Ultra 6807 BRC 1500

[Mazda Man]

Had a little bit of time today to open up the Ultra 1500 and see what can be done to get it going again.
Quick check with the meter showed no continuity across live and neutral at the plug. The rotary on off switch is OC across the neutral pole. Anybody got a rotary switch going spare? amount of this stuff i chucked out years ago!
For test purposes I linked out the switch but set still dead. Closer examination showed the PL504 valve was cracked right around the base. When i removed it it fell apart. So replacement ordered on ebay!
However the valve base is very corroded see pic. Im not sure that I can clean it well enough to make it reliable. Not sure why its like that as the other valve bases look ok.
Has anybody here got a scrap chassis with a ceramic PL504 PC mount valve socket or know where I could source one?
Thanks, Dave

[Heatercathodeshort]

Yes they certainly did! I Have a couple that are practically bald! J.

[AC/HL]

I have a valve base here, you can have for the postage. It's a different shape, but it is a B9D. PM your address if you want it.

[AnalogueMatty]

The first set I ever owned was a later model Ultra 6823, bought from a flea market back in 1995 when I was 20 years old. It was my only set for the next 18 years and was fantastically reliable, only needing repair to the tuner latch when the return spring plastic collars broke up ( the right size washer does the trick !) and a new double ( by god to they stink when they go !) . Since acquired an identical set in much better condition, plus a HMV with the same chassis and beautiful teak cabinet. I have it set up in my living room next to whichever colour set I own at the time, still watch it regularly and love it to bits !
Re. The legs, I adapted a set from an old coffee table to fit my HMV set. Good luck with yours, Regards, Matt

[Welsh Anorak]

Hi
I THINK I've got a NOS rotary switch in the drawer. I'll have a look on Tuesday when I'm in the workshop and let you know.
Glyn

[Welsh Anorak]

Hi
Yes - I have an NOS rotary switch. PM me if you'd like it for the cost of postage.
Glyn

[Mazda Man]

Thanks AC/HL for the offer of a valve base, I have now managed to get the original cleaned up using some small needle files and contact cleaner so hopefully all is well with the original base,
Welsh Anorak, thanks for the offer of an on off switch, I still need that so will give you a PM to sort out postage.
But having got the set powered up for a short while the EHT tray has now failed. Its the 3 stick 15kv one. anyone here got one to sell as i'm in trouble without one.
Thanks

[hamid_1]

You might be able to repair the failed EHT rectifier unit. See this page for an idea:

https://www.radios-tv.co.uk/brc-2000-tripler-rebuild/

This assumes you can open up your old one. Some were filled with resin, making repair almost impossible, but others have a plastic case that is just clipped together. These can be forced open and repaired by replacing the diodes and capacitors with modern equivalents, as described on the above website.

[Focus Diode]

A request for one in the"Wanted" section should help. I was able to get a new "old stock" RS one a couple of years back, but physically proved incompatible with the Thorn 960 portable I have when adapting it to take a 1400 LOPT when the original failed.

As one good turn deserved another I passed it on to someone else who was also looking for one.

As for your set, it looks as if a lot of work and patience will be needed, but will be well worth the effort as you'll be rewarded with a most reliable set.

Seeing the original doubler failed I would check the setting and condition of the width control and its series resistor (if you can the control can be replaced by a 2M2 control and 680k series resistor- as recommended with the 1400 series).

Your width control and series resistor might have changed value and re set during the sets history which will shorten the life of the doubler considerably, especially an older one.

The boost voltage should be checked at the boost capacitor which can be done without the doubler connected. If found high, reset using the width control to the correct level or slightly under.

[Mazda Man]

Thanks for reply focus diode. Indeed the 680k resistor in the width network was completly oc. It was once I replaced it that the doubler failed, pretty quickly too. Shame as the picture was looking quite promising by then apart from a hum on the sync causing badly bent verticals. I have posted in the wanted section but as yet no response.

hamid 1, thanks for the link for repairing the doubler but mine's potted in with epoxy resin so not repairable.

Will keep looking for a doubler so I can get this set finished.

[Tazman1966]

I think I have a couple of Thorn 1500 EHT multipliers lying around but I'm not sure whether they're 3 stick or 5 stick. I'll check soonish and let you know....

[Mazda Man]

thanks Tas, look forward to hearing from you if you can locate one )

[Boater Sam]

Decent paint stripper will destroy the epoxy, the box may survive.

[Welsh Anorak]

Hi
Not heard if you still need the switch. Mind you, the doubler is more pressing I imagine!
Glyn

[Mazda Man]

Thanks Glyn, will give yo a shout once ive got the set basically going. Ive found a doubler now so thats good news.

[Mazda Man]

Ok, so i have been lucky enough to locate a NOS doubler and got the set up and going but now got a fault with the sync / video amp see picture attached.
Basically looks like a large hum bar which is static and very poor sync. the video signal looks very distorted at the collector of the video op tr.
HT2 looks to feed the video and sync circuits. It has about 25v of ripple which did not seem to far off. C38 which replaced C88 in the smoothing block checked. This should be easy to sort but had an hour on it this evening and locate where the hum is coming from. any ideas anyone?

[flyingtech55]

Isn't that the S/C rectifier in heater circuit fault...or is that the 1400?

Tim

[Heatercathodeshort]

Probably the electrolytics in the LT smoothing circuit at the bottom end of the mains dropper 317 ohm section being O/C. They may be the black unreliable type.
Failing that a section of the main electrolytic may be O/C but as the picture size looks about right I suspect the former. Also check C12 100uf and C38 12uf. Looks to be a good CRT. Interesting. Regards, John.

[Mazda Man]

Getting there now! Thanks John for your tip, you were spot on. Ripple was on the LT line to the signal stages, one of the decoupling caps off the 317R Section was actually dry jointed rather than faulty. Had to clean the leads up to get it to solder properly. Few more tweaks needed and an on off switch and we are there.
Really looking forward to watching something on it now

[Heatercathodeshort]

Great result! What is all this foo foo about 1500s not having good pictures?
Regards, John.