Hey guys I just got my new rectifier board installed on my skateball.
I got the board from pin-logic.

But, I'm still having an issue with my MPU board. R113 resistor on the
MPU is heating up and burning in the middle basically. I did replace
the old one because it was doing the same thing. It's value is 2k 1/4
watt.

I believe it's +43vdc on connector J4 on the MPU.

Any ideas what might be causing this to happen?

The game lights power up and the machine powers up, but the displays
don't come on and that rectifier burns up on start up. Where do I go
from here?

Thanks!

Tom

What is your TP3 voltage measured on the MPU, before the R113 resistor goes?
What is the solenoid voltage now present ?

Perhaps that line where TP3 is connected is grounded, via a bad C1 small cap,
or R16 (2K) not the proper value or a short to ground present there.

Bonne chance,
- Sylvain.

r113 blows instantly.

I haven't tested anything yet as I'm fairly new to boardwork. Just trying to figure out where I should start looking.

Got some advice where else to look from a friend. R16 resistor on the MPU is burning/sparking as well.

As mentioned above, measure R16 as well as the solenoid voltage fed to your MPU.
It should not be much higher than +45V DC or so.

You will need to replace both R113 and R16 for sure, with 2K, 1/2W each.

Cheers,
- Sylvain.

I measured test point 3 on the MPU. The schematic says it's supposed to be 21VDC but my meter came up as 148.

Not exactly sure how to measure the solenoid voltage to the MPU. Pretty new to this :/

I do have more 2k resistors to replace both those resistors. Mine are 1/4 watt though not 1/2.

I measured test point 3 on the MPU. The schematic says it's supposed to be 21VDC but my meter came up as 148.

Are you sure ?

It appears you have high voltage for displays instead of solenoid voltage there,
if indeed this is the actual DC voltage reading.
Which would explain why you are burning-up R113 & R16.
Continue with 1/4W then, they are acting-up as fuses!

You can measure the 'solenoid voltage' going to the MPU on J4 pin 15 of the MPU.
This supplies the input voltage on one side of R113. No more than 47V DC or so is expected.

You should also check the fuse for the displays (F2 I think, 3/16 or 3/4A),
to ensure this is not overfused.

If you confirm the reading, then there is a connector/wiring/pin-out issue with the
new rectifier board.

- Sylvain.

First time i ever tested at a test point.

I put it on 200 DC Volts. I put the red lead on the test point and the black lead to ground and it read 148. Is that the proper way to do it?

Okay I think my starting point should be to test all the connections to the rectifier board? Make sure I'm getting all the right readings?

I'll have to figure out how to do that. Can I unplug the MPU connections so I don't wreck something else? Or what's the best way to go about it.

I really don't want to fry those resistors again as I've replaced them twice already..

Okay I've read through the guide a bit more.

I tested all the test points on the rectifier board (with j1 & j3
unplugged)

Here are the results:
test point 1
6.15

2
149

3
11.22

4
6.6

5
44.4

Here is what the specs are from the manual/reapir guides:

    *  TP1 (on AS2518-1 = 5.4 volts DC +/- .8 volts (4.6 to 6.2
volts). Fuse F1, bridge BR1. Used to power the "switched
illumination" (feature lamps).
    * TP1 (on AS2518-49 & -54) = 6.5 volts DC (5.8 to 7.2 volts). Fuse
F1, voltage regulator RP1 and RP2. Used to power the "switched
illumination" (feature lamps).
    * TP2 = 230 volts DC, +/- 27 volts (203 to 257 volts). Fuse F2,
diodes CR1 to CR4. Used to power the score displays.
    * TP3 = 12 volts DC (11 to 16 volts). Fuse F3, bridge BR2. Used to
power the regulated +5 volts DC for the game's logic circuits.
    * TP4 = 7.3 volts AC, +/- 1.0 volts (6.3 to 8.3 volts). Fuse F5.
Used to power the general illumination.
    * TP5 = 43 volts DC, +/- 5.4 volts (47.6 to 48.4 volts). Fuse F4,
bridge BR3. Used to power all the coils.

