Marquee LVPS +-85V refinement - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 8 Old 10-14-2007, 11:36 AM - Thread Starter
Member
 
fvale's Avatar
 
Join Date: Oct 2001
Location: ITALY
Posts: 78
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'd like to replace the 3 x 100V 100uF caps in the LVPS +-85V outputs with higher quality parts (idea is to use FK series BlackGates). Do someone have already worked and tested on this?
Would it be better to higher this capacity a bit?
Can someone explain why on the +85V there are two of these caps paralleled, while on the -85V only 100uF are used?
fvale is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 10-14-2007, 01:02 PM
AVS Special Member
 
mp20748's Avatar
 
Join Date: Nov 2000
Location: Maryland
Posts: 6,339
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
This has already been discussed several times.

Those three caps should be replaced, but 105c (temp) should be the replacement caps. Do not use 85c (that's what the originals are). The 85c caps are not good for switching power supply rails, therefore they flake out. The lower temp caps were used in the supplies, and later it was found that they were not good for SMPS rails.

It's OK to go higher capacitance, but there's no reason to go with boutique caps. When going higher it would be a good idea to not go too high, because the SMPS will delay in firing up (click several times), It may see the added capacitance as a load and try try to shut down.

consider these:

- 100mf @ 160 vdc / 105c

- 100mf @ 250 vdc / 105c

- 150mf @ 160 vdc / 105c

The 100mf @ 259 vdc / 105c seems to be the best way to go, because it keeps the same load on the supply. And the higher voltage rating seems to do the same thing that would be expected from going higher capacitance.

The +85 volt rail also supplies the deflection sweep circuit drive (power mosfets), so that may explain why there's two of them on that rail. While both -85 and +85 are the supply for the neck boards

While you're at it. Also replace C50 (220mf @ 160vdc) on the HDM. And if you can, replace it with a 220mf @ 260 vdc 105c

If C50 leaks, it will not only cause width and unstable width problems, it can cause the heatsink to run hotter, as well as dump sweep noise on the +85 rail into the neck boards.

Stay away from boutique caps. Simply making sure the caps you use are 105c is all that needs to happen in these circuits.

It's all about the performance... Got Marquee!

 

High Performance Marquee Video chain modifications.  Now available!

mp20748 is offline  
post #3 of 8 Old 10-14-2007, 01:26 PM
AVS Special Member
 
nashou66's Avatar
 
Join Date: Oct 2006
Location: West Seneca, NY
Posts: 4,261
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 52
Mike would changing C50 possible help with being able to increase the width of the raster? I added the jumper to p7 on the hdm but it hasnt had any effect in increasing the widht to match my other projectors width. I have to put one projector further back with respect to my ceiling mounted PJ to get it to fill the screen.

Athanasios
nashou66 is offline  
post #4 of 8 Old 10-14-2007, 02:27 PM
AVS Special Member
 
mp20748's Avatar
 
Join Date: Nov 2000
Location: Maryland
Posts: 6,339
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
Quote:
Originally Posted by nashou66 View Post

Mike would changing C50 possible help with being able to increase the width of the raster? I added the jumper to p7 on the hdm but it hasnt had any effect in increasing the widht to match my other projectors width. I have to put one projector further back with respect to my ceiling mounted PJ to get it to fill the screen.

Athanasios


There have been times when C50 has improved on the width, but it's not something I think will happen everytime the cap is changed.

It would also be good to check the +85 volt rail. If it's below +85, it can effect the horizontal deflection range.

There's a +85 pot on the LVPS for this.

It's all about the performance... Got Marquee!

 

High Performance Marquee Video chain modifications.  Now available!

mp20748 is offline  
post #5 of 8 Old 10-14-2007, 02:51 PM
AVS Special Member
 
nashou66's Avatar
 
Join Date: Oct 2006
Location: West Seneca, NY
Posts: 4,261
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 52
Where do i check this ?

Athanasios
nashou66 is offline  
post #6 of 8 Old 10-14-2007, 08:51 PM
AVS Special Member
 
mp20748's Avatar
 
Join Date: Nov 2000
Location: Maryland
Posts: 6,339
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
Quote:
Originally Posted by nashou66 View Post

Where do i check this ?

Athanasios

If you know where the filament connector (P14) is located on the main PC board right near the blue CRT. The +85 volt feed to the board is the next pin over from P14. It is marked "+85"

It's all about the performance... Got Marquee!

 

High Performance Marquee Video chain modifications.  Now available!

mp20748 is offline  
post #7 of 8 Old 10-14-2007, 09:25 PM
AVS Special Member
 
nashou66's Avatar
 
Join Date: Oct 2006
Location: West Seneca, NY
Posts: 4,261
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 52
Yes i know it ok thanks mike!

Athanasios
nashou66 is offline  
post #8 of 8 Old 10-15-2007, 11:41 AM
WTS
AVS Special Member
 
WTS's Avatar
 
Join Date: Nov 2002
Location: Calgary
Posts: 1,769
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi fvale,

Even though the Blackgates are 85c caps don't worry about that, they'll probably last longer than most 105c rated caps, the blackgate cap are an excellent cap, use them. Like MIke said you can go higher in cap value but don't go over board.
The reason there is 2 caps on the +85 compared to 1 on the -85 is probably due to the fact that there is more current draw on the +85 so to keep the ripple down they doulbed up on the cap value.

Walter
WTS is offline  
Reply CRT Projectors

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off