On Sun, 24 Jun 2012, Tony Duell wrote:
OK, but be warned you might not like my answers
Nor mine. For that matter, Tony won't like my answers, either :-)
Since you posted them publically, I think it is reasonable for me to
reply to them, whether yyou like it or not :-). More seriously, different
people ahve differnet views on this and only the OP can decide what will
work _for him_. Sevearl of us here have been doing repairs for more years
than we care to rememebr, and we all have different views on what is
important or not (for example, some people here use a 'socpe all the
time, I only use one rarely, prefering other instruments. It's a personal
thing, if it works for you, then do it that way).
Maybe NOBODY will like the suggestions that I'm
making off the top of my
head, . . .
The first tool for you to buy is a DISPOSABLE multimeter.
Hmm... I am not convicned...
If you asre not careful, buying poor-quality tools and test gear will
cause problems. You might get disheartened by this and decide you will
neve be able to do troubleshooting/repair. It can be a lot better to have
a few good-wualtiy units than a lot of poor ones.
As an aside, I know of several people who were put off photography
becuase thye were given a cheap camera (always a Kodak...) as a child.
The results were poor, they didn't see the point in paying for film and
processing. Later one, when they got a better camera -- not necessarily
an expensive one -- they found how much fun it could be.
Getting back to multimetets. An experienced person might know how a cheap
meter is goign to misbehave and will be able interpret the readings. A
beginner cannot. You will get readings that seem to make no sense, and
will spend consdierable time looking for faults that aren't really there.
And son't get me started on the confusion a cheap sotrage 'scope can cause...
You WILL buy a better one. LATER. When you have a
clue what it is and
can do, have learned what can damage it, and have learned what aspects of
A good meater is alomst impossible to damage....
the cheap one are intolerable. YES, there are dome
aspects of that cheap
one that are HORRIBLE! THIS one is only for learning about
Go to Harbor Freight Tools or online at harborfreight.com
The list price is $9.95 , but they are often on sale in their retail
stores for $3.99, $2.99, or free with a coupon!
Take apart one of their $1 or free with coupon flashlights.
How many things can you measure of it?
What happens if you use the wrong scale, or get it backwards?
measure everything else within reach!
Keep YOURSELF clear of everything! Killing yourself while measuring a
mains outlet could set you back!
And that is soemthing else to be careful about. A friend of mine was
nearely killed by a cheap mete. He measured the voltage of a maisn
socket, it showed 240V or so, so the meter was working/ He flipped the
breaker for what he thought was the right circuit, then measured the
voltage again. 0 or so. So he thought he had isoalted the circuit and
started to remove the socket. Alas the meter had taken that momemnt to
fail (range swithc trouble I think) and he's flipped the wrong breaker.
Result : He got the mains across him. Second result, he bought a good meter.
WHEN you blow up the meter, go get another one, and remember what you did,
so that you won't ever do THAT again.
NOW, for the big moment, . . .
measure all of the voltages of the C64 power supply! (a likely cause of
the problems, anyway!) Look up what each voltage is supposed to be, and
decide whether they are close enough.
You are skipping over something vert important here. Multimeters, and
voltmeters in genral, have 2 leads. The poiunt is that it makes no real
sense ot say 'the votlage here is 5V'. What you mean is 'the voltage here
is 5V _with respect to this point which I am calling ground'. Knowing
what point to take as the common 'ground' is often not obvious when you
are startign out.
IIRC The C64 power supply has 2 outputs. One is5V DC, regualted inside
the PSU. The other is 9V AC, not regualted. The 2 are not connecvted to
each other inside the supply (The 9V AC supply is used ot produce other
voaltages inside the C64, and those _are_ then referenced to the came
ground as the 5V supply. But not with the PSU on its own, not connected
to the C64). So you need to measure the DC votlage between the pins
called '5V' and 'ground' and the AC voltage betwee nthe 2 pins alled
Buy a cheap soldering iron, and some 60/40 rosin core lead solder. ($5)
You WILL buy a better one LATER. In fact, you will NEVER use this POS
one on ANYTHING that you want to keep!
Take a stack of SCRAP boards, that are irreparable and useless (you said
that your friend had destroyed some, . . . )
Unsolder a large resistor from one of the boards. Unsolder another one.
