(Topic ID: 284526)

Gottlieb System 1 - 4 Digit Display Not Working

By EM-PINMAN

1 year ago



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  • 8 posts
  • 2 Pinsiders participating
  • Latest reply 1 year ago by EM-PINMAN
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#1 1 year ago

Installed a new Gulf Pinball power supply board as the Rottendog was bad and I had no displays whatsoever. Now I have all displays except no 4 digit.

4 Digit Display shows nothing (Ball/Match). 6 digit displays for score read fine, but are evenly a bit dim. No corrosion on the filaments of any displays.

4 digit display Molex plug is fine, looks like it was repined at some point. Display glass nipple on back is not broken. NO burn marks anywhere. No white glass.

Game has the original CPU with all ground mods done.

Everything that the Driver Board runs functions fine, game plays as it should.

Ideas? CPU issue??

TIA,

Ken

#2 1 year ago

Measure the 42V from power supply.
You mention the 6 digit displays are a bit dim-- measure the 60V as well.

#3 1 year ago
Quoted from G-P-E:

Measure the 42V from power supply.
You mention the 6 digit displays are a bit dim-- measure the 60V as well.

It tests at 68 (60) and 50(42) which is fine.

#4 1 year ago

The 60V is high which pulls the 42V high along with it.
68 should work but makes me curious as to why it is so high. I thought they used the standard series pass regulator which normally puts the voltage in the 62-63V range.

Regardless - now check the voltages at the small display. Could be bad connection.
Check the +5VDC, the 3VAC and 42VDC *at the 4 digit display*.
Also check the offset voltages going back to transformer. This is a 5VDC and 8VDC wire going back from power supply to the transformer.

#5 1 year ago
Quoted from G-P-E:

The 60V is high which pulls the 42V high along with it.
68 should work but makes me curious as to why it is so high. I thought they used the standard series pass regulator which normally puts the voltage in the 62-63V range.

Regardless - now check the voltages at the small display. Could be bad connection.
Check the +5VDC, the 3VAC and 42VDC *at the 4 digit display*.
Also check the offset voltages going back to transformer. This is a 5VDC and 8VDC wire going back from power supply to the transformer.

Thanks for getting back to me GPE with the helpful advice.

Transformer seems fine 3.5vdc on the 5 volt should be ok. 8v was right on the money.

Now as far as the display I'm pretty sure I have a shorted out 4 digit display pulling down the power from the other displays which confirms it in my mind anyhow. Powered on the machine with the 4 digit Molex unplugged and all the score displays got bright as they should be (Dim score displays gone!).

Power going through to the 4 digit display reads fine checking the 5, 3, and 42v with over 1.5 vdc on the 3 volt being a little low. Overall I think there is no power issue, just a shorted out display.

Luckily I have a good used 4 digit display on the way to confirm if the one I have is bad.

Let me know your thoughts, curious if you agree.

Ken

#6 1 year ago

First thing I would track down is why there is 3.5VDC instead of 5VDC.

Looking into the glass - is there a broken filament wire inside?

#7 1 year ago
Quoted from G-P-E:

First thing I would track down is why there is 3.5VDC instead of 5VDC.

Looking into the glass - is there a broken filament wire inside?

Glass looks fine, took out the display for closer inspection, both front and back look fine, no burn marks on traces, etc.

I'll look into the 3.5 v issue when the new display arrives if it does not work. I know there can be some variables on voltage, so I'll wait and report back either way.

Thanks again for your help GPE.

#8 1 year ago

Alright, Installed a good used Status Board today and all is well in the land of SS pinball.

The board was shorted as I suspected dragging down all the voltages from the score displays.

Thanks again G-P-E for your assistance in what to test.

Ken

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