PYE TT1 - First Transistor Portable UK TV
 

Good evening

I have just acquired this. Why, because I liked its looks and its very '60s'. All transistors (26) and a valve EHT rectifier. Got it home, adopted the gung ho approach and powered it up. Nice line whistle but no picture. Hooked up the Aurora and there was life, albeit just a thin white line across the screen. So, I think its another one of those sets that doesn't produce a raster unless a signal is present

I was unsuccessful in locating a schematic - there doesn't appear to be a Trader Sheet (not on my BVWS discs anyway) and nothing apparent on the interweb.

So, having worked out how to extract the chassis I noted numerous wax caps alongside the more 'modern' components. They were changed for new ones and some sort of a picture appeared. After various twiddling, the best I could produce was an image (of the Test Card) that was almost a 'negative' in appearance. Switched it off as I noticed one more cap that I had missed. That was replaced and when switching it back on again shortly after it had 'warmed up' there was (and still is) a loud buzzing from the speaker which didn't vary much when using the volume control. It sounds like the sort of interference experienced when an electric motor is running nearby. I have checked for any loose/touching connections and have re-checked all the joints soldered when re-capping.

I am embarrassed to admit that I am now stumped. I have heard this buzzing before when 'doing' a TV but I can't recall the cause or remedy.

Are any of you worthy folks familiar with this set (I have searched the Forum to no avail)? I would really appreciate sight of a circuit diagram and any information about this model - as I say there's nothing I can on the web so its all a bit of a mystery.

Any help will be gratefully received.

Many thanks.

Re: PYE TT1 - First Transistor Portable UK TV
 

Info for the Pye TT1 can be found in the 1961/2 Newnes radio and television servicing book.
You have inspired me to bring down my TT1 to the workshop.
The frame timebase is free running.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Thank you Fernseh, I am glad that I have inspired you to play with your TT1 too. Unfortunately, as luck would (wouldn't) have it, I only have one volume of Newnes and that is for 1959/60.

You wrote - ' the time base is free running'. Forgive my perhaps apparent ignorance but what is that statement telling me? Is is a statement of fact i.e the time base is of a type that free runs because that's how it is or it is free running but it shouldn't be. I am sure that you're being helpful but am I to presume that it IS a fault and if so what would be some clues as to the reason. I will check the time base circuit for 'duff' resisitors but with little knowledge of transistor technology and no circult diagram I shall be free running without a safety net....so to speak.

Many thanks

Re: PYE TT1 - First Transistor Portable UK TV
 

For starters, a picture of the Pye TT1.
The frame oscillator is free running in the sense that it does not need sync pulses to activate it. The set displays a blank raster when no signal is received.
Transistor V25 is the blocking oscillator and works in a conventional manner. The transistor conducts only during the flyback time and discharges the sawtooth forming capacitors C74 and C75. Frame repitition frequency is determined by C72, R74 and and the frame hold control R75.
The oscillator drives the V26 and V27 in a straight forward circuit.
It follows that to make a start on the restoration all those capacitors in the frame timebase should be checked or replaced as a matter of course.
The transistors OC72 and OC23 can still be found or the later types AC128 and AD149 could be considered as subsititutes.
The Pye TT1 is actually mentioned in the 1960/61 Newnes R & T serviving book.
I consider this to be an important historic receiver. It has a big 14" CRT, when around the same time it was made other manufacters were using quite small tubes for their transistor TV sets. Perdio and Ferguson used small CRTs.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Here's a better shot of the frame timebase.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Thank you Fernseh, that is all very helpful information and now I understand the free running point. I have changed all the wax caps anyway and now that I have the circuit diagrams (thank you) I now have a map to follow, which will help.

I have been 'playing' with the set for most of the day and resolved the 'buzzing' that I mentioned. It was simply a wire that had come adrift. All resoldered and noise gone. I have a picture which is ok-ish. It locks and with a fair amount of fettling the contrast, sensitivity and brightness controls the picture is watchable. However, it is a bit 'soft', with a slow 'ripple' effect continually scrolling up the screen and the sound is distorted so I think I have some more work to do.
I took the case apart and removed the tube for a good cleaning including the plastic front screen and the side knobs which have been polished and the lettering re-done with a gold paint stick. It is all back together now and looks quite presentable. As you say an interesting set and not one that I have seen before.

