[TechAssist] Re: RCA-CTC169AM,chass-f31221wn-32''

  • From: <hartstv@xxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Fri, 25 Jul 2003 11:56:54 -0300

Tks for your reply Al;Yes I reinstalled the 15ufd,checked the 3v zener &
every resistor in the p/s.Voltages on the chopper Q4101 are ;
E=varies from +0.0 to +0.032vdc
B=varies from --0.023 to --0.32vdc[this should be --2vdc]
C=varies from +165 to + 169.5vdc
These are STBY volts & HOT removed.All the voltages in this p/s are varying
up/down .I can hear a low pitch buzz motor boating when set is plugged
in.Replaced U4101so many times I installed it on a socket.?????
Don of HARTS-TVCR-ASC
9 Robert St,Oromocto,NB,Canada,E2V3N2
Tel-506-357-9785,Fax-506-357-6010
hartstv@xxxxxxxxxxx



----- Original Message -----
From: "al m" <ampm@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, July 25, 2003 10:00 AM
Subject: [TechAssist] Re: RCA-CTC169AM,chass-f31221wn-32''


> Put the 15Mf back in if it was original. Did you check the resistors in
the
> power supply, and the 3V Zener?
> al marquardt
> ampm@xxxxxxx
> Al Marquardt Electronic Repair
> 206 W Main
> Girardville Pa. 17935
> ----- Original Message -----
> From: <hartstv@xxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, July 24, 2003 8:59 PM
> Subject: [TechAssist] Re: RCA-CTC169AM,chass-f31221wn-32''
>
>
> > Tks for your reply,Larry.Here are the values of the orginal caps removed
> > from the smps;
> > C4102=2.2ufd/100v
> > C4104=15ufd/50v
> > C4108=47ufd/50v
> > The voltage at Q4101 is varying from 159vdc to 164vdc.
> > The voltage on the collector pad of the HOT Q4401 is varying from 13vdc
to
> > 40vdc;NOTE this is without the collector of HOT connected to pad & yes
I'm
> > using the correct grounds.
> > Pin 3 of U4101 is varying from 0vdc to .013vdc.
> > I know there are hot & cold grounds for these measurements.The HOT
> collector
> > voltage is low because the chopper is not in it's proper duty cycle.This
> is
> > the same voltage measured at the cathode of CR4116,the 145vdc source.
> > I did replace C4104 with a 4.7/100v cap,as per your email but have same
> > voltage readings.What I don't understand is the orginal cap was
> > 15ufd/50v.Man this is wierd?? Tks again for your help...regards...
> > Don of HARTS-TVCR-ASC
> > 9 Robert St,Oromocto,NB,Canada,E2V3N2
> > Tel-506-357-9785,Fax-506-357-6010
> > hartstv@xxxxxxxxxxx
> >
> >
> >
> > ----- Original Message -----
> > From: "Larry E." <videotech@xxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Thursday, July 24, 2003 8:56 PM
> > Subject: [TechAssist] Re: RCA-CTC169AM,chass-f31221wn-32''
> >
> >
> > > Hi Don, you need to be carefull changing parts in a 169 chassis with a
> pa=
> > > rts list from a 27" proscan, there are 4 different families of 169
> chassi=
> > > s`s and some of the parts
> > > are very different, for example C4108 in your set (family 1) is
supposed
> =
> > > to be a
> > > 47uf @ 50 volts but in a family 4 169 it`s a 39uf @ 100v,  BIG
> difference=
> > > =2E
> > > The usual cause of pin 16 on U4101 fluctuating up and down is the 3
caps
> =
> > > you changed, or U4101 is bad check the values, C4102=3D 2.2 @ 100v
> C410=
> > > 4=3D 4.7 @ 100v(not 47uf)  C4108=3D 47uf @ 50v. If those are good then
> th=
> > > e set is either in ovp or ocp You should have the following in standby
> (s=
> > > et plugged in but not turned on), Raw B+ on C of Q4101 =3D approx. 165
> vo=
> > > lts, Regulated B+ on C of HOT=3D approx.144 volts, 5v standby on E of
> Q46=
> > > 01. If the above are correct, check voltage on pin 3 of U4101, it
> shouldn=
> > > `t be above .6v (point 6 volts) if it is the
> > > set is going into ocp shutdown. Let me know the results of these
> measurem=
> > > ents,
> > > I don`t have a scanner but I do have the schematics and 169
> troubleshooti=
> > > ng guide.
> > > Remember that a lot of the capacitor values are different for the
> various=
> > >  169 models
> > > so be careful to replace what you pull out with the same value, Larry
E
> > > Larry Eastman
> > > American TV & Electronics
> > > Crystal River, Fl. 34428
> > > 352-795-0124
> > > pulling out
> > > hartstv@xxxxxxxxxxx wrote:
> > >
> > > > This direct view 32'' unit has me baffeled.Orginally came in with
the
> H=
> > > OT shorted.Replaced with an OEM 2SD1885.Everything else was ok so
fired
> i=
> > > t up.The HV was 38.5KV,too hi,so took the chass out to bench
test.Turned
> =
> > > it on without a yoke plugged in & I think that's when my problems
> started=
> > > =2EQ4802 smoked in the pin cct.Replaced it & plugged a yoke to the
> set.No=
> > > w my smps won't start.Pin 16 reads 8.5vdc then slowly goes up to
10.5vdc
> =
> > > & then starts going back down to 8.5v.So changed all the normal parts
> for=
> > >  this smps,ie,the U4101,C4102,4,8,Q4101.Did not help.Replaced the
> infamou=
> > > s CR4118.Checked or replaced both LM311 in the vert & pin cct;also
> C4403,=
> > > CR4401,CR4402.Again no go.Checked or replaced all trans in the PWM
> cct,Q4=
> > > 405,6,7,8,9.Same results;the regulator is trying to start but keeps
> going=
> > >  up/down from 8.5v to 10.5v.Raw B+ is solid at 165vdc,no ripple.All
> these=
> > >  tests were done with HOT collector lifted.I have checked all my tips
> for=
> > >  this unit,& I know there's a ton of them but
> > > >   can't find the problem.I have changed so many parts too numereous
to
> =
> > > mention,ie caps,diodes,transistors but I'm stumped.Any assistance
would
> b=
> > > e greatly appreciated or if someone would be so kind to email a pdf
for
> t=
> > > his brute.The only print I have is a profax for the 27'' set.BTY i
also
> c=
> > > hecked all transistors in the Q4300 & Q4700
> series.........TIA...........=
> > > =2E
> > > > Don of HARTS-TVCR-ASC
> > > > 9 Robert St,Oromocto,NB,Canada,E2V3N2
> > > > Tel-506-357-9785,Fax-506-357-6010
> > > > hartstv@xxxxxxxxxxx
> > > >
> > > >
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