It comes out of reset which is good, but only 1 reel
Spins (reel 2) - IC34 (robbed for another board) missing
but I think all 3 reels should spin on start up. I'll have new
ICs tomorrow so that can be replaced.
Time for testing and reading.
Just to finish off this repair thread. (Only centre reel spins on start up) - ACE
SYSTEM 1 - Board 1
After reading the manual, it said that the reels are directly driven from IC17 (2803A)
which is not correct. (Magik pointed out that the output from this IC isn't directly
linked to the reel motors). Just goes to show, you can't always trust the manual.
On System 1 the reels are driven from IC21 (a transistor array), another 2803A. (this
is also found on MPU4 so I had some handy)
I had already replaced IC17 by the time we realised it was bum steer and so I replaced
IC21 as well. No change, same fault.
Next we work back and check IC25 which is a 40 pin 8255 PIA. It was difficult to
get the probe on this IC with the board in the machine, but I am fairly sure the
outputs from this chip are suspect. Magik suggests changing IC25.
I didn't have a spare so I had to order from ebay (was £3.50 + £1.50 postage). While
I was waiting for it to arrive, I replaced a few rough looking caps around the reset
circuit. I removed the old 8255 in tact and put in a socket and plugged in the new
All 3 reels index and stop. Sorted. Good Result, very pleased.
All 5 boards now boot OK, just need to add batteries and check over the charging
SPECIAL NOTE ON SYSTEM 1 BATTERY
When changing a system 1 battery, particularly when attaching fly-leads, you must
have continuity between the top of the board, so ensure your soldering is good. Also
there is a small mini-cap in the battery area C30 which is very easy to over-heat.
I strongly recommend changing this cap as a matter of course. If this cap is damaged
by over-heating with the iron when changing the battery, it can short the 12V rail
and take out the power reg board. (It happened to me). So becareful!