Studer A-810 problem

[tinearpaul]

Hello:

I live in California and Christoph suggested I post my problem about my machine here. My German is limited to holidays in Germany so I can't do any technical, just order more beers!

I was given a Studer A-810 Serial number 2883 about a year ago, It had sat in a warehouse for many and unknown years. The unit was very dirty on the front panel, appeared rain had hit it. Was mounted in wheeled console with meter bridge. There was a mouse problem in the meter bridge, they had eaten some of the blue ribbon cables and made a nest inside. All that was cleaned out and meter cables repaired before I started to look at this machine. I replaced all four meter bulbs.

First turn-on, immediate display of EE14 error. Printed copy of service manual from Studer FTP site and found this error code. Cleaned all connectors, made sure all cables secure etc. Power-on again EE14. Unit was VERY eratic in operation. Only speed was 76 cms. SYNC LED on. No CCIR/NAB or TAPE A/B selection. Could not select PLAY directly, only by tapping FF key would machine go to PLAY. REW and FF work. Tape counter displays EE14 continous. Did get audio out of machine. REC LED on, no problem found four missing record boards in machine.

Continue cleaning unit. Remove all plug-in boards. Use anti-static strap. Clean contacts. Get to MP board (1.820.780) saw much copper sulfate (green) corrosion on SN74159A chip, one battery directly connects to. Battery dead, no voltage. Remove all IC's on board and clean each socket. 24 pin SN74159A was really bad. Cleaned and re-install. Power on, no EE14 error, have 00:00:00 display. Play tapes for hours. Can't record, no record boards. But unit does seem to be working better. Still no capstan speed selection, fixed at 68 cms. No CCIR/NAB or TAPE A/B. Could find 00:00:00 in REW a few times. Even had STOP LED flash at one second interval. Then operation starts to become erratic again. EE14 display, REC LED on again. Try cleaning MP board now multiple errors depending upon how and when plugged in. A084, blank, A184, -1:00:00 and others no pattern. Wiggle MP board errors change. As short time goes on machine operation becomes more erratic. Example, take-up motor would go on-off-on-off-on-off without tape threaded. I was able to DIP switch select 19 cms. fixed so I could play tapes.

About this time I find a complete set of A-810 boards (12) for $475 at FILMCO in Canada. Good deal since I am missing the four record boards. They arrive and the new MP board comes with a new battery. SO I install the new battery in the new MP board (1.810.780.21).
Plug-in new MP and new error F888 display. ALL transport LED's on, No PLAY, FF, REW transport dead. No capstan operation. No CCIR/NAB or TAPE A/B operation.

I decide to rebuild my original MP board. Found new 24-pin AMP tin plate socket. Remove old socket, check all vias after old socket removed and after new socket installed. Bought new battery for my board (reading 3.8 V). Install board in machine, power-on, F888 on display. Again same problems as above, basically no transport operation ALL LED's on even REC. Yes, I have pushed the reset button on MP boards many times.

So now I have two MP boards with same error and I can not find this error in Studer documentation. I have no idea if any of the other 50 DIP switches are in the correct position, can someone help me here? I have no history on this machine so I don't if it failed and someone was working on it and messed with DIP switches or it failed in storage.

Since I had spares of all other transport boards, I have swapped out all others (all have same part number as original) and get the same error message.

I was told you must have the same series of MP installed or the transport will not work. I do not know if these two boards are compatible? I was also told the machine goes through a self check at turn-on and displays firmware revision, this machine has NEVER done this, even when I had 00:00:00 on display. Normally it immediately goes to an error message and ALL LED's light up.

I should have lived with EE14 error, at least the machine played tapes. But since BOTH MP's display the same error, then that could be telling me it's something else.

I have a remote serial card installed as well. Do I need this card? I do not intend to run it remotely. Could this be causing my problem? I did not get an extra of this board from FILMCO.

I have test equipment and have a small repair business at home working on audio gear and do repair work for three high end audio stores in Sacramento. I worked at Hewlett-Packard for 25 years and am an Amateur Radio Operator so I can and do fix electonic products so don't feel limited to ask me to check something. I also have two Revox A-77's IV's (2 and 4 track), a B-77 2 track, Technics RS-1520 and an AMPEX AG-440C all of which I have worked on.

Thank you all very much for any help in fixing this machine.

Kind regards

Paul Warenycia/KA6NFP
Roseville, California