CurtPalme.com Home Theater Forum

[johey]

When I got my Electrohome ECP 3500, I first thought the blue tube had a burn-in, but I'm not so sure anymore. I think it is another kind of problem. Let me try to explain the issue:

If the picture is full black or dark grey, and if brightness is set to a level >3 (on a scale from 0 to 10), the blue tube shows a vertical stripe on the left side of the picture, from the very left to about 1/5 of the total width. The higher brightness, the more if this effect. If I turn up the brightness to about 6, it starts showing a thin vertical shadow stripe in the area of light. As soon something is shown on the screen, no matter where, the stripe is gone. It is very clear when looking directly in to the tube.

As the stripe is not there all the time, I do not think it is a burn-in. Not that I have much experience with CRT projectors, but at least that is not a sign of a burn-in in a CRT monitor. I would rather think it is some issue with the electronics. Could it be caused by old/bad capacitors? Or do you have any idea what it could be and how to fix it?

Thanks!

[barclay66]

The Technical Bulletin TC92-4 (available on this site) mentions a similar issue and might be helpful:

DATE: 23 March 1992 File No. TBC92-4

Technical Bulletin

RE: Dark vertical line at left edge of picture

SYSTEM/SUBSYSTEM:
800913 RGB Sync 2 Input
800914 3,4,5 Wire Loop Thru
800916 RGB Sync 10 Pin
800919 2 Input Monochrome


APPLIES TO: Any system using any of the above modules.

SYMPTOM: When connected to some high scan sources like DEC 5000 or Apollo 4500, there is a dark vertical bar along the left edge of the picture.

CAUSE: Back porch clamp pulse too wide.

SOLUTION: Add 15K resistor across R12 and change C59 to 100pf. Perform this modification on all modules which passes this computer signal.

RESULT: No dark line on left side of image.

VERIFICATION TEST: Make sure all other sources connected to the projector are behaving proper.

NOTE: Perform the above only if required.

COMPATIBILITY: N/A

E-HOME REFERENCE: Non.

[Tim in Phoenix]

Guys


ECPs are officially Fossilized. They were never reliable, I was the Video EMS driver for Metro Detroit and it wasn't much fun. Get a Marquee 9500, or Two and have some fun with blending! At least parts are still available.



Tim at E-Tech Scottsdale