Maxon - DUE-400 compressor, distortion, Chorus / Flanger and Delay

[luctrev]

Greetings

This is my first post, but I follow the forum for a long time and the information contained here was already very useful for me.

Today I'm asking for help.
I'm having trouble repairing my MAXON DUE-400. It has a compressor, distortion, Chorus / Flanger and Delay effects.

The distortion and compressor effects are work great, but the Chorus / Flanger and Delay does not work. At the exit I have only the signal dry, not the wet signal. I checked the switching stage and everything okay.

Firstly, I checked the power supply and didn't found nothing suspect. The Chorus / Flanger LFO is running ok, but I do not understand how the delay work so I don't know what looking for.

I got the schematic for analog stage, but I didn't find the MC4101F datasheet!


Could someone has experience with this device and can give me a starting point for verification?

Thanks
Luciano S. T.

[luctrev]

Hi

Attached are the schematic files and the steps for adjustment.

Following steps to adjust

[Digital CH / FL]
[A] - Clock Frequency: setting SR4 I can not reach more than 50kHz on CP4!
- OffSet voltage: OK

Since I could not adjust Clock Frequency I did not go through with the rest of the settings.

PS:
The LFO was not working so I replaced C133, C135, C136, C137, C138, C139 and the oscillator ran again.

Thanks
Luciano S. T.

[Dirk_Hendrik]

Do you have an oscilloscope available? If not, get one first. Troubleshooting without in systems like these is a PITA.

[luctrev]

Do you have an oscilloscope available? If not, get one first. Troubleshooting without in systems like these is a PITA.

Yes, I have an oscilloscope. I used it to find the LFO problem and then certify the solution!

For now I'm trying to get the correct frequency in CP4, the SR4 is ok, but I have a certain fluctuation at CP4 and I cannot get over 50 Khz!

[luctrev]

By the way ...

I don't know how the MC4101F works, so I do not know what to expect in its pins!