Dying 1942 monitor?

[desantii]

I fear that my trusty 1942 is on its last legs? Today when I turned on there was a fuzzing electric noise for 2-3 seconds and then it went away, now the screen has a blusih tinge to it. The grey from teh workbench appears almost light blue and the reds are almsot black.

Any thoughts? Can it be fixed?

thanks

[chiark]

Hmm, the power switch on these can be faulty, and I wonder if that was the cause of the fuzzing noise (arcing/shorting). That *might* have damaged something further downstream?

Hopefully a 1942 or monitor expert will turn up, but the switch is the first thing I'd check... That wouldn't explain the colours though.

[Loedown]

Originally Posted by desantii

I fear that my trusty 1942 is on its last legs? Today when I turned on there was a fuzzing electric noise for 2-3 seconds and then it went away, now the screen has a blusih tinge to it. The grey from teh workbench appears almost light blue and the reds are almsot black.

Any thoughts? Can it be fixed?

thanks

I would look around the high voltage section, most likely a 3kV cap or something similar has cracked and is / was arcing, they can be identified because they are sky blue. Make sure you clean all the dust off the components first using a vacuum cleaner and a paint brush. Other things it could be but less likely

1. Internal tube arcing, with the unit on look for arcing in the picture tube

2. Caps on the neck board, electrolytics, most likely not the 1uF, 4.7uF or 10uF ~ 350V, that usually causes bright over smeared picture with retrace lines.

3. Supply caps for the driver transistors on the neck board, 3 transistors usually with 120V on collector I think it is, if any are reading way off that value then check back otherwise replace.

4. Split flyback / tripler, look for visible signs of arcing including cracks and alike.

[8bitbubsy]

I feel it's important to add that one mistake is enough to kill you:
The tube can hold a charge of many thousands volts for days (or weeks), you better discharge it properly first. Also discharge the main capacitors, even those can kill you if it goes through your body somewhere near your heart or on the left region of your body. Don't touch any grounded materials while using the second hand to touch something that can have a loaded lead.
This is really dangerous stuff, always be sure you have the control when you operate inside a tube monitor. If this is your first time, only do it if you feel you're ready (after reading on how to operate inside monitors and when/if you have the proper tools).
If you feel anxious, that's good - anxiety keeps you being careful.

The main capacitors are probably getting drained by resistors, but you should always be 100% sure of the load in a tube and in big capacitors before you work with them.

[desantii]

I have a friend that does elctrical work, I'll send to him to take a looka t it, definitely not comfortable working with the monitor

thanks

[mech]

also check the CHOKEs,i have fixed 3 and all had cracked solder joints on the choke coils.the flyback too usually can exhibit some of this. the solder on some of these boards looks terrible in general ;/

but knock on wood,my 3-1942's continue to run flawless since fixed.


IMHo what murders these old monitors is people keep running them when they start to show effects or make noise instead of stopping to investigate/fix them. i have a 1960 here case in point that literally burned holes in the pcb where the fets were, the fets turned to crunchy burnt plastic.. this was my friends monitor and i gave him grief for letting it get that bad..

mike