60 in 1 iCade PCB - red colour missing

Yesterday i got a 60 in 1 multiboard from my friend Henrik

it had a error... the red colour is missing!
Perfect for a littel field action.  I still need all the practise i can get :o)
So lets hook it up to the super gun and see what we got

Well that sure dont look right... i have hooked it up to the super gun, but am here using the VGA port (for use on an old PC monitor, but my test TV also have a PC in)

Lets try to put in in test mode by moving dip switch nr 4 on

Yup, still bad clours. So its time to finde our magnifying glass and pretend that we are mr sherlock holmes :)

If we look at the Jamma Pinout, we can se that nr 12 on the parts side is the RED clour.

By following the trace on the PCB an confirming with my multimeter on connectivity (with beeb sound) i first trace it to resistor R78 on the left side of the VGA port

To be sure i am on the right track i used a "poker" ( a test lead hooked directly to +5V.. a trick i found in my master and mentor Elgens repairs blog) and hit resistor R78 with +5V. When i did that the screen quickly flashed red... OK.. we are on to something here. Those SMD components are sure small, and the PCB looks nothing like the old one from the 80´s and 90´s we are used to work on.. Phewww, be carefull with the "Poker"!!!

I also found the resistor R79 is green, and R80 is blue... so lets continiue up stream

The trace ran fro R78 under the cap C77 and ended on resistor R52

On the other side of the resistor it went to a HC273 TTL Octal D Flip-Flop and thats were it ended. So by eliminating all other options, it got to be a faulty TTL..

Luckily Henrik gave me a spare 60 in 1 that had sound issues, so now i had a good reason to use my new SMD rework station :)

Man those SMD components are small

I replaced the the right TTL that i have traced the signal back to, tested it in the super gun, still using th PC input...

And hey presto.... nice clours all around :o)

 But when i went back to the scart cable (using Jamme RGB ) the clours were still a little off !????
Well , there were 2 x HC273 TTL´s , and lets guess.. If there are 2 TTL´s next to each other, and 2 RGB outputs, maby they each controll an output, and if one TTL is bad, maby the other one is also faulty.. Lets change the left TTL also, just for the hell of it.... And wouldent you know, all the clours is now back on the Jamma out put also

 Thanks to Henrik for the boards :o)

First arcade pcb repair - Cabal bootleg pcb

Ok, so here goes my first repair blog..

I traded 3 Nintendo n64 controllers for 3 arcade pcb's, 2 were faulty, this one working but no sound.. 

Think this is a good repair to start with

It works fine, but no sound, so lets start the detective work

I already know that the amps on these old boards have a tendency to go bad, so i pulled up a datasheet for this amp.. An uPC1241H

Ok, so pin #6 is audio out, lets test that with the scope

That looks fine, i hooked up a external speaker to Ground and pin #6 and i got good sound.. So it looks like the amp is fine..

The board have had som repair and mods, somewere in the past.. Like the mod from track ball to joystick (with looks easyer on this bootleg) but the pcb had also some poorly done repair , like this cap,hooked directly to the amp

But wait, that is pin #6, the output!! Lets trace that backwards..

By tracking it back to the edge connector, i realised that speaker + and - were reversed, and since my super gun dont use jamma - for the sound but just ground due to the scart cable i use, i Got no sound.. So i quickled reversed the bad repair, and fitted the right cap

And now Cabal play with all the sounds!

Job done, for my first pcb repair.. I know my Master and mentor (Elgen) will be proud :)

By the Way, if you like arcade repair done by at true repair wiz, go check out his blog at 

http://elgensrepairs.blogspot.dk

 

 

Who am i? And why this blog?

Who am i? And what is the purpose of this blog?
Well,to start , my name is Anders Lübeck, im 35 years old and a Big fan of Retro gaming, both console and arcade.
Im a trained mechanic but is working as a salesman for a small company that delivers car care products for car detailers and large auto houses.
Im married with Karina, and have a 5 year old daughter .
I have always been a "gamer" ever since my frist computer the mighty Commodore vic 20 some time back in the early 80' then the commodore c64 and up to different consoles in the 90' and 2000'
For about 2 years ago, i was wondering how it would be to own all the old systems again, and started my collection, quite fast i found out that it was cheaper for me to buy faulty systems, and repair them myself.. And that became a kind of obsession. I then started to collect arcade machines, and repairing them also.
By making this blog, i can not only keep track of my own repairs, but also get help and advice from otters, or helping other repair guys who might have similar problems.
To tag along, and drop a line in my repair blogs
Best regards
Anders