83 Chexx help (need wiring pics)

jm2u

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I just bought a game that's been hacked just about everywhere. Most notably right at the CPU. Im guessing they used a wiring harness meant for the newer games but hacked it for the 1983 CPU.

They split the teal and violet wires and patched them into the ribbon cable that goes to the dome.

There are also 2 wires that come off the orange displacement connector that connect to a 2 pin molex. In the picture I'm holding that molex. Then that molex has 2 additional grey wires that aren't terminated!

http://img193.imageshack.us/i/img4067a.jpg/

To top it off there is a board hack which I can't figure out? I looked at the schematics and it has something to to with credits? Free play hack? The game does nothing so I can't tell.

http://img580.imageshack.us/i/img4069vq.jpg/

Could anyone please send me pictures of their 83 Blue Chexx wiring? I've got extra connectors, and cut wires, its a real mess.
 
I was just going to suggest that you try the ChexxFan forum, but I see you've already done that! It seems like one of the least active forums I've seen on the web, so you might not get an answer for a while. It may be a longshot, but you might even want to contact ICE to see if they can help you out... at least with a manual or something.

Edit: There's something in the Super Chexx manual about the old style ribbon cable that looks like it has the 2 pin molex (page 21). Might want to check that out too.
http://pdf.textfiles.com/manuals/ARCADE/S-Z/Super Chexx [Owner's & Service] [English].pdf
 
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Edit: There's something in the Super Chexx manual about the old style ribbon cable that looks like it has the 2 pin molex (page 21). Might want to check that out too.
http://pdf.textfiles.com/manuals/ARCADE/S-Z/Super Chexx [Owner's & Service] [English].pdf

I have that cable for sure! But, when I look at pinrepair, I don't see any additional molex connector coming off the original ribbon cable. I'm not sure why they would add that when its not there originally. Even stranger mine has those 2 grey wires attached to that molex connector that aren't on that PDF. They look factory too...
 
Have you looked here: http://www.pinrepair.com/arcade/chexx.htm

I have a Chexx that I could take pics of if you need more.

Pictures would be very much appreciated, thank you! Yes, I've been through that guide. It's helpful, but the pictures don't show the harness very well. I'm particularly interested in the wires and connectors from the scoreboard. Voltages from the Red, Yellow, Violet, and Green wires from the power supply would also be great. I have the original manual and schematics and they don't list them. The only thing helpful was the Fuse rating on the power supply: 2a slo-blow. And par for the course, I found a 7a Fast Blow in mine.
 
Let me know if you end up needing a photo of Super Chexx -- you may not though since I think they're pretty different. I didn't read through the PinRepair page in depth, but definitely take note that some of those pictures are for Super Chexx and some are for regular Chexx, and they're kind of all mixed together.
 
That's great! Could you get one more of the big grey ribbon cable that goes to the score board? It has the orange header. You've got two but at that angle its hard to see. That's the area that I'm really wondering about.

Also, are you missing some sound ROMs? You have a couple empty sockets at U12 and U13.

I don't suppose I could push my luck and get the power supply voltages from you? I've searched all over the net and there is literally no documentation on the voltages from the power supply. Pinrepair mentions the voltages it outputs, but doesn't indicate which wire is which voltage. I you've got a meter I would think you could use the Green/Yellow strip ground wire as ground and then probe the Yellow, Red, Teal, Green wires to find their DC voltage.

Thanks again!
 
I took a longer look at the schematics and they do show the voltages for some of the wires from the power supply. Everything but the RED wires.

Violet=12v, but my meter comes up with 14v (not good)
GreenishTeal=Ground
Yellow= Ground
Both RED are supposed to be the SAME but I can't get a reading using yellow wire as reference. However I found the 7805 Vregs that are attached/upstream to the Red wires and read 14 volts on the input leg and the output is supposed to be 5v. One of the 7805s checked out OK, but the second is outputting only 1.5v. I replaced this 7805 but had the same low output. I'm going to recap the power supply and recap the transistor that acts as a decoupler? to the "bad" 7805.

EDIT: RED AND YELLOW ARE A/C not D/C. They go through the Bridge rectifiers on the motherboard where they are converted to 14v DC and regulated down to both 5v and 8v DC.
 
