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The Yorkshire Rediffusion MK1 CU2213

 
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The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 2:31 pm

Hi all,

Well at last I've dug out the Rediffusion MK1 and managed to give it a once over.

Generally the cabinet is OK on the top and right hand side but the left hand side is quite poor, I think the set has been sat on end in storage and dragged around on it too but I should be able to sort the finish on it at a later date.

Removing the back everything at first glimpse looked to be OK but looking closer the 6 pots on the right hand side of the convergence board look like they've suffered from damp and have a lot of white around them.

Next I snipped out the mains filter cap and applied power.... Nothing. The fuses were checked and found to be fine the trip however does not have continuity and does not reset, possibly another victim of damp.

So that's it for now until I find a replacement trip.

Marc.
DSCF3446 forum.jpg
CU2213

DSCF3447 forum.jpg
All looks as it should at first glimpse

DSCF3452 forum.jpg
Pots don't look too healthy on the convergence board

DSCF3456 forum.jpg
The offending trip has no continuity

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Tue Oct 13, 2015 2:37 pm

The trip works in two ways, ht shorts and beam current limiter. Short out the o/c section will be ok. Later psu have the trip removed and a fusible resistor fitted in cct, Malc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 3:11 pm

Hi Malc,

Thanks for that info, I have to confess that working on a CTV is all new to me.

Right, trip bridged and power on, valve heaters lit but not much else happening.
Powered down whilst I fetched my DMM and organised the 'stock fault list' then re-powered to do some voltage checks but this time up came sound hash followed by green raster.

Marc.
DSCF3457 forum.jpg

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Wolfie » Tue Oct 13, 2015 3:12 pm

Those trips can be given open can surgery, the little tabs just bend up and Robert is yer mothers brother..
I'm sure a man of your calibre would soon see why it doesn't perform.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 3:17 pm

Wolfie wrote:Those trips can be given open can surgery, the little tabs just bend up and Robert is yer mothers brother..
I'm sure a man of your calibre would soon see why it doesn't perform.

Hi Wolfie,

Was already thinking on those lines :qq1

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 3:26 pm

Hi all,

Just tried putting signal into the set and.....
DSCF3461 forum.jpg

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Tue Oct 13, 2015 3:51 pm

Looking good, on the RGB panel are 3 drive pots. Remove these and fit shorting links. This was an official Rediffusion mod. If the convergence panel still has the 3 beam switches fitted, remove these and fit shorting links. Let it run for a few days and crt should wake up ok. Malc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 4:41 pm

Hi Malc,

As it turns out the green drive pot had already been shorted out but not the red and blue pots which were falling apart, anyway they have now been removed and shorted
The 3 beam switches have already been removed in the sets past.
Powering the set up still gives a very green picture so to be on the safe side I checked the CRT and it looks good on all three guns.

Marc.
DSCF3473 forum.jpg
The two remaining pots were not good, now shorted out

DSCF3476 forum.jpg
Still very green

DSCF3468 forum.jpg
CRT test looks good

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Jamie » Tue Oct 13, 2015 4:45 pm

Well they're always banging on about eco-friendliness... Seems they had it back then! :aad

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Tue Oct 13, 2015 5:06 pm

Check the 680k next to the A1 pots.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 5:47 pm

malcscott wrote:Check the 680k next to the A1 pots.

Sorry Malc, A1 pots ? are they the pots I removed if not can you give me the 'r' number please.

Apologies if it's a dum question but I am starting almost from scratch here. :ccg

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Cathovisor » Tue Oct 13, 2015 5:49 pm

If you're removing drive and A1 pots.... how the h*ll do you greyscale it? :aaq

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Tue Oct 13, 2015 5:54 pm

The A1 pots are on the convergence panel at the top of the set. The drive pots are on the RGB panel. Malc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 6:15 pm

malcscott wrote:The A1 pots are on the convergence panel at the top of the set. The drive pots are on the RGB panel. Malc.

