Ferranti 14T4 made in 1954.

[System A]

Last Sunday I drove down to Stockton-On-Tees to collect this Ferranti TV set.
Today I had the opportunity to examine the set. First observations show that the set is in excellent condition. There's evidence that it was in use well into the sixties, the give away is the substitution of the PZ30 HT rectifier with a silicon diode. Let's hope an addition heater supply dropper resistor has been inserted in the chain to compensate for the 52volts demanded by the PZ30.
The third picture shows the silicon diode and series resistor which was added to compensate for the lower forward voltage drop compared with valve rectifier. It begs the question should I find a PZ30 valve and remove the silicon diode?

System A.

[System A]

Follow up to my last post. The attached picture shows the unusual channel selector. The large disc tunes in the Band 3 channels 6 to 13 and the small toggle switch selects the preset BBC channel or Band 3.

System A

[Heatercathodeshort]

That looks a nice one Gary.
I would definitely replace the silicon diode with the original PZ30. I'm not too keen on replacing valve rectifiers with silicon. In most cases when this has to be carried out the original rectifier heater is left in circuit, otherwise it requires a messy addition dropper of around 173 ohms to replace the 52v heater. Good luck with it. Should be basic servicing! [We hope]
I have a 17T4 [17" version] somewhere, given to me by a customer decades ago. It is very clean and tidy but I have never plugged it in. Maybe you could tempt me... 14 screen size T television 4 1954. John

[Peter.N.]

Looks to be in good nick, should make a good restoration. I don't know why the PZ30 has been replaced with a diode either, its a pretty reliable valve, I don't remember many failures. Could be that it was a 'nothing' job and they didn't have a PZ30.

Peter

[System A]

Upon further examination of the chassis I find that there was no need to be concerned about the fact the PZ30 had been removed from the heater chain.
Two Radiospares power resistors had been inserted into the heater chain, the total resistance is 175ohms, the correct value for 52volts @ 0.3amps.
Although the silicon diode and it's associated components had been fitted in a competent manner I believe the set should be returned to it's original specification so I'm on the look out for a PZ30 valve.
So the restoration of this set is held up until a valve is found.

The attachment shows the additional heater chain resistors.

System A.

[Mikey405]

That's rather a nice looking set Gary. I like the large "bevels" (is that the right word?) on the front although that disc / switch arrangement on the side looks a bit industrial.

As for the PZ30, I think I'd be inclined to leave the solid state one in as long as everything worked out okay electrically speaking - but perhaps that's just me - although I wouldn't let that hold up the restoration.

[ms660]

We used to make a coil with a few turns of wire and connect that between the surge limiter and the silicon diode to reduce heat transfer from the surge limiter to the diode.

Lawrence.

[FERNSEH]

Hi Gary,
I've found a good PZ30, it's yours if you decide to remove the silicon diode.

DFWB.

[ukcol]

Those Ferranti sets had a very nice build quality, you can see what I mean in the second picture in post #1.

[FERNSEH]

I regret giving away a Ferranti 17SK6. The set was a 17"CRT console cabinet model and was one of the last TVs to be made by the Moston, Manchester works. From 1957 on all Ferranti TVs and radios were made by E.K.Cole.
Since my last post #8 today, I've found another PZ30.

DFWB.

[System A]

Hi David
Many thanks for the offer of the PZ30 that will be a great step forward in making the the original.
Gary.

[System A]

Collected the PZ30 valve from Fernseh's shop. It's Saturday afternoon and I have some spare time to work on the set.

First examination of the chassis reveals that the wires from the rear mains connector and fuses to the on-off switch are badly perished, strange why the manufacturer used rubber insulation wires because most of the other wiring is PVC?

The attached pictures show the bad state of the wiring. I have some silicone rubber wires of the correct colours and these will be used to replace the old wires.

So today the plan is to get the heater chain working. To play safe I've borrowed a Variac so that the mains supply can be supplied in stages before the full voltage is supplied to the set.

Regards, Gary.

[System A]

Got the valve heaters glowing so the next stage of the restoration will be to reform the HT electrolytics. This will take some time so my next service report will be sometime tomorrow or Monday.

Gary.

[Heatercathodeshort]

Looks much better with the PZ30 Gary. I'll give you a good start then I will open another thread and I will slowly have a go at my 17T4. It will be interesting to see if we have similar problems. Good luck with it. The LOPTS are reliable and if the CRTs don't have partial short circuit heaters, all should be well. Regards, John.

[System A]

Hi John,
We look forward to your restoration of the Ferranti 17T4.
Yesterday, I spent all day on my 14T4. After a considerable long time the output from the variac was finally set to full mains voltage. Pre-empting that there would problems with the boost capacitor C106 and the coupling capacitor C103 to the grid of the PL81 these parts were replaced. After switching on the HT voltage rose to 200 volts falling back slightly after two minutes to 190 volts. A healthy spark is already present at the anode of the EY51 EHT rectifier and as the filament is lit we can assume that EHT is present at the anode of the CRT. But there is no illumination of the screen. I measured the voltages on the CRT base, the cathode was about 150volts, the first anode 260 volts, a bit low perhaps. The control grid volts were low so the tube is cut-off. Two capacitors are connected to the slider of the brightness control and these were found to be leaky, the capacitors are marked as C86 and C113 in the Ferranti circuit diagram. After replacing the capacitors a distorted raster appeared on the screen. All the TCC waxies in the frame timebase needed replacement, see the attached picture of the component group board. The results of this work is a perfect linear raster. A further improvement of picture brightness was secured by replacing the CRT first anode decoupling capacitor C114.
Now it's time to connect up the Aurora standards converter. After finding out that the set was tuned to channel 3 a test card appeared on the screen. Later on the Band 1 tuning was reset to channel 1. As you can see from the attachment the picture is very good, focus could be better and I'm sure after the jammed focus magnet has been released a really sharp picture will be the final result.

Regards,
Gary.

[Heatercathodeshort]

That is quite an amazing result Gary. I suspect this example was still working when 'laid down' to rest, probably in the 1960's. The faults you encountered were probably mostly age and damp related.

Many of these grand old girls simply became obsolete and were finally replaced when the swinging sixties burst upon us and slim stylish [?] models became available. Thinking about it you could have gone straight to colour 1954-1968 is only 14 years!

I will dig up my 17T4 and see if it is viable. Regards, John.

[System A]

This evening I had sufficient spare time to reassemble the Ferranti TV.
The only tricky part of the reassembly after refitting the chassis into the cabinet is the reattachment of the tuning control parts. That done, the set was giving a final test before the card back cover was fitted.
The attachment shows the excellent results the set is capable of now after all the work that has been done to the set.
I've a good feeling about this set and I'm certain the long term reliability will be very good indeed.
More about the history of the set. Very few valves have been replaced during the time the set was use by it's first owner. One Pinnacle ECL80 and an R-F-T branded PL81 were fitted at some unknown date. A replacement boost diode was fitted in 1964. The valve is a Tungsram 17Z3 and has the Mullard date code: B4C3 = 1964 March third week. It would be interesting to speculate how long the set remained in service after the 17Z3 was fitted.

Regards,
Gary.

[McMurdo]

looks a nice bright tube!