Hardware repair needed

Champion (372)

30-04-2020, 21:13

So it's confirmed. I've got a motherboard hardware issue in my 8250. Slot 1 has a very bad contact with the motherboard. Sometimes the cartridge stays unseen, sometimes something happens but hangs, sometimes it more or less works.. When I put MG2 in slot 1, it boots, I get graphics but the only sound I get is clicking of the PSG. The 8250 doesn't have these issues with slot 2. It had its audio fix.

Who can diagnose and fix this machine ( in The Netherlands please ).
Thanks all.

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Por OeiOeiVogeltje

Paragon (1439)

30-04-2020, 22:11

repairbas

Por Wolverine_nl

Paragon (1160)

30-04-2020, 22:15

go to http://www.bas-ditta.info/
then use the contact form.

Por rolandve

Champion (372)

02-05-2020, 16:18

Thanks all, Bas was kind enough to send me a replacement slot connector. That did NOT solve the issue. The slot stays unreliable in three ways
1) The system does not see the cartridge inserted
2) The system sees there is a cartridge inserted, tries something and hangs
3) The system seems to boot OK (ex. Carnivore 2) but when I try sound from Carnivore 2 I only hear the PSG (MG2 has SCC and uses PSG)

when I insert the Philips audio module, I get the same results: only when the built-in program starts, I get no sound whatsoever. Slot 2 works fine. This is definitely something on the print.

Por meits

Scribe (6576)

02-05-2020, 16:37

A little over a year ago I had some slot problems as well. It affected only one slot. It turned out it was a cold solder joint of the connector on the mainboard.
This is where I had almost found the culprit. Wiggling the connector dropped the -12V. What I didn't know at that moment was that the ribboncable wiggled the pins on the mainboard.

(yes, that's a 8250 as well ;) )

Por rolandve

Champion (372)

02-05-2020, 16:57

Ok, the good news I take from this: its probably something stupid, the bad news about this is that I can only open the NMS 8250 for so far. Taking the front off, easy, disconnecting cartridge... watch out for the power and the 7 MHZ buttons wires... Done I've got no idea where this cold solder joint might be. This video looks like you put your 8250 in a PC tower.

I got my NMS 8245 and its up and running. Now looking for someone to add a V9958 and MSX basic 3. Bas does not do this. Vintage computers are not the best things to practice on, when you want to achieve a rank in home-soldering.

Por meits

Scribe (6576)

02-05-2020, 17:10

I'll ask a friend to check this topic.

Por Daemos

Prophet (2170)

02-05-2020, 17:40

Rolandve,

If you want a resolder of your cartridge connector and a checkup I am willing to do it for you. Are you located in the Netherlands?

Por rolandve

Champion (372)

02-05-2020, 18:11

Daemos wrote:

Rolandve,

If you want a resolder of your cartridge connector and a checkup I am willing to do it for you. Are you located in the Netherlands?

Yes I am, near The Hague. It's not the connector that needs to be soldered on. Thats a brand new one. Its one of the components on the board that makes my slot #1 malfunction.

Por Daemos

Prophet (2170)

02-05-2020, 18:53

Near the hague. Westland, rijswijk, delft? Do you have an idea which of the components is failing or are you suspecting a bad solder. You are very close so a visit with some tools is no problem.

Por Omega

Master (233)

02-05-2020, 19:35

A friend is here.

I can repair your 8250 motherboard and upgrade your 8245 to full 2+.
2+ without F4 register 50€, 2+ incl F4 register 65€
repairs 10€/hour + parts.

email triszon atat gmail.com
Cheers!