23 Mar
2004
23 Mar
'04
3:34 a.m.
Hi folks,
I think I posted this on here first but I'm not sure :)
Anyway, (slight OT drift here) my '97 vintage 21" PCXAV monitor (the one
with the paper-white case & trinitron screen) has decided to start
flickering and dimming itself. Lee's already given me a couple of pointers
but I thought I'd ask here too in case he's not about.
I've got the PSU here and there's a couple of things on there that make me
worried:
http://www.wowrarelook.co.uk/resistors.jpg
http://www.wowrarelook.co.uk/burnt.jpg
http://www.wowrarelook.co.uk/solder.jpg
http://www.wowrarelook.co.uk/solderside.jpg
The middle 2 are the front and back of the same components on the board.
Should I be worried that so much solder is escaping/has escaped from the
joints? Also the soldering in 'solder.jpg' looks decidedly iffy. I haven't
checked the resistors yet to see if they've failed.....is it normal for them
to get so hot they burn the board?
Probably more pix to come when I get the logic board out :oD
cheers
--
Adrian/Witchy
Owner & Webmaster, Binary Dinosaurs
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
23 Mar
23 Mar
4:55 a.m.
Probably more pix to come when I get the logic board
out :oD
I had mine partly open late last year/early this year to
replace the little fuse. That's what blew in mine after
it had been doing a "crack-disappear-reappear-instantly"
cycle a few times a day for a week or so. Since swapping
the fuse it's been fine.
I don't recall mine having any obvious burns anywhere,
but it was only open long enough to locate the fuse
and then swap it.
Antonio
--
---------------
Antonio Carlini arcarlini(a)iee.org
5:15 a.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of Antonio Carlini
Sent: 23 March 2004 18:56
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: More on my flickering DEC monitor
Hmm, no blown fuses here and it'd been behaving badly for a few weeks before
I swapped it for a Compaq S910....
I've been over the back of the logic board with the soldering iron to remake
the joints on the lop/flyback transformer and all the caps etc so I'll do
the same for the PSU board and we'll see what happens once it's all back
together. Hopefully the magic smoke will stay intact......
(I don't like working on monitors too much!)
Cheers
--
Adrian/Witchy
Owner & Webmaster, Binary Dinosaurs
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
Probably more pix to come when I get the logic
board out :oD
I had mine partly open late last year/early this year to
replace the little fuse. That's what blew in mine after it
had been doing a "crack-disappear-reappear-instantly"
cycle a few times a day for a week or so. Since swapping the
fuse it's been fine.
I don't recall mine having any obvious burns anywhere, but it
was only open long enough to locate the fuse and then swap it. 
5:36 a.m.
I'd say either those components shown in solderside.jpg were replaced
at some point, or the person doing the hand-soldering wasn't
particularly competent. More likely the latter since the signs are
there at every pin that's a hand-soldered part, as far as I can see.
It doesn't look like re-melting as you suggested. So it's not that
solder has escaped from the joints, it's simply that more was
originally put on it than the rules of good workmanship call for.
Look at D910 (a bit further to the right on that photo) for an example
of good work. (I think that one is the wave solder machine at
work...)
The brown gunk looks like flux (rosin) that wasn't cleaned off. The
solder joints have more solder on them than they should, but not so
much that you'd get solder bridges as far as I can see. Excess flux
can cause corrosion and leakage current, but I don't see corrosion
here and some leakage is not all that likely to be an issue for a
power circuit such as this.
It probably wouldn't be a bad idea to re-heat those joints with a
piece of Solder Wick to suck up the excess solder, and then clean off
the rosin with a suitable flux remover. (Unfortunately the good ones
are all Politically Incorrect. Maybe acetone would work, I haven't
tried lately.)
The dark spots on the board seem reasonable. Those resistors are high
power wirewound units, those get *very* hot in normal use. Raising
them -- and high current diodes like D907 -- off the board is a
typical trick to get better cooling. The radiated heat tends to
discolor the board at some point, that isn't necessarily an issue.
Something to look at, though: on the "solder.jpg" picture I wonder
about the funny rings on the right solder joint of R923 and R924.
