Author Topic: Hantarex Polo 25" Flyback / Cap Replacment Issues (Read 16958 times)

Arm123 · « **on:** June 09, 2011, 02:16:28 am »

Hey there,

I have a KI cab that had a sparking flyback... and no image

I ordered a cap kit and new FB (1242.5001) from Bob Roberts.

After capping and replacing the FB i noticed that the new one is missing a pin, like in this picture...

I started it up and it fired up to the test screen and comes up with an unstable image... and its making a crazy rythmic ticking / arcing sound, thats seems to be coming from higher up on the monitor area... I know its not the chassis arcing (i pulled it out of the frame and ran it), but i cant see any flash anywhere else.

It seems as if its coming from the neck or anode cap.

Went over the whole chassis for cold solder joints and the B+ is around 135v to 138v

I also, tried adjusting the FB screen control and it doesnt do anything (missing pin on FB ?)

Iv run out of ideas and cant find anything on the net about this. Could i have the wrong Flyback installed ?

Here is a video of what it does... You have to listed carefully... but you can hear the rapid arcing / poping.

Arm123 · « **Reply #1 on:** June 09, 2011, 02:18:32 am »

Did some digging around in the PSU section...

TP6 +133v
TP7 0v
TP8 +26v
TP9 +16v

Looks good except that TP7

Checked at R130: +83v

Picture appears to be rolling vertically.... checked T110, T112 as good. I don think IC04 would cause this as its ment for Hrz control.

Kind of stuck here... i hate just swapping parts...

Ken Layton · « **Reply #2 on:** June 09, 2011, 12:02:54 pm »

The original sparking/arcing flyback probably damaged additional parts.

grantspain · « **Reply #3 on:** June 09, 2011, 01:00:17 pm »

whats the hr flyback number you installed

Arm123 · « **Reply #4 on:** June 09, 2011, 01:50:09 pm »

Hey there Grant, Ken thanks for your replies.

Honestly, i dont remember seeing the hr #.

Grant, I just ordered the Polo kit from Bob Roberts and saw these numbers on the original and the replacement: 1242.5001

I did note the missing pin on the new one... and the lack of a screw terminal that mounts to the frame. Just a shot in the dark, as this is my first Polo that i have worked on... Perhaps its the flyback for a smaller Polo model ?

Ken, ill have to check the parts around the flyback more carfully, but perhaps i should look at swapping the vertical deflection IC ? Ill also take some voltage reading and post em up.

Thanks for your time guys... much appreciated.

Arm123 · « **Reply #5 on:** June 09, 2011, 01:55:37 pm »

Oppss... Forgot to mention that i socketed and swapped out IC1 LM120 on the neckboard... same result.

grantspain · « **Reply #6 on:** June 09, 2011, 04:02:04 pm »

most the replacement lopt do not have those extra ground pins or fixing so you can ignore that really

observe what happens in the dark around the anode cap and in the neck

grantspain · « **Reply #7 on:** June 09, 2011, 04:05:28 pm »

also that number does correctly cross reference to a hr7191 lopt which is correct

Arm123 · « **Reply #8 on:** June 11, 2011, 09:44:53 pm »

Replaced IC103 TDA1675
Replaced TI18 BDX53A

Tested +3.2v at TP17 (IC103 TDA1675) supply.... somethings wrong there

Arm123 · « **Reply #9 on:** June 11, 2011, 10:00:29 pm »

Also noticed that R168 is a 12k resistor, not a 22k like the schematic says...

TP8:+26v

PSU voltage is good... its getting eaten up somewhere bween the PSU and the vframe IC

TP38: +10.5v
TP31: 0v

Found completly open T119... see if i have a replacment to try

grantspain · « **Reply #10 on:** June 12, 2011, 06:25:27 am »

r167(2r7) is the safety resistor for the 25v to the vert ic
c189 can be an issue also

Arm123 · « **Reply #11 on:** June 12, 2011, 04:06:16 pm »

Replaced T119... now have +26v at TP8

Tested R167 and c189... checked out.

Still have the ticking / arching sound coming from around the neck. The picture is rolling vertically and cant stablize... seems to be synced / rolling with the arching sound.

I checked the wiring for the hr / ver yoke connections, coming from the chassis. No markes / gashes to cause arching.

