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CTV Ultra 6713 repair

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Jayceebee
(@jayceebee)
Posts: 2027
Prominent Member Registered
Topic starter
 

I must apologise for not posting any repairs recently as although now retired other stuff seems to take up a lot of my time, garden landscaping /drainage project and grandson seem to take up the most although unlike the former the latter is not begrudged.

This afternoon has been quite a stormy Saturday and unusually no GS today so I dug out one of my sets that would hopefully be a quick and easy repair. The set in question is an Ultra 6713 fitted with the Thorn 8500 chassis which I obtained about a year ago. I did take the back off a couple of months ago to inspect it but it was found to be missing it's EHT rectifier tray and focus unit which I had no stock of. Just recently I managed to source said items so lets see how it went.

The smoothers were successfully reformed and after fitting the missing items, changing the two filter caps across the mains the set was powered on. After what seemed like an age a very dull raster appeared, it was quite evident with first light all was not well with the CRT. Surprisingly I found it to be a Mullard A49-120X fitted instead of the normal Mazda A49-191X. I doubt whether it's original and I suspect was swapped some time ago, I don't ever seeing Mullard CRTs in Thorn sets until the AX51 types made their appearance in the 9900 and mono CRTs in very late versions of the 1500 series and portables. Running for an hour didn't help much so the B&K 467 was hooked up and it told me what I already knew that all guns were very poorly. Running with a higher heater voltage was tried then a clean and balance. Unfortunately no significant improvement was gained, in fact it made the blue gun even worse so no other option to try a rejuvenate. This did the trick and a reasonable picture obtained, how long it will last is unknown.

The tuner has the usual plastic rot the repair process of which well documented elsewhere on Vrat and will be done later. Other than a clean of the awful Lorlin/Preh sliders used the set performs reasonably well. The picture did look a bit soft with slight lack of definition and this was resolved by a waggle of the tuner IF input lead to the decoder. Anyone with an 8000/8500/8800 should always give this leads connections a clean when the back is off as the improvement can be quite dramatic.

Below shows a now quite presentable picture with a bare minimum of work needed.

6713

John.

 
Posted : 15/07/2023 9:22 pm
Lloyd, Cathovisor, RichardFromMarple and 3 people reacted
crustytv
(@crustytv)
Posts: 11905
Vrat Founder Admin
 

Nice write up John, and I'm glad you managed to nab some bench time, a rarity for you, I know. Like you, I've not touched its twin, since getting it at the same time, so I've no idea how the set will fair.

p.s.

Hope it wasn't you that paid £100 for the 8500 rectifier tray that sold recently.

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Posted : 15/07/2023 9:32 pm
Jayceebee
(@jayceebee)
Posts: 2027
Prominent Member Registered
Topic starter
 

Posted by: @crustytv

Hope it wasn't you that paid £100 for the 8500 rectifier tray that sold recently.

How much, really? No I did a trade with Chris "The Teleman" for some PCBs I did for him. Unfortunately he is at present recovering from a suspected heart attack, I don't know if you knew.

 

John.

 
Posted : 15/07/2023 9:41 pm
crustytv
(@crustytv)
Posts: 11905
Vrat Founder Admin
 

Posted by: @jayceebee

Unfortunately he is at present recovering from a suspected heart attack, I don't know if you knew.

No I wasn't and OMG! Not another ratter, after Gary. 😮 

CrustyTV Television Shop: Take a virtual tour
Crusty's TV/VCR Collection: View my collection
Crustys Youtube Channel: My stuff
Crusty's 70s Lounge: Take a peek

 
Posted : 15/07/2023 9:50 pm
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