Folgender Benutzer sagt Danke zu Drahti für den nützlichen Beitrag: | ||
Murat (21.09.2023) |
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Re: Problem with MM V
Hi,
Drahti is right. As I've already written, once it's flashing, a lot of things are working (in particular the microprocessor, partial access to the roms and rams needed to make these I/Os, the flashing diodes and part of the LCD). One (if more than one, there's little chance of the program working and continuing) bad contact with a ROM pin can generate errors when checking the hardware when the device is powered up (checking the pieces on the chessboard, for example). The RAMS are soldered, so only the ROMs need to be removed and replaced in their socket. With a medium-sized flathead screwdriver inserted between the IC and its socket, rotate the screwdriver through 15-30°, then to the opposite side, and repeat until it is completely extracted. The aim is to avoid bending the pins. Of course, pay attention to the direction of the circuit when reinserting it. In any case, this type of 8-bit hardware is repairable (no comparison with the GALs on my Risc 2500). Cordially. 2878FE54DE3E6571AB155EEFA1F81C0E751173F0 Geändert von Mychess (21.09.2023 um 17:26 Uhr) |
Folgender Benutzer sagt Danke zu Mychess für den nützlichen Beitrag: | ||
Murat (21.09.2023) |
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AW: Problem with MM V
I mean that the modular boards, at least the first ones, ran at 6 volts. I can't say whether this was also the case with the first Exclusive boards.
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Folgender Benutzer sagt Danke zu udo für den nützlichen Beitrag: | ||
Murat (21.09.2023) |
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Re: Problem with MM V
Hello everyone
The seller was super nice about the refund. Not only he did a full refund and he asked me to keep the modules in case in the future I get access to a 6volt board. I promised him to compensate for his kindness if I can get it to work. I did remove the CPU and the eprom from the sockets and used contact cleaner spray plus air to dry. After carefully reinserting the chips the same issue persists. Random lights flashing on the board and module. And garbage characters on display. I am going to try to purchase a CPU from ebay and if possible a replacement programmed eprom from a member here if any one is able to sell me one. I feel bad for the seller to be honest. I will try to post pictures here. Thanks for looking in to this for me all. Murat |
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Re: Problem with MM V
Hello Andreas.
Here are the pictures you requested. I did clean the sockets and re inserted the chips. Did not see any broken solder points. Thanks again Murat |
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AW: Problem with MM V
This looks a bit strange.
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Folgender Benutzer sagt Danke zu udo für den nützlichen Beitrag: | ||
Murat (21.09.2023) |
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Re: Problem with MM V
You are right Udo,
there is some damage done by soldering there but I was thinking it is part of the modification to use a bigger eprom for the integrated HG 550. perhaps I am wrong. I am adding a close up for that area. maybe we got something Murat |
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AW: Problem with MM V
Thank you for pictures.
CPU is rated at 3 MHz, so in MM V it is overclocked by approx. 65 %... Not unusual for devices designed by H&G. And not likely to cause the problem. Yes, some solder eyes look odd. Ideas: Incompatibilty with your modular board. Try another one if possible. Eprom could be corrupted. Do you have other modules oder chess computers with 65c02 inside? If you buy a CPU on ebay... you don't know whether it is working or faulty. I would try: another modular board new Eprom another CPU In this order. |
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AW: Problem with MM V
The "problem zone" with corrosion (!) has nothing to do with HG550 modification.
Some part of modification you can see in the upper-left corner of the first picture. There is a region of three solderpads. The connection of middle and right pad is opened and left to middle one has been soldered. |
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AW: Problem with MM V
That would probably have to be measured.
![]() I know something about it, but I'm not an electronics engineer. |
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