I had the same thing happen on a Future Spa. The 4 inline drops and a 5th standing target are all on the same strobe. The PIA could not power it. In my case I was able to swap the two 6821s around and it worked.

I'll disconnect and try testing the board alone first before trying to swap in a known good 6821.

Thanks buds.

Tried shorting pins on J2 in test mode and all 8 associated switches were recognized, but again with the short comings of the orig. Self Test, it can only show one switch # at a time and defaults to the lowest.

Removed U10 and checked it for shorts, tested good. Swapped with U11, which also tested good for shorts when removed.

While I did not test them in either socket for voltages while in circuit, once swapped, all my switch issues went away. And I mean ALL. I had another issue start to occur where two different switches (both on the same return line as the "O" target) would register VERY slowly, even after new diodes and capacitors.

FWIW, of the two IC's, the U10 was a Singapore non-motorolla 6820P and the U11 was an original Motorolla 6821P.

Another indicator the 6820 is failing is, now with it in the U11 spot (responsible for signals to the soundboard), the game makes the correct sound 90% of the time but makes the incorrect sound at sometimes, e.g. when counting down bonus, the last *bleep* of each cycle will be a sound associated with a different area.

..now to Destroy Centaur.

Power play
Need some assistance in identifying where these wires in picture go.
Located near MPU J1 wire colors are
black / yellow 83
2nd wire white / yellow 53
Game is Power Play
Connector diagram in manual doesn’t show these colors.
J1 connector doesn’t have empty slots

Any one with BOPP can look and see where these wires go

image (resized).jpg

Those two wires are for the knocker in the head. You'll see them near the middle of the wiring diagram.

PowerPlay_Knocker.jpg

You might also find this forum helpful in the future....
https://pinside.com/pinball/forum/topic/bobby-orr-s-power-play-club

Thanks wasn’t even thinking knocker because whole knocker assembly is missing

New problem
Displays are blank, have glow so displays are getting power.
All voltages are good
New MPU, transformer board repinned all connector have check pin outs w manual
Perform continuity check on A1 to A2J1 pins associated with displays
MPU boots upas it should

Thought?

What was the last thing you did before this happened?

No numbers are shown in display test mode?
Blanking signal at pin 10 on the display connectors stuck high?

Did you measure the voltages at the display test points and use the display board TP3 as the ground connection for the meter?

Repinned connectors last thing done
Nothing in display
Display board tp1 = 0.5v tp2=177.6v

There you go, you're missing 5 volts for the decoder chips on the display boards.

5v @ sdb A3J3-17
5v A1J1-20
Tp1 should be 5v, disconnect all connectors on MPU in case it loading it down

No change
Other thoughts?

Also tried another spare display w all others disconnect same effect 0.5 v tp 1

Did you measure these with your black multimeter lead on the display TP3 ground? If not, then you might have a ground connection issue between the solenoid driver board (J3 pin 20) and the displays at pin 13 I think.

Yes been measuring TP3 w black lead, note tp1 = -0.5v

I presume you can sort this? The displays are not getting 5 volts for the decoder chip.

Ground for the displays comes from the solenoid driver board at J3 pin 20 and arrives at the displays at pin 13 (brown wire)
5 volts for the displays comes from the solenoid driver board at J3 pin 17 and arrives at the displays at pin 20 (green-white wire)

Note: the solenoid driver board schematic in the Power Play manual is wrong. It incorrectly says 5 volts goes to pin 18 of the displays and ground goes to pin 11 of the displays.

SDB_DisplayLogicPower.jpg

Wiring checkouts & measures out correctly as described above:

To eliminate possible board issues, i replaced SDB, MPU, rectifier / transformer one at a time with known good working boards.
No change, issues must be a wiring issue

Rechecked transformer & SDB J3 connectors both are correct

So with the machine OFF, and your multi-meter set to resistance mode (200 ohms scale if your meter isn't auto-ranging) do you measure:
a) Zero ohms between SDB test point "GND" and any displays test point TP3 (ground connection)
b) Zero ohms between SDB test point "TP1" and any displays test point TP1 (5 volt connection)

A) 3.6 M ohms
B) 0 ohms

Display boards TP 3 all measure 0 ohms

It means you have an open circuit on the ground wire from the SDB to the displays. Please check it again.

"Ground for the displays comes from the solenoid driver board at J3 pin 20 and arrives at the displays at pin 13 (brown wire)"

J3-20 to display Gnd is 0 ohms

Pull the brown ground wire at SDB J3 pin 20 out, and very carefully inspect the crimp..

