View Single Post
  #5   Report Post  
Posted to sci.electronics.repair
Ian Field Ian Field is offline
external usenet poster
 
Posts: 1,405
Default Substitutes for this TV thermistor?


"klem kedidelhopper" wrote in message
...
On May 17, 10:47 am, "Ian Field"
wrote:
"Franc Zabkar" wrote in message

...

On Wed, 16 May 2012 06:29:55 -0700 (PDT), Goldfish
put finger to keyboard and composed:


Hello
I need a replacement for this thermistor, here are the markings:
T(thunder symbol)9
MZ73BLL
9RM


Data sheet (see page 7):
http://www.ancol.cn/upload/20078316361776520.pdf


That looks like a typical 9 ohm degaussing resistor. Just about any
3-pin PTC degaussing resistor should do.


Er..... not quite!

The most common type has 2x PTC pellet - one of which is directly across
the
incoming mains after the switch, this heats the degauss pellet to cut off
any residual current that would cause picture shimmer.

Some makes (notably Philips) sometimes use a PTC/NTC combination - the
NTC;
as you would expect is in series with the mains to the rectifier, where it
serves the dual role of limiting inrush surge and using the current drawn
for heating to raise the PTC above residual current.

Putting a PTC/NTC combination in place of a 2x PTC is likely to result in
vapourised PCB tracks and welded switch contacts.

If you've salvaged your replacement degauss resistor from a scrap set; you
can trace the circuit before binning the board - or you can measure the
resistance of both thermistors, then heat the middle pin with the
soldering
iron for a minute or two and check that both resistances increase.


I'm sorry but I have to ask the obvious question. Why not try to get
the OEM part? Lenny
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

Might cost more than the value of an old CRT telly to do so.