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

  • From: "jonas miglinas" <miglinasj@xxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Thu, 24 Jul 2003 19:36:22 -0500

To eliminate one circuit as being the culprit, pull the plug from the audio
board. I believe its J/P1906 or 1904(not at the shop). Then see if it fires
up.

Jonas Miglinas
Miglinas TV
Chicago
----- Original Message -----
From: "Larry E." <videotech@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, July 24, 2003 6:56 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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