Yesterday's board repair experience (long post)

komodo

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I know we beat this horse quite a bit a few weeks ago but I thought I would give a "real life" perspective on board repairs for those that want to try their hands at fixing boards themselves and saving some money.

I recently purchased some boards with known issues because they are scarce and I needed them. Fortunately Talon2000 isn't too far away and he offered to tutor me on the finer aspects of vector board repair. I took him up on that offer and brought 6 boards to his house to work on.

First off, a word of caution. If you have a rare/expensive board, DON'T try to fix it yourself if it is the first board you have troubleshot.

Board number one was a Lunar Lander with the reported issue of a RAM error on self test. Sure enough, the self test gave us a bad ram but did not complete the entire self test. Hooked up a Fluke 9000 and tested the ROMs and RAMs and got some strange results. Pulled chips and tested them but they were fine. Note: This board had been worked on before. Found 2 torn via's under a memory buffer that had been replaced with machine pins for a socket and a torn trace next to a vector RAM (I think that is where we found it) from someone's pry tool and bad soldering/desoldering before. I seem to recall finding a bad chip on the board, (might have been a memory buffer) . Got it to pass a self test now with all the correct sounds but game still wouldn't come up. No image. Checking the voltages in the vector section proved very confusing. Voltage were missing. Turns out there was a blown trace right at the edge connector of the board. Fixed and now picture. Put it in game mode but no sounds. Found 2 missing mylar caps on the edge of the board that control sounds. I know there were some other issues with this board but don't recall what they were. Total time to test and troubleshoot about 2.5 hours. My part in this was getting sockets out of the drawer and replacement chips. Talon2000 was very fluid in troubleshooting the issues and was patient enough to explain to me the logic he was following (no pun intended) to troubleshoot everything.

Board number 2 was a real disaster. Lunar Lander as well. It was sold to me as missing 2 chips. It was indeed missing one of the roms and the vector prom. Kevin burned replacements. Fortunately he had a Data I/O 29b with the unipak mod to burn the eeprom and vector prom. For some reason, the other burner didn't like the 2716. Testing the board gave us nothing. The board was dead. Looked for dead shorts and found several questionable pins bent over on the back side of the board. Probably at least 7-8 of them. Still no luck. The 15volt regulator on the board had been desoldered/resoldered poorly at one point. Pulled and replaced it just because it looked nasty. No joy. Trouble in the reset circuit. The CPU was being held low on pin 40. Also, testing of the board had blown a fuse on the power brick and replacing that gave us power to the board again. Testing the board indicated a dead short somewhere on the board. Spent 20 minutes going over all the questionable parts of the board with no success. Kevin then followed traces looking for the short but could not find any bad spots. Split the questionable trace in half and found a short on one side of the cut. Isolated it to a specific chip which we replaced. Problem fixed. Turning to the other half of the trace, still had a short. Found another bad chip thru intuition and testing. Still yet another bad chip was found. Resoldered the cuts. No more shorts. Powered up board, No picture. Kevin then turned to the schematics/memory map and other bits of the manual to determine that there were some issues in the vector state machine. We didn't have the parts necessary to fix that area so we will have to wait on that. Time on this board. At least 3 hours so far.

In between the two boards, we tackled a Star Wars board set with a starfield issue that I bought from a klov'r. I suspected a bad prom. It was indeed a bad prom. Replaced and Board tested good. Total time 30 minutes.

All in all we spent 7 and a half hours to get 3 boards working and one of them still had issues. I certainly don't have the smarts to do what Kevin did but I was fortunate enough to learn from him. I probably slowed him down a little but I did get a reality check into board repairs. It will take me a very long time to get to his or Channelmanic's level. (Most likely never)

I've decided to stick to what I am good at (vector monitors) and let them do the "hard stuff." I know neither of them like to mess with monitors so I am set.

I guess what I want to impart to potential board repairers is this. Don't blindly charge into something you know nothing about. Try the simple fixes like a board that you own that was working and now isn't. Hopefully there wasn't a power surge or something like that so it could be a simple fix. Most of the newer games have a self test that is a little better at defining what is wrong. Try the simple fixes first and when you are in over your head. Stop. Get somebody that knows what they are doing then ask them to show you how to troubleshoot.

If you have a "ebay" board, there could be lots off issues with it. Both of the LL boards had been worked on before and we could see the repair route the previous guys had followed in troubleshooting. They were on the right path, they just created more issues for themselves with their "repairs." If it had been me, I would have thrown the board against the wall.

If you are an experienced board repairer, you already know to check other people's work. I've seen my share of bad fixes and it sin't always easy to undo a bad repair job. Nobody wants to spend $100-200 to somebody to fix a board. Sometimes it isn't that much. Sometimes it is more. Some of the chips used on the vector boards are getting scarce and pricey. Others are unobtainable and fortunately there are some replacements out there (AVG's) while other's are sorely needed. (chips on G08 deflection boards).

