[TechAssist] Re: Sony TV KV24FV10, no start- just chirping
- From: "Technotronic Dimensions" <steve@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 25 Jun 2004 10:04:55 -0400
Not Sure if this will help, but if you have a Cap Checker like a Sencore
that you can apply a few hundred Volts with to the Anode to FBT Gnd (out of
Circuit) , measure the Capacitance there. All Flybacks Have an Internal
Capacitor that ought to not change in value. For Monitors , the Value is
suppose to be like 3-10 nF. I am just starting to get into measuring this in
TV Flybacks, and so far it looks like its suppose to be larger, like perhaps
2-5 pF on a good TV FBT for say a 20 Inch set.
I just had one Yesterday where I could see the Value Change on the Sencore
as I applied heat to the left Side of the FBT's Focus / G2 Pots. The Value
went down from 1.5 - 2 pF to like 0.5 pF as soon as the heat hit it.
Likewise, the Problem in the TV Would lessen when I decreased the G2 Pot.
Not sure if that is something you can try there, but when the Internal Cap
opens up in Flybacks, you get a variety of unusual problems. The One I found
Yesterday seemed to Cause Acoustic Noises to eminate from the FBT, much like
a Speaker Coil would do, (have seen this once before on a Monitor FBT) and
the sound would be reflected as Distortion in the Picture. Of Course,
depending on the severity of your problem, I suppose if the FBT had an open
Cap, or possibly even a shorted Rectifier Diode in the Secondary, it would
activate the ABL Protect, and merely shut down the set. Let us know how you
make out.
Steve Hearns
Technotronic Dimensions, NY [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1-877-817-9885 (Voice / Fax Toll Free - US Only)
----- Original Message -----
From: "Shoreline Electronics" <jstielau@xxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, June 25, 2004 9:46 AM
Subject: [TechAssist] Re: Sony TV KV24FV10, no start- just chirping
Lift the collector lead and see if the B+ is good .
Scope the collector when the set is pulsing....is the waveform clean or
ringing?
If the latter , the flyback is prob defective.....no matter what the HR
ringer says.
==========================
Jeff Stielau
Shoreline Electronics Repair
344 East Main Street
Clinton,CT 06413
860-399-1861
860-664-3535 (fax)
jstielau@xxxxxxxx
========================
"If you push something hard enough it will fall over."
Fudd's First Law of Opposition - Sir Sidney Fudd
----- Original Message -----
From: "peggs" <peggs@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>; <techassist@xxxxxxxxxxxxx>
Sent: Friday, June 25, 2004 11:47 AM
Subject: [TechAssist] Re: Sony TV KV24FV10, no start- just chirping
> 39v on the HOT shouldn't be right.
> Either it's being pulled down(HV,Pix Tube,yoke,secondary Rectifiers)
> or it can't handle a load(Power Supply)
>
> Peggs
>
> At 12:25 PM 6/24/04, Gary McCartney wrote:
> >I have a Sony 24" KV24FV10 flat CRT set in the shop. The set doesn't
> >start up. It just chirps continuously. On the odd occasion, the sound
> >will come on for maybe 3 seconds then the power simply turns off. The
> >waveforms on the HOT base and collctor are also pulsing but don't look
> >proper. I get 39V dc on the HOT collector as it pulses.
> >
> >I have removed the flyback and tested it with my HR Diemen flyback
> >tester and I get a perfect looking collector waveform with it. Tester
> >shows flyback to be working fine (those not familiar, this tester
> >actually connects the anode lead and drives the flyback just like the TV
> >hor. output stage, although at a reduced test rate. I haven't had this
> >tester fail me yet). I have also soldered the hor. driver transformer
> >and other connections on main board and power supply board. Have checked
> >for bad transistors diodes and resistors as well. I downloaded the
> >manual and am looking it over now.
> >
> >Are there any common faults for these symptoms? I've read that the
> >flyback is a possibility but with my test, I'm not sure what to make of
> >that.
> >
> >Thanks for any help.
> >--
> >
> >
> >
> >
> >Gary McCartney
> >
> >McCartney Electronics
> >Guelph Ontario Canada
> >Est. 1984
> >email: gary (at) number63.ca
> >
> >
>
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