TECH: 1978 Bally SS Power Play no display

Hi,
I recently picked up a Bally Power Play machine. After doing some fixes on the rectifier board and reseating some chips on the MPU board, I get the full 7 flash boot sequence, and a neat little chime song.
When I hit the start button I get another song which would indicate the game should start (I think the free play fix was already made before) but the game doesn't start.

If the displays would light up I could try to troubleshoot that, but I guess this should be at the top of my list. I checked the TP3's on each display board and they all get the correct +5V. I don't see them light up at any moment.
Where should I look next?

Thanks,
Phil

#2 10 years ago

BOY

vid1900

Pinside member

What does the high voltage section read?

#3 10 years ago

ALK

Goonie

Pinside+ Frequent

Quoted from vid1900:
What does the high voltage section read?

Specifically, Test Points 2 and 4, yes?

#4 10 years ago

BOY

vid1900

Pinside member

First test the rectifier board (we want to start at the beginning):

TP2 = +230 vdc with connector J3 attached, 150 vdc with J3 disconnected.

Then test the solenoid board:

TP2 = +190 vdc (but often turned down to 170 volts to increase score display life).
TP4 = +230 vdc

#5 10 years ago

PGR

PhilGreg

The rectifier board is A-OK on all test points. Will check the solenoid board, I didn't know that could impact the display.

#6 10 years ago

BOY

vid1900

Pinside member

OP
Quoted from PhilGreg:
Will check the solenoid board, I didn't know that could impact the display.

Yes, the upper left side of the board has the HV components.

#7 10 years ago

PGR

PhilGreg

I cranked up the little potentiometer labeled HV and I only get 120V on TP2. It goes down below that if I turn it the other way.

#8 10 years ago

ALK

Goonie

Pinside+ Frequent

OP
Quoted from PhilGreg:
I cranked up the little potentiometer labeled HV and I only get 120V on TP2. It goes down below that if I turn it the other way.

Hmmm, that's probably too low to power the displays. If the potentiometer is cranked all the way up, then it sounds like you either need a new potentiometer, or a complete HV rebuild. It's common to do a full rebuild on those boards given the age of the components...particularly the two large capacitors. Hard to tell which part is the culprit. At least for me.

#9 10 years ago

PGR

PhilGreg

So then, if I understand correctly, replacing the potentiometer and the two large capacitors would be a good first step.
I'll give that a shot.

#10 10 years ago

ALK

Goonie

Pinside+ Frequent

http://www.bigdaddy-enterprises.com/repairkits/bally_kits.htm#b-reg

OP
Quoted from PhilGreg:
So then, if I understand correctly, replacing the potentiometer and the two large capacitors would be a good first step.
I'll give that a shot.

Yes, but actually if the High Voltage is the problem, you only need to replace that associated capacitor, which is at C26. That's the horizontal one at the top. The other large capacitor is for 5v. With that said, it could also be the HV regulator at Q21. The one on the large black heat sync. If you don't want to do a full rebuild, get those three switched out, and you might nail it.

For reference:

_{Post edited by Goonie : Link added for reference.}

#11 10 years ago

BOY

vid1900

Pinside member

http://www.bigdaddy-enterprises.com/repairkits/bally_kits.htm

If I was to guess at one part, it is the C26 cap (160mfd 350v)

You can get a complete HV rebuild kit for $25:

Well worth your time!

#12 10 years ago

BOY

vid1900

Pinside member

You can, of course test the three transistors and the 1004 diode, if you are comfortable in that level of repair.

#13 10 years ago

PGR

PhilGreg

Thank you guys.
I'll see if I can find a C26 replacement locally first just to get it done quicker and if not I'll get the Big Daddy kit.