I presume that it had an external telescopic aerial(s) and some sort of a front cover because there are two hinge connectors monted on the bottom of the front - your's has them too. Are you aware of either of these features and what the hinges are for?

Thanks again for the information.

Re: PYE TT1 - First Transistor Portable UK TV
 

Hello Stevitee
Please find attached a PDF copy of the service information for the Pye TT1 television, from the 1961-62 volume of Radio and Television Servicing. The information includes a circuit description and set up notes. I hope this information will be of some help in your restoration of your receiver.
Regards Stan.

Re: PYE TT1 - First Transistor Portable UK TV
 

That 'slow ripple' effect & the distorted sound: Check/replace the rectifier diodes, V12 & V13 and also look at the reservoir & smoothing electrolytics, C32& C33.
I have seen that problem before with a portable.

Re: PYE TT1 - First Transistor Portable UK TV
 

The internal battery is an essential part of the power supply of these receiver,
it serves as a smoothing element and a stable voltage reference.
It is missing in my set so I'll have to make up a substitute battery pack or engineer in an alternative 10 volt supply stabilising arrangement. Of course it is lot easier nowadays to do circuit modifications but back in 1960 when the set was designed there was a limited number of specialised components available for the designers of transistorised TV sets.
The video output transistor presented problems. Special high voltage devices were not available. The TT1 employs a special CRT which can operate with only 15 volts of video. A few years later the AF118 became available.
Remember that the 1967 Thorn 2000 all transistor TV employed two stacked transistors in the RGB output stages. Of course that was from a >200 volts HT supply unlike the 40 volts video output stage supply in the TT1

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Do any examples of the Ferguson "Transvista" survive? Looking it R+TV S it looked to be a more "complete" piece of work than the Pye set (it has a properly styled cabinet instead of a sheet metal box...) but yet it seems to be far more unusual.

Can it really have been so bad that BRC didn't make another solid state monochrome set (the 1590) until over 10 years later?

Re: PYE TT1 - First Transistor Portable UK TV
 

Stan, thank you very much for this - it will be very helpful.

Re: PYE TT1 - First Transistor Portable UK TV
 

First of all, thank you to Neil P for those helpful points. I was going to look/check the smooothing caps but have just noticed that they are both 10,000 uf which is not the 'usual' size that I keep so changing them may be a challenge for a while. I do know (or was told) that the set spent most of its life being run off a lorry battery because the person who owned it lived in a house with no mains electricity (true!). However, the house was deep in the country. And, moving on to Fernseh's points, the battery is also missing from my set and the wiring that I assume was for the battery has been snipped/partly removed. Not sure that I'll go to the length of making up a 10v battery /substitute but I'll certainly follow up on the components suggested by Neil.

Once again, thank you all

Re: PYE TT1 - First Transistor Portable UK TV
 

I believe that one Ferguson model 743T "Transvista" is known to exist in the UK. The line output stage of the 743T differs from the Pye TT1 in having one output transistor, a Mullard N7D, later to become the AU101. The TT1 uses two 2G221 transistors. I notice that the Ferguson uses an OC170 for the video amplifier.
Certainly the Ferguson looks a better product compared with the Pye which has a "prototype" look about it.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The Ferguson 743T. http://www.freewebs.com/405tv/galleryno2.htm

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

A quick update on my post dated 16 July. I duly replaced the rectifier diodes with modern equivalents (courtesy of Maplins) and the smoothing caps (by using two 4.7k uf 'strapped' together in each case). The result has been a good improvement but its a far from perfect picture which I will put down to Fernseh's observations about the lack of a 10v battery and its inherent stabilising attributes. Essentially, I am quite pleased. It is watchable. Thanks everyone. I'd like to post a couple of snaps of it but haven't established how to do this yet.

Re: PYE TT1 - First Transistor Portable UK TV
 

I have now created an album in my profle so I think if you follow this link https://www.vintage-radio.net/forum/...hp?albumid=416 you can see the set.

