[TechAssist] Re: Toshiba CF3054J,TAC8950 still vert lin troublesafter C301 & C305 repl.]
- From: Gary McCartney <number63@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Tue, 10 Sep 2002 09:20:42 -0400
I have also found that ESR is sometimes higher in capacitors rated with
higher voltages. Maybe just my ESR meter (capacitor wizzard), but thats
how they measure anyway.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
Wayne Vanaman wrote:
>
> In the military, at least in the Hi reliability circuits, the design
> requirements (specifications) are that a capacitor on a line be 2x the
> maximum possible voltage. In other words, a 5v line regulated down from 24v
> would require a 48 volt cap to be 2x24 in the event the regulator would
> short. Furthermore, the mil-spec caps require that they be able to
> withstand 24 hours at 100 centegrade at 100% OVER voltage and not change 5%.
> Which means that the cap on our theoretical 5 volt line would be rquired to
> withstand (2x24)x2, or 96 volts.
>
> The problems I see with using a higher voltage rating cap is the added
> expense of the higher voltage device, and the physical size.
>
> Wayne Vanaman
> Omega Electronics
> 6904 W Fairfield Dr
> Pensacola, Fl. 32506-3310
>
> 850-456-5995 voice
> 850-458-6369 fax
>
> Mailto:Wayne@xxxxxxxxxxxxxxxxxxxxx
> WWW.PensacolaTVRepair.Com
>
> ----- Original Message -----
> From: "Kevin" <kevinstv@xxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Monday, September 09, 2002 5:49 PM
> Subject: [TechAssist] Re: Toshiba CF3054J,TAC8950 still vert lin
> troublesafter C301 & C305 repl.]
>
> >
> > If you use a cap with, lets say a voltage of 4 times the original, you
> could
> > run into problems with the cap failing prematurly depending on the type of
> > circuit. The voltage should be the same or higher but not too much
> higher.
> > A capacitor likes to work close to its rated voltage. But, does the
> higher
> > voltage have anything to do with timing? I don't think so either. I have
> > noticed that 105 degrees C caps do have higher ESR values than 85 degrees
> C
> > ones.
> >
> > Kevin Wilks
> > Kevin's TV and Video Repair
> > Penticton BC Canada
> > kevinstv@xxxxxxx
> >
> > ----- Original Message -----
> > From: Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Monday, September 09, 2002 3:12 PM
> > Subject: [TechAssist] Re: Toshiba CF3054J,TAC8950 still vert lin
> > troublesafter C301 & C305 repl.]
> >
> >
> > >
> > > I don't believe the voltage rating has anything to do with discharge
> time.
> > > That is a factor of capacity, esr, and possibly dialectric absorbtion
> > > ("memory").
> > >
> > > Check for ANY not-black caps, I believe that most of the Toshibas, but
> not
> > > all, need three- c301, 305, 308, and sometimes the the 100uf or 220uf.
> > >
> > > Wayne Vanaman
> > > Omega Electronics
> > > 6904 W Fairfield Dr
> > > Pensacola, Fl. 32506-3310
> > >
> > > 850-456-5995 voice
> > > 850-458-6369 fax
> > >
> > > Mailto:Wayne@xxxxxxxxxxxxxxxxxxxxx
> > > WWW.PensacolaTVRepair.Com
> > >
> > >
> > > ----- Original Message -----
> > > From: "Ed Gaidies" <teltek2@xxxxxxxxxxxx>
> > > To: "TechAssist" <techassist@xxxxxxxxxxxxx>
> > > Sent: Monday, September 09, 2002 4:05 PM
> > > Subject: [TechAssist] Re: Toshiba CF3054J, TAC8950 still vert lin
> > > troublesafter C301 & C305 repl.]
> > >
> > >
> > > >
> > > > Phil......
> > > > Always....always.......C308......220ufd/35volts.
> > > > Due to the fact that these 2.2ufd/35 volts are timing
> > > capacitors.....should
> > > > never use higher than 50 volts.....discharge time is too great with a
> > > > 250volt cap. I have never tried to go higher for that
> reason,,,although
> > > you
> > > > may be lucky.
> > > > BTW...you may have to change the vertical O/P IC too.
> > > >
> > > > -Ed-
> > > > Tel-Tek Electronics
> > > > Midland, Ontario
> > > > Canada.
> > > >
> > > > teltek2@xxxxxxxxxxxx
> > > > teltek3@xxxxxxxxxxxx
> > > > teltek@xxxxxxx
> > > >
> > > > "Quality will be remembered....long after Price is forgotten"
> > > >
> > > >
> > > >
> > > > Phil Bader The above is the reply to your message dated 9/9/02
> 2:33
> > PM
> > > >
> > > > >
> > > > >
> > > > >
> > > > > 31" Toshiba TV CF3054J: Orig. symptom was very narrow vert.
> deflection
> > > > > and fold over.
> > > > > ESR'd C301 and C305, both 2.2/50V red electrolytics.Both very high,
> > > > > almost infinate ESR. Replaced both with 2.2/250v @105 deg. (all I
> > had).
> > > > > Increased vert. heigth but still narrow by 4 inches top and bottom
> > with
> > > > > a top fold over. These two caps always do it. I measured the caps
> > before
> > > > > install and are exactly 2.2 mfd. What else am I overlooking here?
> > > > > Phil Bader
> > > >
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