EHX frequency analyzer issues

[Zouto]

Hi, a good friend asked me to spread the following request to get his Frequency Analyzer working again:
Hi, my big box EHX frequency analyzer EH 5000 box / EC 9000 pcb suddenly quit working, I only get the pure tone generator sound on output, Blend ctrl. and tone switch do not work anymore. Switching tone switch ON cuts down output signal completely. The pedal is modded to FX On Status LED and EXP pedal Output, using the Direct Out with a stereo jack, wired parallel to the Shift ctrl. It used to work fine during a long time after the mods. So I need some help to fix that great pedal.
Thanks for help and hints
Klakto

Hoping for reply
Zouto
https://www.audioservicemanuals.com/...-new-schematic

[pdf64]

Do the +/-15V supply rails check ok?
Are the opamp outputs close to 0VDC?

[Zouto]

Thanks pdf, checking +/- 15 rails, I found no negative voltages anymore, zener D2, C11 and 2K resistor shorted. All op amps run on positive voltage at the moment, great damage. I‘m not sure what part caused it.

[Zouto]

Unsoldered Anode of D2, checked it, found it shorted, replaced it with ZD15 zener, checked the pedal and found it working Great again in Ring Modulation Impro Music Space….. Klakto is happy again, solid creative comfort in political seriously hard times!