If there is no way to send it back... we can try to find out what the problem is.

I have a suspicion...

Please, open the MM V Module, take pictures. Show the pictures here.

Some of the "chips" on the circuit board (PCB) are placed in an IC-socket (CPU, Eprom, RAM, ...). Maybe on shipment something happened and this causes contact problems... You can try to loose the chips slighlty and then press in correct position again.

Good luck!

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

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.

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

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

This looks a bit strange.

Miniaturansicht angehängter Grafiken

 

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

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.

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.

That would probably have to be measured.

I know something about it, but I'm not an electronics engineer.