Vintage Memory Man deluxe

[szybki360]

Hello everybody hope you all doing well, I'm trying to repair my old EHX memory man deluxe, sounds very distorted it's not clean,a lot of nosie I notice that the chips been changed from RC4558 to TL072CN not sure if that's the fault... I was trying to play a little bit with the trim pots in order to eliminate the noise with no luck also  planning to replace the big 200uf cap perhpas that's the issue. Thanks for your help,happy to upload a video in order to demonstrate the sound issue.

[Kevin Mitchell]

The first thing I would do is audio probe the inputs and outputs of each SAD1024 channel (these are dual 512 stage devices). Always best to rule out a bad BBD first.

What model is that board? Trying to find the schematic.

                                                                                          And welcome to the forum!

[szybki360]

Hi thanks for the reply, the board is eh 1307b

[Kevin Mitchell]

Here's a page someone had done for calibrating that unit.

Assuming you don't have a signal generator, oscilloscope, frequency counter or a multimeter you could just plug your guitar into the pedal's input jack and use an audio probe at each test points to dial down any distortion from the SAD1024 chips. If you find a point where you can't dial it out then you've found something worth investigating.

Here's the sacred audio probe


Alternatively, you could just use the pedal's output by disconnecting the output wire (jack tip) from the PCB and probe the test points with the tip wire.

[szybki360]

Thank you Kevin, I have a multimeter( digital one) I will try to purchase a audio  probe or I could  just build one

[bluebunny]

Welcome.  You won't find one to buy.  Build it: it'll prove very useful.