Vendetta PCB repair

[Mike A]

I am not sure what the interest will be on this forum. I will be posting the stuff I learn as I go along.
I started collecting arcade games in 2015 or 2016.
I built my first MAME cab a long time before that, but I was never really engaged in this stuff.
I have no formal training in electronics or computers or carpentry.
I attended U of I at Champaign Urbana enrolled in the pre med program.
After 2 years I knew I didn't love it and bailed out to help my dad expand his business.
I have been working in warehouse management ever since then.

I think that gives me a good realistic background to post this stuff. If I can do it. You can do it too, and probably better than me.

Anyways. Hopefully this is the first in a series of topics. You will see my successes and my ---fudgesicle--- ups. I will tell you when I had to lean on someone else. Questions and criticisms are welcome.

I am formatting pics and stuff. Stay tuned.

I should mention that this repair is completed already and the board functions 100 percent.

[Mike A]

I bought a Vendetta PCB from Opt2Not.

https://www.arcade-museum.com/game_detail.php?game_id=10300

He had done some repairs to it, but it needed more and he would rather have the money than the headache.

Vendetta is  a JAMMA PCB. You have probably seen that term thrown around here.

This is the pinout for the JAMMA standard.


I will go more into that in another thread. I plan on explaining JAMMA and how it can and should be used in your cabs.

[Mike A]

He gave me the bro price for the board.

He said audio was not working. I thought that would be a good repair job for a guy like me.

The board mostly worked, but had one isolated problem.

[Mike A]

The first step for me was to boot up the game. After all it mostly works as is.



Many arcade boards do a self check on boot up.

This one showed a bad ROM, but the game continued boot up and I could play the game, but no sound.

[Mike A]

So next I did a physical inspection of the board with a magnifier. I will explain why that should have been the first step now.





The audio amp was fried. And there was no heat sink on it. I have seen no heat sink on several boards I have acquired.

Upon inspection of the schematic the amp installed was the wrong one.

It tested bad on my meter. I wasn't sure if this amp fried or if the previous one did since this one was a replacement. I will explain how that works in another thread. And then I will put a link back here.

[Mike A]

I went back to the schematic and then ordered the correct amp from eBay.

I will explain how to do that in another thread. I want to try not to side track too much for the meat of any particular thread.

I will post links to reference them when necessary. It should create a web of good information.

[Mike A]

I soldered in the new audio amp and I had to make a heat sink.







My metal working tools and skills are basic. With a better jig I will be able to make a nicer one...Or I can just by some aluminum U channel in the appropriate size.
It is a skill building and learning exercise.

If I skip anything that you want to know more about just ask.

I will continue this later. I need to write up my JAMMA explanation and some other things.

As you can see I am terrible and cleaning up after myself.

Now I have good sound FX , but the music is scratchy and wrong.

That is not totally surprising because the ROM that handles that stuff is the one that tested bad.

So progress but not success.

[Mike A]

The next step was to address the bad ROM problem.

I didn't have a ROM programmer so I couldn't directly test the ROM.

I put in a call to bperkins01. He told me to check traces going to and from that ROM. He told me that if there was bad communication with the chip, it could be okay and still test bad.

That I can do. And that is why it is important to reach out and make friends in this hobby.

There are a bunch of people who will gladly help you out.

I told him I already checked the traces. He said check again really close.



There it is. That tiny spot broke continuity for that trace.

[Mike A]

The next step for me was to see if fixing that trace would fix the problem.

I just took a 18 or 20 gauge wire and soldered it to a point before the break and a point after the break. I found suitable spot by continuity testing large enough solder points.

I figured I would do a cleaner fix later if it worked.



One of these magnifiers is a pretty essential tool for finding broken traces and stuff. Especially on these later boards. The traces are smaller and closer together.



Did it work?

[Mike A]

Yes it did. The music and sound now work perfectly. Hooray.

I asked bperkins01 (you will see his name pop up a lot) how these things are normally fixed.

It was a small break so he said to scrape the spot with an exacto, to use some flux and then make a solder bridge.

Well I was not crafty enough to do that. I made the gap wider. 

Next I tried using a tiny bit of wire to bridge the now wider gap. 

I ---smurfing--- suck at this.

I ended up using some tiny 30 AWG Kynar wire to bridge the trace at the same points I originally used.

It looks much better now, but not as professional as the other techniques would have been.

I put the PCB back in the machine and had my buddy's kids play test it for a couple of hours.



The repair has been solid. Victory.

I will post pics of the final repair sometime later.  I forgot to do that before I put the PCB back in the machine.

[opt2not]

This is a great thread. This board went through so much. From custom Sprite generating QFP’s gone bad, to amps burned out, to micro trace breaks. It’s great to see it on the path to full recovery.

[Mike A]

I am glad I could continue what you started.

More importantly, a new generation gets to enjoy this game now.

[pbj]

This is good BYOAC.

Of all things, a staple laid across breaks like that, soldered in place, and then clipped works really well.

[bperkins01]

Nice writeup MikeA   
Great pics too..  they help

[jamieww]

Many yests ago I used a metal paint then a sealer to repair, it was excellent for pcb repairs as it could be applied extremely thinly & the sealer could effectively be sprayed or painted to cover everything.
I haven't bothered much with repairs for some time as I stepped completely away from it, parts became so cheap it wasn't worth my time vs the cost.
Now I'm starting to get back into the electronics side of things with various arcade gaming units & bandits it's great to see so many passionate people still doing actual repairs!
Its given me a bit more respect for repairing over replacing for the sake of cost... plus some PCB's are becoming harder to find replacement for!

Great start on your write up, thank you.

Sent from my SM-N950F using Tapatalk

[bobbyb13]

I can only hope to learn how to do work like this before somebody is sprinkling me around to fertilize the bananas...

Many yests ago I used a metal paint then a sealer to repair, it was excellent for pcb repairs as it could be applied extremely thinly & the sealer could effectively be sprayed or painted to cover everything.
I haven't bothered much with repairs for some time as I stepped completely away from it, parts became so cheap it wasn't worth my time vs the cost.
Now I'm starting to get back into the electronics side of things with various arcade gaming units & bandits it's great to see so many passionate people still doing actual repairs!
Its given me a bit more respect for repairing over replacing for the sake of cost... plus some PCB's are becoming harder to find replacement for!

Great start on your write up, thank you.

Sent from my SM-N950F using Tapatalk

And this reminds me of stuff I have used for repairing defroster circuits in rear windshields of people's cars.
Just have to find the stuff that is almost entirely silver is the only concern.
Maybe could work for repairing burned traces?

[mourix]

I really like how far you got with some research. Well done.

The patch wire can be made to look quite good if you keep 90 degree angles and hot snot it for protection.

[Mike A]

Thanks. Yeah I used kynar wire for the final repair and it looks prettier.

[jennifer]