Echoplex EP-3 - almost no output

[eternal slang]

HI all,

I'm troubleshooting an echoplex ep-3 with a very faint output.

All the voltages points checked all right as on the schematic except on Q4 emitter
where I read 1v instead of 16v and after Q5 0.1uf cap where I read 0v instead of 14,4.
Does anyone know where could be the fault?

Many thanks for your help!

Fabien

 

[PRR]

Q4 emitter should not be higher than base (or collector!). Clearly this is a typo: 1.6V, not 16V.

The "14.4V" should be on the Q5 drain side of the 0.1u cap. Point 23 has to be zero V.

 

[CJ]

those things need a lot of TLC to get them to work right, mechanical and electrical ,

here is a great page for info and help >

http://www.regiscoyne.com/echoplex/

we did a pwr transformer rewind, and also modified the motor for sealed bearings, since those old motor bushings are not that great over time, and new motors are very expensive,

the mechanical relay also can cause trouble so we modified that with different springs and voltages etc,

 

[eternal slang]

Thanks PRR for pointing me towards these errors in the schematic.
So the voltages I read seem correct.

And thanks CJ for the link, very useful info indeed.

This unit has been overhauled last year by Tony Krank in Arizona.
He also replaced the motor and everything was working fine.

I checked the signal with a tracer and it is present until point 23 after the 0,1uf cap for the clean signal and on point 19 before the 220k resistance for the recorded signal. After these points a huge drop in amplitude occurs.