That may just be a shadow, or it may be a mechanical problem in that
joint. It wouldn't hurt to find joints like that and re-melt them.
paul
5:52 a.m.
I'd say either those components shown in
solderside.jpg were replaced
at some point, or the person doing the hand-soldering wasn't
particularly competent. More likely the latter since the signs are
there at every pin that's a hand-soldered part, as far as I can see.
It doesn't look like re-melting as you suggested. So it's not that
solder has escaped from the joints, it's simply that more was
originally put on it than the rules of good workmanship call for.
Look at D910 (a bit further to the right on that photo) for an example
of good work. (I think that one is the wave solder machine at
work...)
Hmmm,
The brown gunk looks like flux (rosin) that wasn't cleaned off. The
solder joints have more solder on them than they should, but not so
much that you'd get solder bridges as far as I can see. Excess flux
can cause corrosion and leakage current, but I don't see corrosion
here and some leakage is not all that likely to be an issue for a
power circuit such as this.
I'm curious what a leakage and corrsion looks like with flux left on
the circuit board?
It probably wouldn't be a bad idea to re-heat
those joints with a
piece of Solder Wick to suck up the excess solder, and then clean off
the rosin with a suitable flux remover. (Unfortunately the good ones
are all Politically Incorrect. Maybe acetone would work, I haven't
tried lately.)
Actone from paint dept works well. Get a box of swabs (Q-tips is
best, generics sucks; excuse me).
The dark spots on the board seem reasonable. Those
resistors are high
power wirewound units, those get *very* hot in normal use. Raising
them -- and high current diodes like D907 -- off the board is a
typical trick to get better cooling. The radiated heat tends to
discolor the board at some point, that isn't necessarily an issue.
I call those golden brown spots as slow bake. Perfectly normal.
Real black and crumbling (always when a part fried) is no good, has
to dug out. I do sometimes on the TV & monitors at work. I work for
a electronic repair shop daily.
Something to look at, though: on the
"solder.jpg" picture I wonder
about the funny rings on the right solder joint of R923 and R924.
That may just be a shadow, or it may be a mechanical problem in that
joint. It wouldn't hurt to find joints like that and re-melt them.
This is called fractured joints, fix them. Before soldering,
get a pink eraser or rod eraser that can take off oxidization on old
penny, give it a few scrubs over those suspect joints including the
component lead to break the oxide barrier to let solder wet properly.
Blow out the eraser crumbs.
Remove the CRT tin cover, you will see some cracked rings on many
parts too. Ditto to any hot parts, heavy parts and/or large pins.
Those soldered joints I made looks like factory originals and
extremely shiny, wetted, sometimes looks black due to flawless shine.
Ditto no sign of flux, I clean them depending on products, if it is
junky or too little estimate, do good job but no clean up. Those
excess solder in that photos is sign of a rushed, lazy tech.
What kind of digital camera taken those outstanding photos that
showed those cracked rings in those solder side joints?
Even sony who reworked their stuff, still is sloppy. :-)
Cheers,
Wizard
paul
11:12 a.m.
>>>> "jpero" == jpero
<jpero(a)sympatico.ca> writes:
> The brown gunk looks like flux (rosin) that
wasn't cleaned off.
> The solder joints have more solder on them than they should, but
> not so much that you'd get solder bridges as far as I can see.
> Excess flux can cause corrosion and leakage current, but I don't
> see corrosion here and some leakage is not all that likely to be
> an issue for a power circuit such as this.
jpero> I'm curious what a leakage and corrsion looks like with flux
jpero> left on the circuit board?
Corrosion would look green typically.
Leakage: I had a circuit that was flaky until I washed it better.
That was water soluble flux, probably more conductive than classic
rosin flux.
paul
24 Mar
24 Mar
4:42 a.m.
Snip
jpero> I'm curious what a leakage and corrsion
looks like with flux
jpero> left on the circuit board?
Corrosion would look green typically.
Leakage: I had a circuit that was flaky until I washed it better.
That was water soluble flux, probably more conductive than classic
rosin flux.
paul
Got it. Only ones that is "dry" were had water soluble flux and was
washed off properly. Yet those "dry" boards made resoldering jobs
tedious because I have to buff off oxidization on component leads.
