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Old 20th May 2010, 5:52 pm   #581
oldticktock
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Default Re: Pye v4

Another oddity I have rectified was upon power on the screen grew very slowly to fill the screen this took about 2-3 mins. Today a replacement PL82 (Frame Scan Output Valve) arrived I put this in a that cured that problem and the whole picture is much better but for this LOPT issue this set would be done.

Last edited by oldticktock; 20th May 2010 at 5:58 pm.
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Old 20th May 2010, 6:00 pm   #582
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Default Re: Pye v4

Hi OTT
As PJL says the PL81 will fail and probably take the PY81 along with it although the HT fuse should go first, It could well damage the lopt too as the current flowing through the windings will rise possibly enough to blow it.
Heat it up externally you will not harm it that way unless you go daft with the applied heat.
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Old 20th May 2010, 6:36 pm   #583
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Default Re: Pye v4

Been hair drying the lopt for 15mins not sure who's going to melt first me or the LOPT i'm in the loft workshop and its so hot Phew!

Got a drip of tar, thank heavens, so stopping and will start again in 5mins
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Old 20th May 2010, 7:05 pm   #584
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Don't worry about the odd drip of pitch, Iv'e done a TV22 lopt and was left with no pitch and the tranny still works! Aim for a core temp of 70-80 degrees, can you not lodge the hairdryer, I wouldn'd expect you to hold it for 2 + hours!!
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Old 20th May 2010, 7:27 pm   #585
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Default Re: Pye v4

Some pics ........ managed to wedge PHEW!

Edit: 77C Boneless Veal
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Old 20th May 2010, 7:41 pm   #586
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Default Re: Pye v4

The hairdryers rather close, you will heat one side, bring it back a little and give about 4 inches, make sure you dont heat up one side of the tube as well, remember about unequal expansion so a metal heat deflector may be needed.
The advantage of the hairdryer is the very dry hot air that will effectivly blow away the moisture.
My V4 has a very rusty chassis which I am sure I mentioned very early on in the thread, the scan coils had "green Spot" and were duff also the lopt only gave 4.5kv eht due to saturation but after cooking the transformer give 9.5kv and is stable after 8 hours of use.

Wow, I bet you feel hungry now with the tranny smelling of roast turkey. Brill
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Last edited by murphyv310; 20th May 2010 at 7:44 pm. Reason: Added a Joke!
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Old 20th May 2010, 7:51 pm   #587
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Default Re: Pye v4

Knew that clock movement and stand had a purpose..... I tell you the loft is so hot now, so got to get a Velux put in, next job.

MMmmmm LOPT and roast pots with pitch gravy
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Old 20th May 2010, 7:58 pm   #588
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Default Re: Pye v4

Chris
Ideal, the loft is a great place anyway they get so hot in the summer and the tranny could well dry out even being in there during the summer!
I am sure the set will make a great account of its self now.
I will be on the look out for another tube for you and I am sure others here will as well.
Don't forget I have a spare VT4 chassis if you need the droppers.
The very best of luck to you.
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Old 20th May 2010, 11:23 pm   #589
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Default Re: Pye v4

A bit OT but I would stick a skylight each side Chris. This will allow air to blow through when needed. Both my windows are at the front one above the other (MOE at bottom, centre hinge at top) and I am planning on fitting a third at the back (centre hinge) as it gets really hot up here & it's my main room. It's boiling now & both windows are open on the 2nd catch. Good for the tellies though as you say, Trevor. I bet it gets cold in winter though, as I don't see any ceiling boards in your photos?

I used Wickes' roof windows and they are just as good in my opinion but less than half the price of Velux.

Looking forward to seeing the results of the drying out process on your LOPT.


Brian
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Old 21st May 2010, 9:53 am   #590
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Default Re: Pye v4

How did you get on Chris - any improvement?
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Old 21st May 2010, 10:24 am   #591
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Had to stop yesterday evening as the little lads bedroom is below and the hair dryer noise was keeping him awake. Restarted the process this morning should be finished at 12 noon then will have to let it cool so expect an update around 3:30pm.

