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2010-05-21 07:34

j0x

Registered: Mar 2004
Posts: 215

Repairing C= monitors

Hi all

I have two broken monitors (1901 and 1084). Knowing nothing of analog electronics, and being wary of high-voltage circuits, I thought: Why not send them off to my local oldskool TV repairman to get them fixed? However, he tells me that it's the high-voltage generator ("flyback transformer" might be the proper term) that's busted, and he can't get a new one. Can any of you hardware wizzes tell me about some typical failures, and whether they can be fixed by replacing only parts of the transformer?

If I could point the repairman to some frequently failing transistor or whatever, that might help him fix my hardware.

[symptoms: black screen, CRT seems to get power (the regular brief high-frequency zizz can be heard on power-on), sound works fine. One monitor had problems with vertical hold until warm, which got worse over the months].

2010-05-21 07:42

Archmage

Registered: Aug 2006
Posts: 185

I would think that the hardware forum over on Lemon64 is a better place to ask this question. At least I have been aided in solving some obscure hardware questions there over the years. Good luck!

2010-05-21 09:52

raven
Account closed

Registered: Jan 2002
Posts: 137

Hi J0x

Without having some experience with electronics It'll be a little hard to help, but here are my thoughts:

The 1084 model is notorious for cold/open solders on the Flyback's legs, which cause exactly what you describe (black screen with sound).
In this case, picture might return momentarily if the monitor is hit gently...
I recommend properly re-soldering the Flyback legs.

As for the other problem, it might be dry or leaky capacitors.
How exactly did the repairman come to the conclusion that the fault is with the Flyback?
I've fixed many C= monitors over the years but only once did I encounter a monitor with a dead Flyback.
Since the Flyback supplies most of the voltages the monitor needs, its highly unlikely such a monitor will power on at all.

A few years ago I was able to buy a replacement Flyback for my 1901 locally, so I'm quite sure you can get one as well, if needed.

Btw, its impossible to replace "only parts of the transformer" as its a sealed unit.

Good luck!

2010-05-25 10:30

j0x

Registered: Mar 2004
Posts: 215

Thanks, both of you.

I'll ask the repairman to try and resolder the flyback. If that fails, I'll get him to replace the flyback (HR Electronics in Spain seem to make replicas).

2010-05-25 17:56

Danzig

Registered: Jun 2002
Posts: 428

Or you can buy my C=1081 (yeah, with SCART and RGB \ö/). Just place your bet :)

2010-06-07 19:34

j0x

Registered: Mar 2004
Posts: 215

Thanks for the offer, Danzig, but I don't trust the parcel services with shipping an old fragile monitor like that...

Besides, I already have a 1701 working.

The repairman said he suspected the flyback on both the monitors, but was unable to get a replacement. When I told him I could get him one, he refused to mount it, as "he didn't want to spend any more time on it". Weird, he seemed a nice enough bloke. He did say he had checked and/or resoldered the solder joints.

Oh, well, on to the next repairman.

2010-06-23 05:36

j0x

Registered: Mar 2004
Posts: 215

For those of you who couldn't go on living without closure: :D

I bought a couple of flybacks directly from HR in Spain ( http://www.hrshop.es/ ) and asked another repairman to fit them. In the end, the 1084 is back up and running, whereas the 1901 still doesn't work. According to the repairman, an "expensive IC" was fried, and he suspected the tube of being the culprit. I'm not going to have the tube changed, so I'll put that one back in the basement.

I know you've been riveted to the edge of your seat for the final chapter in this exciting saga, and there you have it -- and now you know one place you can buy flybacks at a reasonable price.

2010-06-23 11:52

Devia

Registered: Oct 2004
Posts: 401

Awesome shop!

2010-07-30 04:08

The Phantom

Registered: Jan 2004
Posts: 360

I would have asked....

Is there a crackling noise when you turn on said monitor? If yes, replace the flyback..

Is there power? If no, check the solder connections where the power get's plugged in. Same if you get power when you jiggle the cord and it fluctuates on/off.

If you put the back of your hand to the screen, does you hair stand (if any)... Could be an indication that no power is going to the crt.. Replace the flyback..

I so wish I caught this when the issue came up :D

PS.. You can likely still fix the other monitor, just check the solder connections. MOST monitors are always on, and the solder connections always "fry" or "burn" and eventually, they have to be resoldered.

There is still a risk of shock though! Most monitors can hold a charge for YEARS! Simply unplug the thing, take out the 4 screws and slowly pull the board out. Look at the bottom where the power connects (likely location). And look hard.. You will see it needs to be resoldered. There is still a risk of shock unless you discharge the flybacks connection to the monitor, but you should be ok by checking the solder connections and resoldering if needed.

Chips hardly go bad. It's possible, but they hardly do.

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