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Discussion Starter · #1 ·
I've attached a pic of a problem that I have with an Electrohome ECP.

The picture was taken from the projected image on a screen using the green only with a full white field input signal running 600P.

The size of the picture is approx. 6in x 6in on a 72in diagonal screen.

It looks like some of the scanned lines have been pulled apart.

The problem is in a small section at the top and also goes in a thin random band vertically down the screen.

It's mostly noticeable on the green but I can just see it very very slightly on the red.

On the blue it's not noticeable at all.

80% of the time with video you can't see the problem but if the image is mostly white then it is noticeable.

The tubes are new so it's not burn.


I've replaced the following PCB's with no effect:

V Defl & H.Reg PCB

Horizontal Defl PCB

Remote Control PCB

Waveform PCB

Video Control PCB

Video Output (neck PCB)


The only PCB's I haven't replaced are:

The power deflection, but I can just see the problem on the red so 2 PCBs would be faulty.

The input PCB , but I can see the problem if I look carefully at the internally generated text which is done on the Video control PCB after the input PCB.

It might be the convergence PCB, I don't have a spare, but I've swapped all the socketed IC's around on the top PCB which would be RGB channels & the problem didn't change.

I haven't replaced the 2 power supplies or Bias module yet.


My first guess is the Convergence PCB but I've removed all the socketed IC's cleaned all the IC's sockets and teated all the IC pins, plus swapped them around with no luck.

I vaguely remember seeing a similar problem like this on another ECP years ago.

Anyone with good Electrohome ECP knowledge hazard a guess as to were to look?



Thanks for any help.

Tony
 

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Or nobody has seen it before!


I know I haven't... It looks almost like the screen is wrinkled, but I'm sure you checked that. :)


if you ever DO figure out what it was, be sure to post it here- I'd be interested to know.


- David
 

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Discussion Starter · #4 ·
Thanks WD-40.

Yes I might do some more board swapping over the weekend.

Tony
 

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Seen it on a sony, and it WAS the convergence board. NO idea why.


Marc
 

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I've seen it before, but can't remember what I did to cure it. I think it was the Dallas chip, but I'm not sure.


Curt
 

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I think the GP3000 could do weird things like this too. Data corruption. But again, in the convergence board. I watched Doug reset a GP3k he picked up from me (for the CRT's) and it had similar issues.


Marc
 

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Discussion Starter · #8 ·
Thanks Guys.

I'm pretty sure it's not the Dallas chip because I've got another Remote Control PCB & after swapping it over it didn't make any difference.

I'm thinking that it might be the convergence PCB but it's the only card I don't have as a spare.

I've swapped over all the socketed chips on the top PCB without a difference so it might be on the lower PCB unless there is a socket problem.


Tony
 

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I have seen that and cured it. It was the convergence board I believe.... Whichever is the board in the back that has a daughter board on it and all the socketed chips. (forgive me it's been many pj's ago since I worked on one.)


What you have to do is take the board out, pull the two boards apart. (unscrew them) Then reseat every chip you can on both boards that is socketed. It's something to do with pin connections oxidizing and not making good contact.


Actually just pull all the boards in the back and reseat everything you can because all connections should be cleaned that way anyway just to be covered.


As long as you are careful not to bend pins and ground yourself from static you can't hurt a thing doing this all anyway. I always do this now on any ECP just to be safe. And I usually stick the boards in and out a couple times to clean the contacts on the boards edges.


You can get fancy with contact cleaner also, but I haven't ever needed it just reseating things has been enough.


If you still see a problem after all that I would be very suprised.


have fun.

Troy
 

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Discussion Starter · #10 ·
Thanks PcCinema


Basically I've done that I removed both layers cleaned all the PCB to PCB contacts and removed all the socketed IC's and cleaned the sockets and contact treated the IC pins.


At least it looks like it's on the Convergence PCB.


I'll try pulling it apart again and see what happens.


Tony
 

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Did you miss the ones that are square? You really need a chip puller for them.



Troy
 

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Discussion Starter · #12 ·
Thanks Troy


Yes I pulled every socketed IC out, including the square ones (I've got a IC puller. I'm an electronics tech.).

When I pulled out the IC's I sprayed some contact cleaner on the IC sockets and contact treated the IC pins. I also cleaned the PCB to PCB connecting pins and the edge connector where it goes into the mother PCB.


Plus yesterday I measured the continuity between the top of the pins of most of the socketed IC's to the soldering underneath.

Then for good measure I re-soldered every pin on the bottom of the lower PC & every pin on the bottom of the top PCB green channel - still the same problem.


I was sort of convinced that the problem was also on the red but it is so hard to see if it is there are not.

I've got a very old version of the convergence PCB which was only a single PCB with a smaller piggy-back board but I think the last time I tried it the PJ would not lock to anything.

I'm thinking that I would have to put a copy of the older software in the PJ before it would work. I might have an older version of the software somewhere I've just got to find it.

I re-tried the remote control PCB again but it makes not difference to the problem. I even tried some different scan rates but the problem stays the same.

I'll just have to keep looking.


Tony
 

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Im just tossing the idea out there, but perhaps one of the power supplies is not stable? Mayb Tim will chime in if he sees this thread...


--Kieth
 

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Looks like the kind of "banding" you get when using green convergence.


Have a check by zeroing this out, and see if your problem vanishes. It's also possible to get this on any colour if large amounts of dynamic covergence are being used.


If this is your problem (and it could well be almost anything else!) then from what I remember the only cure is to update your software ( to a version which has interpolated convergence) (and this may involve several board changes depending on the vintage of the machine...)


What version of software are you running?


Good luck
 

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RUN! IT IS A TORNADO IN YOUR THEATER!


(sorry for the outburst) I typically stick to the barco posts. I'll go back and annoy the barco people..... :)
 

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Discussion Starter · #16 ·
Sorry Glankford we have Cyclone's in Australia that rotate clockwise so it can't be a Tornado.


Thanks Telecine it isn't banding, I installed another remote control card did a full reset which should have zeroed any green convergence, did no adjustments and I could still see the problem. Thanks for trying.


Kieth - you might be looking good. I've got a replacement Low voltage power supply if I'm running out of ideas. I might have to try it.


I've also now ruled out the convergence PCB.

I had a very old version with one main PCB and a smaller piggy-back.

This PCB wouldn't work with the latest version of the software.

Luckily I also had an old remote control (1986) and video control PCB which would work with this older Convergence board.

Well after installing these I've still got the same problem!!.


So I've now replaced:

Remote control

Horz deflection

Vert deflection

Waveform

Convergence

Video Control

Neck board


That's basically every board along the back except the input PCB.

So I decided to have a look at the input PCB.

I tried it in the 2 slots it didn't help.

I found an old video decoder input board.

Installed that, feed it with a S-Video signal but could not see the problem. I'm not sure if it was because the scan lines are so noticeable or maybe the problem isn't there, but it didn't distort the lines in the top like my picture shows?

I tried different input resolutions from 480P to 840P but no difference.


I've found an old 4 input (RGB composite sync) with just relays, no sync processing like the other input PCB I have, and I'll try that tonight and see if that helps.


I 'm still open for suggestions, but I must admit I'm running out of things to swap.


Tony
 

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Tony


Try unplugging the green convergence yoke molex; I bet it clears the problem; I think I have an ECP convergence module here for cheep......
 

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Discussion Starter · #18 ·
Thanks Tim

Are you talking about the Molex connectors at the front of the 3 x Power Deflection PCB's that reverse the deflection?


If you are I'll give them I try.

Anythings worth trying at the moment.


Tony
 
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