Author: Stephen Istvan Farkas
Date: 13:51:06 06/29/04
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On June 27, 2004 at 12:58:03, William Kerr wrote: >Here is my experience with standalone chess computers. > >1) Bought a Fidelity Chess Challenger 10 at Lechmeres department store in Boston >when it first came out. It still has great memories. Two years ago I plugged it >in and it failed to respond. Suspecting a failed 5 volt regulator I took it >apart and sure enough the 5 volt regulator (7805) was defective. Replaced it and >it now works fine. > >2) Bought a Boris Chess Computer also at Lechmeres department store. This is the >one in the wooded box. It had unlimited time per move levels. Recently all the >keys on the left side of the keyboard did not work. Suspected a defective >keyboard driver. Took unit apart and after probing with an oscilloscope found a >defective 75492 integrated circuit which drives the keyboard. Ordered a >replacement from Jameco. Part arrived and unsoldered the defective chip and >soldered in the new chip. The keyboard now works fine. However an intermittent >problem appeared. Taping on the box would cause Boris to put random characters >in the display and it would have to be reset. More troubleshooting. I noticed >that gentile tapping on one of the program PROMs seemed to cause the problem. >Several of the larger ICs in this device are mounted in sockets. Popping the >suspect PROM out of its socket and back in caused Boris to be in-operative. I >suspected the socket to be at fault I rang out each pin to its pad on the >circuit board. Low and behold pin 4 was open. Must have been an internal >fracture of the pin inside the socket. Soldered a wire from pin 4 of the PROM to >the circuit board and Boris is running fine, no more intermittents. >Unfortunately it plays chess no better than it ever did. Oh well. > >3) Purchased a very used Novag Super Forte chess computer on ebay. Everything >worked except there was no sound. Opened up the unit and found a wire had broken >of the piezo speaker. To get at the wire to make repairs would requite removing >the large circuit board that is the heart of this machine. This machine was >built quit well with quite a few ICs. Soldered the wire in the piezo speaker and >that fixed that problem. > >4) Purchased a Novag Sapphire II on ebay that was advertised as intermittently >working. I wasn’t disappointed. When I got it would work intermittently. Seemed >like any flexing of the case would cause the unit to go nuts with what sounded >like Morse code coming out of the speaker and random segments in the display. >Opened unit up and did several inspections looking for cracks in the circuit >boards, bad solder connections etc. Then I found what looked like a bad solder >connection on pin 1 of IC U2 which is a surface mount IC. I used a Loope >magnifier to confirm my suspicions. Pin 1 of this IC did have a lousy solder >connection. Re-soldered connection, unit works fine. > >Machine problems on my too do list: > >5) I purchased a Fidelity Voice Chess Challenger when it first came out (again >probably from Lechmeres). When I plug this unit in the voice combines random >statements that it knows until it finally states it intended welcome message. If >one presses the RE key to reset a game it does not exhibit this problem. >Sometimes during a game it will reset itself. I consider this a game won by me >when it occurs. I also notice the book seems to be disabled since it never plays >a book move. I suspect a power supply regulator problem or filter capacitor >problem. Will report what I find when I tackle this machine. > >6) I also way back when, purchased a Great Game Machine with Sargon 2.5, Morphy, >and the Capablanca endgame modules. The morphy module when plugged in the game >will not always work. When turning on the display is blank. Again, I suspect a >power supply regulator problem or filter capacitor problem. Will report what I >find when I tackle this machine. > >By the way, these old machines are fun to work on and play against. They are a >part of computer chess history. > >Bill Hi Bill, Thanks for the post. Looking forward to the next one! Best regards, Steve
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