Ultra 6807 BRC 1500

[Mazda Man]

Evening all,
Im new to this forum but not new to TV collecting having around 200 sets to my name.
Recently getting the itch to add late 60's and early 70's sets to my collection as they are pretty nostalgic from my early days of Tv tinkering in the lat 70's and early 80's .
so I found this Ultra near to me. Saved it from the local tip which is where it was heading. Had the same owner from new and still had a 2 pin 2 amp plug fitted. apparently it broke down 16 years ago and has sat around since then.
A quick power up showed it to be completely dead so I assume the dropper has an oc section. will take a more in depth look when time permits.
Im trying to establish the release date for this model to see how early it was in the life of the 1500 chassis. Does anybody have the release date? Im guessing around 71?
Anyone got some period leggs or a stand to go on it?
Will post up some pics when I get it fired up again.

[Tazman1966]

Amazing how many Thorn 1500's have survived. Good bread and butter sets - not the best performers but pretty reliable. Enjoy the restoration

[Philips210]

Originally Posted by Tazman1966

Amazing how many Thorn 1500's have survived.

Hi.

That could possibly be due to the excellent jelly pot LOPTs that BRC sets used.

Great for servicing were the 1500 and the d/s 1400.

Regards
Symon.

[Nuvistor]

They were not the best performers but they were rented in large numbers by the many Thorn rental shops, probably many more than other makes so that and I agree about the LOPTX will probably be why there are more around.

Generally very easy to fix as well.

Frank

[Philips210]

Originally Posted by Mazda Man

Does anybody have the release date? Im guessing around 71?

Hi

There is a reference to the 1970/71 Radio & Television Servicing book for the Ultra 6807. Those books were slightly out of date so as a guess the release date could have been possibly late 1970.

Regards
Symon.

[Nuvistor]

I would have thought they would have been available for the start of all UHF service in late 1969.

Is it dust or as the line output valve lost its vacumn?

[Philips210]

Hi.

I have a 'transportable' Marconi 4803 (BRC 1500) which uses the 17" Mazda Gold Star tube and that set displays an exceptionally good picture. I think the 17" tubes were longer lived than other screen sizes.

Regards
Symon.

[Philips210]

Hi.

The 1500 did have quite a long production run, about 6 years as I recall. I think the last ones ceased around 1976. The latest ones would have had a varicap tuner.

Regards
Symon.

[Colourstar]

Always good to see another of these getting some tlc. I really like them. Yours looks in pretty good nick under the dust. Well done for saving it. I recently restored a 1500 from a real basket case and it's now in daily use. Well worth the effort, although I needed to replace all the transistors on the IF strip in mine. I think on the whole they perform well, although the state of the crt can have a big effect. Hope yours is OK.

200 sets? Blimey. I thought I was bad at a mere 25....

Steve

[Andrew2]

We bought that very model when I started work at a local TV shop in mid 1970. I believe they were fairly new at the time. ISTR seeing them arrive at the previous shop where I worked briefly in late 1969.

[MALC SCOTT]

The first 1500 chassis set i ever saw was in 1969.

[mickash]

Hi Mazda Man,

There should be some clues to the production date of your set. The cabinets were usually date stamped somewhere inside, you might need to hoover out the dust to find it. Capacitors were often marked with their production date, especially the main smoother. There might be the odd sticker or two giving a date ie. 2/72 for Feb 1972.
I was surprised to find that my 1500 was dated to 1977. I thought that they had been discontinued before then but I believe that Thorn had had problems with the sucessor 1600 chassis.

Michael.

[Heatercathodeshort]

These are really great television receivers. All the faults are 'stock' so you will definitely get it working. John.

[Heatercathodeshort]

These are most of the stock faults relating to the Thorn 1500 chassis taken from notes I made and kept inside the light brown service manual.

Dead set, mains fuse blown: Mains filter capacitor S/C.H.T. rectifier S/C.

Dead set, fuse intact. Heater section of mains dropper O/C. [Very common] PY801 boost diode heater O/C and not unknown with Mazda 'Gold Star' picture tubes, O/C heater.

Bright raster. no sound or vision. valves glowing brightly. Serious over running: Heater rectifier diode S/C. A disaster if the customer left it switched on...

Very dim well focused raster with brilliance control inoperative. Faint 'wispy' picture: CRT open circuit internal cathode connection. Can often be temporarily cured by tapping tube neck. Very common with Mazda Gold Star crts.

Poor tuner reset: Push bar on tuner dry joint or adrift.

Intermittent loss of signals or failure of local oscillator in tuner. Will work if stations changed: Grease on tuner rotor earthing clips. Clean with great care or replace with double silver plated type as was supplied by Thorn in the 70's.

Poor sync, clean video: 47K resistor to screen of sync separator 30FL1/2 O/C.

