Defender cocktail startup issue

FedExin

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Defender cocktail - 2.5v coming from the PS

I'm in the final throws of a Defender cocktail restore and have powered it up for the first time. When it starts, there is some gibberish on the screen (a sort of multi colored scatter of dots) and the 4 lights on the ROM board all light up and then off, then the screen goes black and all the 4 LEDs on the ROM board light up. Here is a video:

http://www.youtube.com/watch?v=BbRp3aMqyto

- The cabinet was complete as far as parts goes
- The power supply is tested working, as is the CPU board. They were purchased seperately from the cabinet.
- The lights around the cab seem rather dim
- The earth prong on the plug looks to be cut off, but I've re-grounded the entire cab with new braided grounding strap

I updated the title, the power supply is only putting out 2.5v.
 

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the 4 lights on the rom board is caused by a bad ribbon cable to my understanding.

now don't quote me on this one, I'm just going based on what I've seen on another site about repairing/replacing the ribbon cable, but I think you take a block of wood and stick it on the solder side (the part with the pins) and stick the block of wood, the rom board, and the ribbon cable connector into a vise and you can tighten it this way in a pinch (really no pun intended) and see if that clears it up.

otherwise you're looking at replacing the ribbon cable entirely, which can be done with an old computer IDE cable. there's guides on how to do this.

the other cause could be voltages, if the RAMs don't get all the necessary voltages, that will prevent the game from loading too. my mind's a little fuzzy on all this... I get depressed when I work on my Defender lol

I'm still waiting for the day I settle down and put together another part order with Bob Roberts... I have to replace the PIA chip on my sound board I guess.
 
I did an initial meter of the voltage to the lights (I need to find the smaller probes for my Fluke, couldn't get into the molex connector to the rom board) and it came to 2.5v, which sounds about half. How can I up the power? =) As I said, the lights around the cabinet all seem dim....

All three LEDs on the PS light up, but I don't see a pot (ha!) I've got two tested working PS boards, both give the same results. Maybe the transformer? How would I test for that?
 
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if it hasn't been done already, rebuild the power supply. I did mine, it wasn't that bad. lots of guys encourage you use the Stargate (and newer) power supply instead, because the Defender one was designed WITHOUT any overvoltage protection, meaning if a component happens to go bad on that, it's gonna fry some things.

I know, I know, easier said than done. I personally don't want to drop anymore serious money on mine.
 
Well, f$ck. I tested the lead to the ROM board and sure enough, 2.3 volts. I bought 2 boards, one complete PS setup, transformer an all, to nip this prior to assembly. I guess a rebuild is in order. Blech.
 
scroll to the Defender section (use your browser's Find/Search for this) at this site: http://www.cityofberwyn.com/schematics/index.htm

there's a power supply diagram, tells you what voltages are on each pins.

to answer your question, no, there's no 2.5. you need to rebuild the power supply. hardest part is doing the IC sockets... everything else is easy if you know what you're doing. mine looks immaculate now, I gave it a simple green bath before I worked on it lol
 
FedExin said:
Hi Ken,

I believe I tested correctly on the transformer, but I got some weird voltages. I couldn't find a schematic online of the lugs on the transformer. I had my meter set to Volts AC (VAC) and had my black ground lead on a ground strip in the cab. I then probed the molex connection from the transformer to the PS board. The reads were so far off from what should be coming from the transformer it seems.

I don't know which end was Pin 1 but I went from left to right starting with the Orange lead:
Orange: 4.68 VAC
Purple: 4.54 VAC
Grey/White: 14.11
Grey/Yellow: 14.40
Green: 17.80
Grey: 10.79
Black:10.79

The other readings I'm much more sure of:

MPU board power input pins:
1 = GND
2 = GND
3 = GND
4 = key
5 = +12VDC Regulated (Actual 11.91)
6 = n/c
7 = +5VDC Regulated (Actual 5.03)
8 = +12VDC Unregulated (Actual 13.64)
9 = -5VDV Regulated (Actual -4.95)

At the Power supply output pins:
1 = -5VDC Regulated (Actual -4.94)
2 = key
3 = +12VDC Regulated (Actual 11.92)
4 = -12VDC Unregulated (Actual -14.72)
5 = +12VDC Unregulated (Actual 14.37)
6 = +12VDC Unregulated (Actual 14.37)
7 = GND
8 = GND
9 = GND
10 = GND
11 = GND
12 = +5VDC Regulated (Actual 5.03)
13 = +5VDC Regulated (Actual 5.03)
14 = +5VDC Regulated (Actual 5.03)
15 = +5VDC Regulated (Actual 5.03)


Something is amiss, and I don't think it's my questionable testing of the transformer. Some voltages seem ok, but some seem waaaay off. Do I need a new transformer?

