Problem: System 11b board wont boot-no blanking light, only 5 volt light. I believe MPU is running, based on a lot of activity on U 15, 26 &27. (26 & 27 GET HOT TO TOUCH)

Previous work has been done, some driver transistors and ICs U44,45 have been replaced.
Trace jumpers have been installed.

Q 72 and 73, associated resistors and diodes were smoked. When I bought the machine I hoped just replacing the smoked components would solve issue.

First, relocated on board battery pack, although no damage was present .
Second, replaced smoked components mentioned above, Ohmed out traces, powered up did not work.
Third, replaced 6802 Mpu chip.nope....
Fourth, U 43, same result.
Fifth, U 55, same...
No go.
I hooked my logic probe up to a working system 11a board. Checking U51 pin 4 - U44 pin 21- and U43 pin 3, they all pulse the same. On my System 11b board that isnt working, they all probe high. I assume they should all be pulsing like the board in my Tomcat that works. Where should I look to try and diagnose why the signal is not pulsing as it should?

20181229_183610 (resized).jpg

#2 5 years ago

MMM

nerdygrrl

Pinside member

Northampton, MA

11y 82,950 2,093 4

I found this series to be invaluable when trying to diagnose and trouble shoot. Start with your test points, are you getting the correct voltages? Are all of the fuses ok?

http://techniek.flipperwinkel.nl/wms11/index1.htm

#3 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

yes and yes and yes I have read that article as well as pinball rehab, vids bulletproof et.al

#4 5 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,976

Get yourself a Leon test ROM. I always use one of these when I start my troubleshooting. In fact ... I just did this today at a friend's place to get things started.

http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Williams_System_11_Repair

#5 5 years ago

???

wdennie

Inactive member

Canandaigua, NY

8y 37,350 1,321 17

Wow did that board ever work?
The Ic chip that has the jumper wires, looks cracked, and the
pre-driver transistor looks like a chunk is missing.

#6 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

Quoted from wdennie:
Wow did that board ever work?
The Ic chip that has the jumper wires, looks cracked, and the
pre-driver transistor looks like a chunk is missing.

I purchased the (game) board in this condition and have since replaced the transistor and several other components.It looks like it is cracked but it is not. I’m getting pulsing activity On data and bus lines of U15 processor both ROM’s and U51 Which leads me to believe the MPU is running program. Pin three on you 43 is low, and I already replaced it with a new 555 .
I am going to try one more shot gun repair due to what I have read and replace Q 50 C 57 and C 58, rolling the dice...

#7 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

Q50 reads 1.045 from base to emitter, All other transistors I test read between .5 and .7.
Do you think q50 is bad

#8 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

Quoted from DumbAss:
Get yourself a Leon test ROM.

Where might I find this test Rom? Let me guess PBR....Does anyone else carry it Marcos does not to my knowledge

Post last edited 5 years ago: “Spell”

#9 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

Also, I read 3.8 V at the blanking light test point and .08 volts at U20 blanking test point.

#10 5 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,976

OP
Quoted from Heaterguy:
Q50 reads 1.045 from base to emitter, All other transistors I test read between .5 and .7.
Do you think q50 is bad

The general rule I follow is that if the transistor tests bad then it IS bad whereas if it tests good it does not mean that it is good. If all the other transistors in an identical circuit test the same but one tests differently that's another good sign that you have a problem. It doesn't necessarily mean the transistor is bad though because another bad component could be causing the different reading. All this applies IN-CIRCUIT. If you take it out-of-circuit you'll get a much more accurate measurement but there is risk in taking the component out-of-circuit (off the board).

OP
Quoted from Heaterguy:
Where might I find this test Rom? Let me guess PBR....Does anyone else carry it Marcos does not to my knowledge

If you have access to an EPROM writer you can write your own. You will need a 512kb (kilobit not kilobyte = 27512) EPROM. You can use an erasable one with a window or a one-time (OTP) one without a window. If you use the OTP variety make sure the IC is pin compatible.

If you don't have access to an EPROM writer I think there might be merchants that sell them but if all else fails I could provide you with one. If you plan on doing a lot of System 11 board repair this is a good thing to have. If this is one-off then borrowing one is probably a better way to go (assuming you know someone locally with one).

If you can take some more detailed (in-focus) photos of the board and post them there might be something obvious that can be seen.

#11 5 years ago

DAD

uncivil_engineer

Pinside member

9y 91,550 2,012

OP
Quoted from Heaterguy:
Where might I find this test Rom? Let me guess PBR....Does anyone else carry it Marcos does not to my knowledge

Just about everyone who sells rom chips can burn you a copy. What you need is a 27512 EPROM with the Leon system 11 test program written to it. I know Big Daddy Enterprises have custom burned me test roms when I requested it via email.

#12 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

I do have someone that can burn one for me but did not realize that was what needed to happen thank you for the information. I am going to go ahead and replace Q50 c57 and C 58 see what happens pretty sure Q50 is bad. Thanks again, I will report my findings in a week or so when I get parts in and replaced.

#13 5 years ago

PNF

Heaterguy

Pinside member

Indianapolis, IN

6y 46,650 229 61 16

Replaced Q50, C58. was very happy when board powered up with 5 volt and blanking light. Ive not seen blanking light stay on ever. However diagnostic light was solid, not flashing. Unpowered board, repowered board. No diagnostic light. Went ahead and installed board, inserted 2 balls. Turned game on, knocker stuck coil, bell stuck coil, top ball gate stuck coil no attract mode lights. No display. Diagnostic light has not lit since initial power up after Q50 replacement. Pressed test on board, lights came on flippers worked once, Aux pwr driver board fuses 7 and 2 blew, w 6 smoked (may have been previously smoked, w5 had jumper installed) Back to the drawing board....

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