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B.M.
04-02-2003, 12:29 PM
Having bathed in the success of having made huge improvements to an old Monitor by following Billy Tís instructions on how to adjust the focus, along with Ericís Monitor tests, Iím ready to move on to bigger and brighter challenges.

Iíve found another old monitor that needs some colour adjustment. Iíve also found three little variable resistors on the PC board the CRT plugs into. Now, with Ericís colour bars on screen I find one adjusts Blue, one Green, and one Red. (Surprise surprise)

So, the question is what is the correct sequence of events for aligning a Monitor?

Unfortunately, I no longer have access to twin beam oscilloscopes, signal and pattern generators etc.etc. Just a test pattern courtesy of the internet, and a couple of multimeters.

Therefore, Iím looking for some good, old-fashioned, seat of the pants technology. :)

Terry Porritt
04-02-2003, 01:25 PM
There's enough reading matter on this site about monitors to keep you out of mischief for hours and hours Bob.

http://www.repairfaq.org/REPAIR/F_monfaq.html

Terry Porritt
04-02-2003, 01:31 PM
Oh. also forgot, if you go to Simtel, there is a good selection of vga test utils. Svgat350.zip has a Philips test pattern which is excellent for setting up and adjusting the colours.
http://www.simtel.net/pub/msdos/vga/

B.M.
04-02-2003, 03:47 PM
Thanks Terry,

Excellent Site, I printed out all the instructions for future reference, (A small book) so the next thing Iíll be looking to fix is the printer I guess.

What intrigues me is that these Monitors that Iíve been playing with were en route to the rubbish dump when they were "intercepted". Sure, they needed some adjustment, but they are relatively new and I suspect some of the components have only just settled down.

Guess nobody fixes things anymore?

E.ric
05-02-2003, 04:52 AM
Would you like any other patterns ? maybe red & blue crosshatch just for company for the green crosshatch

Maybe I could put together a ZIP file so you could download it, unzip & burn your own self loading CDROM pattern generator.

From Eric

B.M.
05-02-2003, 08:45 AM
E.ric, in my travels I found this site, which has a test pattern developed by Nokia.

http://www.freepctech.com/rode/004.shtml

Iíve thrown it in a folder with a shortcut on my desktop so Iíve got an instant pattern generator. My problem now is establishing a ďbasicĒ procedure for the ďbasicĒ alignment.

Todayís little project is re-soldering a dry joint on the pc board the CRT plugs into. (Yep, I found a genuine fault) Problem is de-soldering the metal screen on the back of the board. Donít know what the manufacturers thought they were doing, but thereís more solder holding it on than they used on the top radiator tank of a í39 Austin 7! :D

Out with the gas axe! :p

Bob

E.ric
05-02-2003, 10:51 AM
Just a quick note

You adjust the backgrounds controls on the black part of the picture (use gray scale)

Then adjust the Highlights controls on the white part of the picture, Some models only have two controls for this adjustment.

Sometimes I found it is better to turn the blue down and adjust red & green for yellow, then adjust the blue for white.

B.M.
05-02-2003, 11:42 AM
Thanks Eric Iíll try that later.

In the meantime Iíve managed to remove the metal screen/cover on the PC board that the CRT plugs into and revealed some of the worst soldering Iíve ever seen. There might have only been one dry joint causing the immediate problem but there are heaps of others, which are potential problems. Guess I can spend the afternoon re-soldering the whole board! A lot of the problem appears to be cheap solder which seems to have crystalised?! :(

Graham L
05-02-2003, 05:50 PM
Just be glad they didn't use the NZ made stuff (from the 70s?) which (to save importing lead) was made with recycled lead from car batteries. It might have been OK for plumbing, but for electronics ... :_| The electronics assembly companies (remember them?) had major problems. The Post Office didn't; they refused to use the stuff.

There are various sorts of lead-free solder being tried because lead vapour is not terribly healthy. Unfortunately, 60-40 tin/lead still seems to be the best for soldering, though a bit of copper, and sometimes silver added may make it better.

I'm happy I've still got a few kg of genuine Multicore ... that should see me out. :D

Terry Porritt
05-02-2003, 06:00 PM
That stuff was awful, guaranteed to produce dry joints ! The Multicore Savbit tin/lead/copper you can get from DSE is ok, in fact quite good, but their own DSE brand ordinary 60/40 isnt very good.

B.M.
06-02-2003, 10:04 AM
Ahhhhhh! Break through!

All up, running and looking good.

What a struggle though, there was no way I could simply re-solder the dry joints. I had to suck all the old solder off (with one of those solder suckers :D ) scrape and clean each connection and then re-solder.

I recall that there was a major problem back in the late 60ís early 70ís with some solders which was traced by the old DSIR to the resin. (Then known as flux.) Apparently, the flux which did such a good job initially, was corrosive and carried on working for years to come, eventually causing a similar problem to what Iíve just experienced.

Anyway, Iíll forgive the Tech that threw this monitor out on the grounds that he knew what was hidden under the metal cover/screen. ;)

Incidentally, Iím sitting here using the screen with the cover/screen off and donít seem to be incurring any electrical interference. (Maybe itís just there to cover up poor workmanship) :^O

E.ric
06-02-2003, 10:08 AM
A fiberglass pencil is good for cleaning PCB tracks.

B.M.
06-02-2003, 12:53 PM
??????? Fiberglass Pencil??????

Youíve got me Eric. What is, & where do I acquire one of these?

Not like a long weight / wait is it? ;)

E.ric
06-02-2003, 01:05 PM
RS components or Trade Tech have a look at TOOL250
http://www.tradetech.co.nz/spares/main-S.htm
that's the green one (or lime) to use HTML colors

E.ric
06-02-2003, 01:10 PM
Drats forgot to test the link, click "Catalogue" on the left side then "service tools" (two lots need to be clicked) down in the middle of the page,