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OK. So first I changed out that ceramic cap that was linked to the voltage regulator. Bingo, 5v output! Great. Then I desoldered the old power supply cap. Its 15,000uf and 25v. Once I had it out it was very apparent it had been fried. I soldered in the new cap (yes, with correct polarity) and turned on the game. I got all 3 period lights to come on (That's new!) then POOF. Fuse is toast. New power supply cap looks slightly distended as well.

There's really not much to that power supply. It just has that 1 large cap and 2 diodes. The diodes seem to be OK, because they only buzz out with the meter one side of the diode. What's causing the fuse to blow and also take out a cap?

Ugh...so close!
 
Make sure that those two big diodes are soldered on well with no cold solder joints and that they are facing the correct direction.

I'm pretty sure the exact same thing happened to me when I brought my Chexx home. Actually, I bought the game with the 'motherboard fried' and there was no power anywhere ... when, usually, there should be GI at the very least, hence a PS issue. It was simply due to one of the two diodes falling off from the heat over the years. It was sitting at the bottom of the cage. When I resoldered it back, it faced the wrong direction and I blew a fuse too. I heard the music for 1 second then kablooey. Righted it and 'Game On'. Lucky and easy fix.
 
I saw your post when I was researching, if yours is used as a reference my diodes DO NOT look original. They look similar to the one in the picture you posed of your problem, but not exactly the same. Also in the manual someone circled them and wrote "reused". According to the previous owner the game was working at one point, and I'd wager he was not the one who replaced them. The manual doesn't give a specific part number on those diodes either. I would order new ones, but I can't figure out their specs. EDIT: MR752, thank you manual parts list!

It's funny/sad that if you google for tech help on Chexx you only come up with Pinrepair's guide, and your diode thread, and now mine.
 
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It's funny/sad that if you google for tech help on Chexx you only come up with Pinrepair's guide, and your diode thread, and now mine.
Ha! I forgot I documented that fix and it was only just a month ago. Well, I'm glad it was partially useful and reaffirming that it is worth the extra effort to take pics during the troubleshooting process. Maybe I'll take a pic of the diodes showing their proper direction for future reference as well. It appears as though DigiKey carries them but no price.

Chexxfan has a message board with quite a few questions and answers: http://chexxfan.proboards.com/index.cgi?board=games. It doesn't look like it gets a great deal of traffic though so one can't expect an immediate answer.
 
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Yeah, Chexx fan is a good resource for game mods like painting your players. But I notice anytime someone asks a technical question they are just directed to the MFG, and that's no help.

The diode's arrow should point up. Because in this case, that's the direction current is supposed to flow and shouldn't go the other way. I wonder if its just failing under load, I guess that's another 20 bucks at Jameco and another week of waiting for delivery to find out. I hate waiting on parts!
 
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I thought someone wrote "reused" above the power supply diodes in the manual, but it actually says "Reversed" So now I'm not sure which way the diodes go. I assume the arrow should point toward the Cap, and block any returning voltage to the transformer. But I've tried it both ways and the cap has exploded twice. I'm quite sure I have the cap polority correct. Negative pole and side facing the green and violet wires.
 
It appears that the diodes/resister discs both both go in the same direction, arrow in the direction facing closest edge, away from the big cap.
 

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Really? To me the diodes are each going an opposite direction. Also the negative side of the cap is facing Away from the side with the green wire? That is not what the schematics say at all!
 
No, they are not. Flip back and forth from the 2 pics and notice the confusing curves. I desoldered and flipped the heavy 'wire' on the one because I thought it would be easier to solder off the board but I was wrong and installed it back upside-down. They don't look it but they both go in the direction of the yellow and red wires. I found it to be a pain to solder these things.

Either way, there aren't too many variations here. If the fuse blows one way, then try flipping it. That's what I did and have been enjoying the Canadian national anthem since.

Really? To me the diodes are each going an opposite direction. Also the negative side of the cap is facing Away from the side with the green wire? That is not what the schematics say at all!
 
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Oh I see, its just flat against the board.


The good news for me is that if yours is correct, I have also been installing the capacitor in the wrong polarity. The stripe is the negative side, and the schematics say that goes toward the side with the green wire. Your game is working, so I'm going to say that they are wrong. This better explains why my Cap keeps exploding (I'm up to two blown caps).
 
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