[TechAssist] flyback tested good but was bad--test equipment
- From: Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Sat, 02 Apr 2005 07:11:01 -0600
I consider myself a test-equipment junkie. I love different pieces of
test equipment.
The "thing" about test equipment is that it tests "something". Is it
testing the correct thing?
A flyback can have a shorted HV diode. Will a ringer test catch that?
A cap can be shorted. Will an ESR meter catch that? If the capacity
changed and the ESR stayed low, would an ESR meter catch it?
As for testing flybacks, I use a Digital Storage Oscilloscope with a
100x probe. If the set tries to come on the scope will capture the
horizontal output wave form. That will show severe distortion pointing to
1 a defective yoke Unplug the yoke and try again. If the distortion
goes away the yoke is bad.
2 a defective hv splitter. Unplug the HV lead and see if the distortion
goes away.
3 a defective flyback.
In the event that a timing cap or other part in the HV section is bad it
loads the circuit without distorting the pulse.
Wayne Vanaman
Omega Electronics
6904 W Fairfield Dr
Pensacola, Fl. 32506-3310
Wayne@xxxxxxxxxxxxxxxxxxxxx
WWW.PensacolaTVRepair.Com
850-456-5995 voice
850-458-6369 fax
Paul wrote:
> Hi Kevin
> Isn't that a sad commentary? What the ------ can you depend on? The test
> equipment ? Sometimes. The parts? sometimes. The Mfg? Hardly ever. What a
> great business ! If it wasn't so lucrative I would get out.
> Paul
> Kevin <kevintv@xxxxxxx> wrote:
> The HOT shorted instantly at turn on. All the timing caps, P/S caps, B+
> and horizontal frequency tested good. The flyback tested good with the
> ring test, and the HR Diemens tester which tests the diodes and HV out.
> I finally subbed the flyback out with a known good one and the set
> worked. My question is how could the flyback test good 2 different ways
> and still be bad? I guess the final and best test is substitution.
>
> Kevin Wilks
> Kevin's TV & Video Repair
> Penticton BC Canada
> kevintv@xxxxxxx
>
>
>
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> Paul ,B
> Central TV&Video
> 911W Grand Ave
> Grover Beach Ca.
> (805)481-8084
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