CurtPalme.com Home Theater Forum

hansilili · Joined: 09 Mar 2007 Posts: 302 Location: Köln, Germany

Guys,

a friend called me for help. His 10PG started messing with the horizontal width of the picture. At first this only occurred during warm up but the finally resulted in the pic to collapse to about 3/4 of what would be needed to fill the screen. RC amplitude or the pot on the deflection board don't help.

Full recap is not an option. As currently there is no plain PG available I advised him to buy a 9PGplus that was advertised on the web. He drove 400 km only to find out that this actually is a GP5000 in non working condition. Took it home anyway.

So please, which boards would you try to swap first to locate/solve his problem? We might be able to source single boards in GErmany but shipping a whole unit is too much effort.

If he can cure the machine with little effort - fine. If not he threatened to go digital and we can't accept that, can we?

Cheers
hansilili

barclay66 · Posted: Wed Aug 12, 2015 8:49 am Post subject:

Hi,

I'd first check all connectors around the deflection board. Second I'd check the deflection board itself for broken solder joints.
See here: http://www.curtpalme.com/NECPG_Layout5.shtm

Regards,
barclay66

hansilili · Joined: 09 Mar 2007 Posts: 302 Location: Köln, Germany

yeah. Currently we are trying to find a spare deflection board for testing. I guess those would fit: 72137091, 92 or 93 If we would be sure that the def board is the only culprit we would even spend some money on it but at this stage it would be only guessing.

barclay66

Sure.
An additional potential source of the problem could also be the LVPS (supply voltage for H-Deflection below normal level). Measurements of the main supply voltages could be helpful.

You wrote:

hansilili · Joined: 09 Mar 2007 Posts: 302 Location: Köln, Germany

a or b? I understood it's a but the owner needs to confirm.

Where are the LVPS circuits located? Is that in the big powersupply box sitting under the lenses? Can it be exchanged with parts from the 6 or 9PG PGplus?

barclay66 · Posted: Wed Aug 12, 2015 11:32 am Post subject:

**Curt Palme** · Posted: Wed Aug 12, 2015 2:23 pm Post subject:

Recap the board, there will be a bunch leaking. It may also be as simple as tweaking the H width trimpot on the deflection board.

**Curt Palme** · Posted: Wed Aug 12, 2015 2:24 pm Post subject:

Yes, a PG deflection board will work, maybe a + one as well, and I don't think it's the LVPS. When they die, they usually go dead.

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

I think the DEF-PWBs are backward compatible, at least when I hacked one late PG plain DEF PWB into my PG xtra back then It worked right away, only the extra geometry controls didn't worked properly, so since the connections are essentially the same on all DEF board they all newer DEF boards should work in a plain PG.
You should check different scanrates and see if the width is narrowing with the higher scan rates, if so then the H-def supply voltage is most likely dying (LVPS - the power supply unit under the lenses).
My strong guess is that ALL electrolytic capacitors are leaking in that machine already...

hansilili · Joined: 09 Mar 2007 Posts: 302 Location: Köln, Germany

Thank you for your input.

Re the H-Width pot function. The issue develloped gradually (sounds like cap issue to me). At first the pot was sill reacting but couldn't bring the width to the size needed. Later then, when you turned it too much, the picture collapsed horizontally ans started pumping.Now, the witdth is too small and the pot has only very minimal effect. Vertical heigth is totally okay though.

So far I am happy to hear of no other suspects than the Def board and power supply. We knew about exchangability of the different board versions. Maybe we can try the scan rate test. A replacement LVPS unit for a 10PG will be much harder to find than a 7" PG or PGplus.

I will keep you posted...

Tinman · Posted: Fri Aug 28, 2015 7:34 pm Post subject:

IIRC, the PG9 power supply will work fine, it is just in a smaller metal housing. I used to power up my PG10 with one when testing for leaking caps, which the power supply also suffers from now.

hansilili · Joined: 09 Mar 2007 Posts: 302 Location: Köln, Germany

Okay, we nailed the culprit! He bougt a 9pgxtra and swapped deflection, focus and convergence board. Those seemed to be compatible to the 10PG but it didn't help the issue. He couldn connect the power supply unit because ist has differen't plugs.

So after all I mailed him my spare power supply and with that one, his 10PG is rock solid Thumbs Up

Now I see three options.

1 He takes his broken PS to an electronics repair shop to try to have it repaired. If someone could mail me the schematic circuit this would probably help. Any hints where to look for first? I guess leaking caps?

2. You tell us how to connect a PGxtra or GP5000 PS to the rest of a 10PG unit. Would that really deliver enough power? With my own 10PGplus I notice distortes vertical lines in PC desktop windows, the typical sign of PS limitations. With the xtras I never had that. Would it make sense to switch the PS anyway because the more modern cicuits can deliver better voltage stability and more current?

3. Someone offers to ship a working PS to Germany

4. He keeps mine until I go digital and he then gets the rest of my CRT stuff or until my PS dies.

Anyway, thanks to everybody for guiding us towards the power supply!

hansilili

**Curt Palme** · Posted: Thu Oct 01, 2015 2:49 pm Post subject:

I believe Marc is right, the regular PG supply will work, but physically it's different. Guaranteed his PS has bad caps, so it might just be an idea to replace all the smaller caps which are the ones that usually fail and leak. Can either of you do that work?

ON the NECs, a lot of the 47uF caps go bad, so I'd start with those.

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

I've seen every cap in the PSU leaking -OK maybe except for the mains filter caps.
Here is the list of the capacitors for the power supply unit. It's not my work.

Otherwise the PSU of the PG xtra isn't good because it has +110V and -75V power lines fo the neckboards, while all other PGs need one +190V.