Crimp is good, measured 0 ohms

How much resistance do you measure between:

a) SDB test point "GND" and SDB J3 pin 20
b) SDB test point "GND" and Displays connector pin 13
c) SDB test point "GND" and Displays GND test point TP3

A)0.1 ohms
B)0.3 ohms
C)0.3 ohms

This is the exact same test you did in post #2369 but you measured 3.6M ohms there.

First time I measure wrong pin on J3

Sdb gnds to display have continuity and so do 5 volt lines

And you're still only measuring 0.5V at the 5V test point on the displays?

Ok went back connected everything and it now works.
Guessing a pin must of been misaligned. Removing and replaced solved issue.

Thanks for walking me through this.

Drop target coils don’t reset at start or new game, coil test, DT sw score.
43 volts on both sides dt coil.
The save again post between flippers looks fried, could that be causing issues.

All flippers work fine

Driver transistor Q12 on the SDB drives the Left drop target reset coil.
Driver transistor Q16 on the SDB drives the Right drop target reset coil.

What happens when you *very briefly* ground the metal tabs on these driver transistors?

Targets reset both do

Do any other coils not work (besides the cooked play more post coil) or activate at the wrong time? Go through solenoid test mode to check.

Interesting you mention wrong time activation.
Left & right PB will engage when either one is hit, but not the middle.
During coil test PB work like they should only popping one at a time. During game play L& R engage.
All other coils are working as should w exception of play more post.

This might be switch issues. Go to switch test mode and check the three pop bumper switches.

BTW it's really time that you open your own tech support thread:
https://pinside.com/pinball/forum/forum/tech-early-80s-solid-state

BTW2, I've got to head out and won't be back til later.

The reason he's mentioning it is because it's extremely common for one of the signals to drop out between the MPU board and the solenoid driver board. Look at the displays when you are running the solenoid test vs. the manual and ensure that the CORRECT solenoid activates, and none activate TWICE during the test. If they do, you have a bad solder joint on a header, a defective header, a defective connector, or a break in the wiring.

This is a very common symptom that needs to be added to troubleshooting guides like pinwiki if it's not already there, because it trips up lots of people. The main diagnosis issue is that you'd need to watch all 4 lines at once which you can't do with a simple logic probe, and also, it's usually the connector pin causing the issue, and sticking a probe on it, gets it to make contact.

Went through all switches and numbers do match.

Not switches the solenoid test.

If you notice a problem in solenoid test like slochar mentioned above (some skiped, out of order, multiple fire at wrong time)... Go to the driver board and with a logic probe or digital multimeter set on volts DC check all four A-B-C-D momentary solenoid signals circled in the pic below. The signal that sits at HIGH / 5vdc and never moves anytime during solenoid test is the problem. MPU J4 gets wasted by the leaking battery. Driver J4 often has cracked solder joints.

Those 33k resistors pull the signal to always high (5v) when the connector is open circuit. So one never moving from high is pretty good sign there is a connector problem (which is super common and comes up here a LOT).

Untitled (resized).png

Looking to replace the speakers in my Bally Flash Gordon. Anyone have a link to product they would suggest or have used?

I used that one for my Centaur
https://www.amazon.com/dp/B0765CWG64/ref=cm_sw_em_r_mt_dp_AtBOFb43V7X9Q

I need a quick comparison. This is a globe trotters machine.

I have a pair of loose green wires I’m trying to determine if they have any use. Inside the cabinet near the incoming power cord connection.

Are they supposed to have a similar wire nut as seen on the black and white? Perhaps a ground wire?

The machine boots up so they may be for other electrical outlets.

2771D3B0-55DD-4D09-80AC-36E5D3568013 (resized).jpeg929E11A9-33AC-4C44-85E3-5300B3D5DB04 (resized).jpeg

This is what a factory QC miss looks like. The incoming line cord was never screwed onto the ground braid.

On my Bally SS (1978 Black Jack) they're grounded on the filter / cabinet braid.
Interior 01 (resized).jpg

Mine look to soldered to a clip which is earthed.

123742597_3627010720682822_1789955621076970499_n (resized).jpg

123914526_1069473126824154_8465622323238431321_n (resized).jpg

dup

My above post is from my Harlem.

Thanks Jardine & Mathazar!

Do any of you folks have a good working solenoid driver board? It looks like I may need one.

Toasted coils on a “project” Harlem GT probably related to the lack of ground in above post 2392.

Both upper saucer kickouts, one jet bumper, one slingshot and the knocker.

The plungers are all frozen solid!

9702869C-9A57-43F3-B4ED-5930BF4C2C2D (resized).jpeg

Are the coils related to one CA3081 U3?

YUK