[TechAssist] Re: Testing Flybacks
- From: "Technotronic Dimensions" <steve@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 19 May 2004 17:59:47 -0400
I agree that they are Identical in basic Design.
If you notice, there is usually no internal Capacitor Depicted in the
Diagrams of Flybacks in the Schematics provided by the Mfr. I understand the
CRT actually acts as a Capacitor. But also there is suppose to be an
internal Capacitor from Anode to FBT Gnd in every FBT. I believe the Value
is anywhere from 9-16 nF depending on the CRT Size. In alot of Cases in
Monitor Flybacks, the internal Capacitor Opens up....and the result is a
lour Crackly / arcing noise on startup usually accompanied by shutdown.
Some Older Projo's by Sanyo have the rectifier Diodes in the HV Block
instead of the Flyback....as Well as the Internal Capacitor and Bleeder
resistor which is several hundred megohms in value.
I believe the Diodes Used in the Flybacks or the Blocks will not be able to
be tested with a Bench DMM because its unable to break the Junction due to
the low Voltage and test Current they produce. Probably easier on a curve
Tracer or Huntron Tracker where you can increase the applied Voltage and
monitor the "knee".
Steve Hearns
Technotronic Dimensions, NY [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1-877-817-9885 (Voice / Fax Toll Free - US Only)
----- Original Message -----
From: "Ron Miller d.b.a. Country TV" <rlmbkm@xxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, May 19, 2004 5:28 PM
Subject: [TechAssist] Re: Testing Flybacks
The same test is valid on TV IHVTs.Zenith flybacks are natures for this type
of failure.
Country TV
Ron Miller
Inez, TX. 77968
----- Original Message -----
From: "Kevin" <kevintv@xxxxxxx>
To: "TECH-ASSIST" <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, May 19, 2004 3:21 PM
Subject: [TechAssist] Testing Flybacks
> I learned on tech-assist that if a flyback from a computer monitor rings
> 'good', but you suspect it is still bad, you can measure from anode to
> ground and if there is any ohms reading at all, the diodes inside are
> shorted. What if these diodes go open? How does it read then? Does
> this test also apply to flybacks for TV's? I have found many bad
> computer monitor flybacks, but no bad TV flybacks this way. Are
> computer monitor flybacks designed differently from TV flybacks?
> Thanks.
>
> Kevin Wilks
> Kevin's TV & Video Repair
> Penticton BC Canada
> kevintv@xxxxxxx
>
>
>
>
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