Finally, there usually isn't just a one chip fix especially on boards that have been on an ops shelf or stacked with other boards for a long time. Count on a lot of time trying to repair things. If you are looking for assistance, it isn't as easy as "just tell me the chip I need to replace". Very few boards have the same issue although there are known issues with many boards. Galaga resistor packs come to mind. Finally, give the board repairer's their due. Find somebody with good skills and excellent feedback and your money will be well spent. You can spend your time fixing the things you know how to fix and enjoy your games a lot more than pulling your hair out. Finally, if you don't have money to pay for board repairs, how about digging through that stack of boards you got for $5 at the flea market/ operator closeout/auction and perhaps offer a trade to these guys. I know for a fact that both Channelmanic and Talon2000 will take full or partial trades for their work. You may also have the gonkulator rubbermaflange they need to fix the gas pedal on their Mariocart extreme with sensaround.

Finally, this is not meant to in any way discourage you from fixing your own stuff. Just a recommendation that you recognize your limitations and stop before you get expensive. Best of luck to you in your repairs.

Thanks to Kevin for his tutelage and Channelmanic for his previous repair forums and not giving me stupid looks when I ask even stupider questions than I should.
 
Oh yeah, it helps to have good test equipment and tools to do what you need to do. Kevin's shop is quite impressive and some of the stuff we needed to do could not have been done without them.
 
Just a quick comment. Even worse than trying to fix a board is the guys on here that buy a working board and then just pop it in their game WITHOUT EVEN CHECKING THEIR VOLTAGES.
Now the person has 2 dead boards because the +5 was over +6 and they had no idea. Checking your +5 is THE most basic thing to learn before you EVER put a working board in a dead game.
 
I know we beat this horse quite a bit a few weeks ago but I thought I would give a "real life" perspective on board repairs for those that want to try their hands at fixing boards themselves and saving some money.

I recently purchased some boards with known issues because they are scarce and I needed them. Fortunately Talon2000 isn't too far away and he offered to tutor me on the finer aspects of vector board repair. I took him up on that offer and brought 6 boards to his house to work on.

First off, a word of caution. If you have a rare/expensive board, DON'T try to fix it yourself if it is the first board you have troubleshot.

Board number one was a Lunar Lander with the reported issue of a RAM error on self test. Sure enough, the self test gave us a bad ram but did not complete the entire self test. Hooked up a Fluke 9000 and tested the ROMs and RAMs and got some strange results. Pulled chips and tested them but they were fine. Note: This board had been worked on before. Found 2 torn via's under a memory buffer that had been replaced with machine pins for a socket and a torn trace next to a vector RAM (I think that is where we found it) from someone's pry tool and bad soldering/desoldering before. I seem to recall finding a bad chip on the board, (might have been a memory buffer) . Got it to pass a self test now with all the correct sounds but game still wouldn't come up. No image. Checking the voltages in the vector section proved very confusing. Voltage were missing. Turns out there was a blown trace right at the edge connector of the board. Fixed and now picture. Put it in game mode but no sounds. Found 2 missing mylar caps on the edge of the board that control sounds. I know there were some other issues with this board but don't recall what they were. Total time to test and troubleshoot about 2.5 hours. My part in this was getting sockets out of the drawer and replacement chips. Talon2000 was very fluid in troubleshooting the issues and was patient enough to explain to me the logic he was following (no pun intended) to troubleshoot everything.

Board number 2 was a real disaster. Lunar Lander as well. It was sold to me as missing 2 chips. It was indeed missing one of the roms and the vector prom. Kevin burned replacements. Fortunately he had a Data I/O 29b with the unipak mod to burn the eeprom and vector prom. For some reason, the other burner didn't like the 2716. Testing the board gave us nothing. The board was dead. Looked for dead shorts and found several questionable pins bent over on the back side of the board. Probably at least 7-8 of them. Still no luck. The 15volt regulator on the board had been desoldered/resoldered poorly at one point. Pulled and replaced it just because it looked nasty. No joy. Trouble in the reset circuit. The CPU was being held low on pin 40. Also, testing of the board had blown a fuse on the power brick and replacing that gave us power to the board again. Testing the board indicated a dead short somewhere on the board. Spent 20 minutes going over all the questionable parts of the board with no success. Kevin then followed traces looking for the short but could not find any bad spots. Split the questionable trace in half and found a short on one side of the cut. Isolated it to a specific chip which we replaced. Problem fixed. Turning to the other half of the trace, still had a short. Found another bad chip thru intuition and testing. Still yet another bad chip was found. Resoldered the cuts. No more shorts. Powered up board, No picture. Kevin then turned to the schematics/memory map and other bits of the manual to determine that there were some issues in the vector state machine. We didn't have the parts necessary to fix that area so we will have to wait on that. Time on this board. At least 3 hours so far.

