More Black Hole Questions

ComputerSpace

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Hello all, sorry for all of these...but I'm making progress.

I just performed all of the mandatory ground modifications to the boards in my game. I also removed the DataSentry battery. There was a bit of corrosion, but only on the legs of the crystal. Cleaned it with white vinegar as directed. Looks ok.

I also replaced the main power supply filter capacitor that was recommended as well.

Some questions now...

The player # and # of balls display is completely out. Nothing from it that I can see. It did display very very dimly earlier but not anymore. Is there anything I can do with this or is the display shot? I saw on the pinrepair.com docs about rejuvenating them. Any one ever try this?

Also, the score displays are 'pulsing'. I thought the capacitor and the ground mods would fix this, but it did not. Any thoughts about what would cause the displays to do this?

Also, for awhile yesterday, the game was playing and it had background sounds during game play. I found the dip switch that controls this and it's on. Now it's not making the sounds anymore for some reason. I cleaned the switches by spraying them with contact cleaner and working them off and on, still no sound. I'd like to have it back, thought they sounded cool as I've never heard them again. Speech is working fine.

Any ideas?

Thanks
Tom

Here is a video of the display issues.

 
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As far as the background sound problem, I had a similar issue where it would come and go. I replaced the dip switches and that fixed it. On the displays, make sure you have repinned all of the connectors as they cause most of the issues.
 
That "pulsing effect" is normal for Gottliebs... All of my Gottliebs form that era have that issue. To my knowledge there is still no remedy for it yet.
 
Check the solder joints on the back of the credit/ball display board. Mine did not work when I got it and I took the display out to look it over and found some of the connections looked like they never had solder on them or very little. I retouched all of the connections and it worked like a champ afterwards.

Stephen
 
Check the solder joints on the back of the credit/ball display board. Mine did not work when I got it and I took the display out to look it over and found some of the connections looked like they never had solder on them or very little. I retouched all of the connections and it worked like a champ afterwards.

Stephen

I'll have a look at it Stephen, thx for the tip.

Tom
 
Hoping still to find the reason my score displays are 'pulsing'...

Last weekend I changed out the two large caps in the power supply at the bottom of the cabinet. The one that has to be replaced, I had done earlier but did not like that particular cap I had found and put in earlier. I got the new pair from Big Daddy. They're much nicer.

I also bought a cap kit for the power board in the head. I pulled it and changed the 3 caps on the board. Looks like they've been changed at some time in the past as well. WTH is with that power transistor / heat sink design?. Took longer to take it apart and put it back together then to do the cap kit. Finally able to put it back together and test.

Made no difference in the display pulsing, sigh.

One thing I did discover that the +42vt test point on the power board that is only putting out about 27vts. What is that +42 used for, anyone know?

My credit and ball in play display still do not light up unless the game is being played and then they're very dim and pulsing badly.

Any more insight would be appreciated, thanks!
Tom
 
Hoping still to find the reason my score displays are 'pulsing'...

Last weekend I changed out the two large caps in the power supply at the bottom of the cabinet. The one that has to be replaced, I had done earlier but did not like that particular cap I had found and put in earlier. I got the new pair from Big Daddy. They're much nicer.

I also bought a cap kit for the power board in the head. I pulled it and changed the 3 caps on the board. Looks like they've been changed at some time in the past as well. WTH is with that power transistor / heat sink design?. Took longer to take it apart and put it back together then to do the cap kit. Finally able to put it back together and test.

Made no difference in the display pulsing, sigh.

One thing I did discover that the +42vt test point on the power board that is only putting out about 27vts. What is that +42 used for, anyone know?

My credit and ball in play display still do not light up unless the game is being played and then they're very dim and pulsing badly.

Any more insight would be appreciated, thanks!
Tom

Tom, the pulsing effect is normal for Gottlieb displays. I believe there is no fix out there, at least not that I know. If it's any comfort to you, every Gottlieb I've seen from this era does this. And that's including a Caveman I played this past weekend.....
 
Bah. My BH & HH displays don't pulsate.
At least nothing like what is shown in that video.

