Ferguson 3645 16" 1400 chassis.

[Heatercathodeshort]

Following on from the interest with the BRC 1500 chassis I have now added its big sister the 1400 dual standard chassis. [A proper telly..]
This was produced from 1967 and replaced the popular 950 series flat chassis that was a great success. The visual similarity to the later 1500 single standard series is very obvious but all marital links end once you have swung the chassis open. The position of the top cap of the PL504 is interesting and certainly kept you awake if it was late and you were becoming dozy.....
The 1400 series is a fully valved receiver except of course the transistor UHF tuner that will be found in either rotary or push button form. The system switch is cleanly operated by a solenoid that is switched out of circuit once the system change has taken place. Access for service is about as good as it gets. All components are to hand and it takes only seconds to remove 90% of them with a flash from the soldering iron. The valve line up is rather strange but very reliable. By 1967 Thorn had acquired Mazda through their acquisition of A.E.I. Their long term contracts with Mullard were obviously brought to an end but this left them with a slight problem. The Mazda range did not include a modern video output valve such as the incredibly high slope Mullard PFL200 introduced in 1964 and used by most manufacturers. They chose for the 1400 series the aging 6F28 originally employed in the 625 line conversion plinth for the Murphy Astra series. It was a little used valve and suddenly reappeared in the 1400! Another old timer, the 30FL1 also sprang up as line oscillator and sync separator [replacing the other pentode section in the PFL200] in the 1400. This valve dated from the mid fifties and was used extensively by makers contracted to Mazda. Both these valves were very reliable, outstandingly so and fitted very nicely in the 1400 design. The line output stage employs the Thorn 'Jellypot' line out transformer with solid state rectifier tray producing around 16 or 20 kv depending on the type fitted. These early open type trays were not very reliable and tended to break down producing the classic 'rotten eggs' stink so familiar to engineers of the 60's and 70's. If you were following the familiar red Ford Anglia vans used by DER you could often see a couple of these trays trapped by the leads hanging out of the rear doors..The engineers had to return the faulty ones to stores and didn't want the van stunk out! The 1400 in the picture still has this type of tray. If you broke open the paxolin rectifier sticks you would discover hundreds of selenium discs, similar to microscopic Smarties all in series! The later 'solid' type were more reliable and didn't produce the familiar stink upon failure.
Performance was very good with very high sensitivity on VHF/405 capable of pulling in the very weakest of signals. Thorn manufactured very reliable tuners rarely matched by other U.K. manufacturers. Picture contrast was not as high as the earlier 950 series due to the 6F28 video output valve but the reliability of the Mazda valve against the highly strung Mullard PFL200 was well worth the slight loss. PFL200 valves tended to run into grid current on 625 causing the picture to rise in brightness over a 30 minute period. Later versions did not suffer this problem but an annoying vision buzz on UHF was often cured by replacement of the PFL200.
The UHF performance of the 1400 was good but high contrast settings caused sync crushing caused by too high a sync coupling to the sync separator 30FL1. This could be completely cured by halving the value of the coupling capacitor. It had no effect on 405 but cleaned up UHF incredibly.
Sound intercarrier buzz was unfortunately a problem with the 1400. Various modification sheets were issued and the final bulletin gave the required data.
A tiny turn on L6 completed the mods and cured the problem for good. Most of the other faults were minor, intermittent preset pots, the occasional PY801 boost diode, S/C heater rectifier diode or the odd exploded mains filter cap all very cheap parts. They were VERY predictable and I used to whizz through a number of them at my 'instant repair bar' on Saturday mornings while their owners waited in the shop in anticipation of 'GRANDSTAND'. Oh it was easy back then!
These sets cleaned up well for resale and could be sold with complete confidence with a written guarantee for 12 months parts and labour. I rarely had a bounce back and many ran for years without a service call.
The pictures show a 16" Ferguson transportable model 3645 complete with 1960/70's dust. As you can see, very little has been done to it in the way of repairs. It was a part exchange around 1978 and decided to keep it. There were very many versions of the 1400 under the Ferguson, Ultra, Marconi and HMV brand names together with the rental specials in all screen sizes and presentations. Often not considered as an interesting receiver today by collectors but fondly loved by most engineers of the 60's and 70's.
Regards, John.

[thermionic]

That looks a great chassis, John. I must admit to never having come across one.
I was given my aunties 950 as a child 'to play with' and spent many happy hours tinkering - finally getting it to work.

