echoplex ep-3 repair

[gitaar0]

Hi,

I have an old echoplex ep-3 that I am trying to repair.
I have dry sugnal and only one, but distorted repeat.

I have cleaned the heads, demagnetized them and I am using a new cartridge and tape. It seems that the echo sustain pot does nothing. Where should I be looking to repair this?? I am using this schematic as a reference as it seems closed to mine: http://www.guitar-parts.com/images/ep3a.jpg

My thoughts are:
- as I have signal the input buffer should be ok.
- I have one repeat so the recording and playback head are working.
- I can raise the recording level with the record level trimpot.
- the repeat is distorted so either the signal coming from the buffer to the recording head is not ok or the recording head is not ok.
- as I have almost no repeat there could be a problem of the signal coming from the echo head back to the recording head is not ok.

What would you start with?

I read almost every thread there is on this subject and read all of regiscoyne's site (thanks!) but it does not put me in the right direction. There is an old post with a similar problem but that was never finnished.

Help would sure be appreciated.

Thanks, Marc

[52 Bill]

The question is whether or not the signal is being recorded on the tape cleanly or distorted, and whether or not the signal is passing through the playback circuit at Q1 and Q2. This could include the playback head as well.

Because the playback is so greatly effected, I'd start by checking all of the circuitry around Q1 and Q2. If there are no bad parts or connections and all of the voltage readings are where they should be, then inject a signal and see if it passes cleanly.

[gitaar0]

The question is whether or not the signal is being recorded on the tape cleanly or distorted, and whether or not the signal is passing through the playback circuit at Q1 and Q2. This could include the playback head as well.

Because the playback is so greatly effected, I'd start by checking all of the circuitry around Q1 and Q2. If there are no bad parts or connections and all of the voltage readings are where they should be, then inject a signal and see if it passes cleanly.

Hi Bill,

Thanks for reacting. I will start as you suggested. Probably this weekend.

Thanks for putting me in a direction.
I am open to further suggestions.

Best, Marc

[Enzo]

Adjust the recording bias and the bias trap.

Scope the signal going through the record amp. Clean? Distorted? Breaks up where?

Guide the tape a little higher and lower with a finger. See if the record and playback heads are striping teh tape at the same point width-wise.

[gitaar0]

Hi,

I followed up on some of the suggestions. I checked the playback section, which seems to work ok. Signal in is amplified quit a bit but is not distorting. I still have to figure out how to work with my scope so I can set the recording bias.

It will take a while as I will be away a while.

Thanks, for now Enzo and Bill.

Marc