Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Solid State CRT Televisions

Notices

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 02-06-2022, 12:02 PM
AlanInSitges's Avatar
AlanInSitges AlanInSitges is offline
VideoKarma Member
 
Join Date: Nov 2017
Location: Sitges, Catalonia, Spain
Posts: 451
Quote:
Originally Posted by zeno View Post
The trouble makers are the hoz output. Its called a gate controlled switch.
They are marked SG-### and are on a heat sink on the HV board.
It takes nothing to blow one & some other parts. Finding the actual
cause is sometimes imposable. When I was at Sony service they would
often change the whole HV board to get one right. That was the mid 70's
and almost nobody would touch one. Those that did charged $125 + parts
sometimes the bill went over $200, a lot back then.

73 Zeno
LFOD !
A while back Shango had one of these that kept eating all of the semiconductors in the HO section. After lots of back and forth he tracked it down to a broken - what do you call it, wire? bracket? clamp? - through the flyback core. I can't remember the whole reason this caused it to happen; it was a really complicated circuit.
Reply With Quote
  #2  
Old 02-06-2022, 02:05 PM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,918
Watched that & communicated with him. It was a broken U-bolt on the FBT.
Holds the ferrite core halves together. Without it the resonant freq goes off
& you would see garbage on the drain of the SG. Normal wave form would be one big clean spike. Normal transistors in Hoz out can also instant destruct &
sometimes cause a chain reaction BUT most the time there are easy ways to
fix them. The real bad ones were the 17" sets with the controls along the bottom. At the time they were the BEST you could get. The first runs had TWO SG-613's one for hoz out & one in the power supply. A nightmare.
So to Shangos set. Cost was the big thing In the day SG-613 = $25,
OEM damper $8, OEM 2SC867 $12. Add a C-note for labor. A few weeks
later the customer hears a click & everything is blown again. You
have to eat the SG613 as Sony WILL NOT warranty them ( along with
video heads, some clocks & other things).

Nuff fer now, always a pleasure Alan.
LFOD !


Quote:
Originally Posted by AlanInSitges View Post
A while back Shango had one of these that kept eating all of the semiconductors in the HO section. After lots of back and forth he tracked it down to a broken - what do you call it, wire? bracket? clamp? - through the flyback core. I can't remember the whole reason this caused it to happen; it was a really complicated circuit.
Reply With Quote
Reply


Thread Tools
Display Modes

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

Forum Jump


All times are GMT -5. The time now is 08:57 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2026, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.