Solder them back on. remove EVERY component from the board. Put every
Hmmm... Even if I say so myself, I consider that I am reasonably good and
PCB rework. And I have great difficulties using a cheap soldering iron.
A freind at HPCC wented to learn some basic electroncis. I had some
'spare' simple kits to solder up, I suggested he bought some tools and
had a go. Als he didn't want to pay for a sodlering station... He had
great ddifficult soldering the new components ot a new, simple, PCB. In
the end I asked him to bring everything to a meeting so I could see what
he was doing wrong. Nothing obvioiusm so I had a go. I had problems too.
So I pulled my Weller TCP out of my bag and tried that. Dead easy. I let
him try it. He had no problems pouplating the complete PCB.
Cheap tools really can make things difficult, I know that good tools are
expesnive, and that if you are starting out you ight not want to lay out
a lot of money on tools you might not want. But eqally, you have enough
real problems when you are learning without creating more due to
one back on. How many did you get backwards? How
many did you destroy?
Once you've soldered and desoldered everything on a few boards, Start
planning to buy a REAL ("temperature controlled") soldering iron. (try
flea markets, eBay, etc.) You might find the POS one to be useful for
rewiring lamps and toasters, etc., but once you've used a REAL soldering
I am not convinced they are even useful for that. You find high melting
point sodler in such places (for obvious reaosns)
iron, you'll never want to touch the POS again.
Get a better screwdriver for taking apart your computers. A cheap one
with 1/4" bits will do until you understand WHY you need a better one.
My list of simple hand tools for ocmputer repair is quite long, and to be
fair you problaby don't need all of them. But I find I need screwdrives
from 1mm to about 8mm, Phillips and Pozidriv ones too.
And Allen hex
tools, torx drivers, nutdrivers, etc. In some cases it does depend on
what you are sorkign on. If you stick to C64s, you will not need Bristol
Spline tools. If yoyu work on Flexowriters, or even IBM 5155s, you do.
Get some decent pliers and cutters. Over here expect to pay \poudns 30.00
for each (!). You will use them a lot .
Another case where cehap tools make life dififuclt are tweezers. Cheap
tweezers are made from spring steel. Expensive ones are stainless steelm
and not magnetic. You might wonder if it's worth paying for the expensive
ones (about 10 times the price of cheap ones). Well, if tyuo've ever
tried to put a small screw or simiar into a mechanism and hand other
parts jump out of plate ot the end of the tweezers, you'll know why...
Learn resistor color codes. Do you know what an ohm is? farad?
"If your car headlight draws 10 amps, how many watts is it?"
Read a few basic electronics books. Used textbooks from the local
community college, perhaps? Maybe even TAKE some of those classes!
"Art of Electronics" by Horowitz is GREAT, but it costs money.
Got relatives who XMAS shop?
Buy some kits and assemble them. Now get them to WORK.
Kits are great at teaching you to solder, to identify compoennts and to
put things together. They are less good at teaching electronics. I was
amazed (when i had to sort out a so-claled 'educational electronic kit'
sold over here that it didn't even include a schematic, or a block
diagram or the theory of oepration. Of course _I traced out the scehamtic
in a few minutes, but...)
SInce youy need ot learn to solder and handle the tools kits are
certianly sueful. But it's worth realsing they don't teach you everything.
Get all of the technical documents for all of the machines that you want
to work on, or are even just curious about
Easier said than done in soem cases :-). Although there are plenty of
technical manuals and scheamtic for the C64.
If you got this far, you've almost certainly
abandoned these "silly
steps", and have taken off on more interesting projects and tangents.
I think one thing that Fred and I agree on (fro reading this ) is that
tyhere is no short-cut to being able to repair computers. You _do_ need
to learn to use tools,. you do need ot learn how things should work, you
do need to learn basic (and more) electronics.
Sure there are 'stock fault lists'. Thigns that tell you that if it
starts up with this sort of image on the monitor then you need ot change
that chip. 99% of the tiem they're rignt./ 1% of the time they are not.
And at that point, if all you have is the stock fault lsit, you are stuck.
If you are runnign a repair shop and have hundreds othe same model coming
in, then such lists are valuable. You cna send 99% of them back out the
door quickiy, leaving 1% hat reauires an experienced person to look at.
But if you are doing it for yourself, if you want ot finx that machine no
matter what, then you have ot learn the 'real' methods of fault