Okay I should now be testing ALL the wires that go into j1 & j3? To
make sure the proper wire is going to the right place?

How do I test the wires coming into j1 & j3? I have a chart that says
all the proper voltages and what not. But I'm not sure where to put my
multimeter exactly to test each wire individually..

Slowly learning guys..I know alot of my questions sound stupid. But I
am trying. I've got this far, no use stopping now

The monitor points on the rectifier board seem fine, according to your readings.

How's your J3 connector plugging into the rectifier board?
Is it broken in half, or missing its key pin, where it could have been connected backwards or offset ?

You will have to trace wires, from the rectifier board J3, to the harness then MPU J4, using the schematics.

Cheers,
- Sylvain.

All the connectors going into the rectifier are brand new. I replaced ALL the connectors and the entire board on the rectifier side.

It's this board (DUAL-PLUG-PCB W/"E" BOARD $108.00) from pin-logic.com

From the schematics and your description/voltage measurements, there is most probably
some reversed/incorrect wiring on the J3 connector on the rectifier board,
since the monitor point voltages appear fine on that board from your earlier post, yet
you are getting high display voltage on the MPU input where it should be solenoid voltage
input (via TP3).

Please recheck J3 and trace it/confirm to the MPU, then report the result.

Unfortunately I am unable to guide you any further, as I am not there in person,
plus I have very limited spare time.

Good luck!
- Sylvain.

Thx Sylvain! I've had a few people tell me to check that connector. I'll work on it some more today. Thanks so much!

Ok I traced all the wires by hand and using the schematics. All the
wires line up for connector J3 on the transformer board going to the
all the other boards. Except for one exception.

I have the transformer wire from a2j3-13 going to Solenoid Driver
board a3j3-5. The plug connector schematic says its supposed to go
from a2j3-13 to SOL. BUSS

I have no wire at a2j3-9. The plug connector schematic says its
supposed to go to a3j3-5, a8j1-9.

Thoughts? Would this cause my issue possibly?

sounds like those 2 wires go to the same place..maybe i have a short on the board or in the wiring..going to dig some more..wish i was better at using the multimeter so i didnt fry things and could test it first

Try tracing from the reverse: Start from the MPU, J4 pin 15.
This pin is the +43 VDC input (solenoid voltage), for
the zero crossing circuit, feeding the R113 resistor on the MPU.

The wire from that board/pin should connect directly to J3 pin 12
on the rectifier board. Pins 9,12,13 are connected together on the
rectifier board.

Basically, you want to prove that your MPU J4-15 is NOT connected
to the rectifier board J3 pin 5!).

The rectifier board's J3-5 should connect only to the Solenoid Driver
J3-9 (high voltage raw input to HV regulator).


Question:
Was this machine working prior to the swap of the rectifier board & connectors there ?
Were any other connectors/wiring also worked on ?

- Sylvain.

The machine was working fully, but there was a problem with the flipper relay on the solenoid driver board. They had a piece of cardboard jammed into the relay, thats the only way the flippers would work.

They also had hacked the wiring going to the transformer board. They had j3 hacked and some wires spliced together, and j1 was majorly burnt. Instead of some wires going to the connectors like j1 or j3 they had a few of them soldered directly to the transformer board instead because of the burnt connectors I believe.

I took out all there wiring hacks, installed all new connectors going to the transformer board as well as the board itself.

I'm sure I checked that when I was checking the wiring from j3. I can double check just to be sure though. I went one by one and traced ALL the wires from J3 and they all went to the proper spots.

K I just double checked and j4pin15 MPU definately goes to j3 pin 12 on the transformer board.

I do not understand why you had +148 V at the MPU J4 pin 15 then,
when the monitor points were fine on the rectifier board.

