[TechAssist] Re: RCA D52W20, ITC222, Convergence power supply problem

From: daryls_tv@xxxxxxx
To: techassist@xxxxxxxxxxxxx
Date: Fri, 22 Jul 2005 23:20:19 -0600
No... I don't have any schematics on this set.
I think I may have found the problem.  I have absolutly no resistance readi=
ngs between pins 3 & 4 of the opt-coupler, even on high meg scale.
I will post the results when the part comes in.
Thanks,
Daryl
Daryl's TV
2402 Wyoming Ave.
El Paso, TX  79903
915-565-9184 Voice/Fax
daryls_tv@xxxxxxx
www.angelfire.com/tv2/daryls_tv

----- Original Message -----
From: Damon <damoneb@xxxxxxxxxxx>
To: techassist@xxxxxxxxxxxxx
Subject: [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply prob=
lem
Date: Fri, 22 Jul 2005 22:20:41 -0500

>=20
> Do you have schematics? If so, one of the transistors driving or being
> driven by the optoisolator can be jumpered (screwdriver) and maybe the un=
it
> will start, I'm pretty sure that if that's the case, replacement of the
> board will save you some time/money.
>=20
> Damon B
> Telrad Electronics
> Fort Wayne IN
> ----- Original Message -----
> From: <daryls_tv@xxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Friday, July 22, 2005 1:10 PM
> Subject: [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply
> problem
>=20
>=20
> > After re-checking the power supply, I discovered that the chopper is not
> os=3D
> > cillating.  I guess I was in a hurry and used the wrong ground as
> reference.
> > I rechecked every component on the primary side and still not finding
> anyth=3D
> > ing bad.
> > I thought I would sub another chopper into it but I couldn't find any
> cross=3D
> >  for it.  I hate to order one and wait several days only find out that =
may
> =3D
> > not be it.
> > Daryl=3D20
> > Daryl's TV
> > 2402 Wyoming Ave.
> > El Paso, TX  79903
> > 915-565-9184 Voice/Fax
> > daryls_tv@xxxxxxx
> > www.angelfire.com/tv2/daryls_tv
> >
> >
> > ----- Original Message -----
> > From: Damon <damoneb@xxxxxxxxxxx>
> > To: techassist@xxxxxxxxxxxxx
> > Subject: [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply
> prob=3D
> > lem
> > Date: Fri, 22 Jul 2005 08:00:20 -0500
> >
> > >=3D20
> > > Daryl,
> > > I have yet to see a defective convergence power supply on the ITC 222,
> > > HOWEVER.....
> > > The CTC 195/197 series has had intermittant conv power shutdown, and =
the
> > > board cost was cheap enough to just replace it entirely. It might be =
the
> =3D
> > way
> > > to go on this unit.
> > >=3D20
> > > On the boards I worked on, I was able to eventually see it fail, then=
 by
> > > jumpering  two leads on the primary side I was able to restart it and
> ver=3D
> > ify
> > > it was the smps, and it was not a "shorting" type of failure. The
> oscilla=3D
> > tor
> > > just quits oscillating for no good reason. But in your case oscillati=
on
> > > isn't the issue, tranferring power to the secondary is......does the
> final
> > > output drive the transformer at all?
> > >=3D20
> > > Damon B
> > > Telrad Electronics
> > > Fort Wayne IN
> > > ----- Original Message -----
> > > From: <daryls_tv@xxxxxxx>
> > > To: <TechAssist@xxxxxxxxxxxxx>
> > > Sent: Thursday, July 21, 2005 6:18 PM
> > > Subject: [TechAssist] RCA D52W20, ITC222, Convergence power supply
> problem
> > >=3D20
> > >=3D20
> > > > RCA D52W20, ITC222, Convergence power supply problem
> > > >
> > > > Another looser here.
> > > > Customer claims they changed channels and lost the convergence.
> > > > What I found is no control of convergence and a distorted picture.
> > > > There are no voltages out of the convergence power supply on the
> > > secondarie=3D3D
> > > > s.
> > > > I do have power on the primary of the smps and does appear to be
> > > oscillatin=3D3D
> > > > g.
> > > > I checked all of the semi's, resistors and electro's. I ohmed out t=
he
> > > switc=3D3D
> > > > h mode power transformer. I didn't find any bad components.
> > > > I hope someone has encountered this before and can give a few
> pointers.
> > > > Thanks,
> > > > Daryl
> > > > Daryl's TV
> > > > 2402 Wyoming Ave.
> > > > El Paso, TX  79903
> > > > 915-565-9184 Voice/Fax
> > > > daryls_tv@xxxxxxx
> > > > www.angelfire.com/tv2/daryls_tv
> > > >
> > > >
> > > >
> > > > --=3D3D20
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>=20
>=20
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Follow-Ups:
- [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply problem
  - From: Damon
- [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply problem
  - From: J Silverman
[TechAssist] Re: RCA D52W20, ITC222, Convergence power supply problem

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