Could i have a short in the yoke ? Which i cant see ?

Also, could IC104 cause vert rolling ?

grantspain · « **Reply #12 on:** June 12, 2011, 05:18:55 pm »

yes could do,extremely rare though
check your remote board for a burnt out resistor

Arm123 · « **Reply #13 on:** June 12, 2011, 09:43:02 pm »

Im actually leaning towards it being the yoke shorting... but im not sure how to verify.

I have a FB tester here... wondering if it could be used to test the windings on the yoke as well.

Would the resistance measurment on the v-coil / h coil be affected by a short ?

Will be a shame if its the yoke.

Arm123 · « **Reply #14 on:** June 12, 2011, 10:09:28 pm »

Here are my yoke readings...

Hantarex POLO: Tube A63ADT10X05
Horizontal yoke wire color Orange / Yellow 1.5 ohms
Vertical yoke wire color Blue / Purple 5.6 ohms

Arm123 · « **Reply #15 on:** June 13, 2011, 01:08:00 am »

plying around with this... R255 i get +20v on one side... +0.2v on the other.

R255 meters to 180 ohms... and TP14 is +0.2v so im guessing there is a short somewhere after R255 ?

It seems to be leading up to the neckoard... where the sound is coming from

grantspain · « **Reply #16 on:** June 13, 2011, 02:13:10 am »

yoke is reading fine,do me a favour and take a photo of where the focus and scrren volts wires go into the neck card

Arm123 · « **Reply #17 on:** June 14, 2011, 03:26:54 pm »

Here it is... sorry for the delay

grantspain · « **Reply #18 on:** June 14, 2011, 05:00:47 pm »

white lead being the thinner of the two then thats correct,seen it a few times where people have muddled the focus and screen due to change of colours

of course you may have a faulty lopt

better off putting on a dummy load and then checking all your voltages

Arm123 · « **Reply #19 on:** June 15, 2011, 12:45:08 am »

These are the PSU measurements...

TP6 +133v
TP7 0v
TP8 +26v
TP9 +16v

Everything seems to be fine... TP7 doesnt appear to even be in circuit with anything... so im not sure there what to do about that.

I hav enever had to trouble shoot a lopt before... Any advice?

grantspain · « **Reply #20 on:** June 15, 2011, 12:19:36 pm »

i reckon you may have a bad flyback

Arm123 · « **Reply #21 on:** June 15, 2011, 04:25:58 pm »

Hmmm....

Well, i have to order a bunch of parts from good old Bob Roberts again... I may as well get a couple extra flybacks to play with.

Ill keep you updated ;-)

Arm123 · « **Reply #22 on:** September 27, 2011, 11:47:21 pm »

Alright... I finally pulled this out again and its dead, with no ticking.

I hooked up a 60W light bulb to the deflection end of L103 and it lite bright and stable... so the PSU seems to be ok.

The PSU seems to be shutting down because of a short some place on the deflection side.

Im gonna need a bit of help on this one. Any suggestions ?

grantspain · « **Reply #23 on:** September 28, 2011, 03:23:04 am »

i guess you could disconnect the yoke plug and then put a link in the header between the the 2 centre pins-that will prove if the ssue is the yoke

Arm123 · « **Reply #24 on:** September 28, 2011, 11:50:27 am »

Made a descovery today, I pulled the anode cap off and saw the metal cap that holds the connection prongs and bare wire pop off.

The wire is not even soldered to the damn hooks ! Its just sitting loose in the cap. This could be my poping / arching sound ! I soldered the wire to the connection hooks and put the metal cap back on.

The last time i powered this thing up, i saw smoke coming from the chassis. So there is definetly a dead / shorted part somewhere.

Need help tracking it down. I feel like im starting all over with this... So ill post my test voltages again with the chassis assembled running with and without the light bulb.

Arm123 · « **Reply #25 on:** September 28, 2011, 05:21:37 pm »

Ok, reading of the PSU TPs with the light bulb connected to L103
Tp 6 and 7 are 0v because of L103 being lifted... but i have a solid 130v coming from there

Tp6 0v
Tp7 0v
Tp8 22v - 24v
Tp9 15v

Im guessing the fault lies in what ever is running off the B+

Where should i start looking ?