Can you then remove the J3 connector on the rectifier board,
and measure the voltage at its J3 pin 12 ?  It should be +43 to +47V DC...

Yep I can do that. Do I need to have the machine turned on then? If so what should I have disconnected so I don't wreck something else?

To test j3 pin 12 I just put the red lead on that pin and the black lead to ground on the rectifier board?


I do not understand why you had +148 V at the MPU J4 pin 15 then,
when the monitor points were fine on the rectifier board.

Can you then remove the J3 connector on the rectifier board,
and measure the voltage at its J3 pin 12 ?  It should be +43 to +47V DC...

Just want to make sure what I need to have hooked up and what I need to unhook on all boards to make sure I don't do more damage.

Also how exactly (in dummy terms) to test that pin on j3

Last post for tonight.

You probably should read about proper DMM usage and basic electronics...
I really have no time to do this on-line for you.
There are tons of info on the 'net... Hopefully this 'experience' and guidance
here will be a good motivation for you to learn more about this on your own!
This is how I started, but with books, before the internet...
So you can certainly do it !

- turn the machine OFF
- unplug both J1 and J3 on the rectifier board. Leave J2 plugged-in there.
- put the red lead of your DMM, to J3 pin 12 of the rectifier board.
  Make sure the red probe does not touch anything else !! Put tape if needed.
- put the black lead of your DMM to the ground.
- Set your meter to Volts DC (or 200V DC if not auto-range)
- Turn the machine ON (well it won't work now, but you can read voltages)
- Read the voltage displayed on your meter on that J3-12.

Turn the machine OFF, then unplug your meter, then re-plug J1 & J3...


Good night!

Cheers,
- Sylvain.

I have been reading and researching a ton. But sometimes it can be hard to relate the information straight across to pinball for me. I want to learn and am definately trying my best This is my first real dive into diagnosing problems. I have replaced some bridges and switches and things like that but this is my first major project.

I HUGELY appreciate your time and effort to walk me through this. I also try to help out friends and others on the different internet boards I'm on. Usually easier problems then this though haha.

Ok I just tested it like you said and I get 44.4.

Maybe I didn't test that TP3 right? I just put the red lead on the TP3 on the MPU and the black lead to some metal on the backbox. Should I have done that a different way.

Maybe I have a short on my MPU board or something?

Have a good night. Wish I could invite you over for some beers and pinball. Little bit of a commute though haha

Ok I installed a different SDB in the pin and tested at all the test points on the SDB,MPU,and rectifier board. The machine works great now and all test points tested perfect on all 3 boards. Everything works perfect, except for the flippers don't work. The flipper buttons work fine however, just the coils won't fire.

All the other solenoids work and I am getting 43vdc to the flipper coils. I replaced q15 xsistor on the SDB and that didn't help. I can get the flipper relay to pull in when I ground q15, but that's it. Ideas???

I also checked the diode buy the flipper relay and it tested perfect..

Not sure what to try next???

Replace the diode and resistor associated with Q15. When you ground out Q15 and the relay engages, do the flippers work? They should.

If Cooke's flipper relay and CR15, R37, R38, R39 check/replacement does not help,
then you will need to move upstream, as follows:

Check the following, in order:
- check the pin/connector on the SDB J4-8 (flipper disable signal input)
- check for cold solder joint under SDB J4-8 header pin
- this signal wire should originate/connect to the MPU J4-7
- make sure there are no cold solder joints under the MPU's J4-7
- make sure that the pin into the connector for J4-7 on the MPU is good and not broken or corroded!
- try replacing the 6820/6821 PIA U11 on the MPU
- and, if nothing above helped, then the U4 transistor array chip on the SDB is probably faulty.

Good luck !
- Sylvain.

P.S. I still have no clue how your previous Solenoid Driver Board caused +148V to be fed to your MPU,
       if all wiring was fine and the new rectifier board all OK.

