CurtPalme.com Home Theater sales, calibration, service, and discussion forum. Hundreds of free manuals & setup tips.
   


 
Sign up and receive the latest newsletters by email!     Join the Forum discussions!    
    Site Map  
Home Products
For Sale
Referral
List
Photo
Gallery
Links Contact
Us
CRT Primer
Troubleshooting Tips
Mounting Methods
Definitive CRT
Projector Setup Guide
Tube/Raster Setup
Tube Condition (Wear)
Projector
Specifications
Projector Rankings
Video Processors
Ampro 1500/2000
Ampro 2300/2600
Ampro 3600/4600
Barco (Older Analog)
Barco 70x/Cine7  
Barco 500/800/801
Barco 808/Cine8
Barco 120x/Cine9
Dwin 500/700
Electrohome ECP 
Electrohome Marquee 
Mitsubishi
NEC PG
NEC XG
Panasonic 108x
Runco
Seleco
Sony 10xx
Sony 125x/127x
Sony 1292
Sony D50
Sony G70
Sony G90
Zenith 841/851
Zenith 895/900
Zenith 1200

Marquee Maintenance & Improvements
(by Mike Parker)

  (Page 7)

Back to Advanced Procedures Index

Page: 1 2 3 4 5 6 7 8 9 10 11
 

 



 

4. VIM

There are three types of VIM boards:

• 50-2005-03P
• 50-2035-02P
• 50-2023-03P

The boards above are listed in chronological order. 50-2035-02P board is a later version than 50-2005-03P. It has a wider bandwidth video chain. It also has the blue gamma chip (U22) some of the early 8000 VIM’s did not have the gamma circuit. There are several other technical differences, and they were mostly added for higher scan rate use (super computer presentation), and may not have any benefit for HT. Older boards use H1100 op-amps, but if you like the high band go with the CLC449's.

Early version 8000's did not have the blue gamma circuit on the VIM. It was included on all of the later models. That circuit is a simple op amp, and maybe we can add it to the boards that does not have the circuit, I'm sure someone could make that little circuit and make it available, it'll be quite easy to install.

The same IC's on the neck board (U2) could be found on the VIM. You should look for the same chips (CLC409, H1100, CLC449). The same upgrade applies here on the VIM. The only difference would be that the CLC409 may not cause smearing if on the VIM, you would more likely have a problem getting a very clean resolution pattern, or the image would suffer from a weakness in detail, either way, it could have a noticeable effect on the image. If the neck boards tested ok, or have been corrected, you'll now need to perform a visual check for that IC (CLC409) on the VIM, it's much easier to get to than the chips on the neck boards.

These pictures show the offending op-amps removed. U1, U4, U5, U35, U37 and U42 and replaced with the new chips:



Next, you'll want to re-solder the mini RCA jack's on the PC board. And clean both sides of the VIM with denatured alcohol and a tooth brush.

I'll throw in a mod:

The first thing that we'll do on this board (after the chip upgrade) is a Sync Mod. This is the removal of the sync circuit from the green input (sync on green), this is very important especially if using component to RGB conversion, because that could cause TRI- level sync on the BNC's (composite sync on all three BNC's). The problem that this could create is that you could have sync on all five BNC's. That's not a problem for the Red and Blue, but by having this signal on both the 'H' and 'V' BNC's to include the green BNC can confuse the auto sync detect circuit that automatically detects what type of sync that's being feed to the projector. The auto detect circuit looks for sync on the following: separate sync on 'H' and 'V' BNC's, composite sync on green BNC, composite sync on 'H' BNC. This circuit worked fine before component sync conversion came along possibly placing sync on all five BNC's.

This is a simple fix, remove R152 (it should be located about 1" from the blue relays) on the VIM module. By removing that resistor, you remove the sync circuit from the green BNC. There is presently no present modern application for sync on green (that I know of), especially for HT use.

See the top part of the image below for a picture of a VIM. The upper part shows "U22", but the RGB jacks are straight. This VIM is laid out different compared to the previous VIM. This VIM has the gamma circuit.


The lower picture shows R152, this is the resistor to be removed to do away with sync on green. Take the resistor (200 ohm with marking 201) out.




... Previous Page

Next Page ...


 

© Copyright CurtPalme.com. All Rights Reserved.