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New CTV haul: The magnificent 7

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malcscott
(@malcscott)
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The best way is to remove the pbu and carefully clean the contacts and tuning pots with servisol and an old toothbrush. Check the afc defeat switch on the back of the pbu, Malc.

 
Posted : 26/08/2018 5:11 pm
Lloyd
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Them Mk4’s are damn good sets! I’ve still got the teletext one I found left in the car park at the NVCF, mine also has temperamental tuning which will randomly go off tune without warning, and the remote version is a pain to retune... 

regards,

 Lloyd 

 
Posted : 26/08/2018 6:34 pm
crustytv
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Posted by: malcscott
Check the afc defeat switch on the back of the pbu, Malc.
The AFC switch is mechanically operating in as much as it makes and breaks contact depending on the door position.
 
Its a strange fault, once you have the channel locked you only have to tap the front panel, flex it or touch the tuning stick, to send it off lock, also tapping the tuner on the PCB does the same. This is the same for all channels 1 thru 8, the varicap tuner is very clean, no tarnishing. This is very reminiscent of the tuner fault I had on the HMV 2725 which turned out to be a faulty ELC1043 which was cracked/bad earthing, resoldering did not fix that, replacement did. Tapping that set in a similar fashion would cause the same effect as this one is displaying.
 
tun1

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Posted : 26/08/2018 6:48 pm
Red_to_Black
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Nice one Chris ?  glad you fixed it.

 
Posted : 26/08/2018 6:52 pm
Jayceebee
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Posted by: Chris
This is very reminiscent of the tuner fault I had on the HMV 2725 which turned out to be a faulty ELC1043 which was cracked/bad earthing

The button unit on the 2725 was also prone scratchy/int tuning, the same type (Preh?) was also fitted in other non remote 8800 and 9000 models. In DER we had two types of cleaner, Amberlube and Genklene the latter being a solvent. It was common for the field engineers to use the wrong can and turn the button unit into a gooey mess rendering it useless.

 

John.

 
Posted : 26/08/2018 9:24 pm
mfd70
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The Mk 4 8 way tuner is pretty rough, a squirt of servisol and a good thrashing would sort it out for a few weeks, but a strip down and cleaning the contact strips with isopropanol was eventually required. 

A few sets rented out to cable only subscribers had a plate fitted over the tuner buttons, I'm saving it in case I ever get a 20" non-remote Mk4 that I can covert to HF only operation.

 

DSC005260001

 

 
Posted : 26/08/2018 9:37 pm
Red_to_Black
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The tuner was also "tappy" according to Chris so still worth a reflow/resolder of the Earth lands in it, agree though that the button unit was touchy at the best of times, or at least by the time we saw these sets, and a complete strip down and clean was usually necessary, even then not all were successfully "cured". 

 
Posted : 26/08/2018 10:02 pm
Jayceebee
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Hi Baz, my post was basically a warning about what could happen if the wrong kind of cleaner was used to clean the switch bank. I agree the tuner may benefit from reflowing the connections and earth legs, I'm not sure about the U321 that may be fitted but the later U341 which I encountered in other chassis seemed pretty reliable.

John.

 
Posted : 26/08/2018 10:46 pm
malcscott
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These are a Preh pbu. A good soak with switch cleaner should improve it. The UHF tuner is a Mullard U341 if i remember. It has a take of point for the pre-scaler on the r/c text versions. I should have these in stock, Malc. 

 
Posted : 26/08/2018 10:49 pm
crustytv
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Looking through my stores whilst doing a tidy up, I found a brand new tuner control unit complete with twiddle stick. Unfortunately its the single band type not multi-band as fitted to mine, still I now have a twiddle stick for my MK4

tun

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Posted : 28/08/2018 11:39 am
crustytv
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Got to hand it to Pye/Philips, the 1980 K30 chassis in the 56Ks1060/05T is still capable of giving a great picture, tube is very good. Amazing to think, even these sets are now 38 years old!

pyetcf

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Posted : 04/09/2018 4:16 pm
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malcscott
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One of the best sets made.

 
Posted : 04/09/2018 5:10 pm
Lloyd
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I really wish I’d kept mine!! I remember when we got it my Dad helped me splice a new mains lead onto it, then we all stood back and poked the power button with a stick! It fired up and worked first time, picture was a little dim, but still good enough, I had it in my bedroom for a while with a Hitachi video recorder, I was only 10 at the time! 

I remember when you switched it off the picture would disappear and then a ball of colours would quickly flash up on the screen, for some reason that always amused any of my friends when they came round. Does yours do that Chris?

Regards,

 Lloyd 

 
Posted : 04/09/2018 6:23 pm
crustytv
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Painted and finished the replacement back for the Fergy 3712. As a finishing touch and to reflect where the set came from, I attached a label to the back. This card was found inside the set, the TV hailing from Metervision in Bournemouth.

newback
bk2

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Posted : 04/09/2018 6:56 pm
crustytv
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Posted by: Lloyd

I remember when you switched it off the picture would disappear and then a ball of colours would quickly flash up on the screen, for some reason that always amused any of my friends when they came round. Does yours do that Chris?

I can't say I noticed that Lloyd.

 

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Posted : 04/09/2018 7:05 pm
RichardFromMarple
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in the 1980s my Aunt & Uncle had an older set in the 1980s for their back room, where the screen would fade into a ball of colours.  Me & my cousin like to turn it off to see it.

IIRC it was ex-rental, & my Grandad later had it when he moved closer to them.

 
Posted : 04/09/2018 9:29 pm
crustytv
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Oh dear, the 9800 CRT is looking a bit pooped  https://www.radios-tv.co.uk/1978-ferguson-3749/

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Posted : 09/09/2018 3:09 pm
Red_to_Black
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The Delta guns boosted a lot better than the later PIL tubes, the AXX540X and later tubes never really boosted well at all.

We tried boosting the A56/66 540X (30AX) early doors and they often fell flat again before our very eyes within minutes.

We quickly learned there was little point attempting this endeavour, the earlier 20AX types faired a little better, the delta guns normally responded well most of the time.

We had (still have) the BK 467

 
Posted : 09/09/2018 3:19 pm
crustytv
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With a little assistance from the B&K, it has a second life.  ? 

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Posted : 09/09/2018 3:31 pm
Red_to_Black
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I suppose the good thing now as where a set is part of a collection rather than used all day every day is that the boost is more likely  to "hold" than in days gone by ? 

I have a feeling I am preaching to the converted ? 

 
Posted : 09/09/2018 3:39 pm
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