Tech U51 or U52 System 11a

[Guest]

Archived from groups: rec.games.pinball (More info?)

I probably over my head on this repair job anyway..... I wanted to ask
a few questions to help me come to a decision on what I ought to do.

I picked up a project Pin-Bot that was DOA. I rebuilt the high voltage
board and replaced all the chips. The game now powers up with the
exception of rows 1 through 4. Those switches seem to be locked on.

When the game is turned on the two coils for the eyes (sw 25 and 26)
will alternate firing. When is switch edge test, engaging any switch in
the first 4 rows it will activate several switches.

While doing my reading, trouble shooting system 9 machines, it mentions
that if all rows 1 through 4 are locked on you could have a problem
with U51 or U52. It mentions that a short could happen between Flipper
EOS switch touching the lane change switch. When looking over the game
I noticed that someone recently replaced the EOS switch recently on the
right flipper and the soldering was done poorly. There are a few
strands of wires hanging freely. Dumb question but, am I right to
assume that the Lane change switch is the second set of switches
attached to the EOS switch?

My soldering skills are not first-rate. Replacing chip U51 or U52 needs
to be done by a professional. Any ideas on what else I might want to
check before I have to send the board off to get repaired?

Thanks,

Jeff

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Frank,

Thanks for the info. I did find Q42, a 2n3904, was shorted open. And
when looking close at the board it looks as though someone has replaced
and repaired Q42 and SRC6 sometime in the past.

I am currently going through all the switches and checking out all the
diodes in each row. Looks like I am going to need to order more parts
from ED.

Thanks,
Jeff

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

>>While doing my reading, trouble shooting system 9 machines, it mentions
>>that if all rows 1 through 4 are locked on you could have a problem
>>with U51 or U52. It mentions that a short could happen between Flipper
>>EOS switch touching the lane change switch. When looking over the game
>>I noticed that someone recently replaced the EOS switch recently on the
>>right flipper and the soldering was done poorly. There are a few
>>strands of wires hanging freely. Dumb question but, am I right to
>>assume that the Lane change switch is the second set of switches
>>attached to the EOS switch?
>>
>>My soldering skills are not first-rate. Replacing chip U51 or U52 needs
>>to be done by a professional. Any ideas on what else I might want to
>>check before I have to send the board off to get repaired?

This is U30 and U39 on the System 11 CPU. They seldom go bad. Usally either the
resistor netwwork at position SRC6, SR11 or SR14 is broken in half. Or one or more
of the 2N3904 driver transistors are fried but then the switches in row 5 to 8
wouldn't register properly also. Might also be a combination of both. If you do
not have a scope remove J10 and measure voltage on each pin. Same for J8. If you
see any differences between the pins you can check further. Then switch the pin
off and measure resistance between pin 1 of the network and pin 2 to n. It's in
circuit and you might get false but always consistent results. SRC6 is actually an
RC network. Pin 10 is grounded. You can replace it with a 1K 9-8 SIL and left pin
10 free. Getting the networks out is not that easy. Small traces and even smaller
holes. If you do not have the proper solder skills do not do it and give the board
away for repair. If you have identified a bad component you local TV repair shop
might do it for you.


Regards
Frank-Rainer Grahl
(frgrahl@REMOVE.ME.gmx.net)

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

The harder you work the more you learn. It's 1:00am where I live and I
have to be at work at 6:00. However it will be worth it in the morning.
I just played three game on my Pinbot with no issues. The problem was
SRC6 and SR 10 in the switch matrix.

I would like to thank everyone who gave advice. Not only in this thread
but with all the other old threads. Getting into this hobby with no
knowledge of electronics is like trying to reading a braille book 10
feet away.

The hardest problem was trying to figure out how to make a resistor
network. There is information out their but most of the threads were
hard to understand until you read all of them 20 times over. If their
is a newbie out their reading this thread in the future trying to
figure out how to make a resistor network give me a shout. I will do my
best to pass on what I learned tonight.

Thanks Again,

Jeff
www.jeffpinball.com

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

The hardest problem was trying to figure out how to make a resistor
>>network.

Clay's guide demonstrated how to do this.

Mario
Pinthetic

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

>>The hardest problem was trying to figure out how to make a resistor
>>network. There is information out their but most of the threads were
>>hard to understand until you read all of them 20 times over. If their
>>is a newbie out their reading this thread in the future trying to
>>figure out how to make a resistor network give me a shout. I will do my
>>best to pass on what I learned tonight.

Great that it works now but why did you make the network using resistors and not
just buying it? They cost here about 0.3 Euros each (about $0.36). You won't save
much my making one using discrete parts.


Regards
Frank-Rainer Grahl
(frgrahl@REMOVE.ME.gmx.net)