Whirlwind Display Segment Issue

FrizzleFried

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Hey guys...

The old PINREPAIR site had a common issue/fix for 1990 era (Whirlwind) display issues...

I have same right top angle segment out across all digits... I want to say it calls for a resistor replacement or something... of course with the Pinrepair site gone (THANKS CLAY!) I can't find the info I'd read prior.

Anyone have a good working link to this fix?
 
I don't have a link, but off the top of my head...

Is this for both the upper and lower display, or just one of the two? I'm assuming just one.

<snipped to avoid confusion!>

Brent
 
Last edited:
off the top of my head


Testing the UDN7180/UDN6118 Chips and Score Glass for Shorts.
Both UDN chips are 18 pin chips. The four corner pins of the chips do *not* need to be tested (pins 1,9,10,18). But all the other pins can be tested. Repeat this test for each of the UDN6118 and UDN7180 chips:
Turn the game off.
Remove the high voltage power supply power connector (3J5 or 3J2, depending on which power supply the game has).
Put the DMM on the *diode* setting.
Connect the red DMM lead to ground.
Put the black DMM lead on each UDN pin 2 to pin 8.
A reading of .5 to .7 should be seen.
Put the black DMM lead on each UDN pin 11 to 17.
a NULL (no) reading should be seen!
Note if the display glass itself is shorted (it does happen!), it MAY show up when testing the UDN pins 11 to 17.
So how do we isolate the problem to the UDN chip or the display glass? First test the UDN chip. If any of the pins (but mainly pins 11 to 17) fail the test, desolder the suspect UDN chip from the master display board WITHOUT DAMAGING IT (these chips are expensive, and if it's good it would be nice to save the chip from desoldering damage). Install an 18 pin socket for the chip, and buzz out the socket making sure there are no shorts, and all traces connect to the socket.
Now again use the DMM and repeat the above UDN test procedure ON THE SOCKET (no chip installed). That is, with the DMM on diode function and the red DMM lead connected to ground, test pins 11 to 17 of the SOCKET with the black DMM lead. Again, a null reading should be seen. If a null reading is seen, the UDN chip has failed and needs to be replaced. If a null reading is *not* seen, chances are really good that the score display glass itself is shorted.
If the score display glass fails the test, it will need to be replaced (there is no way to fix it). After the score display glass is removed (and before the new glass is installed), put the UDN chip in the newly installed socket and retest the chip as described above.
 
14049 Partial Segment Failures on Score Displays.
Sometimes only parts of a display aren't displaying or are locked-on, and only on certain numbers. For example, the top part of a "0" or "7" are not displaying or are always locked-on. It can even be so strange so that the missing segment will work on some numbers or letter, but not on others.
This can be caused by one of the hex input buffer 14049 or 4049 chips at U10, U11, U15-U18 or U7-U9,U10-U11 on 16 character display boards. Note on the schematics sometimes these are mis-labeled as 4050 chips! But these 4049 chips are CMOS and very static sensitive. You can check these with your DMM set to diode test:

hopefully this is your solution
 
Looks like my memory wasn't so good; 18 pin chips instead of 16! Splatter's posted the info you need - should get you on the right track.
 
Replace the 39k ohm Power Supply Resistors.
The major villain in the system 11 power supply are resistors R1 and R4. These are both 39k ohm, 1 watt resistors. Very often either or both of these resistors will go out of spec, or even completely open. This will prevent the +100 and/or -100 volts from getting to the score displays. These two resistors are mounted on the system 11 power supply board. (on newer WPC games with alphanumeric displays, these are resistors R48 and R49 on the alphanumeric display board). As a general rule, I always change these resistors (trust me, they've had a tough life, and need to be replaced, even if they test as "good").

If the high voltage fuses are not blown, and the score displays do not work, first replace the 39k ohm resistors. These are cheap and easy parts to replace (a lot cheaper and easier than replacing score display glass!) Or at least check these with a DMM. Replace these two resistors with "flame proof" 1 or 2 watt 39k ohm versions. And make sure to mount the new resistors slightly off the circuit board, so air can get under them for cooling.
 
I had some issues with segments when converting a Whirlwind Display to Taxi (Taxi Schematics are incomplete, so I ended up getting close using the ones from Police force). I believe the segment that you are have issues with is the "K" line (right angle) according to the manual (page 89). This segment is tied to U7 pin 4 (4049 - Hex inverter/buffer = $0.35). On the display I fixed, I had issues with one of the segments just like you. If you believe that the display board is where your problem is, I would try replacing this part.

Hope this helps,
Kid
 
FrizzleFried, just bring this PIN to CAX and sell it to me for a good deal and then you will no longer have a display segment problem :) ;) :cool: :eek:
 
Replace the 39k ohm Power Supply Resistors.
The major villain in the system 11 power supply are resistors R1 and R4. These are both 39k ohm, 1 watt resistors. Very often either or both of these resistors will go out of spec, or even completely open. This will prevent the +100 and/or -100 volts from getting to the score displays. These two resistors are mounted on the system 11 power supply board. (on newer WPC games with alphanumeric displays, these are resistors R48 and R49 on the alphanumeric display board). As a general rule, I always change these resistors (trust me, they've had a tough life, and need to be replaced, even if they test as "good").

If the high voltage fuses are not blown, and the score displays do not work, first replace the 39k ohm resistors. These are cheap and easy parts to replace (a lot cheaper and easier than replacing score display glass!) Or at least check these with a DMM. Replace these two resistors with "flame proof" 1 or 2 watt 39k ohm versions. And make sure to mount the new resistors slightly off the circuit board, so air can get under them for cooling.

This is the "fix" that I'd read about... THANK YOU! Thank you too Splat for giving other areas to look at should the resistor fix not work.
 
FrizzleFried, just bring this PIN to CAX and sell it to me for a good deal and then you will no longer have a display segment problem :) ;) :cool: :eek:

I actually just sold it to a local (he's picking it up Saturday). I'd told him about the resistor "fix" i'd heard about and he asked for the info...

:(

Sorry bro.
 
I had the resistors (39 k ohm) go out on my Whirlwind's power supply and the symptoms were not similar to what you are experiencing. With mine, both displays started flickering, went dim, and eventually you couldn't see much at all. It won't hurt to replace the resistors, and if you are placing an order I'd get some just in case. But I don't think they are your problem.

It also wouldn't hurt to pick up the lower voltage Zener diodes to drop the display voltage a little bit and prolong the life of your displays.
 
I honestly think you should try to replace U7 (4049). I have repaired many displays in the past that had the issue you are talking about. Check the +/-100 volts, if it is good - the resistors are probably okay. If you have problems with the voltage, it will show up in all of the segments in the display (dimming and flashing).
 
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