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Old 24th Feb 2023, 1:20 am   #41
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Default Re: Horizontal Output Transisor Question

everything around the LOPT has been re-soldered and the LOPT has been changed. haven't taken the back off it since it 'came on' as described in my last post. Im going to take the back off shortly and attempt to start it again, if it does agree to start i wanna see if the heaters are lit.

my thoughts keep turning to CP37, it seems to fit the bill for a fair few faults with this chassis, including no start and no picture, only problem is its a 4700uf and I dont have any, i'll have to check through my catalogue of scrap boards and see if there's a 4700uf on any of them.

i'm fairly confident the power supply (primary) is working fine, and the standby supply is working fine also, its still in standby now an hour later.
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Old 24th Feb 2023, 2:18 am   #42
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Default Re: Horizontal Output Transisor Question

Took the back off the set and it agreed to start (still no picture) I was able to measure some voltages:

158V supply 160v
23v supply is 23.9v
13v supply is 13.1v
200v supply is 198.2v
8v supply is slightly low at 7.3v-7.4v

tube heaters are lit, deflection is apparently working as i can hear the scan coils, there is nothing on screen though, turning the G2 up nothing happens screen stays dark

the longest ive let it run for is 5 mins just because im not sure if its going to go again and i dont wanna risk allowing anything else to go, still strange that it came back on its own (at least partially) its doing far more now than it was earlier, ive had it on and off a few times since it came back and each time it seems to be running as if everything is normal, just no picture on it.

any ideas?
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Old 24th Feb 2023, 2:53 am   #43
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Default Re: Horizontal Output Transisor Question

Well i feel like a right wally....

Figured out exactly why the set wouldn't start, and why there was no picture and why it was intermittent and why it came back to life on its own

when I changed the LOPT yesterday i didn't have the Focus cable fully inserted into the focus unit on the neck board, i only noticed when I was looking to see if the heaters were lit and noticed the focus cable was two different shades of red one brighter and one a bit dull, thats when i realised it wasn't fully inserted.

fixed it up and powered on, set came on with a perfect picture.

I dont know if the original fault is still present, I'm going to leave it off over night and i'll soak test it tomorrow and see how it gets on, hopefully with all the parts that have been changed and the solder touch ups it may have also fixed the original fault.
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Old 24th Feb 2023, 8:38 pm   #44
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Default Re: Horizontal Output Transisor Question

You will really need a scope at some point if you are going to continue to play with older Tv's, something like a Hameg HM203-6 or similar, not the best scopes in the world but easy to drive and adequate for what you are doing.
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Old 26th Feb 2023, 11:07 pm   #45
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Default Re: Horizontal Output Transisor Question

Set still has its original fault, it runs for about 6-7 mins then shuts down, until this evening it would shut off without warning or any visual indication of a fault, that changed today.

Had it running a few minutes ago after changing some more parts, I changed CP37, RV82, DL55, CL55 and CV82. This time about 5-10 seconds before the set shut down the whole picture very slowly started shaking left to right then it got more violent with the picture kind of tearing at the top, middle and bottom then it shut off, didn't trip, just went dead, no LED nothing.

I hope that description makes sense and might be able to help someone point me in the right direction.

my own thoughts are beginning to point me towards LG11 EW Coil breaking down under load/heat but the EW remains perfect while the fault is happening and after a cool down and restart its also fine, could the EW coil be responsible and cause the demise of the 3 Horizontal Output Transistors its had since this fault began?
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Old 27th Feb 2023, 10:11 am   #46
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Default Re: Horizontal Output Transisor Question

It can be a drive fault. I know from once working in a CP110 touching the wrong component around tha tda2579 can really let scream the line stage/ all kind of shaking errors. Will not be suprised if a bad drive signal can kill a LOT and even the transformer

Did you replace the driver transistor too? Otherwise I am afraid without a scope we can just guess. I would really save up to get one. Will make working in these sets also much more fun!