Cheers Malc, I must learn the terminology :ccg
Back to the plot... 680k is O/C so off to rummage for another.

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Tue Oct 13, 2015 6:24 pm

A 1meg will do if your stuck.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 6:46 pm

malcscott wrote:A 1meg will do if your stuck.

680K found, back after tea. :)

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Tue Oct 13, 2015 7:15 pm

OK 680K fitted
This time picture is very dark almost black with highlights breaking through followed shortly after by smoke, sorry to say I couldn't see where it came from and I can't see any heat damaged components.

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Refugee » Tue Oct 13, 2015 8:45 pm

There are blue tants on that RGB board and some red ones too.
I would check them once all the obvious tatty components have been checked/changed.
They look like C304 and C305 on the green drive but I can't see the other four.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Wed Oct 14, 2015 12:15 am

If the trip is also o/c or int o/c on the bcl side, it will destroy the two transistors in the bcl cct and the bcl pot on the rgb panel. Also replace the 100mfd cap on the eht tower next to the PL509 base, check the 1k next to it, Malc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Wed Oct 14, 2015 12:40 am

malcscott wrote:If the trip is also o/c or int o/c on the bcl side, it will destroy the two transistors in the bcl cct and the bcl pot on the rgb panel. Also replace the 100mfd cap on the eht tower next to the PL509 base, check the 1k next to it, Malc.

Hi Malc,

I did manage to repair the trip earlier this evening, just dirty contact.
I'll get to the 100mfd & 1K tomorrow.
One thing that caught my eye whilst closing up the set for the night was what appears to be a very fine hairline crack near the base of the PL509 running up the glass, I've tried to get a photo of it but it doesn't show up, it's difficult to see with the naked eye but it's there. I'm guessing the valve still has good vacuum as it still glows and hasn't started going white but never the less it will need changing.

Marc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Cathovisor » Wed Oct 14, 2015 5:40 am

marc wrote: I'm guessing the valve still has good vacuum as it still glows and hasn't started going white but never the less it will need changing.

When it starts glowing lilac/blue you have a problem.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by Refugee » Wed Oct 14, 2015 11:15 am

A quick test for a valve like that is to take it out of the set and feed the heater with 24 volts or whatever the heater voltage is and measure it with a diode tester.
It may well just be a mark on the glass.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Wed Oct 14, 2015 1:39 pm

Hi all,

As Malc suggested the 100uf cap and 1K resistor at the base of PL509 have been checked and replaced (1K was 1.7K & 100uf was O/C)

Picture still very dark, after a short while hissing can be heard in the EHT tower followed by smoke but I still can't see exactly which component it's coming from in the tower.

Marc.
DSCF3483 forum.jpg

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by malcscott » Wed Oct 14, 2015 3:15 pm

Check A1 volts on A1 pots 550v - 600v. Try adjusting the bcl pre-set rv303 on the rgb panel. There is also a pre-set brill pot on the small t/base panel at the bottom of the set, RV405. Try adjusting it, if the A1 volts are low there is a 220k resistor and a 0.01mfd cap on the small pcb inside the eht tower. Suspect these, Malc.

 
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Re: The Yorkshire Rediffusion MK1 CU2213

Post by marc » Wed Oct 14, 2015 6:07 pm

malcscott wrote:Check A1 volts on A1 pots 550v - 600v. Try adjusting the bcl pre-set rv303 on the rgb panel. There is also a pre-set brill pot on the small t/base panel at the bottom of the set, RV405. Try adjusting it, if the A1 volts are low there is a 220k resistor and a 0.01mfd cap on the small pcb inside the eht tower. Suspect these, Malc.

I haven't done the A1 voltages just yet as I was already looking at the EHT board trying to spot where the smoke was coming before I got your post, however it gave me the chance to check the 220K resistor which was fine but if I've got the correct cap C512 0.1uf 3KV disc type it's reading 0.006uf.

Marc.

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