Thx again guys. Ya I'm not sure why I was getting that reading on the MPU. I have a friend that's going to look at the old SDB board for me and repair it most likely. Maybe that will give me some answers. Or maybe there is still an underlying problem somewhere.

I'm going to do some more troubleshooting tonight. I'll post back my findings.

The new SDB is from a fully working game from a buddy. So the SDB components should be fine. I'm going to start by looking at connections and U11 and the MPU in general.

The easiest thing to check first is if the flippers work when Q15 is grounded. That will at least rule out the wiring/connectors to the flippers themselves, the relay and the traces from J2-1, 2, through the relay to J1-8, 9 on the SDB. This check takes two seconds.

If the flippers work when Q15 is grounded, then you know your problem is that the transistor is either not getting the signal to engage the relay or not passing the signal through to the relay. At that point you can focus on all of the info that Sylvain provided, which is excellent (after you verify that Q15, R39 and CR15 are all good - just replace them. ).

Awesome thanks cooke, wish I lived closer to some more pin hobbyists Would love to have someone to tutor off in person. I've learned a ton already just trying to fix this pin. Even though I'm still obviously a newbie tech. I've already gotten better at reading schematics, learning the power flow, soldering, using my DMM, crimping molex pins. Just from this one project..anyhow enough rambling back to work!

Okay I got a logic probe from a friend. Never used on though. It has a black lead and a red lead. I'm not exactly sure how or where to put the leads so I can probe the U11 chip.

Red is supposed to go to +5vdc and black to ground.

What settings do I put the probe on?

TTL & Pulse?

Also goiing to check on the info sylvain posted...

The flippers flip fine when q15 is grounded.

Ok I'm pulling my hair out :/ Now when I turn it on the center drop
target coils keep firing every few seconds and some sound plays but
you can't start a game or anything. I must have some MPU issues. There
was some shoddy work done on it. Maybe I just need to send it in for
repair. Think that may be my best bet at this point.

Check the female pins in the J4 MPU connector (power in / solenoid/lamp/sound control out),
as well as the J2 & J3 (switch matrix). This could cause issues as you just described.

Fixing a board will not help if you have connector issues !
... but it will remove an 'unknown'...

- Sylvain.

Thanks sylvain. I think I will just splurge and get a new or rebuilt MPU. I'll also replace the female connectors going to the SDB as well as the MPU just to be on the safe side.

You can see where the previous owner has done a few repairs to the MPU and they don't look that great.

I'm calling the game Flakeball now, not Skateball haha.

MPU will be my XMAS present to myself.

Least I got the rectifier/transformer board sorted out myself, that was a fair amount of work, and I have learned quite a bit in the process of troubleshooting.

I wasn't sure how to get the logic probe to work either. Black lead obviously goes to ground, but i wasn't sure where to hook up the red lead? Do you just clamp the alligator clip directly to one a wire that is +5VDC? Wasn't sure on that part...

Quoted from tomdotcom

I wasn't sure how to get the logic probe to work either. Black lead obviously goes to ground, but i wasn't sure where to hook up the red lead? Do you just clamp the alligator clip directly to one a wire that is +5VDC? Wasn't sure on that part...

Yes: Red lead connects to +5V, black to GND. There are +5V/GND TP connectors on the boards.

The logic probe is to check CMOS & TTL logic levels on chips.
It is NOT to check solenoid voltages, you will damage the probe if
you try to measure a point that has higher voltage than its +5V supply.

For usage of a Logic Probe, you need a clear understanding of TTL/CMOS Logic,
the schematics of what you are troubleshooting, and understand what the probe does.
Google is your friend...

Bonne chance!
- Sylvain.

Ya I was going to use it to test the U11 IC as per some help from some RGP guys.

Just thought I'd update the thread. Skateball is now fully functional
for the first time since I got it! I replaced the solenoid driver
board, replaced/rewired in a new power board, and replaced the MPU
with a working one from Chris Munson. Thanks everyone for your help
troubleshooting. Let's hope it stays working, you all know how that
goes haha

Tom