Blitter Issues, 1040 STFM

[Cimmerian]

Hi There - newbie here, I wonder can anyone help?

Ive installed a recently purchased Blitter from one of Exxos' recent batch in my 1040STFM (C103175). By way of a SMD mount PLCC socket.
Also installed is the 1.5 Booster and TOS 1.2/4 Mods also from Exxos.

With the Blitter installed, Machine will boot in GEM fine, however upon moving the mouse to the Menubar, the machine freezes, at least I Think it does, the pointer just disappears and doesn't come back. If I take the blitter back out of course everything is working fine.

I have checked and double checked continuity around all 68 pins, I'm pretty sure there's no shorts and Ive tested each pin to most of the vias that they go off to. Also Ive removed the solder on W4 / W3 as I understand is the usual procedure.

I'd really appreciate any hints / tips on troubleshooting this? I did see a post related to the STFM remake where the blitter sounded like it was doing the same thing, however there wasn't any follow up on that.

Thanks

[exxos]

Problem with installing 2 things at once is its difficult to work out which one is causing the issue.

Normally issues like this are things like bad connections or shorts on the blitter. Or you may need to change all the address and data bus pull ups to 2.2k. There can be noise on the clock line, so 47pf from the clock to gnd can sometimes solve such issues.

[Cimmerian]

Thanks Exxos - sorry to be clear The TOS / Booster upgrades were carried out some time ago last year with no issues.
Clock seems an easy place to start, Ill have a gander at the clock line on the scope and share what I see.

[exxos]

Thanks Exxos - sorry to be clear The TOS / Booster upgrades were carried out some time ago last year with no issues.
Clock seems an easy place to start, Ill have a gander at the clock line on the scope and share what I see.

I suspect its probably going to be the bus pull ups if your soldering is all OK. 10K barley works on a stock machine.

[Cimmerian]

I suspect its probably going to be the bus pull ups if your soldering is all OK. 10K barley works on a stock machine.

Thanks! Ordered a bunch of 2k2 SIL arrays. Will report back when I swap them out !

[Cimmerian]

Me Again!

Still no luck for my new blitter.
I didn't have any 47pF around, but I double stacked 20pF over clk / gnd at the 68k side, thought that would be sufficient. I put the 'scope over clk :

DS1Z_QuickPrint1.png

Looks clean to me?

Also swapped out the 3 SIL 10k Arrays around the 68k for 2.2k.
Further , I took the socket off and resoldered again to be sure.

Any other suggestions I could try or stuff I could probe to see whats going on?

Thanks for the help!

[exxos]

There are 5 SIL arrays for address and databus..

There is also another one which has control lines such as DTACK on it which should be changed also.

[Cimmerian]

Thank you - yes I see them , going to swap them over now :)

[Cimmerian]

Traced DTACK to RP1 on my board.

For anyone playing along at home Arrays to change (correct me if I'm wrong)

RP1 RP4 RP5 RP6 RP7 RP8

back in a min .... :D

[Cimmerian]

OK all 6 recommended SIL arrays are replaced. Unfortunately for me hasn't cured the issue. Heres a pic of what I see if it helps:

blit_crash.jpg

Exxos, anything else I could try? Thanks for the help so far!