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

  • From: "J Silverman" <greentron@xxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Tue, 26 Jul 2005 11:57:53 -0400

If you buy generic ones in bulk they are only about $0.50 so it costs more
to test than to replace. Costs a little less to test in circuit rather than
removing.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
Fax/Phone 864 232 3889
mail to: greentron@xxxxxxx
----- Original Message -----
From: <gulftech@xxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, July 26, 2005 10:07 AM
Subject: [TechAssist] Re: RCA D52W20, ITC222, Convergence power supply
problem


> Jerry,
>
> That is a truly outstanding suggestion.  I have often wondered how I
> could check an opto-isolator, but usually just replaced them if I had any
> doubts.  Bet I've replaced lots needlessly.
>
> May try to build a test jig with a socket, battery, limiting resistor,
> and posts for a meter.
>
> You have helped many techs with that suggestion.
>
> Thank you,
>
>
> Ken Smith
> Gulf Technical Services
> 3034 Gulf Breeze Parkway
> Gulf Breeze, FL  32563
> 850-934-8324 (Voice) 850-932-0819 (Fax)
>
>
> On Sat, 23 Jul 2005 14:28:31 -0400 "J Silverman" <greentron@xxxxxxx>
> writes:
> > That sound normal to me! If you put some current into pins 1 and 2,
> > say from
> > an ohm meter, then you should see some ohms appear at terminals 3
> > and 4, if
> > your meters have the right polarity.
> > Jerry Silverman
> > Greentron Inc
> > 4 Newland Ave
> > Greenville SC 29609
> > Fax/Phone 864 232 3889
> > mail to: greentron@xxxxxxx
> > ----- Original Message -----
> > From: <daryls_tv@xxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Saturday, July 23, 2005 1:20 AM
> > Subject: [TechAssist] Re: RCA D52W20, ITC222, Convergence power
> > supply
> > problem
> >
> >
> > > 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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