More BRC 950/960 Problems

[FERNSEH]

The reason for the pulse capacitor running hot is likely to be the properties of the dielectric. Mechanical vibration takes place in the capacitor, between the plates and the dielectric. That's the nature of this kind of component when operating at 15Khz and the high AC currents that exist in line timebase circuits. Nevertheless, it is desirable that the component is replaced.

DFWB.

[Focus Diode]

Many thanks Tas and David. Some tidying is needed such as shortening the extended PL504 anode lead which I'll do once the pulse capacitor is replaced. The 180pF capacitor I fitted is new old stock!

Cheers,
Brian

[Hybrid tellies]

Originally Posted by Focus Diode

As expected the intermittent wobbles and shimmer persist, an entirely different problem of course, I'll look into it another time

Excellent job, I have been avidly following this story. As for the shimmers and wobbles I had this problem on my own Decca Bradford. The fault would clear after the set had been running for 20-30 minutes. Closer observation revealed a glowing blue cloud within the glass envelope of the PL509, this would vary in size and intensity until almost clearing after about 20-30 minutes. With this in mind it might be worth trying a replacement PL504 an/or PY800.

[Focus Diode]

Many thanks Simon. I've already tried another 30FL14 and PFL200. The PL504 and PY801 were new when fitted last November, this of course doesn't rule out the possibility of them being faulty. I'll try replacing them when I find the spare ones. Gently tapping them in situ has no effect on the fault which seems worse on 405.

Cheers,
Brian

[Focus Diode]

...Not forgetting the EF80 of course.

An update- Simon, it looks as if you're right. I dug out a used PY800 and an interesting French Mazda PL504. These were fitted and functioned very nicely with no signs of the horrible shimmers or ragged verticals. The set performed like a monitor. The PL504 gave a nice blue glow as can be seen from the photo which soon faded out after a few minutes.

The last three pictures show the set in action on programme. The first is a typical Macrovision effect from a DVD on 625-lines, taken from an episode of "Van Der Valk". Interestingly the Aurora cancels it out when viewed on 405-lines. The 405 image from "Special Branch", a most excellent 1969 series, shows some dotted interference resulting from the DVD player. Doesn't distract from the enjoyment of viewing.

It's worth noting the dramatic reduction in the intensity of the 405-line whistle with the 1400 LOPT in the set. It was very strong and loud when the original red transformer was working.

Many thanks again for everyone's suggestions, help and support. One doesn't like to assume new components or valves could result in problems and are often the last things to check when tackling a puzzling fault condition!

Next step is to work on a permanant heat shield for above the PL504 & PY800.

Cheers again,
Brian

[Hybrid tellies]

That's great news Brian, it's really cheered me up. That picture does look good. An interesting set well worth the pain and trouble saving.

[Focus Diode]

Cheers Simon. Inevitably the CRT is beginning to show signs of failing emission so would be nice to obtain a replacement in the near future. I'm sure anything from the original CME 1601 (unprotected) to a later Rimband type would be suitable. I'll be putting a request in the "Parts Wanted" section in due course.

I'm also looking for a VHF telescopic aerial to replace the broken one at the back. Although holes for a UHF loop aerial are provided it looks like one has never been fitted to this model.

Cheers,
Brian

[Hybrid tellies]

My friends in Cornwall had one of these sets, no UHF tuner but it would switch to 625. It also had a telescopic rod aerial. In the main two rooms of the house it worked off the main loft aerial but anywhere else it worked well off its fitted telescopic aerial pulling in BBC1 from either Redruth on ch1, North Hessary Tor on ch2 and Westward TV from Caradon Hill on ch12. I think this set was very high gained on 405 but never seen it work on 625.

[KeithsTV]

I have a telescopic aerial from a GEC set I scrapped recently. You're welcome to have it for the cost of postage or I can take it to NVCF on 11th May.

It may need a little fettling to get it to fit though but the telescopic part is complete and comes with a cable and co-ax plug.

Keith

[Focus Diode]

Brilliant Keith, many thanks. I'll be sending you a PM shortly.

Wonderful memories there Simon. The VHF gain is indeed very high, UHF is potentially good though the tuner is faulty in my set, giving low/varying gain on the lower UHF channels but OK from Ch60 upwards. I've set the modulator to Ch64, our old BBC-2 channel. I'll replace it should another turn up in the future. Some models were indeed sold without UHF tuners which could be fitted at a later date. Seeing no loop aerial was ever fitted to mine it's possible it was such an example. There's also no channel markings on the UHF tuner knob!

Cheers,
Brian

[Focus Diode]

No problems with the set to report! Had a look at the broken VHF whip aerial this evening. Unfortunately the aerial kindly supplied by Keith turned out to be unsuitable for the set. Very many thanks again, if you want it back please let me know.

I also purchased a whip aerial at the NVCF event. This again turned out to be too thick to fit through the ball bearing. I found a famous supermarket sell this magnetic telescopic rod intended for retrieving screws etc. For £1 I thought I'd fit it to see how it looks in situ.

24" (60cm) doesn't seem long enough but it certainly has improved the appearance. Here's some images.

Cheers,
Brian