Echoplex ep3. Anyone knows it well ?

[Xplorer]

i still didn't figure how to remove some noise and bugs from my ep3's, even if on one i changed all the resistors, twice ( !!!! ) , all the elctrolytic caps, worked on the transistors fets etc .
you'll need a lot of patience and see this as some fun anyway. there are not that much components after all.

my method, for mine, will be to compare the circuit with the schematic, and desolder each component, make sure it's to spec, and resolder it or replace it.
you may have a damaged head, who knows ... there are some tests to do on the heads but i don't remember.
you could compare the noise between the echo and the SOS, to compare both reading heads. you know ... stuffs like this ..

i'll replace some pots on mine, re analyse the heads, swap some boards with some spare ones i have , etc ... long road. i'm not able to use a scope so ...

use a pencil on the schematic, on the parts and zones that have been checked, and it should help you to locate the bug, the faulty part ...

with your clip, i heard the amp alone doing some noise so i thought it was the echoplex without the echo.

[rgorke]

Well, I've done something. I changed the caps on both boards. I also put in a new echo/SOS switch. It maybe the wrong type. I now have a different problem but similar to my other echoplex. On Echo, I still get noise, now SOS is cleaner but I get both echo and SOS.

Same on my other one. I must have the switch wired wrong. Regardless, at least now my noise is 1/2 gone. I need to order two switches that are truly the right spec.

[rgorke]

Some progress....

I think the root of my problem is in the switch wiring. I installed an on-on-on or on-off-on DPDT and now have the same noise on Echo, but no echo. But on SOS, I have no noise (!!!)-but I have echo AND SOS. I have changed all the caps on the boards.

In examining the switch I took out, it appears to be an on-off DPDT. I have a new one to install.

Does anyone have a good diagram of how the switch is suppose to be wired?

[rgorke]

Well, I got it fixed. It was related at the switch. I made sure I had the absolute right one and that it was wired correctly.

Whoo hoo, we definitely need some sort of Echoplex wiki.

[Xplorer]

congrats ! so before, you had echo, sos, but noise, and now just thanks ( mostly ) to the switch wiring it's gone ? i'm curious of what tiny undesired connection made it wrong.
maybe some picture before/after ?

yes, an echoplex base here would be nice, very nice. This is a classic, and here it would be the best place ... exchanging infos, building a base of knowledge, trading/selling parts ... to have these mike battle wonders to work for a loong time.

i created a facebook echoplex specialized group by the way, but i don't even have the time to entertain it.

[rgorke]

Well, I also changed all the electrolytic caps in the top boards. Not sure if that was. Help but it could 't hurt. I think, frankly that a wire was working loose and finally came undone or a solder joint went bad or all of the above.

Gotta make sure the switch is on-on DPDT too.