Hantarex Polo 28" - Bad Flyback?

[bertthedefender]

Hi everyone,

I've just powered up my 28" Hantarex Polo monitor for the first time in about 18 months.  It was working last time it was used, but not any more...

I get no picture, but I do get neck glow and it looks like I'm getting some high voltage to the screen, as there's a sticker on the tube that moves to/away from the tube (can't remember which) when the power is applied, and the other way when powered off.  No detectable static on the front of the screen though.

I also get a slightly irregular ticking sound, definitely from under the suction cup and there was a bit of a burning smell. Also the "whistle/whine" that you associate with CRTs is very loud. Adjusting the horizontal frequency pot changes the pitch of the whistle a lot, and if you turn it down enough, the monitor powers off and the neck glow goes out.   If I set the horiz. freq back, and unplug it then plug it back in it powers up again, but just back to the way it was before.

The monitor is out of the cab at the moment, as I said it worked when it was last powered down. I've been using the built-in signal generator on the adjustment board to test the picture as I don't have any other video source at the moment.

From what I've read, I'm thinking flyback and/or HOT as a starting point but I thought I'd ask the experts before I start ordering parts....

The monitor has not been recapped, and appears to be running its original flyback from 1994.  The tube is great with no burn.

Thanks for any help and best wishes to all,

b.

[grantspain]

i would say your tube is very damp
remove the anode cap and clean away any dirt,just use a dry cloth.Also clean the anode cap itself and the ht lead

after you have done this re-power the cab and once you are sure there is no more arcing you can turn the screen volts clockwise a little to see if you get a raster

imo its working just fine apart from being very cold

[bertthedefender]

Thanks Grant, I hope that's all it is - I'll follow your advice and report back!

Cheers!

[bertthedefender]

Hello, and firstly apologies for re animating this old thread!  Finally ive got to test my monitor - I took Grants advice and checked the anode cup - gave it a clean and repositioned it.  Now ive just got a horizontal whitish-purple line across the middle of the screen, which I understand from other posts is a faulty IC1 (lm1203)...  Fun and games!

[grantspain]

if its mounted horizontally then its a vertical fame collapse,that is normally down to the tda1675a ic and the 2r7 fusible resistor on the 25 volt line
lm1203n is a video decoder ic,when they go faulty you lose colours or get blanking issues

[bertthedefender]

Thanks again for your fast response Grant - but this time, I've got to hang my head in shame...

I had the adjustment board on backwards...

   

But thanks very much for the advice about the anode cap - that looked like it had moved out of position somehow judging by the ring of dirt around it, and taking it off and repositioning it certainly  sorted my ticking issue.

I'm now going to retreat back to my hole, and think about checking everything before making more posts...