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Stevitee,
You are getting good results from your set, a good start with it's restoration. Still no results from my TT1. The CRT heater was lit for a while, then a smell of burning and the set went dead.
I'll place the set on the "to do later" pile.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The TT1 looks a positively crude affair when compared with the 1960 Zenith 19" portable TV set. In fact I believe this set was announced as ready for sale in the US in late 1959.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

I thought it would be a good idea to have another look at this set. Well it seems because the voltage regulator was missing, the DC supply to the receiver was too high. The set was designed to operate from 10 volts. Something like 15 volts was being supplied to the receiver. You'll recall the NiCad battery serves as the voltage regulator.
The first casualty seems to be one of the 2G221 line output transistors, it has a emitter to collector leak, the meter reading is 75 ohms.
The set is full of OC171 transistors so there could be a likelihood that many of them will have the metal whisker fault.
This not going to be an easy restoration. What's more it's a difficult chassis to work on.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Ten volts from the bench power supply has been connected to the line oscillator and driver stage. The line oscillator circuit is working at 10Kc/s. The correct 15 volts P- P waveform is present at the collector of the line driver transistor V34, a Mullard OC23.
Without the line output stage the current drawn by this receiver is a very modest 0.5amp @ 10volts.
The circuit diagram was posted up #7 by Valveman.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The frame oscillator is of the blocking oscillator type. Transformer feedback is between the emitter and base of V25, an OC72 transistor.
The collector of V25 is supplied from -60volts which originates from the collector of the line output transistor.
Obviously without the -60 volt supply the frame oscillator will not work, but by momentarily short circuiting the frame hold control to ground the oscillator can be kicked into action. About 0.5V P - P sawtooth waveform is present across the ramp forming capacitors C74 and C75. Ref to post #7 for the circuit.
The frame output stage is working OK.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

I have only repaired one Pye TT1 and that was around 1968. The receiver was around 10 years old even then.
This is my Ferguson 743T. It is missing it's sun shade but other than that, very clean and complete. I must sort it out.
The 743T dates from 1961 and was manufactured in very small numbers. The TT1 was very advanced and I think was manufactured 3 years earlier.
I hope you get it working David. Regards, John.

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi John,
The Ferguson 743T is the rarest of the early UK made all transistor TV sets. Information for the set can be found in the 1961/62 Radio and Television servicing book. Pages 325 to 331. The 743T seems to be a considerably more developed set compared with the Pye. The latter is somewhat crude in it's construction. The Ferguson has five stages of vision IF amplification using five AF114 transistors. The Pye uses the earlier OC171 in the four stage vision IF amplifier.

More progress with the Pye. The no sound fault was traced to one of the output transistors gone base to emitter short. The original push-pull output stage employed OC72 transistors, these must have failed a long time ago and were replaced with two AC128s. It was one of those AC128s which had failed.
Work is going well with this set. The sound stages are working and so are the vision circuits up to the base of the video output transistor.
The video amplifier does not work because the -60volt supply from the line output stage is absent.
Interesting to note that in the Ferguson and Pye the CRT is grid modulated, supplied with a positive going video waveform.
The reason for this is because the sync separator transistor is a pnp type.
The transistor conducts only on the negative going sync pulse tips.
In normal valve practise the valve conducts on the positive going sync.

The next stage of the restoration is line output stage. The 2G221 is unobtainable but there is a limited number AU101/3 transistors available from on-line traders.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

AU113 from an early BRC 1590 should work if you get really stuck.

Re: PYE TT1 - First Transistor Portable UK TV
 

As two line output transistors are employed in the TT1 the AU113 ratings will be more than necessary for the job. The -70 volt flyback pulse at the collector of the "upper" line output transistor V35 is distributed across both transistors.
The flyback tuning capacitor C97 has the remarkably high value of 0.17microfarads.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Late production BRC 1590 sets employed a silicon transistor as the replacement for the AU113. In fact the later PCBs were fitted with links to allow this.
The NPN silicon transistor was wired "upside down", that is,with the collector to ground. A type BD160 comes to mind.
The BRC 1612 mono TV of 1974 employed modern silicon transistors so the power supply line was positive. According to the circuit diagram a PNP line output transistor was employed. The transistor VT8 was wired into the circuit with the collector to ground, again, upside down.

The attachment shows the circuit arrangement in the 1612 chassis when a PNP line output transistor is employed. I'd consider something like this for the TT1.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Simplified circuit of the line output stage. Note the capacitor C95, connected between the junction of the two line output transistors and a tapping on the line output transformer primary. The efficiency diode V38 is an OC28 transistor. The collector is connected to ground and the base serves as the diode anode.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Ah the pye TT1 would love to get one of those , never seen one for sale . Oh well I'll keep looking
Nice to see someone managed to get one , can't wait to see it working .
Interesting article , I'll be following this with great interest .

