Author: William Kerr
Date: 09:58:03 06/27/04
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
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