The +42V is derived from the +60V... and both are used in the displays (the 60V for the 6-digit, and the 42V for the 4-digit).
Are you sure the +60V is good? There's a zener diode that should keep it 18V below the 60V supply... if your 42V is reading 27V, either your 60V is actually 45V, or there's an issue with the zener.

Which caps, specifically, did you change on the A1 board? Because C1 & C2 are the ones that filter the voltages for the display grids.

Look for AC content on those DC lines.

You might also check the 5V & 8V DC offsets for the 3VAC & 5VAC display filaments.

Lastly, I think there are electrolytic caps on the display PCBs, that filter the grid voltage. You might consider checking or replacing them.
 
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Darren,

Since I'm pretty new to pinball repair, can you tell me where I would check for the 60vt supply? I'd be willing to bet something is up in that area.

It's pretty confusing to me how those displays use 42 and 60 vts but the schematics show 3 and 5vts going to them....I'm confused how this all works out.

Thx
Tom
 
Bah. My BH & HH displays don't pulsate.
At least nothing like what is shown in that video.

The +42V is derived from the +60V... and both are used in the displays (the 60V for the 6-digit, and the 42V for the 4-digit).
Are you sure the +60V is good? There's a zener diode that should keep it 18V below the 60V supply... if your 42V is reading 27V, either your 60V is actually 45V, or there's an issue with the zener.

Which caps, specifically, did you change on the A1 board? Because C1 & C2 are the ones that filter the voltages for the display grids.

Look for AC content on those DC lines.

You might also check the 5V & 8V DC offsets for the 3VAC & 5VAC display filaments.

Lastly, I think there are electrolytic caps on the display PCBs, that filter the grid voltage. You might consider checking or replacing them.




http://groups.google.com/group/rec....&q=gottlieb+displays+flicker#6e0b5af9fe197eb8


See post #2

And this is coming from the Gottlieb guru!

Edit: Maybe you don't have the original displays?
 
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Darren,

Since I'm pretty new to pinball repair, can you tell me where I would check for the 60vt supply? I'd be willing to bet something is up in that area.

It's pretty confusing to me how those displays use 42 and 60 vts but the schematics show 3 and 5vts going to them....I'm confused how this all works out.

Thx
Tom

Ah, you have the schematics, and are looking at them. Awesome!

To check the 60V DC at the A2 board:

-Put your DMM in the "20VDC" range if it is manual; if it's autoranging, turn in on to DC Volts mode

-Ensure your red lead is plugged into the "V" jack on the meter (some have a seperate "A" jack for measuring current)

-Place the black lead on "TP3" (test point #3) on the A2 board. It's in the top-left quadrant, below a big resistor. It just looks like a little silver dot. This is the GROUND test point. Keep it here for the measurements below.

-Place the red lead on "TP1" on the A2 board (located in the top-middle area). This should read fairly close to 60VDC.

-Now move the red lead to "TP2" on the A2 board (top-right quadrant). This should be close to 42VDC.

-Now, if you have a decent DMM, you can also switch the mode over to AC Volts (lowest range, if its manual), and repeat the measurements above. There should only be a fraction of a volt of AC (as in 0.xxx V) of "AC ripple" I'll check mine tonight to see what kind of AC ripple I have.

To answer your other question, about the voltages at the displays. If you look at the schematic for a 6digit display (A4), you see "5V AC (FILAMENT)" and "5V AC RETURN (FILAMENT)" lines. Just below them you'll find one labeled (a little further to the right) as "+60V DC (VDP)". The short answer is, the displays need both voltages (the 5VAC and to 60VDC) to function. They're VFDs (http://en.wikipedia.org/wiki/Vacuum_fluorescent_display), and bear some similarities to CRTs, which require seperate filament (heater) voltages, and grid voltages.
 
http://groups.google.com/group/rec....&q=gottlieb+displays+flicker#6e0b5af9fe197eb8

See post #2

And this is coming from the Gottlieb guru!

Edit: Maybe you don't have the original displays?

Steve said "If you're talking about the intermittent flicker you get on individual digits, they all do that."

