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Dave Moore
 
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Default CTC169 and sub flyback 232191 incompatability notes

Hello folks,
I came across this thread in the freelists group
and thought I'd re-post to SER.
=^^=DM




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[TechAssist] Fw: RCA projection TV- sub flyback transformer (Part#
232191)

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To: "walter wood" wwood_38478@xxxxxxxxx,"Shoreline Electronics"
jstielau@xxxxxxxx,"Mouton's Electronics" moutons@xxxxxxxxxxxxxxxx,"Excel
Distrubiting" Excel1819@xxxxxx,"Ed Gaides" teltek2@xxxxxxxxxxxx,
drvcr@xxxxxxxxxx,"Charles Betzler" repair1@xxxxxxxxxxxxx,"Bob's TV"
woodman1@xxxxxxxx,"Jeff Dougherty" jeff@xxxxxxxxxxxxxxxxxx,"Techassist"
techassist@xxxxxxxxxxxxx,"Larry E." videotech@xxxxxxxxxxxx,
tvservice@xxxxxxxxxxxxx,"tvservice" tvservice@xxxxxxxxxxxxxxxxxxx,
"Ampm" ampm@xxxxxxx
Subject: [TechAssist] Fw: RCA projection TV- sub flyback transformer
(Part# 232191)
From: "Gemini Computer & TV" geminitv@xxxxxxxxxxxxxxxx
Date: Thu, 6 Mar 2003 15:20:54 -0500

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Sorry to post this to so many at once, however I felt it important enough to
do so. Here is a forwarded post from Steve at HQ Electronics that may
benefit us all. Here is his excerpt:

Bob Waterman, CET® #RI-28
Master Technician License #9109
Service Manager
Gemini Computer, TV, & Security Alarms
(508)695-7302
(508)695-7769 FAX




We ordered a 232191 IHVT from Union Electronics. This was for a PTK169.
The first one we received failed to work. Many hours troubleshooting time
spent and unneeded replacement parts were installed determining something
was wrong with the new flyback. (Holly at Union again verified the part
number was correct.) Another was ordered again from Union. Again many hours
of time was spent determing that this part was also bad. This was confirmed
when a known good flyback from a working set was substituted temporarily and
the set fired up and worked beautifully. A third transformer was ordered,
this time from Andrews. (Willy at Andrews also verified we were ordering the
correct part). The part from Andrews arrived and worked just fine. All 5
transformers, the original, the one from the working set that was used as a
substitute, and all three new flybacks had the same part number on the
flyback, 2G25018 and TCE 30.0KV. All three new flybacks had the part number
232191 on the boxes. During the course of checking the transformers against
one another we discovered that apparently the 2 from Union were MISLABELED
AT THE FACTORY! They appear identical on the outside with one exception: The
two original FB's and the 3rd successful FB all had a green ink splotch
about 1/2 to 3/4 inch in diameter on them, whereas the two that did not work
had no such splotch. I don't know how significant that is. We determined
that these transformers were made to be used in the direct view chassis and
were MISLABELED AT THE FACTORY. According to the tests we performed here, it
has to do with the way pin 6 is connected on the direct view VS the PTV-- In
the Direct View CTC169, pin 6 is the low end of the Anode winding. In the
Projection PTK169, the black wire (also present on the Direct View flyback)
is the low end of the Anode winding and is connected to a circuit that looks
like it monitors beam current and limits peak brightness.

Symptoms of the wrong FB in the Proj set:
Standby is just fine. Hit PWR: Momentary Horiz drive. 200V line only goes up
to about 100 or 120V and the 26V line goes up to about 36V, as measured on a
'scope. If you short pin 4 of T4101 (Run regulator feedback) to hot ground
as per the official Troubleshooting manual, R4762 (430 ohms 1W) on the HV
Reg PCB (mounted on the H.O.T. heatsink) blows the magic smoke. This HV Reg
PCB is not present in the Direct View set.

How to test before installing the FB to make sure that you have the correct
one:
Using the Sencore VA48, Horiz SCR output, connect ground to pin 1 and drive
to pin 11. Use your scope to adjust to 10V positive peak pulse drive. Here's
the key to the test: If you measure the anode voltage using the wrong pin as
ground/common, the voltage is too low. The exact voltage is very sensitive
to the drive voltage, so comparison is the key.

Proj FB using black wire as common on 10M DMM: 220 to 230Vdc.

