🚀 go-pugleaf

I have been trying to fit an expansion into my atari ST 520STFM.
I de-soldered all of the holes, soldered in the sockets, soledered in
the 16 capacitors, and added the three resistors. I then checked the
ST only to find that it won't boot. I have since removed the sockets and
the capacitors and the three resistors, but still no boot.

I have had a hunt around with a logic probe and all seems to be functioning.
The only thing that I did notice is that the 2 of the 3 extra lines from the
MMU are being held high, whilst the third is pulsing in much the same fasion
as the original 9 lines. Does anyone know if these two lines from the MMU
should be held high or if they should be pulsing.
I have been advised that this is probably a solder wisker between two address
lines or two data lines or between an address line and a data line. I have
searched for this but have had no luck.

The processor will sometimes stop altogether, with its HALT line low. When
reset, it will go again for a while and then HALT. Could this be caused by
a sloder whisker ??

If this is wrong then is my MMU blown ??
I am talking abaout the MMU side of the resistors that go to the DRAMs.
The resistors are not in place as they are not in the standard 520STFM,
so these connections go the the MMU and nowhere else !!.
I beleive that only one of these three lines are needed to access the second
512K of RAM.

Any help here would be much appreciated.


S.J.R

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|   Simon Raybould                |  BT Fulcrum   | Are all your pets called  |
|   path : sie@fulcrum.bt.co.uk   |  Birmingham   |      Eric ??? - Python    |
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