Last edited by 3CX15000A7; 27th Feb 2023 at 10:16 am.
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Old 4th Mar 2023, 12:00 am   #47
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Default Re: Horizontal Output Transisor Question

About to dive into this ICC5 again after not touching it for a week, the HOT popped again after the last trip in my previous post and I've been waiting on some new BU508's generously donated by Mick which are on the way but have not arrived yet and as I'm relentlessly impatient I had a thought...

when I repaired the TX98 set not long ago it got two beautiful new S2000AF's one in the PSU and the other for the HOT which helped get it back to life so until such a time the new BU's arrive the TX98 is gonna donate its Transistor/s to the ICC5.

After looking up the list of stock faults and then finding the official little pocket guide Ferguson produced (with 12 pages of ICC5 faults) HT resistor RL10 seems to have a habit of intermittently going open and killing either the TP24 or TL31 BU's so along with changing the HOT im going to change this resistor and see if the set stays running.
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Old 4th Mar 2023, 5:14 pm   #48
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Default Re: Horizontal Output Transistor Question.

its dead, i dont know whats going on with this set, its going from bad to worse, all i get is a slight click and brief red led before it dies out, i have 330v on the reservoir cap, on TP44 where i should have 5v ive got 2.5v etc, its like the primary voltages i should have except the mains cap are halved for some reason. im getting no voltages on the secondary of the chopper
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Old 4th Mar 2023, 11:35 pm   #49
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Default Re: Horizontal Output Transistor Question.

With the HOT removed, does the psu starts? (Use a 60W light bulb as load)
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Old 4th Mar 2023, 11:44 pm   #50
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Default Re: Horizontal Output Transistor Question.

On the ICC5 (and later ICC/IKC2chassis) sets if the Line stage isn't running then the regulation of the main psu will be out of its normal running state proportions, this is already known about, however the 5volt rail should stay the same as the micro needs this to start the set up.

edit: it is not really possible to use a dummy load on this chassis as the line output stage is monitored at several key positions and does to some extent drive the main regulation loop.
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Old 5th Mar 2023, 12:09 am   #51
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Default Re: Horizontal Output Transistor Question.

The ICC5 chassis also remembers the last state it was in, so if it was shut down in stby/tripped then it will also start up in stby, sometimes if not using a remote then you needed to keep the channel up button pressed in for about 5 seconds.

Luke, did you check the scancoil connections at the scancoil/tube itself? on the Mullard/Philips tubes this was a known problem with dry joints on the back of the small PCB attacted directly to the scan coils, I haven't come across this problem on the Videocolour/Thomson tubes myself yet.
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Old 5th Mar 2023, 12:42 am   #52
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Default Re: Horizontal Output Transistor Question.

here's what its doing and some voltages etc....

first the way its behaving -

50% of the time on power on a click comes from the chopper area, red led flash for less than a second and out, if i leave it on sometimes it does another click then a minute later it will click twice and then attempts to start with a Rush of EHT for a second or two then a Click then Dead.

the rest of the time there is no clicks, no attempt to start just the red LED single flash and out.

Voltages:

First there is nothing on the secondary side of the Chopper.

TP45 Collector should be around 12v and its 6v. Base should be around 8v and its 4.4v Emitter should be 11.5v and its 6v. TP45 has been changed same result with both parts.

TP44 Base should be 5.6v and its 2.5 same for emitter.

DP45 has been changed same result.

standby transformer has been changed - same result

Pin 8 of IL14 TEA is 4.4v

the set when it last successfully ran was on not in standby, however it seems the standby circuit isn't working properly anyway, holding channel up does nothing.

Re Scan coils, tag board on scan coils is fine, i re-soldered it.

I have changed the following so far:

TP15
TP16
TP19
RP23
DL28
DP45
TP45
CP26
LP03
CL21

I cant understand what happened to it to get it in this state, in theory all that had to be replaced in it per the original fault (to at least get it to run again) was change the HOT which i did, then the set kept tripping three times then i changed some parts to try fix the tripping and now its in its current state (the parts i changed i have since changed again but its made no difference)

I fully understand at this point why this Chassis was Despised by the industry. Nevertheless I do want to get it going again but i cant make sense of why its gone from bad to worse.
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Old 5th Mar 2023, 3:02 am   #53
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Default Re: Horizontal Output Transistor Question.