I notice you must have a one off on that chassis. I spot a dreaded black Callins in the bottom left hand corner of the chassis - this CAN'T be any good now! They were not much use after a short time in service!

Cheers. Simon.

[Heatercathodeshort]

The picture is the proof! I agree they were very bad but seemed to survive in the 1400 better than the 1500. I'll leave it sleeping..J.

[murphyv310]

OK OK, I'll take one then!!

[Steve_P]

I've got the Ultra version of this. Not powered for ages but it does work. Anyone got a spare VHF tuning knob?

Nice sets.

Cheers,

Steve P.

[Heatercathodeshort]

Originally Posted by murphyv310

OK OK, I'll take one then!!

No your not allowed one. Bin nasty about my beloved 1400 in another thread.
The word has been circulated.. J.

[Heatercathodeshort]

Originally Posted by Steve_P

I've got the Ultra version of this. Not powered for ages but it does work. Anyone got a spare VHF tuning knob?

Nice sets.

Cheers,

Steve P.

Hello Steve,
I have a box of 1400 knobs. No pomises but I will have a look over the weekend. I also have the Ultra version so at least I'll know what it should look like. Cheers, John.

[murphyv310]

Originally Posted by Heatercathodeshort

No your not allowed one. Bin nasty about my beloved 1400 in another thread.
The word has been circulated.. J.

Oh so that's the script is it! Hope your tripler stinks out your workshop na na na na na na

[Heatercathodeshort]

Just to conclude the 1400 I have added a picture taken off screen from live UHF a few moments ago. The transmitter is Midhurst using high channels [ch4ch68] quite a distance away from this location with the aerial mounted inside the single storey workshop roof. It is grain free on three of the channels and only very slightly on the fourth. That is quite an achievement as the signal here is weak and very late sets sometimes struggle to reach this level of sensitivity. J.

[slidertogrid]

A very interesting write up, I always wondered why the 1400 used such a strange valve line up.
I repaired quite a few when I was in my teens and they were old sets even then, I had many a battle trying to cure the intercarrier buzz, some sets were much worse than others I found?!
Your set looks an exceptional example, There can't be many like it left!

Rich.

[Tazman1966]

What a great set John. I'm sure I've seen that one in real life too - nice

[Heatercathodeshort]

Hellooh. My names Julian and this is my friend Sandy.......

As you love 'em so much I brought the pair together for the first time since they sat together on the Thorn production line in 1967. [HMV version on right]
This is fun!
John.

[Heatercathodeshort]

Hello Steve,
I presume it is the channel selector knob you require for your Ultra version and not the fine tuner? I have just cecked my Thorn spares box and discovered this NOS one. The numbers line up with my sets so should do the trick. There may be a slight cosmetic difference but it probably won't notice. Its yours if you want it.
P.M. with your details and I'll drop it in the post. Cheers, John.

[gec2110]

i remember these sets as well my piano teacher had the ferguson version
did these sets have a dotted coating with in the crt?

[Heatercathodeshort]

I'm puzzled by your description. The tubes were standard 16" Mazda types with normal phosphor [monochrome] screens. Under a magnifying glass it may look 'dotted' J.

[dazzlevision]

Hello,

These sets used an unprotected Mazda CME1601 CRT with a plastic "Fenbridge" implosion guard.

The little dots you can see are on the inside face of the Fenbridge guard and prevent an optical patterning effect known as "Newtons Rings", I believe.

Regards,

Dazzlevision

[Heatercathodeshort]

I remember those 'Fenbridge caps'. These two models use the later mk1 rimband tubes. The early Courier 16" [The one with 4 valve heaters in the H.T, line...] did indeed use the plastic cap. [nasty, they went green!] J.

[dazzlevision]

Hello,

Further to my previous post here "These sets used an unprotected Mazda CME1601 CRT with a plastic "Fenbridge" implosion guard", I don't think they did/do, but used the Rimband protected CME1602.

Maybe the set referred to in an earlier post that had these little "pimples" was the earlier 16" version of the 950 series chassis, which could be confused with the later 1400 chassis equivalent (as they looked quite similar)?

Regards,


Dazzlevision

[Heatercathodeshort]

That is the modified 950 with four valve heaters in the H.T. line. Ferguson Courier MK1. From the top of my head I think the model number is 3638 but that might be incorrect. J.

[murphyv310]

Hi.
I seem to remember these "fenbridge" caps on other sets, British Relay used them on some of their sets but what other off air sets used them?