flyback pinouts

[jamey smith]

anybody know the pinouts for thompson rca ctc187cl3 flyback transformer?
trying to diagnose a problem with whining ps. now lost power altogether
trying to diagnose, fuse is blowing,

when i replaced the HOT i heard arcing, then back to the whine.
now no power at all as fuse is blowing

wolf

 

[Tim Kettring]

anybody know the pinouts for thompson rca ctc187cl3 flyback transformer?
trying to diagnose a problem with whining ps. now lost power altogether
trying to diagnose, fuse is blowing,

when i replaced the HOT i heard arcing, then back to the whine.
now no power at all as fuse is blowing

wolf

I would not mess with the high voltage section without the right service
literature and equipment , it can kill on a color set

 

[wolfhedd]

i already messed with it, just short of deslodering it, already tested the
pins, removed the suction, refered the resistance between those pins and
each pin on the LOPT, 1.5 on one side, 2.5 on the other i think it was, but
its not infinite, so trying to find if the windings are shorted at all.
what i need is the pinouts so i can check thewindings as i am getting o 0
ohms on atleast 3 of them referring to ground. any suggestions would be
welcome..
wolf

 

[wolfhedd]

o ps, im using fluke meters, sencore va6a2 vid analyzer and sencore sc3080
osci, so the equiip is good.
wolf

 

[Tim Kettring]

If a single turn of a transformer is shorted , it will read nearly normal to
DC ohms...but still be a near short to AC , especially at that high audio
frequency . The other thing is that if you heard arcking after you replaced
the HOT , you probably have corona discharge . Either condition would
warrent replacing the high voltage transformer ( and blow the HOT ) , but to
set it properly after replacement you need a high voltage probe ( for
safety ) - else emitted radiation can be high .

 

[Ross Herbert]

o ps, im using fluke meters, sencore va6a2 vid analyzer and sencore sc3080
osci, so the equiip is good.
wolf

The majority of LOPT faults will be caused by internal shorts.

You need to get yourself one of these
http://members.ozemail.com.au/~bobpar/fbt.htm

Saves a lot of time and in my experience it is money well spent.

 

[Jason D.]

o ps, im using fluke meters, sencore va6a2 vid analyzer and sencore sc3080
osci, so the equiip is good.
wolf

Good good...
I'm very famillar with CTC187 chassis, done lot of those.

Squeal then dead was SMPS shrieking beause of shorted HOT and STK 730
IC finally blew.

Bad news to you, The STK 730-xxx SMPS blew and it's getting harder to
find new STK 730-xxx ICs because Sanken stopped making them. Use
equal or higher than original suffix. example -020 can replace -010
so on. These suffixes denotes wattages but the markings isn't the true
wattage, to get that info needs datasheet for that. Find that via
google.

On that fly:
3 of pins is connected to the B+, one for B+ input, 200V boost for
cathode supply and last pin goes to the collector of the HOT thru
emitter to the ground.

Good thing you said that you heard the arc. It is the flyback arcing
and almost always takes the HOT, it is usually bad when I find a
shorted HOT. Just in case check 2.4K SMD resistor off the emittor of
the horizontal driver circuit.

Must use quality exact HOT part (there are fakes running around be
wary) or get one from RCA. Flyback is still available from RCA, appox
50 to 60 for that fly, get it.

By the way, I usually often find the fat B+ supply diode after the
SMPS transformer dies when HOT shorts out. Use RCA 243636 diode.

Oh yeah, you must still have to deal with the onboard tuner & micro
shield grounds too, just do it while at it, tuner bottom cover MUST be
removed. This indirectly can be another cause for killing HOT from
wrong horizontal freq caused by corrupt eeprom that was caused by bad
grounds.

Go ahead with that set if the tube is cream puff otherwise junk it,
187 sets were from early to latter half of 90's. Some caps is dried
up due to intense heat around the SMPS check those with ESR meter,
change small 10uF 63V cap behind the HOT heatsink too.

Info for resoldering onboard tuners (17x and 186/7 are same) on
repairfaq.org under CTC17x tuner stuff.

Cheers,

Wizard

 

[Kevin Carney]

Wizard,
You are a very helpful generous person. Regards, Kevin

--
change .combo to .com for correct email

***************************************************
"We ought always to know precisely why a given job
is done in a particular way, and why it is done at
all, and why it can't be done more efficiently,
if it must be done at all."-- T.J.Watson

***************************************************

 

[wolfhedd]

wow, sounds like i have my work cut out for me. i have to mention one
thing. when i got the set into the shop, im not sure if the customer said
he heard acrcing or not, but when i first fired it up, it was arcing. after
checking some basic components i changed the HOT, then when i fired it back
up, thats when i heard the arcing, then i shut it down, and quickly looked
at board where the slightest amount of white/blue if not grey or mostly
clear smoke was coming up from around the stk chip, or near behind the HOT.
so would that flyback arc everytime the hot is changed or did the problem
progress before my eyes do you think? anyhow, i want to also mention that
the hot may have been replaced before i got to it, as it was a BHU, and
happened to find one in the shop the same, so i replaced it with another
BHU, which i think was a 517 if i recall right. also i heard that the
proper hot is a SK isnt it?
thanks for the detailed message, its kind of what i needed, ill get back to
youi after i look at this tv today. one problem i forsee, where is that
2.4K resistor be located?
wolf

 

[wolfhedd]

your thouroughness is much appreciated.
wow, sounds like i have my work cut out for me. i have to mention one
thing. when the set came into the shop, im not sure if the customer said
he heard acrcing or not, but he did complain of the whine, lol. but when i
first fired it up, it was only squeeling. after
checking some basic components i changed the HOT, then when i fired it back
up, thats when i heard the arcing, then the squeel came back again, then i
shut it down, and quickly looked
at board where the slightest amount of white/blue if not grey or mostly
clear smoke was coming up from around the stk chip, or near behind the HOT.
im sure the hot is fried again too.
so would that flyback arc everytime the hot is changed or did the problem
progress before my eyes do you think? anyhow, i want to also mention that
the hot may have been replaced before i got to it, as it was a BHU, and
happened to find one in the shop the same, so i replaced it with another
BHU, which i think was a 517 if i recall right. but, the reason i wonder is
i heard that the
proper hot is a SK isnt it?
thanks for the detailed message, its kind of what i needed to get any
further on this set, ill get back to
you after i look at this tv today. one problem i forsee, where is that
2.4K resistor be located?

oh, also i was thinking that the stk may be bad also, makes sense that it
needs changing, it just so hard to probe those when i dont have the proper
schematics and when the set isnt firing up now.

if i may ask you one more question, how much of this stuff should i get
changed out, before i try firing it back up as the fuse is blowing and i
dont want that to turn back into blowing the stuff i had just changed out.
wolf

 

[wolfhedd]

the second message of my last two has an imperative correction, i mistated
the original symptom. please ignore the first reply.