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!

HUM from NEC PG 9Xtra PSU

 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors
View previous topic :: View next topic  
Author Message
[Frankie]



Joined: 16 Jun 2014
Posts: 86
Location: Italia


PostLink    Posted: Sat Sep 15, 2018 5:56 am    Post subject: HUM from NEC PG 9Xtra PSU Reply with quote


        Register to remove this ad. It's free!
Hi! I've got a problem with my NEC 9PG Xtra. It works all fine except when i calibrate the keystone on the green tube. from -100% to like 0% of the bar of Keystone is all fine. Then when i go from 0% to 100% the psu produce a strong hum that modulates with the increase of Keystone. Some of you know what the problem could be? Maybe some caps on the psu? Thanks in advance!

Another minor problem is that i can get the BOW/PINCUSHION right. The angles and the picture in general are too convex.Does It might depend on that HUM too?
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2641
Location: Budapest, Hungary


PostLink    Posted: Sat Sep 15, 2018 10:17 am    Post subject: Reply with quote

There is a capacitor on the DEF board a 47uF 200V one if you swap it to a high quality 470uF capacitor the hum should go away.
As for pincushion, double check if all connectors and setting are confogured according to the projector's position

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 23695
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Wed Sep 19, 2018 11:06 pm    Post subject: Reply with quote

If you don't have enough pin and key range, check the positioning of the convergence board jumpers. If they are backwards, then you'll get that. Check the manual as gjaky says.
Back to top
[Frankie]



Joined: 16 Jun 2014
Posts: 86
Location: Italia


PostLink    Posted: Fri Sep 21, 2018 8:32 am    Post subject: Reply with quote

Thanks for the replies! Ok, i've swapped the capacitor with a new one but with the same capacity (47uF) and the hum is decreased a lot. Today i will go to buy the 470uF 200V capacitor. For the BOW/PINCUSHION i've managed to invert the convergence jumpers for a ceiling front position. Now the Projector is fully calibrated and deliver an awesome image.

I wanted to ask another thing: if i want to build an hushbox, Do the ceiling will keep both the weight of the projector (a NEC PG9Xtra) and the weight of the hushbox? THe ceiling is made of hollow bricks and i've attacched the projector with 4 expanding bolts. The weight of the Projector is 56 Kg and on the instructions of the bolts it says that they can keep a weight of 45 Kg per bolt. So it should be like 15 kg on every bolt, right? To you what should i do? Is it better to assure the projector with other bolts or i should go safe adding also an hushbox?

Thanks for any reply!
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2641
Location: Budapest, Hungary


PostLink    Posted: Fri Sep 21, 2018 9:51 am    Post subject: Reply with quote

The original capacitor is a special one with very high "ripple-current" capability, exactly what is needed for the horizontal deflection circuits. That is why that capacitor is so big compared to its capacitance. Changing that capacitor to a similar value will only make things worse, only try high quality capacitor, like Nichicon UCY series for example.
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
[Frankie]



Joined: 16 Jun 2014
Posts: 86
Location: Italia


PostLink    Posted: Sat Sep 22, 2018 7:19 am    Post subject: Reply with quote

gjaky wrote:
The original capacitor is a special one with very high "ripple-current" capability, exactly what is needed for the horizontal deflection circuits. That is why that capacitor is so big compared to its capacitance. Changing that capacitor to a similar value will only make things worse, only try high quality capacitor, like Nichicon UCY series for example.


Actually changing the capacitor has decreased the hum a lot. The "special" one you said probably was only very old and defective.

_________________
90' Kid
Back to top
gjaky



Joined: 05 Jun 2010
Posts: 2641
Location: Budapest, Hungary


PostLink    Posted: Sat Sep 22, 2018 6:18 pm    Post subject: Reply with quote

The audible hum may decrease but not for good, the capacitor will die prematurely, that's why you need a bigger cap.
The hum is the result for the capacitor being able to supply high peak currents that eventually leads to audible noise, a simple 47 uF cap will fail to supply those currents hence the silence, using a bigger cap on the other hand will ease the peak current requirement, but it is up to you in the end.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors All times are GMT
Page 1 of 1
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