Who Repairs Bootleg Arcade Boards

Arcade PCB Game Board Repair

Welcome to the Retro-arcades board repair page. On this page you lot will find a skilful bones overview of PCB repair, plus lots of handy tricks and tips to assistance yous get that faulty arcade board fixed, also info on the tools you will demand to get you started. You lot volition besides discover a comprehensive listing of aracde PCB lath manuals. Demand a schematic? Take a look in the list, your bound to notice it there.

Tools for the job

Magnifying Lamp
Soldering Iron with as fine a tip as possible
Solder :)
Solder sucker
ROM/Fleck Puller
Multimeter with continuity beep examination
Logic Probe

Aditional advanced tools

Desoldering station
Oscilloscope
USB Eprom Developer
Hewlett Packard Logic comparitor
ABI Boarmaster 4000
Fluke 9010

Checking for concrete damage on your arcade board

The kickoff affair to cheque for is physical impairment on the faulty or expressionless pcb, these things were kept safe when secured inside the original cabinet, merely were often taken out and mishandled past arcade operators, slung onto shelves or into boxes and damaged. Get yourself a good magnifying lamp or utilize daylight and a practiced magnifying drinking glass. Check for any physical damage/cuts to the tracks underneath the board, use a multimeter on the continuity test function to check whatever suspected damaged tracks. Check for any loose or damaged components on the board. Carefully printing on whatsoever of the socketed chips because they may have become loose! It really is surprising how many faults are due to physically damaged pcbs.

Other components on the lath could besides be damaged , resistors, diodes and capacitors. Electrolytics tend to age badly, wait for smashed bent or bulging electrolytics. Any capacitor with white stuff at it's base of operations needs to be checked, this could exist leaking, or it might just be glue used at the factory to hold the cap down a bit better. Ceramic capacitors will be all over the board, they are pocket-sized orangish disks, they are decoupling caps and ofttimes look very battered. Unless one has gone curt circuit, it is not likely to cause any major bug. Merely look at these closely if your board randomly crashes or resets.

Checking the 5v Ability

Power to and on the PCB is as well i of outset things y'all should check, bank check that a skilful five volts is getting to the chips on the board. Measure the voltage on the actual chips across the board, a small voltage drop beyond a board is normal, you may have a skillful 5V on the jamma border just if that drops to iv.5V at the other end of the lath and so things could go weird. Whatever board voltage measurement should be taken across the ground and vcc pins as it's the all-time reflection of what the chips are truly getting. If low either increase the voltage slightly, or run a power wire to the far side of the board. TTL chips don't like voltages much below four.8V they tin can do strange things below that. Check the ability supply again, some older boards require their 5v to be more similar 5.2V

Locating faulty chips

Finding faulty chips can be adequately simple or close to impossible, at the very least you volition need a logic probe and the knowledge on how to use information technology. Obviously a logic probe is very good at visually showing y'all what the pins of an IC are up to. In terms of inputs and outputs it visually shows you if a pin is high, depression, floating (tri-country), and therefore by definition a logic probe is excellent at showing y'all when yous accept either stuck inputs / outputs (pin stuck high or depression) - a bad matter, or when there is a good amount of activeness - probably a good matter. This might be normal though as some fries are dual, quad or octal fries - i.e. they accept 2, 4 or 8 of the aforementioned logic gates on them, its not uncommon to find a quad chip where only iii of the gates are used. The inputs to the quaternary gate will be floating equally they are not connected.

To bank check this out you will need to google and read the datasheets for that specific chip. If the inputs are agile and the output is floating and then y'all have found a dead chip. You can go one further here, if the inputs are active and the output should be doing something (based on the logic table in the datasheet) still it never changes from low to high then you have a stuck pivot, this gets harder to work out by eye the more inputs a logic function has. If yous have 6 inputs that determine what the output is doing, and all of them are active and flipping then it tin can exist very difficult to tell if the output should exist irresolute at any given betoken.

RAM chips are a common failure, find the datasheet and bank check the accost and information lines. If you find floating lines so you are on to something, follow those lines dorsum and see where they should go. Something is dead somewhere, it might exist RAM .RAM needs controlling tho, you demand to bank check the chip enable pin is actually enabling the RAM, and the WR and OE lines are doing something, if these are dead the flake will sit there doing nothing.

ROMs, aforementioned equally with RAM, the control lines need to be working correctly, check the output pins for signs of life. The contents of the chip will demand to exist checked too, for this yous will need an eprom reader.. The game lath could be in perfect working club, but a single error in an elderly ROM will crusade the board to crash straight away. You could spend a long time looking for a hardware fault that doesn't exist, if the problem is due to dodgy software. PROMs are like EPROMS only they are write-once fries. Contents of these chips can be checked confronting the roms in the MAME set, there are apps and romident websites to do this.

CPUs are very complex and can be most impossible to debug, if they are socketed information technology's easier to attempt the CPU in another board, or endeavor a known proficient CPU in your board. If its soldered in and y'all can't remove information technology, then you lot volition have to assume it works until you have evidence to the contrary. Detect the datasheet and come across what the address and data lines are doing, bear in listen that a stuck pivot doesn't necessarily mean the chip is bad, a track on a board has at least 2 ends, if the flake on the other terminate is shorted then the flake at your end won't be able to drive that line, so you may have found a fault from the other cease.

Sound and audio amps - Audio amps can often be expressionless on older boards, they are commonly the only fleck bolted to the board usaully via heatsink.. A quick test to check the 12V feed is to run your finger across the pins of the amp chip or beyond the pins of the book accommodate pot. You should here a crackle, if not then push firmly on the torso of the flake (if it's firmly bolted or soldered down) yous should here a buzzing noise. If you do get a noise then the amp chip is fine, especially if yous can adjust the volume of the fizz with the volume pot. Bear in listen that the amp scrap depends on the circuitry around it, frequently a cluster of capacitors, if any of these are damaged yous may not go a positive result, fifty-fifty if the amp chip is fine.

Custom chips -Unfortunately these tin can be board killers. They are ordinarily surface mountain, and tin can have upward of 50 microscopic legs, and oft there is absolutely no way to examination they are working correctly, even if you lot could test them, there is no data around these days about what they practice. Swapping them is not an selection equally the merely identify you lot could possibly find a replacement is on some other board of the aforementioned game and without the specialist equipment needed, at that place is no manner to remove or replace them. If you take a dead custom scrap so the board is flake, it'south just cheaper to purchase another working board.

It's a skillful thought to read equally many repair logs equally possible and familiarize yourself with the workings of the hardware your dealing with. Read on!

Handy Links

Check out the following listing of links, they will definetly evidence helpful and informative!

Hamster's Online ROM Identification
New Life Games repair logs forum
Arcadeotaku's Repair Logs
AcradeComponents Repair Logs
Arrangement 16 Arcade Museum
The International Arcade Museum