Board Repair

[John Bennett]

[ukvac] Board Repair
Thought i'd start a discussion about board repairs. It seems to me there appears to be an awful lot of 'broken' boards around. These seem to be sold on e-bay as 'untested' as they fetch more money. The old 'it was working when i took it out but may not be working now' line. This gives the impression that the board is working and gives no guarentees if it doesn't. (Saying that it's not always the case of course! I just picked up a fully working vigilante for 15 squid!).

There doesn't seem to be alot of information on board repair around although i have found 'the basics'. I wonder whether mostly it would be uneconomical to repair boards as it does take a lot of time. I am in the process of trying to learn myself with a few broken boards. I have basic electronic skills but get stuck when it comes to programming roms and things like that. Apparently most broken boards are easily repairable with correct knowledge and a rom programming thing.

I am surprised how little knowledge there is on boards, pin-outs, switch settings and schematics. Although most people look at spies for this information I have found it only comprises of a small amount of boards, and the information is certainly not 100%. I have a taito 'front line' and if i connect it as spies says it will connect ground with +5 and +12 with -5 (any ideas anyone?!?). Finding the pinouts is a long process and as i gather information I can find no way of adding information I find to the website. (Yes I maybe blind!).

Well what do you reckon. I'm interested to know what people do with dead boards. I hope not throw them away or turn them into novelty clocks!! (or even worse sell them as working condition unknown!!). I'll keep pressing on finding out what I can and if your gonna throw a board away throw it at me!



DATA Imported from archives: originally posted by jake.lee (jake.lee@ntlworld.com)

 

[Macro]

RE: [ukvac] Board Repair
Long - hopefully worthwhile!

>Thought i'd start a discussion about board repairs. It seems to me there
appears to be >an awful lot of 'broken' boards around. These seem to be sold
on e-bay as 'untested'

I like the ones where the picture shows a board that has several chips
missing, or my favourite was a pacman bootleg with no roms, no CPU and no
daughter boards - but it was apparently working when it was put away!

>There doesn't seem to be alot of information on board repair around
although i have
>found 'the basics'.

The place that I started was on Galaxian & Pacman boards - there are 2
troubleshooting guides for each of these, that give ideas on what to check
for different types of error - plus schematics, which are invaluable for the
problems that it doesn't mention!

>I wonder whether mostly it would be uneconomical to repair boards as it
does take a >lot of time.

Well, 3 days to do a moon cresta, 2 days for system 1 road blaster, couple
of hours for a pacman bootleg - but with every repair you learn a little
more, and the next one will be that bit quicker - besides it's fun!

>I am in the process of trying to learn myself with a few broken boards I
have basic
>electronic skills but get stuck when it comes to programming roms and
things like
>that. Apparently most broken boards are easily repairable with correct
knowledge and a >rom programming thing.

I have had two boards that needed roms reprogramming where roms (or eproms)
had decayed or died - you can build yourself a basic programmer, costs about
£35 or so, I have PCB's (plug plug) - but see www.willem.org for details. It
isn't the best avaialable, but it's not bad for the price - and there are
other kits / home build ones dotted around on the web, so do a search.

Test gear is another problem, cheapest, most useful tool is a logic probe -
costs about £25 from Maplins (mine was £10 at Tandy in the US) - if you can
read schematics, this can locate where a signal is not coming out of a chip!
(if the signal is coming out but is wrong, then you need an oscilloscope)

Eprom programmer is handy, from £40 upwards - my current one cost a little
more than that, but will do bi-polar proms which is very useful if you are
repairing older boards like galaxian and pacman.

other tools that help include a comparator (plug a TTL chip in the
comparator, set the switches, clip the lead over a chip on the PCB and
little lights tell you if the one on the PCB is doing anything different
from the reference one - doesn't work on all chips, but very good when it
does) - cost? - mine was £30 on ebay, but they are getting more popular

Final tool, if you have lots of money, or are going to repair lots of boards
(or get lucky, and spot an auction no-one else does) is a Fluke 9010 or 9100
- these plug into the CPU socket on your PCB and allow you to access
ram/rom/IO - anything from memory tests upwards (useful with the logic probe
as you can loop it writing to a memory location and probe the pins to see
where a signal dissapears when it isn;t reaching the correct place!) - cost
- £150+ depending on PODS with it (each CPU needs a POD, Z80 is most useful
unless you are a vector freak (6502) or an SI Man (8080) - but most are
available if you keep an eye on ebay!)

plus of course, solder iron, solder sucker, de-soldering station, spare
parts, solder, understanding wife ... the list goes on

and no doubt, I missed out someone elses favourite tool!

>I am surprised how little knowledge there is on boards, pin-outs, switch
settings and >schematics.

