Commodore 1084S-D1 (NTSC) - Convergence Issue?

[casm]

Having a bit of a problem getting a Commodore 1084S-D1 (NTSC) to display a picture correctly, and it looks as though it's probably a convergence issue.  That said, I'm not sure where to go with troubleshooting at this point; it also came to me for free in non-working condition, so I have no clue as to its history.  Here's what the picture looks like:



Note that the picture isn't really as blue as it appears in the photo - the RGB lines are distinct, but the background is actually a fairly bright shade of white.

Due to a couple of visibly-bad caps on the mainboard, I decided to go ahead and replace all of them in one fell swoop.  This was done using Console5's 1084S-D1 cap kit, which was installed without issue.  The work was also double-checked and checked again once this issue was evident; to the best of my knowledge, the caps and their placement and solder joins are good.  Same goes for other components on the mainboard (and neckboard, for that matter).

Adjusting the pincushion pot on the mainboard does not bring the picture back into line.  The convergence rings seem to be unable to get the RGB lines to, well, converge - they get close, but never overlap completely. The yoke is held in place by the usual wedges, which are glued to both the outside of the CRT and the coil.  There is absolutely zero movement possible in the yoke with its band clamp loosened.

The signal being fed to it is from a known-good Dreamcast over composite, and other monitors have no problems displaying it.  The composite switches are set correctly, and other inputs produce the same result.

It wasn't displaying a picture before replacing the caps, so this is at least a step in the right direction.  However, monitors aren't exactly my forté - I've done tube swaps, component repair, etc. but my experience with convergence is pretty minimal so am not sure if I'm overlooking something basic.  Any help would be appreciated!

[princess prin prin]

Bad horizontal coil in the deflection yoke. It's two coils in parallel and one went open. Typically caused by corrosion. If the damage affects several turns it may be a real ballache to fix. In any case you need to remove the yoke as the horizontal coils are the ones underneath that you can't see if the yoke is on the tube. And if you manage to fix it you'll have to reconverge everything (yoke and rings).

[casm]

Bugger.  I'd been hoping it wouldn't be something along those lines, but I appreciate the insight.

Looks like the best plan of action is to reassemble it until I can find a replacement yoke and put it back on the shelf in the interim.  This problem aside, the monitor's in really good shape so is worth hanging on to.

Out of curiosity, does anyone know if there's a Samsung 15-ish inch TV yoke that might be a viable transplant candidate?  This one has the Samsung CRT, so I figure that sticking with the same manufacturer probably has the highest chance of success.

[Zebidee]

Look here. Search by first part of tube number.

https://tubular.atomized.org/

https://crtdatabase.com/tubes

[princess prin prin]

It's a 14" tube (13" visible) so a 90° deflection angle and it should have a small neck which means a 29mm diameter (a 22mm minineck yoke wouldn't fit). If this is confirmed, I have replacement yokes I could part with but not for less than 30 euro plus shipping from Italy.

[casm]

Look here. Search by first part of tube number.

https://tubular.atomized.org/

https://crtdatabase.com/tubes

Thanks for that; I had no idea they even existed.  Cheers!

[casm]

It's a 14" tube (13" visible) so a 90° deflection angle and it should have a small neck which means a 29mm diameter (a 22mm minineck yoke wouldn't fit). If this is confirmed, I have replacement yokes I could part with but not for less than 30 euro plus shipping from Italy.

Let me do a bit of poking around locally, but having one shipped wouldn't be a problem.  I am in the US, however, so it may be a complete nightmare for everyone involved.  If that makes it unfeasible for you, I completely understand.

[casm]

Update:

Today, I was able to get my hands on a Samsung SyncMaster 2 monitor, model no. CVM4963T.  Just got home with it so haven't opened it yet (or dug up the service manual), but I snagged it because of the following specs:

• 14" colour CRT (13" viewable)
• DOM: January, 1993
• 9-pin RGB (possibly) input

This seems like it may be a candidate for a tube or deflection yoke swap with the 1084S-D1.  It'll take me a while to get around to testing it and figuring out if it's a) working and b) usable as a parts donor, but I'm hopeful that between the two of them the 1084S can be resurrected.

[princess prin prin]

That's a PC monitor. The horizontal yoke on a 31KHz will have a very low inductance, in the 0.2-0.3mH range, totally incompatible with the 1084 which is a 15KHz monitor and will have a horizontal inductance of around 2.0mH. You need the yoke of a TV.

[casm]

That's a PC monitor. The horizontal yoke on a 31KHz will have a very low inductance, in the 0.2-0.3mH range, totally incompatible with the 1084 which is a 15KHz monitor and will have a horizontal inductance of around 2.0mH. You need the yoke of a TV.

Beat me to it    Got around to digging up the manual this morning and learned exactly that.  Bugger.  Back to the drawing board...

[princess prin prin]

Be aware that the majority of "newer" (1990-2000) 14" TVs (= US 13") have a minineck tube (22.5mm diameter) so the yoke of these will not fit a small neck tube (29mm) like the one in the 1084.