[TechAssist] Re: citizen model JCTV2704 chassis M3L523S
- From: Alvin Rose <ajroseca@xxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 05 Aug 2004 16:25:32 -0700
Hi Edward
I received this email from you in reference to the jctv2704 tv
and I am not sure what it means..Can you explain..
Regards
Alvin
Edward Gaidies wrote:
>More then I wanted to know.;-)
>Only Bob and I are allowed to talk dirty, as such.
>Interesting..though.;-)
>
>-Ed-
>On Aug 4, 2004, at 11:50 PM, Damon wrote:
>
>
>
>>Ooops, when you stated base waveform, I thought you meant base as in
>>"baseline".....( I rarely check base waveforms), normally they look
>>like a
>>"raggy" square wave anyways.....
>>
>>However the collector waveform should be a smooth pulse, about 12uS
>>wide,
>>anywhere from 1000V to 1100V max on most TVs, probably 80% ride right
>>around
>>1050V.
>>
>>The caps can induce a raggy looking collector pulse or heat up a
>>transistor
>>pretty fast if it's nearly open.....partly open/low value can cause it
>>to
>>fail like yours is. That 12uS pulse width can point to the problem
>>too......more than 12us generally indicates bad IHVT/leaky cap (lowered
>>voltage too), less than 11uS would show opening caps.....so the 12uS
>>check
>>is another tool in our toolbox...
>>
>>Damon Brunger
>>Telrad Electronic Services
>>Ft Wayne, IN 46815
>>----- Original Message -----
>>From: "Alvin Rose" <ajroseca@xxxxxxxxxxxxxxx>
>>To: <techassist@xxxxxxxxxxxxx>
>>Sent: Wednesday, August 04, 2004 9:18 PM
>>Subject: [TechAssist] Re: citizen model JCTV2704 chassis M3L523S
>>
>>
>>| Hi Damon
>>| I will check the capacitors in the collector circuit
>>| and the divider ladder in the pincusion circuit..the waveform
>>| I referred to was on the output transistor Base lead
>>| would this effect the input to the base lead.
>>| Alvin
>>|
>>| Damon wrote:
>>|
>>| >You have open or off-value high voltage caps on the collector, you
>>may
>>also
>>| >find bad caps in the pincushion's "divider ladder" . The spikes and
>>"square
>>| >wave" effect are the indicators.
>>| >
>>| >Damon Brunger
>>| >Telrad Electronic Services
>>| >Ft Wayne, IN 46815
>>| >----- Original Message -----
>>| >From: "Alvin Rose" <ajroseca@xxxxxxxxxxxxxxx>
>>| >To: <techassist@xxxxxxxxxxxxx>
>>| >Sent: Monday, August 02, 2004 9:40 PM
>>| >Subject: [TechAssist] citizen model JCTV2704 chassis M3L523S
>>| >
>>| >
>>| >| Hi Guys
>>| >| we have a citizen tv which is shorting the horrizontal output
>>| >| transistor..Have replaced it twice..Set will run for half an hour
>>| >| and then will short the transistor..Scoped the collector and
>>there is
>>no
>>| >| saddle in the waveform but a small amount of ringing on the
>>reference
>>| >line.
>>| >| The base waveform looks like a modified square wave with a number
>>of
>>| >| high spikes at the start and finish of the waveform..I replaced
>>the 22
>>mfd
>>| >| electrolytic in the primary of the driver transformer with no
>>improvement.
>>| >| Driver transister tests ok..Had anyone had this problem with this
>>model
>>| >| Your help is appreciated
>>| >| Alvin Rose
>>| >| Radio & Tv Centre
>>| >| Marystown, Nl
>>| >|
>>| >|
>>| >|
>>| >|
>>|
>>
>>
>>>|
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>Tel-Tek Electronics
>Ontario-Canada
>
>teltek3@xxxxxxxxxxxx
>
>
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