Maybe it is the same model as mentioned under
https://www.diyaudio.com/community/...eview-in-english-and-schematic-wanted.255097/
but one of the first devices from 1989 :
http://www.hoererlebnis-verlag.de/he/archiv/38omtec.htm
Exactly I know this after check the circuits of gain/RIAA stages.
Unfortunately an annoying problem due sprayed of construction mounting PU foam
(polyurethane foam) into the enclosure after installing the PCB.
Because of some bloated caps in the PS (first attached images), no functional check is possible without risk (danger of explosion - check out image search by google keyword "bad caps").
I also noticed that the usual bypass capacitors are simply missing on the voltage regulators and the rectifier is only a very small bridge version.
https://www.diyaudio.com/community/...eview-in-english-and-schematic-wanted.255097/
but one of the first devices from 1989 :
http://www.hoererlebnis-verlag.de/he/archiv/38omtec.htm
Exactly I know this after check the circuits of gain/RIAA stages.
Unfortunately an annoying problem due sprayed of construction mounting PU foam
(polyurethane foam) into the enclosure after installing the PCB.
Because of some bloated caps in the PS (first attached images), no functional check is possible without risk (danger of explosion - check out image search by google keyword "bad caps").
I also noticed that the usual bypass capacitors are simply missing on the voltage regulators and the rectifier is only a very small bridge version.
Attachments
This images after add bypass capacitors, electrolytic capacitor replace and elimination of contamination between solder joints.
When increasing the gain to values higher than the lowest possible, high-frequency ringing occurred without connected MC cartridge on the cinch input (non inverted input). Reason therefore was the not used input resistor and partly the not used bypass capacitors at the inputs of voltage regulators.
When increasing the gain to values higher than the lowest possible, high-frequency ringing occurred without connected MC cartridge on the cinch input (non inverted input). Reason therefore was the not used input resistor and partly the not used bypass capacitors at the inputs of voltage regulators.
Attachments
This model is those described under
https://www.diyaudio.com/community/...ish-and-schematic-wanted.255097/#post-5180238
https://www.diyaudio.com/community/...ish-and-schematic-wanted.255097/#post-5180238