Arm123 · « **Reply #26 on:** September 28, 2011, 05:38:11 pm »

With the monitor fully assmebled and L103 in place, the PSU is switching on and off with no ticking sound.

All points after the PSU test points will obviously give me no reading, or fluctuating readings.

Would it be reasonable to assume that where-ever i have no fuctuations, is in curtuit AFTER the shorted part ?

Just trying to narrow down my search effort.

Arm123 · « **Reply #27 on:** September 29, 2011, 12:02:42 am »

Since the 139v line has been found to have the fault... im guessing that rules out the vertical deflection section ?

Also forgot to mention that i replace IC104, but its still doing same thing...

grantspain · « **Reply #28 on:** September 29, 2011, 05:14:54 pm »

remove the flyback,solder a lightbulb across ground and pin 3 then read the b+

Arm123 · « **Reply #29 on:** September 29, 2011, 10:17:31 pm »

Thanks for all your help grant. I appreciate it.

I tested the HOT and all active components along the +130 line

d134
d135
T114
T113

I also changed IC104

So i guess i should check the flyback as you suggest.

Arm123 · « **Reply #30 on:** October 02, 2011, 03:06:51 pm »

Ok, i removed the FB and hooked up the light bulb to pin 3 and i get +130v with a solid light.

Upon inspecting the bottom of the FB i noticed that the missing connector pin, i mentioned previously, was folded up !!! I must have missed it !

Thinking i could chalk this one up to stupidity, i put the FB back in with the folded up pin soldered in correctly. Still dead.

I tested the FB with my ring tester across pins 1 and 3... says it dead / bad. Perhaps that was the cause of my problem ?

That pin is ether the screen or focus control... i think its the screen.

Ill order a couple replacment FBs and see what happens. Thanks for your help, ill keep you posted.

grantspain · « **Reply #31 on:** October 02, 2011, 05:21:41 pm »

that pin is a ground-does sound like faulty flyback though

Arm123 · « **Reply #32 on:** October 14, 2011, 03:50:32 am »

Ordered 4 new FBs and replaced... same issue ;-(

I guess i need to keep poking round this thing

Arm123 · « **Reply #33 on:** October 14, 2011, 05:24:30 pm »

found t119 (c547b) dead...replaced with a bc337 can i get a confirmation that this was a good crossref ?

r255 (180ohm) is really scortched and the 25" schematic says it should be 150 ohm, so i replaced with 150 ohm.

still the same problem ;-(

grantspain · « **Reply #34 on:** October 14, 2011, 06:19:27 pm »

mate where are you based?

Arm123 · « **Reply #35 on:** October 14, 2011, 06:52:54 pm »

In Toronto Canada... would have sent to you if i was in EU :-(

grantspain · « **Reply #36 on:** October 15, 2011, 05:29:45 am »

ok looking at the post again I would suggest checking everything you changed so far plus the obvious such as thermal insulation sheets on the back on transistors,ic etc

Arm123 · « **Reply #37 on:** October 15, 2011, 12:28:18 pm »

Hey there grant,

I tried removing the vertical output IC and powered up... still same thing.

Looking over the chassis, i never saw any insulation sheets on any of the transistors that are mounted up against the chassis. Perhaps thats causing the shorting ?

I have plenty of spare sheets here, ill try putting them in... if that ends up being the problem... I need to be SHOT, due to stupidity.

Although, it did come this way... and i never worked on a Polo before... so, i cant totally be blamed.

Its been educational.

grantspain · « **Reply #38 on:** October 15, 2011, 02:18:14 pm »

not all transistors need an isulation sheet-ones in a iso package are fine with heat conductive compound only

Arm123 · « **Reply #39 on:** October 15, 2011, 03:57:37 pm »

I see the HOT doesnt have a metal case on the back, so it probably doesnt need a sheet.

However, the vertical IC and the transistor beside it (which i also changed) have a metal case. Ill try putting a sheet on them both.

Other than that... My thoughts are that there is a short on the +130V line and i just have to keep testing components till i find it. I will try lifting some parts, to isolate certain areas, to see if the light bulb stays solid.

Just feel like im chasing tails here... any suggestions are appreciated, as this is now a quest.


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