Stargate blowing F5 power board fuse

tofudrifter81

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Hey all you Williams fans out there. I recently acquired a stargate vid and have been receiving a Rom16 and Rom 31 error. as the lcd on the video board will flash 131. I was checking the 20 pin and 40 pin ribbon connectors when for shits and giggles I did a continuity test on the fuses. Realized that the F5 fuse was blown, replace the correct 2amp slow blow 6.3VAC with a radio shack 2amp 250V slow blow and it blew again almost instantly. The LED's on that same power board #1 led non illuminated #2,3, are on all the time.

I currently have
119 vac into the switching power supply
5.02 +5vdc
11.43 +12vdc

F-5 is receiving 10.6 VAC at the fuse instead of the 6.3 that the wiring diagram suggests. now the fuse blowing at that location, would that be the start of my ROM errors and cutting out of the sound issue I have been having. and what should I check next to figure out what is blowing the fuse's at the F5 location?
 
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I have heard the original Defender ones were bad because they could go and shoot 25 volts or so down the 5 volt line. They were revised after that. Other than that, I don't think they are bad. They can be rebuilt cheaply. I'm running originals in my Williams. Switchers have issues with high score saves.
 
I am testing my bridge rectifiers. are all of the rectifiers labeled BR1, BR2 Ect... on this board?
 

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well tested out of circuit the BR1 bridge rec. is bad for sure. if I replace it with a another one, will I need to check another reading from a power source in? so I will not burn up a new Bridge Rec.? Br2 and Br3 tested within the 400-600 diode testing range that I did following Dokert's video
 
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When you solder a new BR1 in, make sure to solder the wires to the top pads. Many times the solder will not flow all the way through because of the large surface area causing the solder to cool too quickly.

You should also test the small capacitors or replace them. They are pretty cheap to replace and they will add to the stability of the power.

You have the newer power supply board so the reference to the Defender power supply boards doesn't apply.

ken
 
When you solder a new BR1 in, make sure to solder the wires to the top pads. Many times the solder will not flow all the way through because of the large surface area causing the solder to cool too quickly.

You should also test the small capacitors or replace them. They are pretty cheap to replace and they will add to the stability of the power.

You have the newer power supply board so the reference to the Defender power supply boards doesn't apply.

ken

so do the bridge rectifiers on the newer style power board have a different rating or parameters that differs from the 400-600 diode reading test that I followed?
 
No they are the same for both the older (Defender style) and the newer (Joust style) power supplies.

In fact both are derived from pinball power supplies which also use the the same bridge rectifiers.

ken
 
Cool. Thanks yellowdog for the info. Now I will wait for Mr. B. Roberts to get back with me on my order and get this cabinet back in buisness in my basement.
 
alright, (Removed the switcher) Stargate power board back up and running. Replaced all 24 4116 chips and I can boot the game up with no errors on my LED. All three LEd's on the power board are illuminated game plays great but........THERE is still NO F-ing sound. I can adjust the pot while in sound test mode. I reseated and cleaned the sound ROM chip. I can get the sound to work for seconds as the game is played then it cuts out. Any Ideas on what to check next. Is there something else on the sound board that could be causing my problems. i am receiving 5.02V at the Williams sound chip. I'm so close I can taste it.
 

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1) check the voltages at the testpoints on the sound board. (TP1=+12V unregulated, TP2=-12V unregulated, TP3=Ground, TP4=+5V Reg)
2) Check that you are getting the correct signals to the sound board from the ROM board (requires a logic probe)
--a) go to the diagnostics and turn on the sound test (if it only flashes sound 1, press the up/down button (the middle one))
--b) on the cable from the ROM card check each of the lines while the sounds are cycling. You should see each of them pulse when that line is selected.
--c) on the digital side of the D/A chip (IC13 - 1408 D/A converter) pins 5-12 make sure these are pulsing.
3) on the amplifier chip (TDA2002), you should be getting +12V unregulated (so it will probably be higher) on pin 5
4) if you bring the working end of a pencil type soldering iron close to the amp chip, you should hear a buzzing. If not, replace the amp.
5) Jumper W1 must be present
6) Dip Switches should be set to off position

ken
 
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heres what I have tested so far today still trouble shooting my audio problems.

Williams sound board test points.

TP1 +11.13
TP2 -13.52
TP3 Ground
TP4 +5.02


I tested power coming out of the PS board on the following wires.

orange should be -5 I have -5.15 coming out
Gray yellow should be +12 regulated I have +12.24 coming out
Gray Green should be -12 unregulated I have -14.27 coming out
Gray White should be +12 unregulated I have ONLY 11.92 coming out
Black wires ground is good
Solid GRay wires should be +5 and I have +5.04 coming out.

I have recapped the following places on the PS board c11, c15,c2 / c16, c13, c5, c3, c14, along with the 3502W bridge rectifier. So the low VDC at +12 unreg. seems to be still an issue with my board seeing how +12 -5 are usually designed for audio amplification and power. So is that Big Azz yellow capacitor on the board the next one that would need changed out?
 
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Sounds like you're very close, have you gone over all the header pins on the backs of those boards? I find on Williams games that they trimmed the pins too short on the back side so there isn't a proper solder fillet which results in a weak joint.

I always start by removing the solder and header pin nylon holders, then using a small pair if flush trimmers I grip the header pin and using a prying motion against the nylon holder, pull the pin deeper into the holder. Then when it's remounted to the board, the solder side of the pins will protrude 1/16" or so resulting in a strong solder fillet and no more cold solder.

I'd do all those pins first before digging into the logic any deeper. It could be the cause of your +12 running low and it's just good game preventative maintenance.
 
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