#14 10 years ago

BOY

vid1900

Pinside member

http://pinside.com/pinball/forum/topic/vids-guide-quick-bally-driver-board-repair-bulletproofing

Bulletproof the driver board while you have it out:

#15 10 years ago

PGR

PhilGreg

At my local store they had a 180 uF and 100 uF 400V cap.
Would putting in the 180uF be ok? I guess it just has more capacity, the circuit is still gonna draw whatever current it needs?

#16 10 years ago

BOY

vid1900

Pinside member

Many electrolytic caps have a 20% tolerance, so 180uf should be fine.

The 400v is good as it will make the cap last longer (on average).

#17 10 years ago

PGR

PhilGreg

So... no dice with the new cap. Same behavior. I tested the pot while I was at it and it's looking good - 25kO cranked all the way, 13kO at the middle.
Oh well.. I'll get the big daddy kit then.

#18 10 years ago

ALK

Goonie

Pinside+ Frequent

OP
Quoted from PhilGreg:
...and it's looking good - 25kO cranked all the way, 13kO at the middle.
Oh well.. I'll get the big daddy kit then.

Wait, are you getting 250v at Test Point 2 with the pot turned all the way up?

#19 10 years ago

BOY

vid1900

Pinside member

I think he is saying 25k ohm when turned up?

#20 10 years ago

ALK

Goonie

Pinside+ Frequent

Quoted from vid1900:
I think he is saying 25k ohm when turned up?

Oh, right. Okay. Sorry.

#21 10 years ago

BOY

vid1900

Pinside member

Quoted from Goonie:
Oh, right. Okay. Sorry.

No need to be sorry, that's just my guess!

I could be wrong..........................

#22 10 years ago

PGR

PhilGreg

Yeah, that's correct.
Actually I'm kinda cheap and I like doing things the hard way so I went ahead and just ordered the transistors.
Transistors are amplificators, right? So I guess if I'm getting straight 120V, it means there's no amplification going so that would make sense...
In general, the capacitor's job is to smooth out a rectified sinusoidal AC wave to make it a smooth continuous straight DC line, right?

#23 10 years ago

PGR

PhilGreg

Replaced the transistors, no dice!
On to the diodes and resistors!

I'll check your bulletproofing thread too.

#24 10 years ago

PGR

PhilGreg

I was looking at the board for good continuities... it looks like the j3 connector was redone, and some of the solder looked awfully close so I double checked it.
I do have continuity between traces 2 and 3 starting from the right (see picture).

Does that look right or should I separate them?

solenoidConnector.JPG

*Edit*: Ok, looking at the schematics on IPDB, it looks like it's unrelated with the HV circuit, but I still can tell whether it's normal or not...

#25 10 years ago

AMS

barakandl

Transistors are like a switch. Think of it this way. You have three legs. One is input, one is output, and the third one is the switch. If you apply a small amount of voltage to the switch leg, you turn on the transistor connecting the input and output together and allowing current to pass through.

You should test the transistor before replacing them. All three can be easily tested with a DMM. Save you time and money. The one in the to-3 case is expensive. Look up testing transistors with a DMM on youtube.

If the resistors are bad, they are usually burnt looking. The resistors are often bad in the high voltage section. R51, r54, and R55 burn the most often if I am remember correctly.

Find zener diode VR1. With the power on, carefully check the voltage on the banded side of the diode. You should see +140vdc there. If it is low replace VR1 (this is after replacing / assuming resistors are all good and in spec).

Andrew

#26 10 years ago

AMS

barakandl

The pins in your picture that you have highlighted are ground return pins and solder can be touching / continuity. They honestly look okay from that side of the board. The final bottom pin CAN NOT be touching. That is a 5v pin and will blow fuse if it shorts to ground.

That is a connector i find almost mandatory to replace. It caries all the power for the logic boards and needs to be good shape with no resistance.

#27 10 years ago

BOY

vid1900

Pinside member

Replace that connector, the soldering is super crappy and sloppy. All that solder splatter is just begging to kill the board.

