CurtPalme.com Home Theater Forum

jrh_james · Joined: 12 Jul 2015 Posts: 8

Hi can someone help me. I am having trouble focusing the tubes on my ECP 3500. Basically I can get the centre of the picture focused, but the edges are always blurry. I tried swapping the focus/bias board but it made no difference. It's the same on all three tubes. The photo is of the tube face, not the projected image, so it is not a lens issue.

P.S. Ignore the liquid on the tube it's just a bit of coolant from when I bled the tube.

Thanks James.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4379 Location: Phoenix

Hello

You have lost the east-west focus parabola waveform, not sure which board that is; fifteen years since I messed with an ECP, it might be 50-1873-05P Waveform Generator with 50-1911-03P Pincushion PCB. See this post to locate one: http://www.curtpalme.com/forum/viewtopic.php?t=38193

Also, you will need five posts to send a private message to Barclay.

jrh_james · Joined: 12 Jul 2015 Posts: 8

Thanks I'll swap it out and see what happens. I think I have spares for everything except the HVPS, which is why I try to keep this old thing going.

jrh_james · Joined: 12 Jul 2015 Posts: 8

I swapped out the waveform board and it made no difference. I hope it is not the horizontal driver board, as although I have two spares I checked and they are not the correct version.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4379 Location: Phoenix

Hello

Try a remote board if you have one; the waveform might originate from there.

jrh_james · Joined: 12 Jul 2015 Posts: 8

I have swapped out the remote board, convergence board, gain board, no effect.

I haven't swapped any of the three horizontal deflection boards, but as the problem affects all tubes I would be surprised if these were the problem, same for the CRT socket boards.

I have a spare horizontal driver board, but its a different issue and doesn't fit in the mainboard due to the plastic tab configuration on the board socket. The component layout on the board looks pretty similar and I am tempted to snap off the relevant tab and stick it in. Which I guess could have the effect ranging from frying the board or other components to not working to working. Alternatively I suppose I could try to source a replacement board but I am reluctant to spend money on this thing particularly as I don't know for certain where the problem is. From my reading the service manual I am not sure this could be the faulty board anyway, as it doesn't seem to be involved with the dynamic focus.

Anything else could be at fault?

barclay66

**Curt Palme** · Posted: Mon Jul 13, 2015 1:52 pm Post subject:

The tabs are there for a reason, there's a good chance you'll nuke something if you start breaking off tabs. Been there, done that with the ECPs. I may have a board if you need one, selling them dirt cheap, as I'm blowing out all my ECP stuff. Let me know.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4379 Location: Phoenix

Guys

What we need is someone with an ECP service manual to step in and tell us if James is swapping the right boards

jrh_james · Joined: 12 Jul 2015 Posts: 8

jrh_james · Joined: 12 Jul 2015 Posts: 8

Bit of an update. I tried putting one of the old tubes (red) back in and it fixed the focus problem for that tube. You can also see that in addition to the focus problem there is a keystone problem with the two new tubes.

The old and the new tubes are both the same model 07MS (the photo of the rear of the tubes has the new on the left, old on the right). However I noticed a slight difference in the wiring configuration of the yokes. The new have a few extra wires on one of the connectors. Are they incompatible? Also the astigmatism magnets on the new tubes have not been set, but I wouldn't have thought they would cause this much distortion.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4379 Location: Phoenix

Hello

You have installed tubes from an ECP4xxx and the yokes are different. The correct yoke has two wires for H scan, not four. That would be the yoke on the right in your ecp2 pic. Put the right yokes on your better tubes and you might have it solved.

jrh_james · Joined: 12 Jul 2015 Posts: 8

Hi Tim,

Ok thanks for confirming. I did pull the new tubes from a 4xxx.

Thanks for your help.

James.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4379 Location: Phoenix

Guys

The ECP4xxx used two sets of H yoke windings as did the Marquees; on each yoke the windings run in series up to 33khz, then switch to parallel to get more current into the yokes; this enables uniform raster widths across the entire range. The ECP 3xxx ran one set of windings and saw the width pull in some above 45khz. The ECP3500 was rated to 60khz but width pulled in about 15% up there so it was not very useful at the top end.

stefuel · Posted: Sun Aug 02, 2015 2:20 pm Post subject:

Fungus.

mc86 · Posted: Sun Nov 01, 2015 10:41 pm Post subject:

Hi James - Sorry to reply to this old post as it has been a few months since I've been on here...but my ECP died a month ago (I haven't had time to troubleshoot). Did switching to the correct yokes for the 3500 fix this? Some OCD part of me wants to know the resolution to the issue!

Cheers, Matt