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"Alte deutsche Amps" und der Dynacord Reference 500

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Thinline:
Hi Marco!

I had the same problems with my ref 500 - i found out that the A/D converters (MC 144111) were defective, so the optocouplers didn't react and therefore: no sound! You can check this (pay attention to the very high voltage in the amp!!!) if you pull away one of the black castings of the optos - if there is no change  in brigthness when ypu turn the knobs then the A/D converters are bad!

greetings
Bernhard

Thinline:

--- Zitat von: HubertB am 19.04.2021 17:51 ---Hallo,
danke für die Antworten. Bei Dynacord habe ich nachgefragt. Leider haben sie die Hex-Datei nicht mehr. Haben mir freundlicherweise noch die Bedienungsanleitung als PDF geschickt. Einen antiken Brenner habe ich mittlerweile und konnte das Eprom (27C64) auch auslesen.
wie schon vermutet, sind nur noch Nullen drin. Wenn ich niemand finde, von dem ich das Eprom kopieren kann, werde ich wohl die Digitalplatine überbrücken.
D.h. die analogen Signal der Potis abgreifen und direkt auf den Vorverstärker geben.  Dummerweise sind die Signale invertiert. Da muß ich noch mit OP's die Signale nochmal invertieren. Dann kann ich ihn wenigstens als normalen Verstärker benutzen.

--- Ende Zitat ---

Hi! Hast du inzwischen den HEX Code gefunden - ich müsste den noch haben, da mir auch mal ein Eprom kaputt gegangen ist.
Grüße
Bernhard

marcomeloni1979:

--- Zitat von: Thinline am 25.08.2022 12:33 ---Hi Marco!

I had the same problems with my ref 500 - i found out that the A/D converters (MC 144111) were defective, so the optocouplers didn't react and therefore: no sound! You can check this (pay attention to the very high voltage in the amp!!!) if you pull away one of the black castings of the optos - if there is no change  in brigthness when ypu turn the knobs then the A/D converters are bad!

greetings
Bernhard

--- Ende Zitat ---

Hey Bernhard, thank you very much fir your reply! Im more of a Marshall/Fender point to point guy, dont have any experience with the digital side of amps. 
I see from the schematic that there are two different MC144111. Im assuming is one of these in the first photo and the optos are these? If yes, at least two have no light.  I csn see that one does...

marcomeloni1979:

--- Zitat von: Thinline am 25.08.2022 12:33 ---Hi Marco!

I had the same problems with my ref 500 - i found out that the A/D converters (MC 144111) were defective, so the optocouplers didn't react and therefore: no sound! You can check this (pay attention to the very high voltage in the amp!!!) if you pull away one of the black castings of the optos - if there is no change  in brigthness when ypu turn the knobs then the A/D converters are bad!

greetings
Bernhard

--- Ende Zitat ---

Are these In the first pic the possible faulty parts? Nd in the second pic, are those black cilinders the optos. I can see at least two dont light up...

Thinline:
Hi!

If you can see only one opto lighting then botth D/A converters are faulty. If you look at the schematic you can see that opto I 004 is for the volume - if there is no ligt there is no sound! I would change booth mc144111 (i cant't see anything on your photo (too dark), but you can read the writing on the IC. Nearby the IC's should be written  "I 007" and I 008"  and on the IC "MC 144111". Please watch out for the right name of the IC's when you order them - should be MC 144111 P with 14 pins.
Another posibility for the malfunction could be IC  MC 14447 CP - this is the A/D converter and the heart of detecting your turning on the knobs.
The last possibility is that the optos themselve are defective. To be sure that that is not the case you can messure the voltage on the analog outputs of the  MC 144111 P while turning the knobs (very tricky, because there is rather smale place between the pins!!!) - if there is a change in voltage, then the corresponding opto (or the ribboncable from the digital Board to the tubeboard) is bad.
I hope this helps - dont't hesitate to contact me
Bernhard

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