Technical questions for the MPC2000xl and the MPC2000
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By fantomebeats Thu Jan 31, 2019 2:06 am
Hi guys, I got problems and I need your help.
I got 2000 classic with the description says "It turns on, but not sure it works." So, I thought this has
・broken screen
and
・broken floppy drive

And I already have fully functional 2000 classic with new screen and floppy emulator.

However, when I swapped screen and floppy emulator, it doesn't work. My problem is
・It turns on, but nothing comes on the screen (MPC 2000 boot 1.00 or so)

Do you know what is the problem?? Do I have to change some IC chip??
By richie Thu Jan 31, 2019 2:54 am
In some of my experiences, I've had MPC 2000's that did nothing when I turned it on. Or some situations when I turned it on, the screen would show garbage text. When I changed the bootrom EPROM ic, everything started working again.

So since you have another MPC 2000, you can remove the EPROM from it and try to see if it works in the new one that is giving you problems. If you end up finding that the bootrom EPROM from the working 2000 works in your new one, then you can find a second replacement IC from: https://www.ebay.com/itm/282852065619

Changing the bootrom EPROM didn't always fix the issues as I've had other things to fix on the mainboard but I've had a good success rate with others.

Good luck
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By mr_debauch Thu Jan 31, 2019 10:03 am
also look into the thread here on the forums relating to problems when installing the 8 output expansion incorrectly... i think there is a cap that can be replaced that fixes that issue.
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By fantomebeats Fri Feb 01, 2019 10:34 am
Here is update, I swapped EPROM from my functional 2000 but nothing changes.....

But I found one suspicious thing on PCB which I don't see on working MPC, itis right next to memory card part. I already took solder but ceramic condensor connects ic chip (HM5118160LTT6) and resistor (C51).

Maybe this is broken or something.......

Image
By richie Fri Feb 01, 2019 1:19 pm
That is a ceramic capacitor which is bridged to a resistor on one side and to pin 36 of the on board ram for another reason. At first guess, that mod was done in attempt to stabilize a possible memory timing issue causing crashes.

Have you been diagnosing this the entire time without additional ram installed? If the onboard ram has issues, the PAL should bypass it and rely straight off of the SIMM memory.
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By fantomebeats Fri Feb 01, 2019 3:19 pm
I realized that little pink thing is not resistor but also capacitor.
I already took it and I guess I burnt it by heat from soldering iron.....
Now I have another trouble that I don't know the specifications of this little pink capacitor.... because I thought it was resistor and now it has different color code than resistors....

white, orange, purple, and yellow (or perhaps yellow, purple, orange, and white?) on it but I really can't find any info about this. If you know, please tell me about this. (All I know is its capacitor and thats it :WTF: :WTF: )

Also I will try diagnosing 2000 without ram soon after I got capacitor.....



I checked service manual but there wasn't detailed list in it :fku: :Sigh: :Sigh: :Sigh: