Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!

BG808: changing caps for better video signal ?
Goto page 1, 2  Next
 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors
View previous topic :: View next topic  
Author Message
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Mon Feb 02, 2009 3:34 pm    Post subject: BG808: changing caps for better video signal ? Reply with quote


        Register to remove this ad. It's free!
Hi,

I know that there are different topics talking about it, but I didn't read any definitive answer.
So I am looking to improve the PQ of my BG808 (especially sharpness) and I was wondering if changing caps (by Panasonic FC for example) on the following boards, can make a difference : R7621055 and R7617481 (used for port 3).
Has anybody done that?
Cheers
Back to top
perisoft



Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY


PostLink    Posted: Mon Feb 02, 2009 4:06 pm    Post subject: Reply with quote

I haven't, but my understanding of the 808 (particularly the non-s) is that the tubes are more of a limiting factor for sharpness than the electronics - ie, the electronics can paint a sharper picture on the phosphor than the phosphor can resolve.

If the caps have deteriorated, I guess it could make a difference, but as far as I know with an 808s (with sony tubes) you're maxing out the tubes' resolving power by the time you get to the point where the electronics are an issue.

_________________
Back to top
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Mon Feb 02, 2009 4:20 pm    Post subject: Reply with quote

I am sure there is a possibility of improvement when you see all the mods available (Mike Parker, Greg Eisemann,...)
Back to top
perisoft



Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY


PostLink    Posted: Mon Feb 02, 2009 4:49 pm    Post subject: Reply with quote

Corleone88 wrote:
I am sure there is a possibility of improvement when you see all the mods available (Mike Parker, Greg Eisemann,...)


Yes, but Eisemann sells high-res tubes so you can see the difference the other mods provide. Smile

_________________
Back to top
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Wed Feb 04, 2009 8:41 am    Post subject: Reply with quote

Nobody tried changing caps on these boards Sad ?
Back to top
Ile



Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland


PostLink    Posted: Wed Feb 04, 2009 9:25 am    Post subject: Reply with quote

If input boards are high hour you might see some difference by chancing bipolar elcaps from input boards.
http://gallery.avsforum.com/showgallery.php/cat/500/ppuser/7428372

Chancing caps won't make picture sharper, there is needed to chance also transistors and modify peaking circuits etc. That is very time consuming and good test equipments is needed.

Modifying boards power lines filtering using bigger caps and inductors can make noise level lower. This is already done to 808s input board in factory.
Back to top
Z-Photo



Joined: 07 Mar 2006
Posts: 2753
Location: Huntsville - Alabama


PostLink    Posted: Fri Feb 06, 2009 11:04 am    Post subject: Reply with quote

I focused on the video amp boards and the SMPS.
_________________
Engineer by Day
Photographer by Night
My Portfolio
The Only GOOD AMPRO - is a Dead AMPRO.
wait - are they not all DEAD already?
Back to top
View user's photo album (16 photos)
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Fri Feb 06, 2009 7:45 pm    Post subject: Reply with quote

What did you change exactly in the video amp boards ? What were the results on the picture ?
Back to top
kal
Forum Administrator


Joined: 06 Mar 2006
Posts: 15646
Location: Ottawa, Canada

TV/Projector: JVC DLA-RS56


PostLink    Posted: Mon Feb 09, 2009 1:14 am    Post subject: Reply with quote

I changed a few hundred caps in my old BG800 that had about 24,000 hours on it at the time. Changing the bipolar's in the video input card did wonders for the colours. It was like a grey veil was lifted. The colours were considerably better. Didn't have a colorimeter at the time but it would have been interesting to measure the before & after primaries.

Changing the other caps (mostly the big SMPS ones) greatly improved convergence stability but it did nothing for the image quality/sharpness. In fact, caps won't help your sharpness.

Kal

_________________

Support our site by using our affiliate links. We thank you!
My basement/HT/bar/brewery build 2.0
Back to top
View user's photo album (18 photos)
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Tue Jun 30, 2009 8:16 am    Post subject: Reply with quote

I update this topics because I recently calibrated my BG808. Colors are nice, sharpness is OK, but I see some noise in the picture (1080i/24 with Lumagen HDQ + BD35 + BJC + HDFury1). So I am planning to buy used R7621055 and R7617481 boards and change the caps (with Panasonic FC) in order to reduce the noise. Is this worth it Wink?
Back to top
akajester



Joined: 09 Jul 2008
Posts: 934
Location: Wisconsin


PostLink    Posted: Tue Jun 30, 2009 12:25 pm    Post subject: Reply with quote

I screwed up one of my input boards doing that. I guess I'm just not good enough at changing caps. Only do a few at a time, and test test test!