Those that had old fashioned flux and left on was easier to work with
and kept solder "fresh" looking.
Cheers,
Wizard
23 Mar
23 Mar
7:48 p.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of jpero(a)sympatico.ca
Sent: 23 March 2004 19:53
To: cctalk(a)classiccmp.org
Subject: Re: More on my flickering DEC monitor
I'm curious what a leakage and corrsion looks like with flux
left on the circuit board?
So am I, for future reference......
good, has to dug out. I do sometimes on the TV &
monitors at
work. I work for a electronic repair shop daily.
You're a handy man to have about then :)
This is called fractured joints, fix them. Before
soldering,
get a pink eraser or rod eraser that can take off oxidization
on old penny, give it a few scrubs over those suspect joints
I just sucked off the old solder and put new on - it's nice and shiny now.
Remove the CRT tin cover, you will see some cracked
rings on many
parts too. Ditto to any hot parts, heavy parts and/or large pins.
Yup, I went over everything that was dull and tired looking. The only real
cracks were the ones I photographed. Having gone over the PSU and logic
boards I got it all back together last night and it's sitting next to me now
running my second desktop. So far it's producing a much better picture than
the the Compaq monitor I'm looking at now.....which is 4 years younger.
it is junky or too little estimate, do good job but no
clean
up. Those excess solder in that photos is sign of a rushed,
lazy tech.
So it's been repaired before then.....
What kind of digital camera taken those outstanding
photos
that showed those cracked rings in those solder side joints?
'tis a 2 year old Fuji 6800, possibly the last half decent camera they
produced before coming up with the awful A601. Works best on a tripod though
- those pix were hand held so I'm surprised they came out so well!
Cheers
w
5:58 a.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of Paul Koning
Sent: 23 March 2004 19:37
To: cctalk(a)classiccmp.org
Subject: Re: More on my flickering DEC monitor
I'd say either those components shown in solderside.jpg were
replaced at some point, or the person doing the
hand-soldering wasn't particularly competent. More likely
the latter since the signs are there at every pin that's a
hand-soldered part, as far as I can see.
It could be; I rescued the monitor from the dumpster queue after the
previous user had complained that 'the colours were all fuzzy'. A quick
adjustment of the Purity control sorted that out :)
It's possible it's been repaired in the past too.
Look at D910 (a bit further to the right on that
photo) for
an example of good work. (I think that one is the wave
solder machine at work...)
'K
normal use. Raising them -- and high current diodes
like
D907 -- off the board is a typical trick to get better
cooling. The radiated heat tends to discolor the board at
some point, that isn't necessarily an issue.
Right - that makes sense.....
Something to look at, though: on the
"solder.jpg" picture I
wonder about the funny rings on the right solder joint of
R923 and R924.
That may just be a shadow, or it may be a mechanical problem
in that joint. It wouldn't hurt to find joints like that and
re-melt them.
It's not shadow, that's what made me ask in the first place....I've now
remade all the large joints like that and I'm in the process of putting the
whole shebang back together.
Ta! If you hear a bang in the next half hour you'll know what it is.....
--
Adrian/Witchy
Owner & Webmaster, Binary Dinosaurs
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
6:45 a.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of Witchy
Sent: 23 March 2004 19:58
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: More on my flickering DEC monitor
Ta! If you hear a bang in the next half hour you'll know what
it is.....
Replying to me own message here but IT LIVES!
http://www.wowrarelook.co.uk/yay.jpg
Some of my own artwork there too :oD
I'll give it a soak test tomorrow to see how long it lasts before it starts
flickering again......
--
Adrian/Witchy
Owner & Webmaster, Binary Dinosaurs
www.binarydinosaurs.co.uk - possibly the UK's biggest online
computer museum www.snakebiteandblack.co.uk - ex-monthly
gothic shenanigans :o(
7579
days inactive
7580
days old
9 comments
4 participants
participants (4)
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arcarlini＠iee.org -
jpero＠sympatico.ca -
pkoning＠equallogic.com -
witchy＠binarydinosaurs.co.uk