Quick question about my pentranic ch-288

[gokun]

Ok, so I noticed recently that the picture is off center horizontally and none of the remote board adjustments, etc can correct this...I am always left with about .5" bar from top to bottom on the right side of screen....
so baring in mind that this one has had a cap kit, the hot replaced, voltage is good, etc, etc,  I'm thinking I should play with the horizontal width coil(and possibly replace it depending on the results of playing with it)...does that sound right? Am I thinking correctly or am I way off? Thanks! As always I appreciate any and all input.

Oh and it's probably worth mentioning that I don't currently have a plastic alignment tool...is using an alen wrench really that bad?

[Mauzy]

If you do use an alan wrench, just be REALLY careful due to the risk of touching the wrong component and getting an electric shock AND using an alan wrench could accidentally allow too much force to be applied to the coil, thus breaking it in half.

[Kevin Mullins]

Just a note..... I picked up a couple sets of those TV adjusting tools (3 piece set) from Radio Shack the other day for $0.97 a set.

IF ..... and that's a BIG "if" you absolutely have to use an allen wrench (not recommended)... turn the monitor OFF. Adjust it a little and then turn it back on to see. Turn it off, adjust it some more, etc.
If there feels like there is any excessive force needed to turn the ferrite core..... STOP, you WILL break it.

[gokun]

Ok, so I took the advice(thanks) and got myself a proper adjusting tool(got a cheap kit with several actually)...and I pulled my cab out and opened up the monitor....
first thing I checked was the N/W jumper and it was indeed set to W...

so then I go to look at the width coil(the one I got the tool for) and...it can't be adjusted?!?
There is no visible means of adjusting it...at least not with this tool....it goes down slightly, then just a smooth flat black surface in there...am I missing something or is this part possibly broken? I'll attach a pic below...

 

 
dunno if you can see in there clearly (pics are a little blurry) but it's smooth, black and unadjustable far as I can tell....

Also, I've read there is a cap I can replace with a higher value that will affect the width...is this true, and if so, anyone know which cap?

[gokun]

hrmm....comparing with other chassis like mine this weird coil seems ot be the norm...at any rate, I have been thinking about it and maybe it's not really the width as much as the position...here is a pic to help illustrate what I mean....
 
I turned up the brightness and put some tape on the glass to help you see since there was glare, etc....
the left piece of tape is the edge of the picture, and the right one is the physical edge of the viewable part of the screen...so as you can see it's a bit too far left...between .5" and 1" I would say...
any ideas? anyone??

[Kevin Mullins]

the left piece of tape is the edge of the picture, and the right one is the physical edge of the viewable part of the screen...so as you can see it's a bit too far left...between .5" and 1" I would say...

What does the other side look like?
I'm assuming this monitor is horizontally mounted. (?)

[gokun]

the left piece of tape is the edge of the picture, and the right one is the physical edge of the viewable part of the screen...so as you can see it's a bit too far left...between .5" and 1" I would say...

What does the other side look like?
I'm assuming this monitor is horizontally mounted. (?)

Other side is flush to the viewable area...adjusting the width can pull it in or push it outside it...but otherwise it goes right to the edge like it should...and yes, it's mounted horizontal(l to r)...
I'm researching it, but not coming up with any definitive answers thus far...so any ideas are greatly appreciated.

[EDIT]
After much mucking about I can get the image to appear to be centered in the screen, but I'm then left with about 1" space on either side...and it's still not really centered...I was just able to adjust it so it looks like it is...I would like it to fill the screen from left to right though...hrmmm....this one is driving me nuts...lol

[EDIT 2]
So I've been playing around with this...and something else I noticed is...
the picture seems to get wider and narrower with certain screens or flashes of the screen...hrmmm...makes me wonder...

[EDIT 3]
dangit....I can get it within .25"(maybe slightly less) but not quite to the edge on the right....maybe back to the width after all...I dunno...seems like it just needs to be centered better...but with a little extra width I could manage sooooo....I dunno....running outta ideas...thinking that c908a or c908 might be the width cap? not sure....hrmmm...maybe I'll just play around with them and see what happens....sigh....

[EDIT 4]
ok finally did figure how to adjust that weird width coil....but couldn't get it to move much at all and didn't feel comfortable forcing the issue with it...soooo....
got verification that c908 and c908a are width caps so I guess I'm back to playing with those....both are 250v, with 1 being 104 and the other being 474...so gonna pick up a few new ones of the one smaller and one larger variety and see what happens...prolly gonna try c908 first...anyhoo, any tips or advice is welcomed....

[gokun]

Final outcome....changing width cap fixed it...no one seemed too interested so I'll leave it at that...but if anyone is interested let me know and I can post what the original value was as well as what I replaced it with...
still gonna prolly buy a new chassis as a backup though just in case...lol

[demogo]

Final outcome....changing width cap fixed it...no one seemed too interested so I'll leave it at that...but if anyone is interested let me know and I can post what the original value was as well as what I replaced it with...
still gonna prolly buy a new chassis as a backup though just in case...lol

I'm *very* interested in what you did, with both adjusting the width coil and what caps you put in.  I have a Pentranic CH-288 that is a bit too wide (maybe 5-10% of the picture is being clipped on the sides) even with the horizontal width set to the minimum on the remote board.  I'd love to be able to get that picture to the right size.  The picture is very nice other than this one issue.  (I just recapped the monitor and that fixed a number of other issues).

Any info you'd care to share would be much appreciated.

Also, in your very early posts in this thread you mention an N/W jumper -- I'm not aware of that jumper.  Is that something you could point out to me?