Poor sync, smeary picture: 64uf [Use 100uf] video coupling cap leaky.

Various overheating with very hot dropper: Replace ALL black Callins capacitors on chassis. These decouple various HT and LT lines and can give some odd results.

No signals with reduced raster size: 317 ohm section of mains dropper O/C.

Intermittent frame collapse: Connecting tags on frame output transformer dry joint to P/C board.

Frame collapse with 'wavy' line: Check above, connections to scan coils and the small thermistor within the coils for O/C.

Frame cramp: Cathode bias resistor to frame output valve high or low. 160uf bias cap O/C.

Jittery height/lin: Replace height and both linearity presets.Jittery width: Boost/Width preset.

Focus control inoperative: 1.5M resistor from boost rail to focus preset O/C. Also check the preset itself.

Slight cramp in center of raster: 39K anode load to line oscillator high in value.

No sound/video: Video driver transistor U/S. With volume on full a forein radio station can sometimes be heard.

Low picture brightness with high contrast Decoupling capacitor to CRT A1 S/C to HT line.

Cramp in center of picture: 'S' curve correction cap .1uf C90 S/C.

Line output stage overheating possibly with boost diode anode glowing: 3rd harmonic tuning cap C95 S/C. typically 160pf but may vary.

Rotten eggs smell: Early open type EHT rectifier tray broken down. Not so common now due to solid type supplied as replacement.

Lack of height/width: Check generally high value resistors in width stabilization circuit and R123/R93 in anode supply to frame oscillator.

That is about it with the 1500. By my notes it appears to be an unreliable chassis but the reverse is true. If all the above items are replaced the cost is very small and will make the chassis very reliable. I sold these from September 1969. [Marconi 4800] and experienced all the early running in faults. The Thorn technical service came joint top with Toshiba so I never had any sleepless nights. I continued to sell them reconditioned well into the colour era and were very well liked by customers. RIP British Radio Corporation as It was known by service engineers. Regards, John.

[Heatercathodeshort]

An amazing number of variations of the Thorn 1500 were produced. Cards relating to the various models covering the cabinet and presentation parts were issued for inclusion into the main manual.
This is the one for the Ultra 6807 dated may 1971. J

[AidanLunn]

The Thorn 1500 was produced in very large numbers (at their peak IIRC one every ten seconds and a mathematical average of about a million a year) over a long time (1969-1977/early 78) by a large company that manufactured a large share of TV sets in use in Britain, greatly helped by a large share of the TV rental and retail sectors. They were popular for people who wanted UHF/625 but without having to pay for a colour licence (or "BBC2 on a budget" as I called it), for which there was large demand. It was also well liked by the TV servicing trade for reliability and ease of service.

Result? A very popular (in terms of numbers) TV chassis.

[Mazda Man]

Thanks to everyone for their feedback on this set, and John for all the stock faults you have posted up.
This seems to be an early version of the 1500, which is great. I wasn't sure if the early versions of these sets had a 19" CRT fitted, or if all 1500s were either 17, 20 or 24 inch.
I have ordered a dropper, which is due next week, then its time to get the set vacuumed out and the fault finding to begin!

[Heatercathodeshort]

The 1500 series did not use a 19" [or 23"] tube. The 20" tube became available in 1967/8 [ITT A50-10W] and was widely adopted by all manufacturers. Sadly the Mullard 20" and 24" tubes did not hold up as all their previous tubes had done.
They soon went 'soft' giving poor picture quality, then settled down to give a lack lustre picture. The getters were tiny and probably contributed to this disappointing situation.
The Mazda Gold Star tubes gave a fantastic picture but suffered from bad spot welds resulting in O/C heaters and cathode connections, something they had suffered for very many years. Oh well, all history now. John.

[jayceebee]

I've always wondered why Thorn opted for a 16Kv doubler in the 20", I can understand it being used in the 17" models. My parents owned an Ultra 6656 which was a 19" model 1400 chassis which was a 20Kv tripler version. I seem to think they were listed in the brochure as an "Increased Brightness" model and it did give a good, bright, sharp picture. This particular set resolved the 5.25Mhz test card gratings with ease, never saw that on a 1500 with it's printed IF coils even on a 20Kv 24" model .

Up close the Mazda CME1913R CRT and other types had a sort of yellow/blue phosphor which I thought was better and finer than the type Mullard used. Later replacement 20 and 24" CRTs came from the Eastern bloc, some of the phosphors used were dreadful, certain CRTs gave a picture which could almost be described as sepia.

John.

[Tazman1966]

Towards the end of the production run of the 1500, Thorn started to use "Unitra" branded CRTs imported from Poland (I think). A late model Ferguson 3821 used one. I no longer have this set though.