(Topic ID: 292500)

System 3 - mpu LED is stuck on

By torpedo

6 months ago


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  • 12 posts
  • 3 Pinsiders participating
  • Latest reply 5 months ago by torpedo
  • Topic is favorited by 1 Pinsider

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W65C02 W65C22 (resized).jpg
6522 (resized).jpg
P10428-153433(1) (resized).jpg
P10427-192713(1) (resized).jpg
mpu LED is stuck on  (resized).jpeg

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#8 5 months ago

I see a couple problems with the photos of the parts.
First, as MarAlb stated, the board is running at 2MHz so a 2M or faster part is needed.
The R6522P is an NMOS version rated up to 1MHz and might or might not work in this circuit. Based on specifications, it will not work.
The R65C22P2 as shown in last photo is a 2MHz part (Rockwell changed their speed marking with this part to show speed as the last digit) BUT the parts you show are clearly counterfeits. Those can be anything but are probably not what you wanted.
The G65SC22P2 parts are properly marked California Micro Devices parts for a 2M part (CMD was bought out in 2009).
However, all the parts are shown packed on white foam. If they weren't dead before, there is a good chance that they are dead now. Throw that white foam away!

NEW 65C22s can be purchased today. W65C22N6TPG-14 made by Western Design Center. These are good all the way up to 14MHz.

Is U1, pin 40 really pulsing as mentioned in first post? If so, I would focus on verifying or getting proper ROMs because the CPU isn't clearing the watchdog timer. If you are trying to run this board with an U2 socket empty, then the watchdog timer is behaving properly and nothing will work.

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