Chris

Re: PYE TT1 - First Transistor Portable UK TV
 

I think it is agreed that employing the 10 volt battery as the supply regulator is not all that good really.
The attachment shows the circuit of the supply regulator of the Ekco T544 portable TV of 1972. If the mains transformer can supply sufficient headroom voltage I'd consider using this power regulator in the TT1.
The Ekco T544 draws much less current than the Pye, 1.25amp as against at least 2amps in the Pye so the OC26 or AD149 series regulator will have to be shunted with a 10 ohm resistor. The series regulator transistor in the BRC 1590 uses similar an arrangement in order not to exceed the current limits of the AD149 transistor.

Two AU113 line output transistors have been ordered from an online supplier in Holland.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The 1612 was a lovely set, the best of the BRC portables. Neat and pretty too, shame that most of them went for export (note the German markings on the PCB silkscreen). The way that the line driver transformer has been wired makes it easy to fit an NPN line output transistor if you want to, the only difficulties are mechanical (e.g. dealing with the transistor body which is no longer grounded). From memory, these used an AU113 as well.

I've never seen a 1590 without the links; I had an Ultra one with red resist that was pretty early, that certainly had them. They used a Ge AD149 for the regulator as well, in the late 1951s (14") I think that that was changed to Si too. A PNP Ge line output transistor could have been considered out of date by 1970, there would have been better choices by then (unless you were Rigonda!). Even the Sony TV9-306UB (late 1965) has a Si NPN transistor here.

Re: PYE TT1 - First Transistor Portable UK TV
 

The 1612 portable TV. Sold in the UK as Ferguson, Marconi and Ultra.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Update on the progress of the restoration of the Pye TT1.
Today the two line output transistors were replaced. Not a very easy job, in fact it's an even more difficult task than the replacement of the two line output transistors that are employed in the Rank A823 chassis. The original Texas 2G221 transistors are impossible to find and for that that reason two of the more common germanium PNP AU113 transistors have been fitted.
I've every reason to believe the new transistors will work satisfactorily because even without the line scan coils connected a -30 volt pulse is present at the collector of the "upper" line OP transistor.
With the line scan coils connected the flyback pulse at the collector of the upper transistor is -60volts, the service manual indicates it should be -75V.
The EY51 EHT rectifier heater is lit and there is an audible ticking noise from the frame output transformer.
Things are looking good for this set.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The EHT voltage is down a bit, it's about 7KV. The service manual states it should be 9 to 9.5KV. Even that is a low figure for a 14" CRT.
The auxiliary supply voltages are present and are close to the correct figures. The video amplifier HT is -63V, this is supplied through an OA81 diode which is connected directly to the collector of the line output transistor.
The negative CRT brightness control voltage is 43V, should be 53V. Again supplied from the collector of the line OP transistor.
The first anode supply for the CRT is +285V, it comes from a tapping on the EHT winding. An early silicon diode is used, type FST1/A.
The CRT is grid modulated which means the video waveform is positive going. The brightness is controlled by varying the tube's cathode voltage.
There is no modulation present at the grid of the CRT. It's possible the video output transistor has failed. It's a Newmarket PNP type V15/20R.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

C97 is the line flyback tuning capacitor. It is almost certain that it has developed a leak, it is now rather hot and there is wax oozing out at the ends. The set continues to work except the flyback pulse at the collector of the "upper" line output transistor now down to 55volts.
C97 is 0.17microfarads. The replacement will have to be made from capacitors of various values to get something near the correct figure.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