Ignore the voltages part, I stupidly was measuring from the wrong ground, voltages look to be correct with the exception of the 5V on TP44 which is low at 4.8v.

Question still remains, what the hell could be wrong with it
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Old 5th Mar 2023, 8:33 am   #54
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Default Re: Horizontal Output Transistor Question.

You got EHT very shortly ?

I still suspect a driver issue, no good driver signal and the tv won't start.
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Old 5th Mar 2023, 11:36 am   #55
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Default Re: Horizontal Output Transistor Question.

Try replacing QL07 the ceramic resonator for IL14 (pins 18 and 19), also CL09 100uf. CL01 470uf and CL21 1uf, these three electrolytics are connected to IL14.

The Ceramic resonator provides the clock for IL14 to drive both the chopper and LOT stages, therefore common to both, worth a try.

CP26 470uf on the primary side of the chopper can cause similar problems too

Edit: I see you have already tried CL21 and CP26
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Old 5th Mar 2023, 12:11 pm   #56
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Default Re: Horizontal Output Transistor Question.

after closing the set up and leaving it for a while i tried turning it on again, it did its usual click routine, I powered it off then powered on again, it clicked again then about 20 seconds later it attempted to start, eht came up, the set then tripped and tried to start again, this time i was quick with the remote and hit standby and the set has successfully gone into standby so i know the standby supply is working, and by extension i figure the Micro is working seeing as it accepted the standby command from the remote.

i figured once i powered off as i was going to bed last night that it wouldn't come on (to standby) again if i powered it up this morning and surprisingly i just applied power now and while it made a funny (kind of quiet arcing noise for a second) it came on to standby.

Im going to power it off again and whip the back off it and see if it'll come back to standby again so i can check some voltages and confirm the primary supply is working as well as the standby supply.

I've decided to stick at it all day today and hopefully by this evening i'll have it going again.

RE: driver circuit, I have replaced TL29 (driver transistor), DL28, RL29, CL29, and even LL32 line driver tx.

I've been thinking that DP41 (HT rail diode) might have an intermittent issue and could be what's causing the strange behaviour, this diode i noticed whenever the HOT had shorted also would appear short in circuit until the HOT was replaced, perhaps its been damaged by the repeated HOT blowing or might be the cause of it so i might look at changing that.
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Old 5th Mar 2023, 12:18 pm   #57
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Default Re: Horizontal Output Transistor Question.

Quote:
Originally Posted by IKC2E51R8 View Post

I've been thinking that DP41 (HT rail diode) might have an intermittent issue and could be what's causing the strange behaviour, this diode i noticed whenever the HOT had shorted also would appear short in circuit until the HOT was replaced, perhaps its been damaged by the repeated HOT blowing or might be the cause of it so i might look at changing that.

It would read SC with the HOT shorted as the HOT is shorting the HT rail to chassis, reading across that diode would give a short reading as you would be reading across HT and chassis via the chopper transformer to chassis winding for that rail .
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Old 5th Mar 2023, 2:58 pm   #58
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Default Re: Horizontal Output Transistor Question.

so opened up the set, haven't changed anything, just tried to bring it out of standby, something is arcing that I can hear, the set tripped so I tried again, this time it came on, snow on the screen, there is a noticeable line on the left most part of the screen the set stayed on for about 20 seconds then tripped off again, now its back to just a click and nothing else.

Im not sure if the arcing noise is coming from the LOPT but its in the power supply/LOPT area of the board anyway, am I right in assuming the LOPT is the most likely cause?
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Old 5th Mar 2023, 3:19 pm   #59
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Default Re: Horizontal Output Transistor Question.

Check the resonator QL07 by substitution first on IL14, don't try to measure this! as doing that will destroy much silicon etc.. in both the psu and lopt stages
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Old 5th Mar 2023, 3:26 pm   #60
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Default Re: Horizontal Output Transistor Question.

After this then you are going to need a 'scope, we have tried all of the stock faults now.

As this chassis aged we got more and more obscure faults, there will not be an easy answer now via a forum, only dogged fault finding and taking measurements/scope readings to see where the problem lies and a good understanding of how this chassis actually works, without this you are now just replacing parts on spec
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