The video doesn't look to me like "intermittent flicker" of "individual digits." To me, the video shows constant pulsing on all digits. So, I think Steve is talking about something else in the subject post.
 
Steve said "If you're talking about the intermittent flicker you get on individual digits, they all do that."

The video doesn't look to me like "intermittent flicker" of "individual digits." To me, the video shows constant pulsing on all digits. So, I think Steve is talking about something else in the subject post.

Looks like they're strobing to me.... the issue I see he has is he's missing his comment segment on the displays....

I'm not being trying to be an ass to you... I've own(ed) several Gottlieb pins as well several pinhead buddies have Gottlieb. I bet if not all have some sort of a strobing effect - some may be more noticable than others...
 
I'm not being trying to be an ass to you...

No, not at all. Nor I to you.

It's a tricky thing to describe, compounded by the fact that it's difficult to capture on video, due to aliasing of the framerate and the frequency of any effect.

What *I* see, and interpret that the OP is has an issue with, is a fairly slow (a couple of times per second) pulsating, or maybe "undulation in brightness", of the whole display; proceeding from right to left in a "wave". I might be wrong in my interpretation of the OP's concern.

*To me* that looks different than the higher frequency "flickering" (tens of times per second, not proceeding across the display) seen on the Pink Panther in the video.

In my experience, "flickering" is likely to be caused by poor connections: either old/bent/dirty/corroded pins in the housing, or the edge connector on the display, a bad ground back at the A2, or at the connections to the MPU board. The "undulation in brightness", however, isn't a problem I've had before. So I'm offering my theories as to what I think might cause something like that.
 
No, not at all. Nor I to you.

What *I* see, and interpret that the OP is has an issue with, is a fairly slow (a couple of times per second) pulsating, or maybe "undulation in brightness", of the whole display; proceeding from right to left in a "wave". I might be wrong in my interpretation of the OP's concern.

In my experience, "flickering" is likely to be caused by poor connections: either old/bent/dirty/corroded pins in the housing, or the edge connector on the display, a bad ground back at the A2, or at the connections to the MPU board. The "undulation in brightness", however, isn't a problem I've had before. So I'm offering my theories as to what I think might cause something like that.

Darren is correct. You are not seeing flickering of the frame rate of the video recording, you're actually seeing the display go from bright to dim back to brighter again over and over. It is a kind of 'undulation' like you said.

Seems to me to be a bad voltage (low) or ground loop issue that I've not found yet. I'll be testing as Darren suggested hopefully tonight.

I'll post what I find.

Thanks for the info on this.
Tom
 
I measured the voltages on my BH & HH. The nominal 60V test point is at 62 to 63VDC on both; and the 42V test points measure 44-45VDC. Both lines on both machines have around 0.5VAC of ripple ("True RMS" Fluke measurement, FWIW). A little more than I would have expected, but I've never replaced those caps on the power supplies, to my recollection.

And I looked long and hard at the displays. There is an occational individual digit flicker, but no "undulating" or "pulsating". I tried taking a video with my digital camera, but it doesn't turn out the way it looks in real life. There's a flicker present in the video that isn't there when looking at the display--presumably due to the frame rate being approximately the same as the AC line frequency.
 
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Tested my power board last night as you suggested Darren. I discovered what's happening and got the displays to work!!

I tested the voltages at the board and couldn't believe it. At the 60vt test point I had 60vts which I wasn't expecting. At the 42vt test point I had 43vts, another surprise. When I removed the test leads I bumped the small transistor with the heat sink on it (didn't realize it at the time). I looked at my displays and they were still pulsing...WTF?

Went back and rechecked the voltages and they were low this time. OK, I started wiggling components on the board and discovered the loose transistor. Moved it a bit to the left and all of the displays brightened up and stopped flickering. Even the display on the apron was now working properly. I was pumped. No more flickering. I now have bright displays like it should be.

The bummer is that I have to take the power supply board back out and apart to fix the bad solder joint. The engineer that designed how that large power transistor attaches to the board must've been smoking something. Had a heck of a time getting it apart and back together last weekend. Hopefully I don't screw something new up.

Thanks for your help with this Darren, and everyone!

Tom
 
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