That's more like it. The EHT is now almost 9KV and the video amplifier HT is -75volts. The faulty capacitor had the less critical value of 0.15microfarads.
Now there is the video circuits to sort out and then hopefully the set will be displaying pictures again.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Everything was just about ready to reinstall the chassis into the cabinet, then disaster! Two OC171 transistors in the vision IF strip have gone down with the dreaded whisker problem. Fortunately I found an AF114 which is a near equivalent to replace one that would not respond to cutting off the screening can lead. As for the other OC171 I just got with simply disconnecting the metal can lead.
Now 25volts P - P video is present at the CRT grid connector.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Well, after all that effort the results are to say the least disappointing. Apart from the lack of height and the picture the wrong way, those faults are the least of my problems, it's that strange picture definition that is the real concern.
There is a fault in the vision IF amplifier or possibly the alignment has been got at.
I've always been led to believe the Cathodeon C36-23 CRT is a special tube made for the TT1. Well it turns out to be nothing special at all. For starters the heater is the standard 6.3 volt 0.3amp type, not a low current consumption type made for battery powered TVs. Also it was always thought tube was special high sensitivity type designed to operate on low level video drive. In fact the tube is similar to the Mullard AW36-20.
The attachment shows the peculiar picture.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Looks promising. I think the line scan coils are connected in reverse. Someone once played a trick on me at Mastercare. In my absence the TX9 I was working on was got at by a colleague. He reversed the connections to the scanning coils, luckily I noticed before I sent the set out.

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Simon, it sure is. The line scan coils have been reversed so at least the test card is the right way around. A little probing around the IFs revealed that the final IF amplifier was a bit "peaky". A tweek of the core of the last IF transformer has cleaned up the picture.
The AGC system in this set is a bit primitive. It's a mean level system operating on the first IF amplifier transistor only. An increase of signal strength reduces the negative bias voltage to the PNP OC171 transistor.
A base bias potentiometer controls the gain of the RF amplifier transistor, an AF102
Six years later with the introduction of silicon transistors the forward AGC control system became the norm.

The frame linearity controls will have to be replaced.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Getting there. Even with the CRT heater drawing 0.3amp the total current consumption of this set is under 1.6amps from a 10.8volt supply. 17watts!
Compare that with a 14" all valve TV which can be as high as 160 watts.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

That looks a whole lot better, I take it you have replaced those dodgy preset pots?
I noticed the latches on the front, I take it the set has a removable lid over the CRT?
:beer:
Mark

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Mark,
I don't think the latches are used to fit an additional filter window. It's more likely a protection panel was supplied with the set to prevent damage to the moulded Perspex CRT safety shield.
The replacement frame linearity controls have solved the picture geometry faults.
Interesting to note that the circuit of the frame timebase output stage in the TT1 is very similar to the frame OP stage in the BRC 3000 series CTV.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

The final stage of the restoration of this interesting receiver will be the provision of a 10.8 volt supply regulator. I have three choices: first, use nine series connected 1.2V 2.5A/hr NiCad cells. The cells can be installed into a box to replicate the original battery pack. The cells function as the voltage regulator when the set is operated on mains and car battery. Second, the all germanium transistor series regulator employing an AD149 transistor. The third option is a modern low dropout device like the LT1033.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Am I right in thinking that only option #1 allows running from its own internal batteries ? If so then that'd be my choice.

TTFN,
Jon

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Jon,
I'm also keen on the first option.
1.2volt 2500mA/H Sanyo NiCad cells are available from Conrad:

http://www.conrad-electronic.co.uk/c...omSuggest=true

Or from the same firm: NiMh 1.2volt 2400mA/H cells:

http://www.conrad-electronic.co.uk/c...=detview1&rb=1

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Would one of those Akura DC regs work which they used in various mains/battery colour portables? Malc.???

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Malc,
the Baby 10 regulator? It's possible a spare one is out there somewhere. Certainly it would do the job.

DFWB.

Re: PYE TT1 - First Transistor Portable UK TV
 

Got one here, yours for the postage if you want it.

Re: PYE TT1 - First Transistor Portable UK TV
 

Should have them in stock here if you need one David.

Re: PYE TT1 - First Transistor Portable UK TV
 

Hi Bill, Hi Malc,
The TT1 was bought way back in 2005 at the Birmingham NEC. I was rather surprised the lack of interest in the set. Then Akura Baby 10 regulator module was considered at the time as a substitute for the NiCad battery. The idea was to use the set exclusively on the mains, but portability is what this set is all about so I'm still considering the battery option. The Akura regulator could still be incorporated into the circuit. It's a much better option than relying on the batteries doing the 10 volt supply regulation.

The Akura 10 volt regulator was still available in 2005.

Hi John,
presenting the Pye TT1 alongside the famous Masteradio.

DFWB.