Joust won't boot - Error 1-3-1 Green Screen

MTPPC

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I got this machine broken. It powers up to a green screen and the ROM board reports 1-3-1. If I reset, it just repeats the 1-3-1.

It started with a blown BR1 on the power board which was taking out fuse 4. That's now fixed.

From my studies, I measured voltages on the RAM chips (per the manual) and all the voltages are very close:
Pin 1 -4.94
Pin 8 12.15
Pin 9 4.96

All three leds on the powerboard are on when 4J2 is connected or disconnected. The bottom one does seem a little dimmer.

If I hit the button on the sound board, it repeats what I think is the flapping sound.

I found in another thread that a guy fixed a similar problem by replacing 7410 @ 6I. How can I further isolate the problem. I don't have a logic probe, but if that's what I need, I'll get one.

What should I do?
 
Thanks for the tip. Ordered it on Sunday and got it on Tuesday.. now what?!?!?
 
Thanks for the tip. Ordered it on Sunday and got it on Tuesday.. now what?!?!?

inspect board for any scratches and other damage. Hold up to a bright light to see through also.

Hook the probe to +5 and probe the processor at the address lines and all interupt, rest, clock lines<on the processor if it is a z80 check pin 26 and 3 and see what they are doing. Watch videos to help understand how that logic probe works. Ask here for help where to probe.
 
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I got this machine broken. It powers up to a green screen and the ROM board reports 1-3-1. If I reset, it just repeats the 1-3-1.

It started with a blown BR1 on the power board which was taking out fuse 4. That's now fixed.

From my studies, I measured voltages on the RAM chips (per the manual) and all the voltages are very close:
Pin 1 -4.94
Pin 8 12.15
Pin 9 4.96

All three leds on the powerboard are on when 4J2 is connected or disconnected. The bottom one does seem a little dimmer.

What should I do?

Inspect the header on the MPU for cold solder joints. You may be losing part of your voltage at the header.
 
This sounds like a power problem; typically you will get some sort of display output (the rug pattern) unless the power is bad to the Rams or the Address Decoder Proms are toast. I will usually take a reading on each side on one of the small capacitors near each chip. One side is +5 and the other is gnd. Once you verify that, carefully check the voltages at the Ram chips. Be careful because if you slip while checking the +12 voltage, you will likely pop one of the address select chips (74153s). I've done it...

The harness from the transformer to the linear supply has twin pins for most of the inputs however only one is populated. A cost savings, probably. Check for burned pins and housing and when you replace them, go ahead and splice the wires and use both pins on input. it will save you a lot of trouble in the future. This is one of the weak points on the first generation of Williams games which also plagued the pinball machines.

Kirk S.
 
inspect board for any scratches and other damage. Hold up to a bright light to see through also.

Hook the probe to +5 and probe the processor at the address lines and all interupt, rest, clock lines<on the processor if it is a z80 check pin 26 and 3 and see what they are doing. Watch videos to help understand how that logic probe works. Ask here for help where to probe.
Pin 3 is high when the 1-3-1 LED is illuminated, low otherwise (except just before the message starts).

Pin 26 is indicating a square wave. When I press the reset button, it shows high on my logic analyzer for about a second and a half. This seems backwards to me from what I have read.

Dokert, I've reflowed all the header solder joints and I'm confident that I've got good voltages at the RAM chips.

crayzkirk, the voltages seem to check out at the RAM chips, how would I determine the state of the Address Decoder PROMS?

I checked pin 1 on both decoder ROMS. Decoder ROM 6 shows a steady wave on pin 1. Decoder ROM 4 shows high until the code blinks out twice and then does a second of wave indication.

And my code has now changed to 138. When I reset the machine and power it up again, 131.
 
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The machines are a bit different however the Defender TOP (theory of operations) manual has the wave forms for memory access and the clock signals. A static screen is, IMO, an indication that the program is not running and may be an issue with the ROM board or interconnection between them. Even if one bank is bad, the test program will still attempt to write to memory will show a rug pattern of some sort.

Checking the Decoder Proms can be done with a logic probe. Check for input/output lines that are not changing. It takes some time to recognize what is right and what isn't. Sorry that I can't be more specific. Having another board set helps.

Kirk S.
 
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