Williams Gorgar Display problems popping up

JDAugie

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Have some new display issues on my Gorgar machine. The segment e has been missing since I got the machine in January. Last week, When I turned it on after not using it for a week, segment "b" went missing from the Master, player1,2 displays. I opened it up and jiggled some connectors and now the 100,000 digit on player 2 started flickering and has now dissapeared completely. Any ideas or suggestions?
 

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Master display pics

Here is a pic of the display board and all the electronics.
 

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I had a similar problem on my Gorgar and had to reseat all the connectors on the main display PCB several times. That cleared it up for me.
 
For the missing "b" segment on players 1, 2, and the master display, check R2 (10k) and see if it's cooked. If it is, swap it - if it still heats up and eventually burns, test with players 1 & 2 disconnected. If it no longer cooks, test them individually to see which display is causing the issue.

R2 looks ok in your picture, but worth checking. If it checks out, and the issues persist regardless of how many displays are installed, it may be an issue with IC9 (7180).

Steps for checking that chip from "Pin Repair" (using a logic probe):

"Check the input pins of the UDN7180A (pins 2,3,4,5,6,7,8) for pulsing activity. If there is no activity, either the master display board's connector is bad, or the input chips (4558) are bad.

Now test the UDN7180 output pins (pins 14,15,16,17,18,19,20) for pulsing activity. If there is input activity, but no output activity, then the 7180 is bad."

For the other issues:

From your picture, R12 looks like it's cooked; it controls the "e" segment for players 3 & 4.

R5 also looks somewhat cooked, and it controls the "e" segment for players 1, 2 & the master display.

Seems odd that both would be cooked, so definitely rule out a bad display as noted above - replace both R12 & R5, test with just the master. If neither heat up, and you have "e" active, then add the 1-4 displays back in one at a time, checking those resistors as you go.

If you isolate the issue to a particular display, make sure there are not shorts between pins; I found a display once where there was a short right where the signals went into the glass; scraping away some gunk restored the display to normal operation..

For the missing 100k digit on player 2 - probably a connection issue given how it appeared; reseat the same connectors you messed with previously, and make sure to re-seat J5 on the MPU board while you're at it.

If you've never pulled those (at least the MPU and driver) boards and reflowed the header pins, definitely check that worst-case.

Good luck!

Brent
 
Gorgar Display

Thanks Sprout for the suggestions. I will try and test those resistors and reseat the connectors. The e segment on the Master and 1&2 is working and has not had a problem, only on 3&4. I'll test R5 anyway but it may only be R12. I don't have a test probe, only a MM so the IC testing may be beyond me. I'll try the resistors and connectors and see where I stand. If I don't get a satisfactory resolution, I'll decide wether to but a probe and learn something new or call a service person. On a side note, Access to the pinrepair site seems to have become restricted. I couldn't access it beyond the index.
 
Checking Cables

Hey Brent, Should I reseat the cables while the machine is on or off. Can I disconnect a payer score card i.e. player 1,2, 3 or 4 while the machine is on? Or, should I shut it down, disconnect then turn it back on again?
 
JD,

Shut it down, replace R12, and test with all four player displays disconnected. If you have your "e" segment back, then start by connecting up the player 1 display, then player 2, etc., each one at a time and by themselves, to see where the issue reappears.

Note that the display may come up, and you may see that all four come up without causing the "e" segment to disappear again; if R12 is heating up significantly when one of them is connected, that's your culprit.

Otherwise, shut it all down when disconnecting/re-seating.

Logic probes are relatively cheap (you can probably find one under $30 locally), easy to use, and come in very handy for this type of work - highly recommend getting one.

Example from Amazon: http://www.amazon.com/Elenco-LP-560-Logic-Probe/dp/B000Z9HAP4

Regarding R5 - it looks a bit cooked it the picture; if you confirm it's suffered some heat-related damage, replace it anyway - resistors are cheap, and you're going to be pulling the board to replace R12 anyway.
 
Score display

Just as I was getting ready to test the electronics, the segment b came back on, unfortunately it only stayed on for one game then went out again. Is that possible if the resister is blown or is that indicative of something else?
 
Given that the "b" segment just recently went out, if it's reappearing at all there's a good chance it's connector-related - but it could certainly be a resistor that's on it's way out.

Flaky connections are...flaky ;)
 
Resistors

The replacement resistors that I was able to find locally have a 5% tolerance. The schematic calls for a 10% tolerance. Will the 5% ones work?
 
Testing Results

I started testing the resistors with the following results. R 12 is definitely fried. R-5 is giving me a reading of 16.25K. R-2 reads OK. Just looking at the resistors brings up another question. R 1-7 are substantially bigger than R 8-14. The replacements that I got from Radio Shack are more the size of R 8-14. See pics. Is there some difference that I should be aware of?
 

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R1-7 look like they've already been replaced, and with 1w resistors. . They should all be 1/2w resistors, which is what R8-14 are. Bigger would be better, but what you have is fine.

-Hans
 
Resistors

So you're saying, if I can get them use 1w resistors like the 1-7s on my board, if not, It's OK to mix in .5w? Also does that 16.25 on R5 reading mean anything?
 
So you're saying, if I can get them use 1w resistors like the 1-7s on my board, if not, It's OK to mix in .5w? Also does that 16.25 on R5 reading mean anything?

16.25k? That's wayyyyy out of spec. Replace it.

And that's correct. You can use the 1w's if you have them, but the 1/2w's are ok too. The originals were 1/2w. 1w, long term, would be more durable. But in a home environment it's no big deal. It's not like you're leaving it on 12 hours every day.

-Hans
 
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