Also there is a cold solder joint that needs to be reflowed.

solenoidConnector.JPG

#28 10 years ago

PGR

PhilGreg

Yeah, that's pretty sloppy work right there... those small connectors don't seem too easy to work with either. Those have stopped being used shortly after that, right? (I'm familiar with 90's Data East and Williams machines but nothing else from the 90s on).

How do you see it's a cold solder joint? Looks like the other ones to me.

#29 10 years ago

BOY

vid1900

Pinside member

OP
Quoted from PhilGreg:
How do you see it's a cold solder joint? Looks like the other ones to me.

A good joint pools the solder equally around the component lead.

Obviously, I don't have it in front of me, but it sure looks like a bad joint from here.

OP
Quoted from PhilGreg:
those small connectors don't seem too easy to work with either. Those have stopped being used shortly after that, right?

The Bally just had those tiny connectors, and thinner circuit boards; probably saved a few cents per board.

They are not hard to work with, but because the pins are small (and that means tiny area of electrical contact), it is especially important they be nice and unoxidized .

#30 10 years ago

PGR

PhilGreg

Ok, thanks for the info! Picked up a couple more components, I'll replace them and do the cleaning up and keep you guys updated. Sure picked up more work than I thought with this machine, but it'll teach me something new...

#31 10 years ago

SPM

Fishbeadtwo

Pinside member

Seattle, WA

12y 60,150 900 99

Its a good game so you are going to be rewarded!

#32 10 years ago

AMS

barakandl

Funny thing...

I just repaired a Driver board tonight with the same symptoms as you after rebuilding the resistors/filter cap. Low output voltage (100v), yet i could adjust it with the pot, just not high enough. It was the zener diode.

#33 10 years ago

PGR

PhilGreg

Dang, the zener diode is one of the parts they didn't have at my local store... but thanks for the info.

#34 10 years ago

AMS

barakandl

The one used on the bally board is rated for 1/2w. You can use a 1w version just fine. It has a different part number i can not recall off the top of my head. Maybe your supplier has that version. You can test this zener diode, but you need to lift one leg to do so in this circuit.

Ed at Great Plains Electronics i'm sure sells this component.

#35 10 years ago

PGR

PhilGreg

Well gentlemen, many thanks to all of you!
As you can see, the player 4 display is doing weird things, but I got to play a couple of games and the game seems to be working fine.

I replaced the zener diode (with a 100V and 39V in series), the 1N4004 diode and the capacitors which looked burnt out with 0.005uF 1000V DC caps in parallel.

P1010201.JPG

#36 10 years ago

PGR

PhilGreg

Oh,
just noticed there's an unintentional easter egg in the picture... see if you can find it

Hint: it would make more sense this way...

#37 10 years ago

BOY

vid1900

Pinside member

Resolder the connector pins on display 4. It's got "that look" of cracked solder joints.

#38 10 years ago

PGR

PhilGreg

Quoted from vid1900:
Resolder the connector pins on display 4. It's got "that look" of cracked solder joints.

Will do!

#39 10 years ago

PGR

PhilGreg

OP
Quoted from PhilGreg:
Oh,
just noticed there's an unintentional easter egg in the picture... see if you can find it
Hint: it would make more sense this way...

Ok, no one wins the million dollar prize
I was wearing a Boston Bruins shirt, which shows up in the mirrored backglass... For you non-hockey fans, Bobby Orr played his whole career in Boston and only ended with a couple of games in Chicago, which a little weird to see this machine is Blackhawks themed.
It probably got designed right around the time of the trade.

#40 10 years ago

ALK

Goonie

Pinside+ Frequent

Ah, I never would have caught that. Nice!

3 weeks later

#41 10 years ago

TNT

Fanatic

Inactive member

Unknown

10y 10,900 89

PhilGreg - were you able to fix your 4th player display?

I just resolved a similar problem - tubes being constantly lit
It was the IC decoder on the display's circuit board.

#42 10 years ago

PGR

PhilGreg