Boards, especially bootlegs differ, if you have a bootleg there is no
guarantee that it will be the same as the original, and, of course, whoever
typed up the info in the first place could have had a bootleg, or have been
totally wrong (they probably sold the board as untested afterwards and it
worked when someone wired it correctly!)

>Finding the pinouts is a long process and as i gather information I can
find no way of >adding information I find to the website. (Yes I maybe
blind!).

email them to Al - he will put them on (link on website)

>Well what do you reckon. I'm interested to know what people do with dead
boards.

If they are worthwhile, I repair them - if they are beyond repair (someone
removed the Z80 using a blowlamp etc then I may still attempt to repair it
if it's a decent game, or I'll use it as a donor board for spares to breath
life into several others!)

>I'll keep pressing on finding out what I can and if your gonna throw a
board away
>throw it at me!

or me!

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[John Bennett]

RE: [ukvac] Board Repair
Just to agree with Mike,
when i started in this hobby in late 97 i knew nothing about
electronics - didnt even own a soldering iron. - started off repairing
Galaxians and pacman boards - which are a doddle once you get
into it and went from there - i now actually prefer fixing the boards
to playing them (weird i know) - get yourself a logic probe and a
multimeter - oh and a logic IC data book - so you know what the
chips are supposed to do. thats all you need for the basics -
Farnell do a logic probe/pulser for about a tenner. Pick up a few
untested galaxian or pacman boards from the states and go to
work on em - once you understand how the boards work - it gets
easier and easier. If you need any help ask on IRC - theres usually
people in there to help out in real time ))

On 16 Oct 2001, at 9:38, Mike Coates wrote:

> Long - hopefully worthwhile!
> <Snip>

Gavin Yuill
Dept. Mining and Mineral Engineering
Houldsworth School
University Of Leeds
Leeds
LS2 9JT

Phone: (0113) 233 2808
Fax: (0113) 246 7310
Mobile: 07903 069 638



DATA Imported from archives: originally posted by (mingjy@ecu-01.novell.leeds.ac.uk)

 

[DanP]

RE: [ukvac] Board Repair
My 2p, board repair does seem a hard business to get into without spending a
lot of time at it! You also have to really want to do it I think as it does
need a lot of concentrated effort to get into. What about some of the more
experienced peeps holding some sort of 'master class' at a future UKVAC
meet, from explaining the basics of arcade PCB's to deciphering a schematic,
perhaps with a demo of each of the tools mentioned by Mike? Who knows it
might even persuade more newbies to come along?

Good idea or am I contender for 'Muppet of the month'?

Danny.

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[LukeWells]

Re: [ukvac] Board Repair
50% of boards are easier to repair then you think.

I am no good with schematics, but i can resolder connectors, clean legs on
chips, resocket everything and replace any chips that get redhot. That fixes
about half of boards in my experience and no technical knowledge other then
how to use a soldering iron is required.

I'm trying to get into proper repair ( i have plenty of broken boards to
fix) it's just learning to work out the fault from the schematics thats the
hard part

Luke

 

[guddler]

RE: [ukvac] Board Repair
> plus of course, solder iron, solder sucker, de-soldering
> station, spare parts, solder, understanding wife ... the list goes on

My girlfriend actually WANTS to learn to solder and make up adapters for
me - now is that a bonus or what!!! Oh, most important thing. You need
time. Lots of it, and patience of a saint. :O)

> >throw it at me!
>
> or me!

I'm sure the list could go on and on, but ME TOO!!

Thing is, duff boards go just as quickly as sought after working boards.
Where'd you think people get their hands on all these hard to find
ancient spares?? And if you pay the proper going rate for faulty boards
NOT ebay rates, then it's an extremely economical way to do it.

In fact, probably avoid the ones on ebay that say 'job lot of faulty
boards' you can almost guarantee that the person flogging them knew
exactly what they were up to and they're all faulty because really hard
to get hold of ICs are either broke or missing completely. Maybe
there'll be one in there that's fixable as there was with me, and for me
that justified the price of them all. Just make sure you don't blow up
the bipolar prom(s) in the process like I did :O(

Guddler.



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[Macro]

RE: [ukvac] Board Repair
>My 2p, board repair does seem a hard business to get into without spending
>a lot of time at it! You also have to really want to do it I think as it
>does need a lot of concentrated effort to get into. What about some of the
>more experienced peeps holding some sort of 'master class' at a future
UKVAC
>meet, from explaining the basics of arcade PCB's to deciphering a
schematic,
>perhaps with a demo of each of the tools mentioned by Mike? Who knows it
>might even persuade more newbies to come along?

