Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 9
Default hv sparking problem

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?

  #5   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 9
Default hv sparking problem

I cleaned the anode cap and the tube where it attaches. I experimented
a little more and found that the sparking happens when the horizontal
half of the yolk is connected, but using the horizontal section from
another yolk, I get a dot in the middle of the screen, so the tube
works at least a bit. Can I assume that if i get a dot, then the tube
is fine or could there still be a problem with the tube?

could a problem in the ABL circuit cause these results? I suspect
there may be one because I found some blown resistors.

wrote:
Ancient_Hacker wrote:
wrote:

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?


Bad CRT? Air in CRT?


I dont know what specifically you cleaned, but I know that any arcing
converts anything present to carbon, and any cleanup has to be very
thorough indeed to work.

If youve replaced the EHT wire/rubber cap and cleaned everything
immaculately, the only remaining culprit would be the CRT, if thats
where the sound is coming from. Dont think I've encountered a tube
doing that before, but if it is, it is.


NT




  #7   Report Post  
Posted to sci.electronics.repair
Art Art is offline
external usenet poster
 
Posts: 195
Default hv sparking problem

??Have you checked the operating B+ voltage, and the HV ?? Check the inside
of the anode cup to see if there are any carbon tracks that have built up,
if so you may need to replace the actual suction cup assembly for another
fly, such as the original one. Is the number on the new flyback the same as
the original? Does the neck of the CRT glow a strange bluish colour when
the arcing occurs?
wrote in message
oups.com...
definatly coming from under the cap. Is it possible the HV is WAY to
high? if so and I manage to seal it, would this cause problems?


JW wrote:
On 21 Aug 2006 22:39:29 -0700 wrote in Message id:
.com:

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?


Power up the monitor while in the dark - you should then be able to
locate
where the arc is occurring from and work from there. If it's coming from
where the cap meets the tube, try using RTV to seal the connection.




  #8   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 107
Default hv sparking problem

writes:

definatly coming from under the cap. Is it possible the HV is WAY to
high? if so and I manage to seal it, would this cause problems?


Of course it can do harm to you and the TV.

But first clean the area again and lift the rubber suction cap away from
the tube so that any carbon tracks on it aren't an issue. See if it powers
up without sparks.

--- sam | Sci.Electronics.Repair FAQ:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


JW wrote:
On 21 Aug 2006 22:39:29 -0700 wrote in Message id:
.com:

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?


Power up the monitor while in the dark - you should then be able to locate
where the arc is occurring from and work from there. If it's coming from
where the cap meets the tube, try using RTV to seal the connection.

Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hot water furnace problem. Fred Home Ownership 1 February 9th 06 10:38 PM
Hot water furnace problem. Fred Home Repair 3 February 8th 06 02:26 AM
SONY 35" Dual PIP -Video Blackout Problem papo Electronics Repair 20 February 28th 05 09:46 PM
Widespread problem with HP Omnibook XE3-GFs? Joe Electronics Repair 1 November 21st 04 05:32 AM
Problem with retrace lines on EIZO F55S... [email protected] Electronics Repair 2 October 20th 03 01:29 AM


All times are GMT +1. The time now is 04:05 PM.

Powered by vBulletin® Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
Copyright 2004-2023 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"