My Polo Star Progress

[Mellor]

Hey Grant,

This is the state of the Polo Star you wondered about. The picture is now perfectly stable after installing the e/w board from Hantarex and I have messed about with the pincushion and got the geometry OK, haven't tried pincushion on the other Polo yet.

I've had a few other issues I am unsure of too. Occasionally, which now seems to have stopped. The monitor will make a noise like it has powered down, a loss of static type sound. Create a rainbow stripe and then seemingly lose all horizontal deflection and just leave a vertical white line down the centre. It seemed to alternate with picture and then just line every 15 seconds or so. It hasn't done it for a while now!

Only problem now seems to be a washed out image. The colours aren't balanced perfectly and the screen range seems to be maxed. If you unplug the video plug and turn the screen to full you can't get raster. It only becomes slightly less than black. Also on the neck board the red and blue gain do nothing at all. But the RGB pots all adjust ok.





Now I'm going to baffle you with tech knowledge here so try and keep up. On this pic below the stringy bit that was attached to the white post type thing has snapped off. It did connect the post to the red wire. What the hell is the job of this? Its as fine as fishing wire and only looks thick on monitors because it attracts dust and crap with static.



And yes the Mrs is very happy that this lot has found its way to the dining room

[grantspain]

the horizontal frame collapse is with the polostar or another?
horizontal frame collapse is one hell of a serious fault,judging by the symptoms i would be inclined to say it the flyback transformer shorting out
if its the polostar then i would suggest looking for broken track or bad solder joints

oh yes just saw the end of your post,the stringy bit
that looks like a correction coil,any thing broken around that will cause you problems with deflection

how did it break?

[Mellor]

Yes this is all the polo star.

The stringy bit, now I do hope you update future monitor base threads with this new technical term, did look like this as I have drawn in paint! However the stringy bit had snapped in half and I removed it accidentally by trying to establish what it was. I don't know how it snapped. I can't imagine it does a great deal as the wire is stupidly thin, thinner than cotton. When I held it to wipe off dust it snapped again.



I'll check over the traces and all solder.

What do you think is causing the problem with screen voltage. You should be able to turn it up to the point of white screen and retrace lines shouldn't you? This will be why the picture is washed out. I don't need to get this monitor working or anyhthing but i'd still like to learn.

[grantspain]

i really do not know what that bit of wire is for,i don't ever remember seeing a bit of wire on any of mine like that but i will take a look tomorrow to be sure
the line down the centre could only be caused by a bad connection to the horizontal coil of the yoke or a breakdown in the horizontal frame circuit,maybe even a bad connection on the controls board ,at the extreme even the flyback transformer

as for the washed out colours,did all these problems occur after you installed the east/west board as nothing really makes sense here
the only thing common to low brightness and deflection failure would be flyback but i am sure this is not the case

unless of course you have some bad connections on the controls board,that would certainly cause all those problems

[Mellor]

Hard to tell if the prob occured after the e/w board. The screen was moving so fast I wouldn't have noticed the washed out look. Plus the cabs mirror was covered in dust which would have made it seem dull.

The screen adjustment was and still is on max and the brightness is also a good way on yet the screen isn't all that bright. It seems like i'm out of range on the screen adjustment. I assume this is more voltage to the screen. So it seems my problem is not enough screen voltage!?

Only other probs are a slight wobble, only noticeable on cross hatch to the sides of the screen and not the middle.

[grantspain]

the contast and brightness pot do nothing?

[Mellor]

Yes they both work but with the screen not going up fully they still don't make a big difference. The red and blue gain pots on the neckboard do nothing!

[grantspain]

bloody wierd,do me favour and get me the tube number/make again

[Mellor]

Its a Videocolor A66EGW83X122 . didn't Chris say it was an OK match but not ideal or something!?

I have a picture but imageshack doesn't seem to be allowing uploads at the moment. Will try again later.

[grantspain]

i looked at my polostar today and there is nothing going from the top of the white post to the yoke itself,are you sure its metal wire

what value is the resistor on the neck card at position R35,it should be 4r7,i have seen this problem on polo2 when the chassis is not matched to the tube

[Mellor]

I think I get 560 Ohm. Although the colours have got a bit faded. The last two seem the same colour so I assume brown. Green then blue to start with I think!

[grantspain]

i reckon you have a 5r6 in yours,meter it to be sure-if it is then get a 4r7
also now you need to check r23,26,30-they should be all 470ohm

[Mellor]

Just metering them on the board. Gives 5.8 for R35. I'm pretty sure the second band is blue however! And around the 333 mark for the other 3. So what does changing the values of these do!? I think I have read about matching chassis' to tubes. And some changes that are made. It may have been an Ordy post.

Where did that starting base thread about mointor/chassis matches go?

[grantspain]

r35 is for the heater voltage,if its too low you loose brightness
the other resistors are the colours

the 5.8 you read is to all purposes 5.6,its the tolerence that is taking it a little high

i am working in private on a new monitor guide,it will be some time

[Mellor]

Ahh well that sounds like the job then. Why would these values be in then and why should they be 4r7. Is this based on tube knowledge?

[grantspain]

Ahh well that sounds like the job then. Why would these values be in then and why should they be 4r7. Is this based on tube knowledge?

it sounds to me like the wrong chassis was chucked into this cab,that would explain why it is set for a 33" tube and not a 25"-which what you have

and all this wonderful knowledge does not come from my brain,i have a schematic in front of me

[Mellor]

I thought the picture would be more messed up if that was the case. Does this chassis then do 28" upwards or something? I would have though the opposite was true in that case. The pic would be too bright not dim, based on being set up for a larger monitor. I guess it doesn't work like that! I'll solder in some different ones then at the weekend. And tweak that pincushion on the other Polo one. Apart from painting the plastics i'll have finished that one then!

I also notice someone is selling a LOPT for a Hanty Polo 25" (new). He says on the auction that he thinks it the same as the 28". This true? I may buy it (£20 + delivery) and replace the one on the newly named "Smokey Joe" chassis.

[grantspain]

25 and 28 are the same lopt,just double check the number on the lopt itself-there are a few different types

[Mellor]

Thanks Grant,

I may mail him. I might just keep that board as a spares one though, I don't know!