And I have not checked my B+ on the monitor -- could that be causing the display to be a bit too wide?

Thanks!

[gokun]

basically a copypasta of a pm i sent him with a couple modification...
thought it might help more folks in teh future if it was here too:

well, I haven't found my notes yet...but here is what I recall thus far just to get you going...
my picture was too narrow actually and I wanted it to be wider(but it's the same premise to make it narrower so no biggie)...

anyways...first things to check:

1) the horizontal width adjustment on the remote board. i'm assuming you already did this but i'll mention it just in case. it should have more than enough range to make the pic smaller...if not...well, in my case I replaced the pot with a larger value one, thus giving it more adjustment range. I recall the one i used was about 220k which is probably more than you need. also bare in mind that adjusting it too far out of range can damage your monitor.
so assuming no joy there...

2)adjust the width coil on the chassis...you will need a special plastic toolset for this...they can be obtained cheaply off ebay,etc. here's a link to the first on that came up on ebay: http://cgi.ebay.com/TRIMMING-TOOL-USE-TVS-AND-MONITORS-/310213222558?pt=UK_ConsumerElectronics_SpecialistRadioEquipment_SM&hash=item483a26209e
but feel free to search for others...

you use this tool to adjust the coil in either direction(a mirror comes in handy for this part so you can see the screen from the back)...no more than 2-3 turns in either direction cause otherwise you could break the core then have to replace the whole part(which isn't hard but isn't a lot of fun either hehe)...
It's worth noting here that a combination of 1 & 2 may work best for you here. adjust each just a little to get a good compromise. this is mostly what I did to get mine in shape....but it still wasn't quite perfect so I moved on to:

3)replacing the width cap...I really don't recommend this unless you have a mentor on the forum checking your work and giving advice;people like grantspain, qrz and the other regs are FAR more knowledgable about these matters than I am and can tell you in advance if you're about to so something risky as well as offer you invaluable advice. That being said it basically works like this:

they will range between .1uf (widest) and .56uf(narrowest) generally speaking...so if your width cap(check the schematics to locate it...I seem to recall it's c908a but double check me on that...my memory is hazy...anyways...
say your picture is too wide and you have a .15uf cap on it. then replacing that with a .33uf cap should make it narrower. Make sense? so we're looking at either c908 or c908a...
their values are around.....c08a is 474J...so roughly .47uf (250vpp), so  you could try a .56uf to make it narrower (assuming that's the one...I forget which of the two actually does th fix...I think it's this one but I could easily be wrong so again, I say consult the experts on this one.

moving along...c908 is .39J so....i'm assuming around .33uf 5% (again, double check me on this) so theoretically jumping it up to a .47uf would make the screen narrower too.
I think that about covers it to the best of my memory and I do apologize for my shite explanations so feel to ask questions if anything seems confusing. I'll try to help as best I can...

but to briefly recap...try the remote board...try the width coil with the special tool...as a last resort try the cap.

Also, the NW jumpers stand for Narrow/Wide so you would want it on the N if it's not already. that would go somewhere between steps 1 and 2.  It should be located as ai recall...somewhere nearby the flyback and width caps and coil...although it may not be installed on all monitors...

hope this has been helpful to you...

should you decide you just don't want to bother and want a new one, I have always had fantastic dealing with Rick Neiman...I highly reccomend him and his company.

at any rate, although I don't post as much I'm still a pretty avid reader of the forums so i'll try to help as best I'm able until the big guns step in hehe

PS:
-1 interwebs for necroing an old thread

[demogo]

Thank you for the quick reply!

I've got the H width on the remote board set to minimum and the picture is still slightly cut off.

I have width coil adjusting tools already but there is something odd with this width coil as you noted in your posts above.  There doesn't seem to be anything inside the plastic on top to turn.  Whatever you discovered in your post back in the day is the trick -- but it's not obvious to me.

If I can tweak the width coil then hopefully I can avoid messing with the width caps...

I'll go looking for that N/W jumper but I don't recall seeing one when I recapped the chassis...

I know -- I resurrected an old thread but you had the only reference to my issue that I could find with google anywhere!  I just wish you had jotted down the secrets in your message thread from a year or two ago. 

[gokun]

ok, as I recall, I replaced the Width coil with one that did have the adjustment inside it...problem is, I don't recall how I determined what kind to replace it with...I think I had found a compatible chassis and used the part# from that to get it...the ch288 series is fairly generic, and I'm cheap, so that seems like something I would have done.
Another thought I had looking back is that my tool had 2 ends on it, a small end and a large end, and the larger end actually did fit in there...but I seem to recall it would not turn...hrmmm...
my personal advice would be that if it's only still off a little bit(like less than .25") I would just replace the pot on the remote board with a slightly larger one and that should give you just enough extra adjustment to make it work. The reason I say that is because if you can't find a replacement width coil and happen to mess yours up(which is actually very easy to do) then you'd be kinda screwed.
Also, I did buy one of these chassis from neiman displays(i mention rick a lot cause he's awesome!). I know that they are VERY familiar with these chassis so he might actually be able to tell you a part# or something if you really wanna go that route, but again, I would just try replacing the pot on the remote board first-just don't go crazy with it. hope that helps a little

[demogo]

OK, so it sounds like my options are to possibly replace one or more width caps, or possibly switch to a different h width pot on the remote board -- and call Rick Nieman. 

I wouldn't replace the entire chassis for this issue -- the picture is really very nice except for this one item.

[gokun]

yeah, I don't blame you; I would try to fix it first too.
Let me know how it turns out, and good luck!