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Old 4th Jun 2021, 7:40 am   #61
murphyv310
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Default Re: Murphy V659/759 restoration

Hi.
The oil filled transformers were not overly expensive. I worked with British Relay who were big Murphy devotees, they used mostly Murphy equipment in the relay stations for feeding the low frequency line. In fact we even had dry LOPTs for the M19/11 Line sets and Astras that were running 625 lines only, supplied my RBM even up to around 1974. There has to be the odd Astra out there with the Dry LOPT which was very reliable. We fitted Renvu re gun CRTs and these went all over Scotland and into northern England too, good tubes and longer lived than the original Mazda tubes.
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Old 4th Jun 2021, 9:24 am   #62
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Default Re: Murphy V659/759 restoration

I think the problem with the cost of Murphy transformers was the fact that Murphy and other manufacturers refused to supply spares or service manuals to non accredited dealers. Murphy allowed spares to be supplied to non account dealers but they had to be supplied via the local Murphy dealer. The dealers bumped up the price and you ended up paying at least twice the normal trade price for the parts. British Relay would probably have paid a little over cost price for the transformers.

Direct TV Replacements manufactured an excellent open type transformer but they were a very rare bird and I can only remember seeing one example. John.
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Old 4th Jun 2021, 12:59 pm   #63
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Default Re: Murphy V659/759 restoration

Hi John.
Although a long time ago I think I must have replaced a dozen or so oil filled ones with the dry type as I clearly remember the adaptor plates and fitting kit for them. Also some rewiring was required and disconnection of the system switch.
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Old 10th Jun 2021, 6:04 pm   #64
Niechcial,Steve
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Default Re: Murphy V659/759 restoration

I have made good progress on this set. I have managed to shoe-horn the KB VC1 LOPT into the LOPT enclosure with the Valve EHT rectifier in circuit. With S-bend caps of 0.1 mfd (625) and 0.32 mfd (405- 0.22 + 0.1), I get good width and lin, correct boost and no foldover on either system. Apart from the S-bend caps, the only other mod. I had to make was to short out the width control inductor. I have given up on the extra windings I put on the LOPT for the flywheel sync because they were beginning to break down. In any case it works very well on direct sync- better than the original LOPT did by all accounts.
Another quirk of this design is that Frame Lin. changes much more with boost voltage/height than on a set with the more conventional feedback lin. circuit.
After Dave's comments on the sound noise limiter rectifier I put it across my variable power supply, but get no current through it, so it is in fact o/c.
I wonder why Murphy went in for this strange amalgam of part PCB and part hand wired construction? The hand wired IF bit immediately below the PCB sound panel would surely have been more cost effective to produce as a single IF panel?
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Old 14th Jun 2021, 6:10 pm   #65
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Default Re: Murphy V659/759 restoration

Hello Steve. I managed to leave my 659 on for 2 days this week by mistake. I turned off the RF system but failed to see that the main power switch in the workshop was still on!

It had quite a soggy LOPT that reduced the width by two inches after about thirty mins. It is now 100% and testing it for a couple of hours this morning on TC showed no reduction what so ever! It must have got a bit warm..John.
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Old 17th Jun 2021, 9:02 am   #66
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Default Re: Murphy V659/759 restoration

You lucky devil John! My KB LOPT in the 659 starts to reduce width after about 90 mins, but it is much better than it was when I started.
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Old 17th Jun 2021, 9:33 am   #67
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Default Re: Murphy V659/759 restoration

Quote:
Originally Posted by Heatercathodeshort View Post
Hello Steve. I managed to leave my 659 on for 2 days this week by mistake. I turned off the RF system but failed to see that the main power switch in the workshop was still on!

It had quite a soggy LOPT that reduced the width by two inches after about thirty mins. It is now 100% and testing it for a couple of hours this morning on TC showed no reduction what so ever! It must have got a bit warm..John.
Is that the one that I passed onto you John? I'm glad to hear that the "kill or cure" method worked on the ailing LOPT
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Old 17th Jun 2021, 10:05 am   #68
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Default Re: Murphy V659/759 restoration

Yes Tas! I also sorted out the flywheel sync panel. It is a real cracker. John.
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Old 17th Jun 2021, 10:11 pm   #69
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Default Re: Murphy V659/759 restoration

Hi.
Did that with a V410 accidentally John and it recovered too. Maybe put the LOPT on a low cooker and see if it works..... You never know.
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Old 18th Jun 2021, 3:24 pm   #70
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Default Re: Murphy V659/759 restoration

I had one of these in the 70's. Part exchange against a refurbed Ultra 17" 405 only set.
The tube was beyond stuffed, so bought a 'rebuilt tube' well that wasn't much better than the original so back it went and finally the replacement was fitted and gave an excellent display.
At the time Manor Supplies were selling the 625 convertor which as was said in the original post was a complete receiver in its own right.

It fitted outside and underneath the main cabinet if I remember correctly. Ans as posted changing to 625 did require a warm up time. This put off the first buyer but it quickly sold.

Some time later I picked up the 23" version for a song. The tube wasn't brilliant but quite good. I didn't bother with the 625 conversion with this set but just sold it as a 405 line set as it was.

Those were the days. If I only had a fraction of the sets that came my way in the past I would need several life times to restore them.
Good luck with yours.
Quite a few years later I found out that the original set I sold had been dis assembled -sad but that was the fate of so many sets of the period and

continues today with the souless flat screen jobs!

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Old 19th Jul 2021, 5:37 pm   #71
Niechcial,Steve
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Default Re: Murphy V659/759 restoration

Well this is the final product working on 405 vhf with the KB LOPT. It works well on UHF 625 too. It suffers though from width coming in due to deep dampness on the LOPT. I shall now leave it until one day the original LOPT comes back from rewind
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