Proj FB using pin 6 as common on 10M DMM: 150 to 160Vdc

Direct View FB using black wire as common on 10M DMM: 150 to 160Vdc

Direct View FB using pin 6 as common on 10M DMM: 220 to 230Vdc

I'm sure you see the pattern. :'/ A cross check of the Thomson PTK169
service manual on CD vs our paper Thomson CTC169 is inconclusive as the
schematic of the PTK169 FB circuit labels the low end of the anode winding
as pin 6. The PTK169 service manual lists the replacement part as 232191. I
have wasted somewhere around 100 hours of my time, plus the time of the
other techs and the owner at HQ, plus the time of other techs here. And many
unneeded parts were installed. The customer has waited months for this set
and is not happy, and in the end it turns out it could have been back to him
in the first week of January. I'm not a happy camper. I hope this post saves
some other techs hours of wasted time.

Steve Greenfield
HQ Electronics
218 N 1st St
Shelton WA 98584
360-426-3336 (Shared phone and fax)
http://www.hqelec.com

----- Original Message -----
From: "Larry E."
To:
Sent: Friday, February 21, 2003 2:33 PM
Subject: [TechAssist] RCA projection TV- sub flyback transformer

Jason, AND everyone else, Hang onto the heat shrink tubing because
Thomson has NO Part Number for you to re-order it when you need to
splice the black wire to the HV Regulator and RCA`s 800 parts # people
have no clue what it is. Spent 1 1/2 hours on the phone with them trying
to buy it, they (parts people) finally forwarded the call to a guy in
Indianapolis that knew what I was talking about, but when you run the
part numbers off the bag(s) he sent me to Tri-Tronics, Vance
Baldwin,etc. it comes up NLA !! Larry E

Mouton's Electronics wrote:

I just got one in the other day and installed it. It came with the heat
shrink tubing as if it was meant to be a replacement for the projection tv
and yes, I did have the same result as everyone else. Open resistor and 2
shorted transistors on the HVreg board. I plan on emailing Thomson about
the
many people having this discussion and I think anyone with access to there
support site http://www.thomsonnetwork.com do the same. Maybe they
will
take us seriously.
Jason
Moutons Electronics

----- Original Message -----
From: "al m"
To:
Sent: Friday, February 21, 2003 11:13 AM
Subject: [TechAssist] RCA projection TV- sub flyback transformer

Seems like a lot of techs are using this 232191 flyback with same problems.
Does anyone know the answer to is it the right one or not. I've seen some
say yes and some say no. Would like to know before I get one in.
al marquardt


----- Original Message -----
From: "drcvr"
To:
Sent: Friday, February 21, 2003 12:00 PM
Subject: [TechAssist] RCA projection TV- sub flyback transformer

Thanks Larry & Jeff!
The sub flyback 232191 it generates voltage way too high throu black lead to
Hv reg. PCB caused R4762 burn. Don't try to install any resistor between
black lead to red one from HV board, voltage high enough to kill 33
mega-ohms like I have tried. I have two other PTK169 in my shop, they are
newer sets, set with HV block stay near GREEN crt, took T4401 out and
install to this set it works OK. The only problem is red lead to HV Block
little bit short, so I have to drill hole through cardboard. Draw # on this
one is 2G25038-A2A and part# is 226094. Again 226094 is original or a SUB
one? Please let me know before I order. TIA
Don B.
Dr. VCR est:1994
20 Hanson Ave
Kitchener, Ontario
CANADA N2C 2E2
Tel 519-579-7112 Fax 519-579-1996


----- Original Message -----
From:
To:
Sent: Thursday, February 20, 2003 7:52 PM
Subject: [TechAssist] RCA projection TV- sub flyback transformer

Larry,
The one you did, was it a PTV, or direct view?
I know many other techs that had the same problem Don has, including
myself. I was able to patch the hole in the flyback with HV putty and it
worked like a charm. Before I patched it, I tried a flyback from a direct
view chassis and the same resistor blew. I've came to the assumption that
part is not a good number for the PTV sets. I wish more people would be
contacting RCA on this issue. They assured me I had the right part number.