Thanks!

- Pete

The transformer voltages are probably good. If they weren't you wouldn't be getting the correct DC voltages at the PS board and the MPU board.

When measuring AC voltages, you need to measure between the source and the sink. Unless one side is tied to ground (which they are not in the case of the Williams transformers) measuring between an AC source and ground will yield meaningless results. You actually need to measure the AC voltage between the pairs of lugs in the original message:

Lug 15 -> Lug 16 = 11.3 VAC (pin 3 to 5 on PS Input)
Lug 16 -> Lug 17 = 11.3 VAC (pin 5 to pin 1)
Lug 11 -> lug 12 = 20VAC (pin 8 to pin 9)
Lug 13 -> Lug 14 = 11.5 VAC (pin 11 to pin 12)

Since it is hard to read the numbers on the transformer, that is why I also included the pins on the power supply board.

So you would measure between pin 3 and pin 5 on the power supply input and between pin 5 and pin 1 for 11.3 VAC input. And so on for the rest of the voltages.

The regulated voltages are reasonably close to what is required to run the game. If the voltages at the ROM board are still low, then it is likely that one of the following things may need to tested/corrected:
1) the input pins on the ROM power header may need to be reflowed. There may be some cracks in the solder that are limiting the current flow which will drop the apparent voltage.
2) there may be some corrosion on pins or on the connector pins that are causing a slight resistance in the connection that will drop the voltage.
3) there may be a bad connection at either end of the power connectors. If they are the original wiring harness connectors, the wires can work their way loose from the IDC connectors and this can cause a drop in the voltages.
4) There may be a break in the wires leading to the ROM card. You need to check the continuity of the wires to check this possibility.

ken

This was from a set of PMs regarding this topic, but I thought it would be general interest if anybody was having the same issues.
 
Thanks for posting that here, Ken. I'll be looking more at the voltages to the board, but they seem kosher (except those 14v on the 12v?).

I think I'm going to have to get the rom board serviced, it being one of the boards I haven't replaced from this previously water logged cab.
 
The unregulated voltages are fine at 14V. When these games were designed the wall voltage averaged 110VAC. Most areas of the country average 120VAC now. The higher voltage bumps the unregulated voltages. If they were way higher (16V or higher) I would be worried, but 14V seems to be the common average now.

ken
 
The latest: I checked the voltage at the very dim light bulbs in the CP and the coin drop; they're all around -4.85 to -4.9 VDC.... Before I take the harness apart, is there a simple reason for this?
 
The GI lighting on Williams games comes from the 6.3VAC that is on the small header on the power supply board (6 pin). The power comes from pins 1 & 2 on that connector. You will get incorrect readings on your meter trying to use the DC voltage settings.

Check the bulbs. #44 & #47 bulbs are 6V bulbs. There are 12V bayonet bulbs that will glow dim if put in those sockets (don't remember the bulb numbers offhand).

ken
 
Okay, I do indeed have #44 bulbs and did some more troubleshooting today. I unplugged everything except the CP's and the coin door. I got a reading of 2.4 VAC at the bulbs, but then thought maybe I have a short somewhere?

I unplugged the coin door and got 3.1 VAC. Unplugging one of the CP's gave me 5.01 VAC to the bulbs in remaining connected CP.

After plugging in all of the boards again, I get the same results,

1. The "rug pattern" appears and sweeps a few times (it honestly looks like a Cosby sweater to me.)
2. All 4 LEDs on the ROM board light up
3. Monitor goes black, some high frequency sound changes coming from it.
4. 5 VAC to one control panel!

Should I replace the cord coming from the PS, as the earth prong was cut off from the male end of the power plug?

Is the wiring poo poo and causing a loss of power?

All 3 LEDs are ON on the power supply, is there something I can check on that or something acute causing this lack of current?

Thanks!
 
I would replace the power cord. Not having a grounded machine is a shock hazard.

I would try unplugging everything from the power supply except the MPU and ROM board. If that gets you past the rug screen (RAM test), then plug the sound card back in. Then the control panel. The idea is to see if any of it works and then to narrow down what causes the problem after that.

The bulb sockets are notorious for shorts. You can check the continuity to see if either of the coin door light sockets are shorted.

I am not sure why there would be any AC voltage going to the control panels. Are there sockets there? I don't recall if the buttons are lighted on the Defender cocktail.

ken

Edit: You can also try pulling the fuses and make sure they are the correct values. Also take a 3M Scotchbright (or similar) pad and clean the fuse clips and the metal ends of the fuses. Don't use sandpaper. The clips will start to corrode if the coating is scratched off.Then squeeze them slightly to make sure they will grip the fuses tightly. Many times corrosion in the fuse will cause the power supply not to be able to draw enough current through the fuses.
 
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