system 11 mpu swap

robotype

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anybody tried to put a system 11A board in a system 11B game? in the specific I would like to use pinbot pcb inside elvira...any experience?
 
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from pinrepair.com

[FONT=verdana,arial,helv,helvetica][SIZE=-1]The most flexible CPU board is system11A. The system11A CPU board can be used in any 1986-1990 sys11, sys11b or sys11c game The only exception is if the sys11A CPU board is going into a original sys11 game (High Speed, Road Kings, or Grand Lizard). In this case, connector 1J15 (four pins, .156" molex male header) must be added to the sys11a CPU board (that's all that needs to be done). To use a system 11a board in a system 11c game, don't use connectors 1J16 (volume control) and 1J15 (speakers). Also the sound ROMs at U21/U22 and CPU at U24 and PIA at U9 are not used, since they are moved to the sound board. [/SIZE][/FONT]
 
If you get in a pinch rotten dog has replacement mpu's and I have been wondering how well they function.

actually I almost succeeded in repairing my elvira board, the switch matrix was completely shorted I replaced 4 or 5 PIAs, rams and almost all the audio components so now it is finally playable. the only thing I couldn't fix is special solenoid Q79, it works if grounded manually and I replaced driver transistor 2n4401 but the coil won't be energized both in game mode and test mode so I assume it could be a bad 7402 (U50), 7407 (U49) or the pia (U54) or maybe some other component, I would like to find the problem without replacing all of them...
 
actually I almost succeeded in repairing my elvira board, the switch matrix was completely shorted I replaced 4 or 5 PIAs, rams and almost all the audio components so now it is finally playable. the only thing I couldn't fix is special solenoid Q79, it works if grounded manually and I replaced driver transistor 2n4401 but the coil won't be energized both in game mode and test mode so I assume it could be a bad 7402 (U50), 7407 (U49) or the pia (U54) or maybe some other component, I would like to find the problem without replacing all of them...

Trace through the driver circuit with Leon's test ROM and a logic probe. That's what I would try.
 
Does the fuse blow with U50 removed? If yes, check Q76-79 to see if anyone are shorted, also check the coils and thier diodes. Pins 2-3-4-5 of U50 are inputs from the data bus and output to Q78.
 
Does the fuse blow with U50 removed? If yes, check Q76-79 to see if anyone are shorted, also check the coils and thier diodes. Pins 2-3-4-5 of U50 are inputs from the data bus and output to Q78.

removed Q50, Q49, Q45, Q76, Q77, Q78, Q79 and still blows

slingshot/bumper coils have 4.2 resistance and they work when grounding the tip

the first thing I disconnected was Q70/Q71 (for illumination) because it always had 21 vdc maybe the lamps are shorting somewhere, but where?
 
ok problem is on the MPU, I just replaced it and it works perfect so no short under the playfield.

special solenoid fuse blows only using the other MPU even if missing 7402 and 7407.
 
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On some boards there is a 4.7k resistor tied to +5 and others have a jumper ( w7 ) tied to ground on the PA7 line (pin 9 of u51). You need to see which line is blowing the fuse. One of those lines is shorted to ground either through a bad or turned on transistor, or a solder bridge. Using your ohm meter probe all the output pins with power off for a short to ground, if all good, do it with power on, making sure 1J19 and 1J18 are disconected both times.
 
If I connect 1J19 the fuse will blow immediately as all the special solenoids are energized, the problem is not in the transistors and U45, U49 and U50 are not present on the pcb....could it be an internel short in the U54 pia? I can't find any short to gnd probing the pins of the near chips...
 
Probe the pins of 1J19 for grounded pins. Do all the special solenoids pull in??
Put the chips back in and try again.
 
yes all special solenoids activate when I switch on, no machine gun they just stay on so the fuse blows. when the game is off there is no grounded pin at 1J19 but when I turn on I will read digits from 970 to 1000 but no buzz. If I test the 2N4401 they will all give me about .8 on both legs...so the transistors are somehow activated when I power the game...but 7407 and 7402 are all missing! so I will try to put them in the sockets tomorrow and see what happens.
 
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