In between the two boards, we tackled a Star Wars board set with a starfield issue that I bought from a klov'r. I suspected a bad prom. It was indeed a bad prom. Replaced and Board tested good. Total time 30 minutes.

All in all we spent 7 and a half hours to get 3 boards working and one of them still had issues. I certainly don't have the smarts to do what Kevin did but I was fortunate enough to learn from him. I probably slowed him down a little but I did get a reality check into board repairs. It will take me a very long time to get to his or Channelmanic's level. (Most likely never)

I've decided to stick to what I am good at (vector monitors) and let them do the "hard stuff." I know neither of them like to mess with monitors so I am set.

I guess what I want to impart to potential board repairers is this. Don't blindly charge into something you know nothing about. Try the simple fixes like a board that you own that was working and now isn't. Hopefully there wasn't a power surge or something like that so it could be a simple fix. Most of the newer games have a self test that is a little better at defining what is wrong. Try the simple fixes first and when you are in over your head. Stop. Get somebody that knows what they are doing then ask them to show you how to troubleshoot.

If you have a "ebay" board, there could be lots off issues with it. Both of the LL boards had been worked on before and we could see the repair route the previous guys had followed in troubleshooting. They were on the right path, they just created more issues for themselves with their "repairs." If it had been me, I would have thrown the board against the wall.

If you are an experienced board repairer, you already know to check other people's work. I've seen my share of bad fixes and it sin't always easy to undo a bad repair job. Nobody wants to spend $100-200 to somebody to fix a board. Sometimes it isn't that much. Sometimes it is more. Some of the chips used on the vector boards are getting scarce and pricey. Others are unobtainable and fortunately there are some replacements out there (AVG's) while other's are sorely needed. (chips on G08 deflection boards).

Finally, there usually isn't just a one chip fix especially on boards that have been on an ops shelf or stacked with other boards for a long time. Count on a lot of time trying to repair things. If you are looking for assistance, it isn't as easy as "just tell me the chip I need to replace". Very few boards have the same issue although there are known issues with many boards. Galaga resistor packs come to mind. Finally, give the board repairer's their due. Find somebody with good skills and excellent feedback and your money will be well spent. You can spend your time fixing the things you know how to fix and enjoy your games a lot more than pulling your hair out. Finally, if you don't have money to pay for board repairs, how about digging through that stack of boards you got for $5 at the flea market/ operator closeout/auction and perhaps offer a trade to these guys. I know for a fact that both Channelmanic and Talon2000 will take full or partial trades for their work. You may also have the gonkulator rubbermaflange they need to fix the gas pedal on their Mariocart extreme with sensaround.

Finally, this is not meant to in any way discourage you from fixing your own stuff. Just a recommendation that you recognize your limitations and stop before you get expensive. Best of luck to you in your repairs.

Thanks to Kevin for his tutelage and Channelmanic for his previous repair forums and not giving me stupid looks when I ask even stupider questions than I should.



As a Electronics Tech Myself i VERY MUCH agree with everything Komodo Has Said...i do my own repairs since i'm a retired arcade tech..and i still agree with everything here...THIS SHOULD be Made as a STICKY :)


and Now Komodo is Very Fond Of Electronics Techs :D

Glad You Got To See a Great Tech at Work Komodo :)

Congrats On your Progress & for Having Great Tech Friends !


A+ Gentleman !




END OF LINE.


Daniel.
 
Thanks for the pr0pz Pat!

Remind me to show you and Kevin the finer points of finding short circuits using a simple ESR meter. :)

It's simply a high frequency milliohmmeter and you probe around the voltage and the ground pins until you find the area of the board with the lowest resistance. This is the area where the short is.

I did that to find a nasty short on a Midway board that was almost nothing but surface mount. Turned out it was a surface mount tantalum cap in the -5v section. Found it just a couple of minutes with the ESR meter.

RJ
 
i agree

i just want to say i agree with everything komodo has said.

i have been working with Darthi8nt fixing Nintendo boards and sever others i needed for my games.

he has been showing me many different ways to go thru a board and look for things that are wrong.

and i can say that your tools are a crucial part of board repair.
i know this from fixing monitors for folks.

top notch tools = ease of repairing what your working on.

and believe me i trade him more stuff for fixing my stuff and tutoring me than he would ever charge for the repairs if he did them himself.
Trade and kindness go along way.

i wish i could come to you Texas guy's repair party's to learn new ways and techniques to become a better repair tech.

thanks for all the techs out there that help others get their boards and monitors fixed.

Peace
Buffett
 
Just a quick comment. Even worse than trying to fix a board is the guys on here that buy a working board and then just pop it in their game WITHOUT EVEN CHECKING THEIR VOLTAGES.
Now the person has 2 dead boards because the +5 was over +6 and they had no idea.
Double-facepalm.jpg
 
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