Jeff Dougherty
Intrepid Video TV/VCR
263 S Front St
Steelton PA 17113
717-909-8844
www.intrepid-video.com www.tech-repair.net

----- Original Message -----
From: "Larry E."
To:
Sent: Thursday, February 20, 2003 5:23 PM
Subject: [TechAssist] RCA projection TV- sub flyback transformer

Don, the sub is the right number, did one with the same symptoms about 4-5
months ago and ended up replacing 4-5 parts on the HV Reg. board and the HV
Splitter(205064) this will probably end up being a pricey repair so cover
your a**, good luck, Larry E

Larry Eastman
American TV & Electronics
Crystal River, Fl. 34428

drcvr wrote:
Hello, Techs!
I have this lightbox in for service, model#P52755ST and chassis# CTC169PA
found T4401 open wire( internal) from B+ to collector of HOT, TV is dead.
T4401 draw# 2G25018-A3A, original #200450 has been sub to 232191. I order
one 232191 and install, fire it up, smoke come out of R4762 on HV REG PCB
and 2 seconds later TV dead. I found Q4752 on HV REG. PCB shorted and R4762
open. My question is this is a good SUB of flyback from RCA? Is there any
way to get original one?

TIA
Don B.
Dr. VCR est:1994
20 Hanson Ave
Kitchener, Ontario
CANADA N2C 2E2
Tel 519-579-7112 Fax 519-579-1996


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  #2   Report Post  
JURB6006
 
Posts: n/a
Default CTC169 and sub flyback 232191 incompatability notes

I ran into this myself a few times. Without the Sencore somehow you need to
excite the fly. With nothing connected to the anode output, shorting the black
wire to the normal ABL pin (not sure of the number right now, but it's the one
with the spark gap) will distort the waveform on a direct view fly, but not on
a PTV fly.

Doing this on a Sencore, you should get a "bad" indication with the short in
place. I don't know if it will show up on a normal flyback ring tester. It
would probably have to be excited to the point where it's putting out at least
600-700 volts to show up for sure. With lower voltages you might get false
negatives on some because of normal tolerances.

Let's put it this way, however you excite it, if there is any + voltage on the
black wire it is probaly the wrong part. You should have a negative voltage
there if anything.

Of course now a few of us have some flys in stock, now to figure out what
they're for. Of course they will probably work in many CTC169s but they might
put out a bit too much HV for a 27". I know this much, if you reroute the ABL
line as in a direct view and insulate the black wire a PTV set will run, but
you should disconnect the power to the HV booster board or it will be going
full blast trying to regulate.

I actually had to ship one like that in the past, the customer was getting to
be quite the hothead, but he was told about it. It was safe, but we told him
about, like when something blows up the image will bloom. As far as we could
tell, before we had this thing figured out, the focus voltage going into the
secondary of the HV boost transformer had caused it to fail. We are pretty sure
of this because in the end the only thing it took to fix that set was the
flyback. Of course we went through the lytics in the power supply and we
usually have a look at the 15V line on these, none of these other things were
the cause of failure.

JURB
  #3   Report Post  
JURB6006
 
Posts: n/a
Default CTC169 and sub flyback 232191 incompatability notes

BTW, I forgot to mention, even though I knew about this, we do appreciate the
heads up on it.

Speaking of heads ups, maybe it's time for another one. A few of us have been
bandying around the idea of certain subject lines in here. I think "Heads
Up:_____" wouldn't be a bad idea. From time to time we could post some unusual
stuff like this, like the STK4274s with lot# 7027 will not work in Hitachis,
the subwoofer on XBRs and so forth.

I'll let you go now, I'm going to write one. Wouldn't be a bad idea to
encourage others to do likewise.

JURB
  #4   Report Post  
Dave Moore
 
Posts: n/a
Default CTC169 and sub flyback 232191 incompatability notes


"JURB6006" wrote in message
...

Of course now a few of us have some flys in stock, now to figure out what
they're for. Of course they will probably work in many CTC169s but they

might
put out a bit too much HV for a 27". I know this much, if you reroute the

ABL
line as in a direct view and insulate the black wire a PTV set will run,

but
you should disconnect the power to the HV booster board or it will be

going
full blast trying to regulate.




I actually had to ship one like that in the past, the customer was getting

to
be quite the hothead, but he was told about it. It was safe, but we told

him
about, like when something blows up the image will bloom. As far as we

could
tell, before we had this thing figured out, the focus voltage going into

the
secondary of the HV boost transformer had caused it to fail. We are pretty

sure
of this because in the end the only thing it took to fix that set was the
flyback. Of course we went through the lytics in the power supply and we
usually have a look at the 15V line on these, none of these other things

were
the cause of failure.

JURB



In my case, I used a "direct view" flyback in a PTV and routed
the ABL pin to the HV regulator and simply insulated and didn't use
the black wire ( focus pin)

After a day or two the flyback crapped out.