I suppose it's like giving up smoking, you have to want to do it!

As Luke said, you can start with a soldering iron and some common sense,
that will fix several problems (my hint : check for touching IC pins on the
bottom of the PCB - I have fixed at least 4 boards by just straightening
pins that looked like they were touching other pins or nearby tracks)

I'm fairly new into the repairing side if things, so if people are
interested, I may be persuaded to knock up a better list of the equipment I
find useful, links to resources that have helped me and chuck it up on the
web somewhere

ultimately, the best way to learn is by doing, but at least it may remove
one of the problems I had (OK, so I bought a Fluke - how the hell do you use
it!) and it would have as much as possible in one place.

> Good idea or am I contender for 'Muppet of the month'?

I was lucky enough to have some long standing ukvac members give me some
demonstrations of the various test gear, along with a pile of galaxian PCB's
to play with!

you have to ask around, I can't promise that people will help, but if you
convince them that you are serious, then you probably will get help.

(oh, and Muppet is the almost registered trade mark of Chris Toseland, a
frequent visitor to UKVAC land, and a definate techy!)

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[LukeWells]

Re: [ukvac] Board Repair
> In fact, probably avoid the ones on ebay that say 'job lot of faulty
> boards' you can almost guarantee that the person flogging them knew
> exactly what they were up to and they're all faulty because really hard
> to get hold of ICs are either broke or missing completely. Maybe
> there'll be one in there that's fixable as there was with me, and for me
> that justified the price of them all. Just make sure you don't blow up
> the bipolar prom(s) in the process like I did :O(

I'd just like to add to that, beware of buying untested / was working when i
put it in storage / simple to fix fault boards. As Guddler says the job lots
of faulties/untesteds can often be people who know what they are doing
getting rid of boards that are almost unfixable.

For example i bought a lot of faulty boards once. 2 of them are totally
unrepairable as they are COVERED in glue and paint that wont come off.

I bought a "Was working when put in storage" Gauntlet board from US ebay
some time ago. When I received it I discovered that the board at somepoint
had actually been ON FIRE, rows of resistors and caps all burnt to a crisp,
took 3 months and several replaced components to get that to the stage its
in now, working but no sound.

I have a bubble bobble with most of the roms and all the custom chips
missing

My advice is try and get pictures if you can before buying so you can see if
they have nicked all the ROM's or if its been on fire

Luke

 

[junofirstman]

[ukvac] Re: Board Repair
> I'd just like to add to that, beware of buying untested / was
working when i
> put it in storage / simple to fix fault boards. As Guddler says the
job lots
> of faulties/untesteds can often be people who know what they are
doing
> getting rid of boards that are almost unfixable.
>

I can vouch for this one.. There was a recent ebay auction for 9
boards, which had virtually all the eproms removed.. (I realised this
once I received the boards, and looked closer at the auction pics )

Strangely enough, the same person also had 2-3 auctions of '10x blank
27c512 eproms'... Grrrr

Normally this wouldn't worry me, except I can't bloody identify one
of the boards from the two mask roms left on the board, so I can't
even re-program some more! (bidding on the roms was pointless since
they had been already erased)

Chris
(Who was obviously a bit pissed off about this)

 

[John Bennett]

[ukvac] Re: Board Repair
Am I the only person on UKVAC who recommends a video probe? Nobody's
mentioned it yet but for me it's the most useful piece of test
equipment out there.

If you can call your existing monitor a piece of test equipment that
is.

As coincidence would have it, I've pretty much finished a repair
guide I've been writing for a short while. It's hardly a
comprehensive guide, rather a list of tips picked up over the years.
I'll stick it on my website if I get round to it tomorrow.

Comments welcome when it's up.

- Mike



DATA Imported from archives: originally posted by (mike@mailnet.co.uk)

 

[Macro]

RE: [ukvac] Re: Board Repair
but the expense, I mean it's about 2p for the resistor alone ....

>Am I the only person on UKVAC who recommends a video probe? Nobody's
>mentioned it yet but for me it's the most useful piece of test
>equipment out there.

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[guddler]

RE: [ukvac] Re: Board Repair
Okay, I understood this thread entirely up to now! Someone explain
themselves then. I gather from mikes comment this is more of a method
than a tool and I'm sure it'll be obvious when it's explained, BUT -
video probe ??

Guddler.

----------------------------------------------
Martin White

http://www.guddler.com
Arcade search site with PCB info too...

>

 

[John Bennett]

Re: [ukvac] Re: Board Repair
Mmmm very interesting!!Certainly gave me some interesting reading this
morning, thanks folks(especially Mike lots of useful info). I need some more
kit by the looks of it. I'll get working on my 'dead boards' and shout when
i get stuck!

