Mephisto Exclusive Board Defective Reed Switches

[Scrooge_Mcdude]

Hello,

This might have been asked and answered before but I couldn't find the thread.

My question is - how do I find all the defective reed switches on a Mephisto Exclusive board without necessarily playing a game and find out one by one which squares have defective reed switches? I know that for Conchess, all you got to do is put all the pieces in the center of the board and all the LED's will light up except the squares with defective reed switches.

Thanks for your help.

Regards.

[Steve B]

Hello,

This might have been asked and answered before but I couldn't find the thread.

My question is - how do I find all the defective reed switches on a Mephisto Exclusive board without necessarily playing a game and find out one by one which squares have defective reed switches? I know that for Conchess, all you got to do is put all the pieces in the center of the board and all the LED's will light up except the squares with defective reed switches.

Thanks for your help.

Regards.

Hi
not really sure of your question
set up the board as if to play a game
then take a piece like a Knight and place it on every square one by one
depending on the modules you have in the board you should get an illegal move indication and a beep
except of course squares c3 and f3...this is a legal move for a Knight
you might have to press CLEAR after each turn
this will indicate that the board recognizes that a piece is on that square and the reed switch is working

Willis Reed Regards
Steve

[tkollen]

I did recently purchase a Mephisto Exclusive MMVI, brand new in original box, from someone who purchased this game brand new in 1993. He did never play any game, not even once. Instead he put the chess board with the pieces in their start positions on a high shelf and let it sit there for 20 years.

Now when I try to play the Mephisto it barely turns on. Sometimes I see fragments of some characters on the LCD and that's it. I've read somewhere on the internet that leaving the pieces on the board for a longer period of time might damage the reed switches. If this is true then I assume that 20 years is more than enough to make this happen and this may be the reason for my problem.

With this in mind I plan to replace at least 32 reed switches and I'm interested to get some advise on brand, type and specs for a suitable reed switch and where I can find the at a good price.

[xchessg]

Now when I try to play the Mephisto it barely turns on. Sometimes I see fragments of some characters on the LCD and that's it.

Hi,

If I were you I'd start looking at the adapter and/or the voltage that the board puts on the modules...

Only when you have the module properly powered up and running, then you can spend a thought on the reed switches.

Did it come with the original adapter? Polarity is ok? The plug fits in alright? If you have a voltage meter, try to find out what the adapter puts out and what the board gives through to the modules...

Xavier

[xchessg]

Now when I try to play the Mephisto it barely turns on. Sometimes I see fragments of some characters on the LCD and that's it.

Hi,

If I were you I'd start looking at the adapter and/or the voltage that the board puts on the modules...

Only when you have the module properly powered up and running, then you can spend a thought on the reed switches.

Did it come with the original adapter? Polarity is ok? The plug fits in alright? If you have a voltage meter, try to find out what the adapter puts out and what the board gives through to the modules...

Xavier

.... I think there's an ACL reset possibility on a MMVI, try that as well...

[tkollen]

Thanks for your advise about the power module. Unfortunately I don't have a service manual with circuit schematics and voltages.

This game was purchased in Germany but since I'm living in the US, I can't use the original German adapter but using instead a third party 9V / 1 amp DC adapter. Measuring voltages inside I notice that the voltage on the output pin of the LM7805 voltage regulator is 4.96V which tells me that the adapter is probably not at fault. Also the connector pins to the board and modules with the highest voltage are all measured at 4.2V.

I would highly appreciate someone posting a service manual, advise based on the above info or contact info for some professional who can fix my game.

[xchessg]

I would highly appreciate someone posting a service manual, advise based on the above info or contact info for some professional who can fix my game.

The manual is here:
Here you go: http://alain.zanchetta.free.fr/docs/mep ... MVIeng.pdf

Not quite sure if there's service advice in it...
The modules run at 5V, you now. I don't understand how you can mesure 4,2V at the connector pins when you have about 5V (which is correct) at the regulator. Isn't there an ACL reset button on the backside of the CPU?

Hope the link works

Xavier

[JeffB]

Hi, All -

I recently bought an Exclusive that has an interesting problem that I wonder if anybody has seen:

The C1 square flashes quickly with a piece on it, slowly with no piece (the same flash rate as other squares that don't have a piece). Sometimes if I move a piece while the C1 square is flashing the computer seems to play through a stored game rapidly, with corresponding moves displayed on both the display unit and the board LEDs. (I'm guessing that I'm accidentally hitting some internal undocumented test feature.) The problem is similar (though slightly different) using either an MMII or MMIV module. (The MMII is of unknown functionality, and the MMIV is from my Mobil, which doesn't use the board display functionality.)

I believe the reed switch is working but maybe not correctly. I can hear it when I move the piece on that square, but it's likely not a coincidence that this reed switch is much louder than any others on the board. It also seems to correctly react when I place or remove a piece, though the computer itself is not correctly reacting. Sometimes I can reset the MMII and play the first move of a new game, but then from move 2 on the C1 square starts acting up again.

I wonder if it's possible that this is an indication of something else gone wrong in the board, something that has the C1 square flash rapidly as an indicator. Oh, I've also tried swapping the modules to different slots, but observed no change in behavior.

The power supply is an original Mephisto US supply. I haven't put a meter on it but the way the board starts, I think it's likely not the culprit.

Any ideas?

Thanks!

[Dave C]

With this in mind I plan to replace at least 32 reed switches and I'm interested to get some advise on brand, type and specs for a suitable reed switch and where I can find the at a good price.

Here is a link to Berger's site with info about reeds. Hope it helps you select and purchase reeds: https://sites.google.com/site/bergerspr ... cb/sensors
I'm in the process of replacing a reed on a Fidelity and purchased a dozen reeds on ebay from a chinese firm. In retrospect, considering the amount of work to properly replace a reed switch I should not have purchased cheap reeds.

Poor economizing regards,
Dave