Monitor has a major problem

[smac666]

Hi,

I have a WG K4600 monitor and it was working ok (picture was a bit dim but I had ordered a cap kit)until you tapped the side of the cabinet or monitor chassis. It would then flicker i was trying to located the problem by tapping the side and wiggling the boards and the picture went to a vertical line only see attached photo.
I installed the cap kit and plugged the boards back in and I got a vertical line still, that flickers when you tapped the chassis. Tracked that down to a dry joint on one of the board pins. Reflowed the solder on all the pins and tried again.
Still just get a vertical line but now when you tap the chassis its stays solid no flicker. If you look closely you can see movement on the line so its like the image it just condensed down to that one line.

Does anyone have any ideas about what it might be, someone said the flyback was gone another send the X/Y board was malfunctioning.

I'm sure that one of you guys can point me in the right direction.

Regards
Steve

[grantspain]

very unlikely the flyback,more than likely is a broken trace/frame ic or the voltage feed to the frame ic.also check the yoke connector and flyback  for bad solder joints,what you have is known as a vertical frame collapse.if you have a fault finding guide for this chassis it will direct you to all the common problems

[Ken Layton]

Common problem. It's a bad solder joint on the foil side of the MAIN monitor board not the plug in boards.

[smac666]

Ok thanks guys I'll reflow the solder on the main board tonight if I get a chance.

Regards
Steve

[smac666]

Ok I reflowed all the solder last night on the main board and found a broken trace on the board near the corner. So put a jumper across it and put it all back together.

Plugged everything back in and still have the same problem. :-(

I was sure that I had it when I fixed the broken trace, but I guess not, darn it.
Whats the chances that I have damaged something else when I powered it up with the broken trace?

Regards
Steve

[Ken Layton]

I had one of these a while back that had the female part of the connector on the hor/ver board with the female pins spread open too far (connector was worn out) not making contact with the male pins of the main board.

When you were doing the cap kit, by chance did you accidently tug on the yoke wires at the top of the yoke? Those wires have slide on connectors and can scoot off the terminals easily sometimes.

[smac666]

Thanks for the response Ken,

Yeah the board is a bit of a pain to work on so I probably have tugged on a wire while I was moveing the main board out to work on it.  I'll have a look tonight when I get in.

I cleaned the female connector potion of the XY boards with a wire brush and some spray air but I couldn't see an easy way of adjusting the metal connectors to give a better connection. (it actually feels pretty tight when its seated) I tried wiggling it a bit with the power on and the picture does change at all so I think the connectors are pretty good.

I'll have a look at the wires tonight and see if one of them is loose.
Although touching that part of the monitor always makes me a little nervous even if when I have discharge the tube a few times.

I never reflowed the solder on the flyback connections (the part not attached to the main chassis) so I might try that as well.

Somebody else mentioned that there are a couple of transitors that can go on the XY board and give the same effect, TR305 and TR306 I think. I'll have a look at them as well.

I will triple check that I have soldered all the caps the right way round as well.

Regards
Steve

[smac666]

Ok, I checked the wires and they were good so I checked the two transistors TR305 and TR306. Desolderde them from the board and connected a lead from the ohmeter to the base leg and took the readings on the emmiter and collector legs.
On TR305 both high, swapped the leads around and both went to low. Tried the same on TR306 and no matter which way round the leads are the resistance always reads low.

Can I assume from this that TR306 is bad as it seems to be showing a short.

Regards
Steve

[Ken Layton]

TR306's low resistance both directions sure sounds bad.

[smac666]

Ok the manual says that the TR306 transistor is a

2SC1625YLBGLI

I'm guessing that they don't make them anymore as I can;t seem to find one on Digikey
Do you happen to know of an equivalent replacement.

Thanks
Steve

[Ken Layton]

Type 2SC1625 crosses to a NTE291.

[smac666]

Thanks Ken, I'll order one today and let you know how thinks work out.

Regards
Steve

[smac666]

Part came last night I fitted it and the picture came back on.
Worked like a charm, thanks for all your help.

The only thing is that the picture is to high on the screen by about an inch.
I can't seem to find and adjutment for it on the boards.

I took a pic but left my flash drive plugged into my laptop at home.
The vertical hold just makes the picture roll and the vertical size just make me loose the top part of the picture. Is there a way to adjust the vertical position?

Regards
Steve