As for why, not sure, mighta been the fact that it was salvaged
from a 36" set that had been struck by lightning.

Or it mighta been because I later discovered that a little 820pf
cap was shorted out on the HV splitter and was impeding
the negative feedback to the regulator circuit, which I will
have to guess probably caused the HV regulator circuit to try
to boost the HV as much as it could, thinking that the
HV was low.

However, before I had hooked the HV lead back up to the
HV splitter, I has measured it at 28KV so I assumed all was
ok with the regulator.

I suppose it's entirely possible that the 820pf cap died at
the same time the flyback did,, chicken,,, egg?

Anyway, if I hadn't already fixed over 12 different things wrong
with this TV,, I guess I'd be adventurous enough to experiment
some more with this.

That's right,, this was the TV from HELL.

Now, only thing left to do is to add up how
much money I lost by fixing it :-)

Thanks for the tips -- DM--


  #5   Report Post  
Dave Moore
 
Posts: n/a
Default CTC169 and sub flyback 232191 incompatability notes


"JURB6006" wrote in message
...
I ran into this myself a few times. Without the Sencore somehow you need

to
excite the fly. With nothing connected to the anode output, shorting the

black
wire to the normal ABL pin (not sure of the number right now, but it's the

one
with the spark gap) will distort the waveform on a direct view fly, but

not on
a PTV fly.

Doing this on a Sencore, you should get a "bad" indication with the short

in
place. I don't know if it will show up on a normal flyback ring tester. It
would probably have to be excited to the point where it's putting out at

least
600-700 volts to show up for sure. With lower voltages you might get false
negatives on some because of normal tolerances.

Let's put it this way, however you excite it, if there is any + voltage on

the
black wire it is probaly the wrong part. You should have a negative

voltage
there if anything.



Oh, I forgot to mention,, not having a fly ringer, I simply used my trusty
old ancient (relic from the past) vacuum tube 350V bench supply.

Reasoning that, with a certain amount of voltage, the diodes in the
HV secondary should forward conduct in one direction.

The simple test here is that the flyback for the PTV should not have any
forward conduction to any one of the pins on the bottom of the flyback,
whereas the flyback for the "direct tv" would.

Anyway, I was able to verify that my new flyback was indeed as
intended for a PTV, as I had no forward or reverse conduction
to any pins on the bottom of the fly,, only conduction to the black
wire (as it should be for a PTV fly)

Interestingly enough, I didn't get any forward conduction until
close to 100 volts. So, if anyone wants to try this then, be advised
that you may need a voltage source of 120 volts or more.

Also be advised to use a current limiting resistor as you don't want to
fry the diodes in the flyback HV winding. I played it safe and used
47K

I imagine that one could fabricate a 160 volt source by
simply rectifying the AC line with a diode and capacitor.
( Bearing in mind to be careful with this unless you also
use an isolation transformer)

In fact, I suppose that if one wanted to, they could simply
rectify the line with the diodes in the HV winding itself to
feed a 47K load resistor and simply look at the the polarity
of the rectified pulses on the scope
Only, I guess here, again you would need an isolation
transformer to use the scope, unless you used both vertical
channels set to invert and add.

ah! here's an idea for a simple tester, use the aforementioned
setup with an LED in series with it. The LED would have to
be set up to conduct in the same direction as the diodes in
the HV winding of course.
Ok, lets see how this would be, one wire from the wall
AC would go to the cathode of the LED, then the anode
of the LED would hook up to red HV wire from the flyback,
then the other wire from the wall would go to a 6K-10K
resistor and from there to a test probe that you could use
to probe the pins under the fly or the black wire.



However, AKAIK, the black wire would conduct on
either flyback, so the real test would be whether or not there's
conduction to the pins under the flyback. ( actually the only
two pins in question would be the two that are completely
opposite the side where there are no pins)
Like you, I can't recall which one of these is the one in question,
no biggie to check both though.

A refresher,, conduction ( lighting of the LED) to either of these
two pins would indicate that the flyback is for what you termed
a "direct tv".

If the LED doesn't light up when probing the pins under the fly,
then its a fly for a PTV


Though the black lead would conduct on either flyback,
(PTV or direct tv), perhaps there might be a slightly noticeable
brightnesss difference in the LED that would indicate whether
this lead is being used as a focus lead ("direct tv") or whether
it is the low side of the HV winding ( PTV).

Dunno,, maybe someday I'll build this complicated circuit
and see :-)

=^^= DM


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