Thanks Again!

Jake



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DATA Imported from archives: originally posted by jake.lee (jake.lee@ntlworld.com)

 

[John Bennett]

Re: [ukvac] Re: Board Repair
Yup - Video probe is a fine piece of kit - almost as useful a a scope
and a thousand time cheaper - check out the Galaxian
Troubleshooting guide part 2 for details.

Cheers
Gav

On 16 Oct 2001, at 11:55, mike@mailnet.co.uk wrote:

> Am I the only person on UKVAC who recommends a video probe? Nobody's
> mentioned it yet but for me it's the most useful piece of test
> equipment out there.
>
> If you can call your existing monitor a piece of test equipment that
> is.
>
> As coincidence would have it, I've pretty much finished a repair
> guide I've been writing for a short while. It's hardly a
> comprehensive guide, rather a list of tips picked up over the years.
> I'll stick it on my website if I get round to it tomorrow.
>
> Comments welcome when it's up.
>
> - Mike
>
>
>

DATA Imported from archives: originally posted by Gav (mingjy@ecu-01.novell.leeds.ac.uk)

 

[system11]

Re: [ukvac] Re: Board Repair
If you have any magical tips for getting ICs out of a PCB without damaging
them or it I'd be grateful - tried several methods so far with no success.

james

On Tue, 16 Oct 2001 11:55:49 -0000
mike@mailnet.co.uk wrote:

> Am I the only person on UKVAC who recommends a video probe? Nobody's
> mentioned it yet but for me it's the most useful piece of test
> equipment out there.
>
> If you can call your existing monitor a piece of test equipment that
> is.
>
> As coincidence would have it, I've pretty much finished a repair
> guide I've been writing for a short while. It's hardly a
> comprehensive guide, rather a list of tips picked up over the years.
> I'll stick it on my website if I get round to it tomorrow.
>
> Comments welcome when it's up.
>
> - Mike
>
>
>

 

[John Bennett]

Re: [ukvac] Board Repair
Jake ,
Me too , i've bought boards in the past, saying un-tested but marked
o.k.
Got to the point where you think there must be more i can do. So i am. I
think its always better to have a try yourself then not try at all. When ever
i adopt this approach, its amazing how many times you surprise yourself, and
manage to get somewhere.
I'm not saying that everyone out there is capable, but i am saying if you
don't try, you will never know.
There are some people on ukvac , who are amazing sources of information and
advice. So if people pick up a duff board for a tenner. Buy a soldering iron
and a multi meter and read up a bit, they might gain something rather than
lose a duff board. Even if they can't fix it , at least they will have more
of an understanding about how it works.
I'm still in the process of fixing my first board, i'm enjoying every minute
of it (even the burnt fingers).
And whilst we are on the subject. Atari's The Book
( on spies.com/arcade/bronzeage )is very informative,
again advice picked up on ukvac.
Everyones a Newbie at some stage, so don't be afraid to get stuck in. :0)

PINX



DATA Imported from archives: originally posted by (PINX32@aol.com)

 

[John Bennett]

Re: [ukvac] Board Repair
Good idea,

PINX



DATA Imported from archives: originally posted by (PINX32@aol.com)

 

[MrMish]

Re: [ukvac] Re: Board Repair
> If you have any magical tips for getting ICs out of a PCB without damaging
> them or it I'd be grateful - tried several methods so far with no success.
Heat gun it. (Wallpaper stripper guns are fine).

You'll be amazed how cleanly you can get components out without damaging
anything around them (or them themselves obviously!).

Bryan



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[system11]

Re: [ukvac] Re: Board Repair
On Tue, 16 Oct 2001 14:00:47 +0100
Bryan McPhail <mish@mame.net> wrote:

> > If you have any magical tips for getting ICs out of a PCB without damaging
> > them or it I'd be grateful - tried several methods so far with no success.
> Heat gun it. (Wallpaper stripper guns are fine).
>
> You'll be amazed how cleanly you can get components out without damaging
> anything around them (or them themselves obviously!).

Ooh top tip!

I'll have to try that out on the sacrificial Bad Dudes bootleg board

james

--

find great crazy-mad out-of-head experience from japan.



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[karlcdoe]

Re: [ukvac] Re: Board Repair

I recommend you buy a cheap de-soldering iron: mine cost about £25 from RS.
It's the type with a jumbo sized rubber bulb to generate vacuum and can have
a variety of hollow 'bits' fitted. I've had near 100% success removing
components with this device- except a few piss poorly made Atari boards
where I lifted the odd track

I've also tried the heat gun method but more often than not I remove the
ic's intact while frying the rest of the pcb -don't worry they were old 386
boards....

Karl.