I wish I had discovered this problem at the early stages like you, as I have invested a lot of time and components in this set, one of life lessons I will leave sets on longer to discover this sort of issue sooner from no on.
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Old 21st May 2010, 12:11 pm   #592
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Default Re: Pye v4

I think this is one of those tricky catch 22 problems Chris as I see it! As you have to do a fair bit of work to a set to get in running condition with fair vision on screen and then only do you find this problem when you start to run the set for longer periods! It amazed me what a fantastic improvement I have got on the Pye VT2 I have run it hours and hours now and it just does not lose focus or EHT any more. After drying the lopt out with a heat gun! I will be interested how the hair drier fairs as that's maybe a slightly less intense heat! I got the pitch well smoking on mine!! And re melted it all round I think with a pitch covered damp stored chassis you are maybe always going to find this problem. However I did an Ekco 205T that had a very rusty chassis but no problem at all there with this damp lopt problem. As John W. says there lopts seem immune to this problem and are not pitch covered.

Look forward to seeing and hearing your hair drier results as I have some more Pye set to restore which looking at them are bound to have this problem again I feel!

Kevin.
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Old 21st May 2010, 12:22 pm   #593
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Default Re: Pye v4

Right stopped now the lopt was under a constant 77C heat for 2 hours 35mins

Problem is two of the flat waxy 100pF caps under chassis have lost all their wax, will this stop them from working? don't see why it should.

Now wait for the cool down, not expecting this to work though.

Chris
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Old 21st May 2010, 1:43 pm   #594
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Default Re: Pye v4

encouraging results,

Switch on, Boost rises to 430V after 30mins it drops and stabilised at 412V whereas before the heat treatment, it was dropping to between 375V-385V in under 15 mins. Running for over 40mins at the mo

I think a few more applications of this heat treatment may yield rewards

Chris
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Old 21st May 2010, 1:52 pm   #595
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Default Re: Pye v4

Hi OTT
Told you it would work! My V4 is just about bald most of the pitch has gone.
A VT4 I did about 5 years ago that lost all its pitch in the oven was recovered in Waxoyl underseal, its still fine.
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Old 21st May 2010, 1:56 pm   #596
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Default Re: Pye v4

Trevor,

You did indeed, I shall stick it under the heat again later this afternoon maybe for longer, If I can take the heat that is. What with the hot weather its blistering up here I must have shed a couple of pounds as I did not want to leave it unattended.

Chris
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Old 21st May 2010, 3:49 pm   #597
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Default Re: Pye v4

Second heat treatment underway, this time coming at it from the other side.

This time I decided to put a deflector plate at the other end of the LOPT housing, in effect this bounces the heat back which inturn hits the incoming air and should create a nice hot centre core. At the centre point I have some heat shield tape protecting the EY51 also to stop heat escaping, in through this I have the temparature monitor, this is showing a constant of 76C

Chris
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Old 21st May 2010, 8:22 pm   #598
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Default Re: Pye v4

This is obviously getting better after each treatment, but it's going to take a few more attempts.

3 hours of heating, results are 457V boost dropping down 420V and stabilised. It then occasionally dips and climbs.

Not as quick as the heat gun or oven but it's another option.

Chris
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Old 21st May 2010, 8:31 pm   #599
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Default Re: Pye v4

Hi OTT.
Why not stop now and let the natural heat in the loft do the rest of the work.
The small tail off in boost volts now proves that most of the "water" is gone and a few long runs with the set on should rid the LOPT of the last residue of moisture
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Old 22nd May 2010, 12:25 pm   #600
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Default Re: Pye v4

As usual with this PYE one step forward two steps back.

Decided to switch on to run it for a while today, nothing, no heaters etc..... turns out my dropper lash-up had failed, adjusted the tappings back to the remaining good section, so now back on 220V

Powered up this time test tone heard but not line whistle/picture. Checked the EY51 no glow, the PY81 however was VERY bright, switched off straight away. Unsoldered the EY51 and checked the filament, this was ok.

I now fear the worst, could this mean the LOPT has developed a S/C

Chris
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