 1 on the tester, etc.?
I restored a simple Heathklit TC-2 the same way, replacing the selenium
rectifie with a Si diode, but I had to recalibrate it due to the
different diode voltage drop. It was a while back and I don't recall
all the details but I used a helipot to adjust the DC.
Also, I found al the fixed resistors (carbon) were way off - up to 25%
or so - replaced all with metal film 1% types to factory values.
Cheers,
Roger