Calling all Monitor experts - various issues

[witchfinder]

I've just begun working on the machines in my games room again and my first priority this year is to fix as many of my monitor issues as possible, which I'll be listing below.

I'm either looking for advice on how to fix them (if it's a quick fix that I think I can manage) or otherwise I'm looking for somebody to send the chassis to to fix for me. Cash is ready and waiting!

Issue #1: Nanao MS-2932 (FIXED)

Issue #2: Electrohome EXTEL-25 (G19)

This issue has previously been raised in this thread:

http://www.ukvac.com/forum/electrohome-extel25-monitor-chassis-problems_topic340458.html

I now get a relatively stable picture on it but there's a lot of break-up at the top. See pic below and also the short video linked to later in this post. The above thread suggested recapping but can anyone confirm that should do the job, and also where I would get a cap kit for this monitor?

Issue #3: Wells-Gardner K7000 (I think)

This takes a while to warm up and then runs fine for half an hour or so, then the picture starts rolling intermittently as per the second half of this video: https://www.youtube.com/watch?v=UeEM_6VA6Ik

So if anyone can offer assistance, either with advice for a simpleton like me to follow, or if I can just send all the chassis to on person to fix, that'd be smashing!

witchfinder2016-05-02 16:17:40

 

[RGP]

Issue 1: Not sure, would need to poke around with a meter in a few places when it shuts down.

Issue 2: Possibly linearity issue - never seen that chassis

Issue 3: Dry joints around sync circuit and/or input pins

Issue 4: Most likely LOPT/power section.

 

[obcd]

Issue #2 Is it possible you are missing a color as well? (Like red)

 

[witchfinder]

Issue 3: Dry joints around sync circuit and/or input pins

This sounds like something I may be able to fix myself... if I knew where to look! Any examples of where I should be looking or shall I get a photo of the chassis?

Issue #2 Is it possible you are missing a color as well? (Like red)

I don't think so. There's plenty of red on the games on the 19-in-1. There's a bit of magnetisation in places on the tube but otherwise the colours seem OK.

witchfinder2016-04-05 18:30:03

 

[jengineer]

out of all the monitors I have had my hands on, I have never ever repaired one where it was just a dry joint

but hey, I wish you luck!
jengineer2016-04-05 18:57:22

 

[RGP]

out of all the monitors I have had my hands on, I have never ever repaired one where it was just a dry joint

but hey, I wish you luck!

For things that happen after warming up, i'd almost always go down this route first, if the issue is there from switch on its more likely something deeper.

Sometimes you can just have a run of good luck and equally a run of bad.

Never hurts to clean up and reflow 30+ year old solder.

 

[silverfox0786]

out of all the monitors I have had my hands on, I have never ever repaired one where it was just a dry joint

but hey, I wish you luck!

i have twice on a MTC-9000

first was C40 kept cutting out after 10 mins (the time it took for metal to expand the hole to become bigger and lead not make contact)

and second was R99 main solder point was completely dry jointed and even a multimeter was able to pic up the severed connection against he lead tip and solder mountain around it

both times that was the only fault and works after just fine

silverfox07862016-04-05 20:41:27

 

[witchfinder]

OK, so for the dry joints, is it just a case of removing the chassis and having a look for them, or is there a specific place I should be looking on it?

Issues 1 and 4 are to be resolved by a professional (AKA Gunblade) BTW!

 

[witchfinder]

Anyone got some guidance on Issue #3? Where should I be looking?

 

[gunblade]

it could be just a crappy vertical hold pot otherwise its a fault in the vertical hold circuit

 

[witchfinder]

A small update on issue #3 - when the screen rolls there's also a clicking sound coming from the chassis. Does this in any way help indicate where the issue lies?

If anyone can indicate where on the chassis I should be focussing my search for dry joints that'd be great.

witchfinder2016-05-02 16:29:30

 

[obcd]

The most suspected solderings are those of the heavy components and the components that warm up.

So, the THT is a suspect for bad solderings as it's a heavy piece.

The bigger diodes in the power supply are suspects as well.

If you have some power resistors on the pcb, you should check the solderings of those as well.

All power transistors and ic's that are clamped to metal for cooling might need some attention as well.