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Author Topic: STUDER A810 - help needed: strange message on display - strange behavior...  (Read 1312 times)

Offline OZ1963

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I bought a STUDER A810 (SN 1291) that was said to only have an issue with recording.
I was looking for a playback machine - so that was ok for me.

Unfortunately the machine shows „:41EE“ on the display - does anyone have an idea
what the means?  (the regular error codes are „EE xx“).

Some things still work, some dont:

Fast Forward and Rewind works, but when the machine is put on PLAY the REC-LED is also on,
and after some 10-15 seconds it stops moving the tape without proper tape handling (no “brakes”,
the tape gets unwinded until the wheels stop completely).
But when switching e.g between Fast Forward and Rewind the tape is handled correctly, the
tape tension is ok.

The channel controls seem to work (at least the LEDs behave correctly), but the Master Panel
reacts strangely. It has three switches for CCIR/NAB, Tape A/B und 7,5/15ips.
Only on two of the three pairs one yellow LED is active, on the third group both LEDs are
dark. Pressing the small knobs (while holding the STOP key) does not do anything.
Only from time to time one LED gets on in the “dark group” - making one of the other groups
dark.

What I did try so far was:
- removing all cards, checking them (optically), including the battery on the MP-unit
   and returning them to their slot - to be sure they fit properly, after the machine had been
   shipped
- I also tried the RESET button on the MP-unit
- checked the cable connections (plug/socket) as far as I did get with opening the machine
No change at all….

Does anyone have experience if the is a hardware issue (broken/old component, bad
connection/cable,…) or a software issue (contents of EPROMs damaged,…).
How can I determine this?

How many cards/compenents can I remove to check who the culprit is? E.g. all the audio
cards?

Thanks in advance for any help you can provide!

Offline yjwu

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Hello OZ1963:

All voltage measured O.K.? I remembered one electrolytic capacitor behind the keypad/display usually went bad, causing a lot of strange behavior. That large capacitor has marginal voltage rating, about 9V, for a working environment of 5.6V. When it short-circuited it would blow up a in serial resistor.
Sometimes re-sitting OP amp's also helps. Anything could happen during shipping.

Yeun-Jung Wu
« Last Edit: October 29, 2016, 03:02:57 AM by yjwu »

Offline stellavox

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For "distributing" the 5 volt logic power around certain of the A8.. series of recorders, Studer took the "interesting" path of creating a higher voltage, maybe 6 volts on the power supply board, and then "dropping it down" via a diode, or in some cases a diode / dropping resistor / smoothing choke ON THE INDIVIDUAL BOARDS where logic power was needed.

On the two 812's I "rebuilt", and other models I've worked on,  some electrolytic filter caps on the individual boards went bad OR LEAKY and went as far as charring the dropping resistor / choke.

I suggest checking the logic voltage ON EACH BOARD AFTER THE DROPPING "NETWORK" and see if it is within spec.  Better yet, as many have mentioned in other posts/forums, identify and replace ALL THE CAPS ASSOCIATED WITH FILTERING (only a few on each board - use 105 degree replacements - remember that some boards had caps for the +/- 15V also.  After that, the units worked fine and in some cases readjust the logic voltage DOWNWARD (out of the regulator card) because "something(s)" (combination of leaky caps?) was dragging it down.

Charles

Can't emphasize enough that these machines, being a MINIMUM of 25 years old AND many/most with QUITE a few hours on them, "DESERVE" a FULL electrolytic FILTER cap replacement - especially if you "think" you plan to use the deck "for many years into the future".  A trick I used for replacing the big (hard to find) stud-mount caps (because new "snap-in" equivalents are physically smaller) was to cut the case (with a hacksaw) maybe an inch from the bottom; remove the guts / clean out the case and epoxy in the replacement - making sure to arrange the terminal positions to minimize wiring distances.  Yes it takes time, but only should have to be done once, AND should really add to your "peace of mind" regarding your ongoing relationship with the deck.  Finally, if you can't do this yourself - MAKE SURE any deck you buy has had this done.
« Last Edit: October 29, 2016, 07:30:27 AM by stellavox »