I guess the results will depend on how bad your previous caps were. My unit has 5000+ hours on it, so not too bad. Kal had like 20k+ so it made a big difference for him.
Back to top
WTS



Joined: 08 Mar 2006
Posts: 1227
Location: Calgary


PostLink    Posted: Tue Jun 30, 2009 12:56 pm    Post subject: Reply with quote

Changing the input caps won't help the noise problem but changing the PS caps on the 2 boards might. DOn't worry about screwing up the caps, just remember to get them in polarity correct. You can go a little larger in value but try to stay close to the same voltage ratings.
_________________
Thanks
Walter
Back to top
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Tue Jun 30, 2009 1:14 pm    Post subject: Reply with quote

What are the PS caps?
What is the use of the caps on the video input boards?
Back to top
akajester



Joined: 09 Jul 2008
Posts: 934
Location: Wisconsin


PostLink    Posted: Tue Jun 30, 2009 1:32 pm    Post subject: Reply with quote

Corleone88 wrote:
What are the PS caps?
What is the use of the caps on the video input boards?


I had heard that when the caps get old on the video input board it can dull your colors. Not sure if it's true and never went back to try and repair the board to find out. Smile

Are the PS caps the power supply caps? You can find a service bulletin about that on Curts site.
Back to top
Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Tue Jun 30, 2009 1:38 pm    Post subject: Reply with quote

PS = Power supply capacitors.

The FC caps are nice(i use those) but so are the Nichicon caps that Draganm uses on the marquee boards. He has info on them in the sale area for his Marquee mods.


Athanasios

_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

One Smart Dog!!!

Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
Back to top
View user's photo album (1 photos)
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Tue Jun 30, 2009 2:04 pm    Post subject: Reply with quote

Athanasios,

After changing the PS caps, have you seen less noise in the picture?
Back to top
Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Tue Jun 30, 2009 2:08 pm    Post subject: Reply with quote

Yepp in my marquee i did.

Athanasios

_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

One Smart Dog!!!

Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
Back to top
View user's photo album (1 photos)
Corleone88



Joined: 09 Dec 2006
Posts: 396
Location: France


PostLink    Posted: Tue Jun 30, 2009 2:26 pm    Post subject: Reply with quote

How many hours on your Marquee?
My BG808 has around 12000 hours.
Back to top
Nashou66



Joined: 12 Jan 2007
Posts: 16167
Location: West Seneca NY


PostLink    Posted: Tue Jun 30, 2009 2:36 pm    Post subject: Reply with quote

way way less, you should definitly change the PS caps. I personally think any PJ older than 10 years should have all the caps replaced, but thats just me Very Happy

Athanasios

_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher


"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan

One Smart Dog!!!

Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
Back to top
View user's photo album (1 photos)
1031



Joined: 22 Mar 2006
Posts: 657
Location: Finland


PostLink    Posted: Wed Jul 01, 2009 8:35 am    Post subject: Reply with quote

Those bipolar caps that are series on rgb-lines usually are for blocking dc voltages between video stages. Ok, they work pretty good in theory. There are lines that are terminated to 75 ohm (or something else) and usually there is series resistor ( ie. 75 ohm ) and before/after there is cap (bipolar or normal ) Now caps impedance comes to play. Good cap has low impedance and that doesn't change much lines total impedance (75+ caps internal impedance) Old bipolar can have impedance near 10 Ohm at certain freq. And that cause poor impedance match between video stage´s. Good cap should have small impedance at wide freq.range, then it is good for circuits like that are used in barcos/sonys.
_________________
Marquee 9500LC (Frankenyokes / Thomas electric tubes / HD-10L / +many mod´s)
DVDO VP-50
New hobby, Rally
http://www.youtube.com/watch?v=vX2Rtpr1njs
http://www.youtube.com/watch?v=6ZP9FEFXV5c
http://www.youtube.com/watch?v=j065vei6j6s
http://www.facebook.com/pages/JTS-Racing-team/204443719572685


Last edited by 1031 on Wed Jul 01, 2009 11:23 am; edited 1 time in total
Back to top
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors All times are GMT
Goto page 1, 2  Next
Page 1 of 2
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum