I just picked up an EBD LE and it was playing perfectly for a few days and then while it was on, it got stuck with background sound and only 3 feature lamps and GI on, and when I looked at the Altek MPU, the over voltage indicator was on. Here is what happens during a boot:
1) All boot sequences finish, no over voltage light is on
2) The displays flash for a split second and the coin door lock out coil pulls
3) The game is stuck with the left orbit feature lamps on and background sound. Also, the red test button on the coin door does not work.
4) The over voltage indicator is on (Altek MPU)

With only the transformer and input connector on the rectifier board I checked the voltages and TP3 reads 56.4 VDC instead of 11.9

What would cause this? Bridge Rectifier? Resistor? What should my next steps be.

Thanks,
Dave

But TP3 on the rectifier board does not have the correct voltage (56.4 VDC instead of 11.9) so doesn't that confirm an issue with the rectifier board?

Bump

I only have the Transformer and Input connector on the rectifier board at this time. Is it advisable to plug other connectors in to measure voltages in the backbox or does the problem seem to be isolated to the transformer or rectifier board. Obviously, I do not want to harm the boards. Next steps???

Thanks,
Dave

Bump

Thanks for all the responses.

I measured the voltage from the transformer on pin 3 and 6 directly and it was correct therefore I figure it is something on the rectifier board. I ordered a new one (since I have 4 games that use that board) which will allows me get the game running while I figure out the problem component/s on the original one and fix it. Looking at the schematic, it appears to be one of the 4 diodes, 5-8 however in circuit they test fine. Any ideas what the problem component on the rectifier board could be to cause an over voltage on TP3?

Just to be clear, when I measured the voltage of pin 3 and 6 on J6 from the transformer, it read about ~14.4 AC as per the schematics. When J6 and J5 are plugged into the rectifier board, TP3 measures ~56v DC. That is why I figure the problem is on the rectifier board.

Thoughts.

OK...this is getting weird now!

I pulled my known good rectifier board from Flash Gordon and installed it in 8 eight ball deluxe and got the same results. With only J5 and J6 installed, all voltages at rectifier test points are good except TP3 which reads about 56V DC.

What is so weird is that if I measure the voltage on pin 3 and 6 of J6 (from transformer) I get ~15V AC. I have visually inspected for solder splashes on the board and transformer and can not find any. Once the board is installed back in Flash Gordon, it works fine. Can the problem be in all the other components that mount on the plate which the transformer does???

HELP PLEASE!!!

Thanks,
Dave

I have a Radio Shack DMM. Not quite sure I understand what you mean about phantom readings. If my DMM is not measuring correctly, wouldn't all the voltages at the other test point be off? Only the voltage at TP3 is off.

Bump

G-P-E thanks for all you feedback, you obviously know way more about this than I do.
It seems to me that you are thinking that the readings I am getting on TP3 are possibly false however I have used the same meter on Flash Gordon with J5 and J6 plugged in (as with EBDLE) and it reads ~14 VDC at TP3 as expected. Doesn't that clear any question about the DMM? I do not have the proper resistor at this time or I would try what you suggest.

If we assume that my meter is correct and I am getting ~56VDC at TP3 however the transformer output (measured directly from J6 pin 3 and 6) is ~14VAC and I get the same TP3 (~56 VDC) reading with a known good (other) rectifier board installed in EBD, what could the issue be? At this point, if I assume my meter is measuring correctly the over voltage condition is between the transformer and the rectifier board. According to the Alltek MPU, there is defiantly an over voltage condition somewhere.

FYI...I have not plugged in any other boards (beyond rectifier) since noticing the TP3 voltage.

I am at a loss for next steps.

Thanks,
Dave

1982 Bally Eight Ball Deluxe LE
Boards:
Alltek MPU, all other boards original, SDB and Sound Board recapped by previous owner
Condition: Played completely when I picked it up. Everything worked when initially set up (after minor fixed mentioned Below)

Last fixes:
After 2 hour trip home and first few games in my gameroom, a pop bumper and lead for upper left flipper broke. I soldered them and everything worked fine for about another 10games.

Scenario:
Played perfectly for a few days and then while it was on, it got stuck with background sound and only 3 feature lamps and GI on, and when I looked at the Altek MPU, the over voltage indicator was on. Here is what happens during a boot:
1) All boot sequences finish, no over voltage light is on
2) The displays flash for a split second and the coin door lock out coil pulls
3) The game is stuck with the left orbit feature lamps on and background sound. Also, the red test button on the coin door does not work.
4) The over voltage indicator is on (Altek MPU)

What I did next:
1) Unplugged all connectors going out of the rectifier board and tested voltage at all TPs on the rectifier board. All measured as expected except TP3 which measured ~56VDC.
2) Measured voltage at pin 3 and 6 on J6 from the transformer ~14VAC. All other pins also measured the correct incoming AC voltage
3) Took known good rectifier board from Flash Gordon and installed it in EBDLE and connected J5 and J6. TP3 still measured ~56VDC

Also, with just J6 plugged in the voltage at TP3 is ~26VDC. With J5 and J6 it is ~56VDC

Observation prior to issue:
I noticed that the coin door lockout coil would activate prior to the audio attract. The very last thing that happened before the issue began was activation of the coin door lockout coil and then a pause for a few seconds and then just background music and the feature lamps on the left orbit (to top lane) shot.

Pictures:

459_(resized).jpg
461_(resized).jpg
465_(resized).jpg

Voltages directly from transformer:
J5:
pin 1+7 = 7.2 VAC
pin 6+9 = 45.3 VAC
pin 2+3 = 189.3 VAC

J6:
pin 1+5 = 10.4 VAC
pin 3+6 = 15.2 VAC

With J5 and J6 plugged in to rectifier board:
TP1 7.9 VDC
TP2 185.7 VDC
TP3 56.4 VDC
TP4 7.8 VAC
TP5 45.9 VDC

As you can see, the input to the rectifier from the transformer all look good and only TP3 reads high. If the problem was somewhere within the transformer wouldn't multiple voltages read incorrectly directly from the transformer and on the rectifier board?

OK...so I plugged in the SDB and then measure TP3 on the rectifier board and now it measures 15.6 VDC. So then I think perhaps its the SDB...replaced it with a known good and same situation...over voltage on MPU.

WTF!!!

If there was something wrong inside the transformer, I would not be getting the readings I get in post #27 correct?

TP3 voltage is supposed to be 11.9 VDC...is 15.6 VDC too much and still the cause of the problem?

Thanks much G-P-E.

Well I have narrowed down the issue:
With all cables on the rectifier board and back box except J1 (Playfield) on the rectifier board, the system boots. Once I plug in J1, the same over voltage condition on the MPU exists.

Bump

The voltage at the MPU is exactly as it should be when I do not have the Playfield connector on the rectifier board. When I plug in the playfield connector it goes over voltage and I immediately turn it off so I do not get a reading.

I do not think it is anything on the boards because I swapped in a know good SDB and it acts the exact same way.

At this point, it seems to be something on the playfield. What should I be searching the playfield for?

Thanks,
Dave

Could not find anything that looked out of place or broken.

By process of elimination, I found out that with J1 disconnected on the MPU, the machine boots and play minus feature lamps and score displays. Can someone tell me what this narrows down to on the playfield or rectifier?

Come to think of it, with the SDB plugged in, tp3 on the rectifier is 15.6vdc. shouldn't it be 5 VDC since it is regulated?

I tested the SDB voltage and the 12VDC TP is getting ~17VDC. Also, TP3 on the sound board is getting ~16.6 VC instead on 11 and 2 and 4 are getting the correct voltage.

With all connectors plugged in, TP3 on the rectifier board is getting 15.6 VDC. Is it possible two voltages are being added?

Thanks for all you input G-P-E.

So after 3 weeks I am back where I started from.

With all boards and connectors plugged in the game will play for a little bit and then freeze up with the over voltage situation.

If I leave the game in attract mode, there is no over voltage until the attract mode quote "Quit talking and start chalking" starts and then over voltage. ???

Thanks,
Dave