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Old 26th Jan 2017, 7:55 pm   #21
Colourstar
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Default Re: Philips T-Vette

Nice result! Good to see one of these working. It looks like it's missing the two rubber feet from the front, which angle the set upwards slightly. Believe it or not Philips made a special stand for these little TVs...

By the way, 67gns would have bought you the 19" TV in the Philips range at the time, so that gives you some perspective on the relative price of a T-Vette at 66gns - just one guinea less!

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Old 26th Jan 2017, 8:39 pm   #22
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Default Re: Philips T-Vette

Nice Little set. Well done
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Old 26th Jan 2017, 9:26 pm   #23
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Default Re: Philips T-Vette

Quote:
Originally Posted by EF80TVVALVE View Post
I am a little concerned too for the 11v rail blowing the heaters of the CRT, it's not likely that I'll find a replacement tube any time soon so if anyone does know of any mods to protect it then that will be great, I can see this set having quite regular use so I'd like to keep it protected from irreversible damage.
Hi

I quite agree, a modification could involve taking the 11V feed which normally goes to the heater and feeding this to a fuse. After the fuse, this feeds the heater but with a zener diode in parallel acting as a crowbar. I think the voltage and power rating would have be chosen carefully. I thought I read somewhere this type of modification being carried out on one of these sets. It would be good to see the best way to do this.

I remember in about 1982 I came across a T-Vette that had sound but no raster. I initially thought it was going to be a line output fault but sadly turned out to be the tube heater being O/C. There must have been quite a few scrapped because of this.


Does anyone know how long the production run was for the T-Vette? I think the first ones appeared in 1966. Could it be around 2 years? What model replaced the T-Vette?

Regards
Symon.
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Old 26th Jan 2017, 9:34 pm   #24
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Smile Re: Philips T-Vette

I have one which only required a clean and dusting and a bit of servisol on some crackly pots to get it going. Works well on both line standards.

Makes me laugh the picture on the beach on that stand, I presume that picnic basket hides a thumping big lead acid battery to power it

Christopher Capener
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Old 26th Jan 2017, 9:49 pm   #25
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Makes me laugh the picture on the beach on that stand, I presume that picnic basket hides a thumping big lead acid battery to power it
Hi.

I thought the same but in the text it states "This compact, versatile model operates from 12-Volt miniature accumulator batteries or mains- or from a 12-Volt car battery." Even a compact accumulator would have been quite heavy to lug around. An idea, install a modern lithium battery pack with built in propriety charging circuit.

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Old 26th Jan 2017, 9:53 pm   #26
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Default Re: Philips T-Vette

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Originally Posted by Colourstar View Post
By the way, 67gns would have bought you the 19" TV in the Philips range at the time, so that gives you some perspective on the relative price of a T-Vette at 66gns - just one guinea less!
I think you'll find the Philips-badged version was quite a bit more expensive than the Stella at 85 guineas (plus a 18/11d "surcharge" whatever that is?) or more than twice the price of it's Ferguson rival which was just 39½ guineas.
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Old 26th Jan 2017, 11:57 pm   #27
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Default Re: Philips T-Vette

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Given the age of the set it might be wise not to change line-standard whilst the set is on.
I have never seen a dual standard early transistorized TV like this down here in the Antipodes or made in the USA, so this must be a unique UK thing for 405/625 ? or is it for a 525/625 option ? I totally agree with the remark above though.

Is it possible to get a link to the schematic that works or another that works?

Recently I modified a small 625 line transistorized TV monitor to dual standard 405/625. Changing to a much lower lower H scan rate for 405 means that the time taken for the beam to scan from the center to the left is longer. More energy is stored in the yoke & H output transformer over this time, so at flyback the peak voltage on the H output transistor's collector is increased, and so is the EHT. This requires another tuning capacitor added to the H output stage to lower the peak voltage, lengthen the H flyback time & keeping the EHT the same. Also had to alter the picture width. So at a minimum, three things needed to be simultaneous switched. Any glitches in the coordination of that switching can result in a collector voltage spike that will destroy the H output transistor.

In the case of switching between two closer standards like 525/625 its probably ok just to alter the H scan osc center frequency, but even one glitch in the output of the H oscillator drive to the H output transistor could potentially put the transistor at risk.

One way to protect the H output transistor is to add a string of 50v or 100V 5w zeners in series across the collector-emitter so that if the collector voltage climbs much over its usual value, the zeners snub it off.

(Yes, no point of replacing the electros if the scan linearity is basically good and in the control range)
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Old 27th Jan 2017, 2:24 am   #28
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Default Re: Philips T-Vette

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I have never seen a dual standard early transistorized TV like this down here in the Antipodes or made in the USA, so this must be a unique UK thing for 405/625 ? or is it for a 525/625 option ?
Most programming in the UK was in 405-lines when the set was made, along with a small amount in 625. It was December 1969 before all programmes were available in 625-lines and a single-standard receiver could receive them all.
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Old 28th Jan 2017, 4:16 pm   #29
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Default Re: Philips T-Vette

My first encounter with a T-Vette was a friend who had one for use in a caravan, which was in the Lake District. I was impressed by its ability to work in that rather signal-starved part of the world.

I suspect its main weakness are the AF11* transistors used in it.

It is a set that is well worth keeping going.
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Old 28th Jan 2017, 6:52 pm   #30
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Default Re: Philips T-Vette

Manual in the post to you

Dave
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Old 28th Jan 2017, 7:43 pm   #31
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Default Re: Philips T-Vette

Thanks Dave, that's excellent!

I have replaced the two sound IF AF115s with AF125s. On turning the set on I not only still have no sound but the frame has collapsed leaving just a horizontal line on 405 and nothing at all on 625. I suppose something may have came loose upon replacement of the AF115s? I will continue to take a look but I was extremely cautious with it so I don't think anything has detached itself. I've definitely opened up a can of worms now!

Cheers
Bren
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Old 28th Jan 2017, 8:11 pm   #32
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Default Re: Philips T-Vette

Definitely nothing loose or out of place, there is now a line on 625 too and I can hear hissing/white noise on the speaker which wasn't there before, the set is still receiving video but there is still no sound on the speaker. Both new transistors were soldered in properly, there's no shorts between the solders so I'm not too sure what has happened to the little philips.
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Old 29th Jan 2017, 10:23 am   #33
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Default Re: Philips T-Vette

Quote:
Originally Posted by EF80TVVALVE View Post
I have replaced the two sound IF AF115s with AF125s. On turning the set on I not only still have no sound but the frame has collapsed leaving just a horizontal line on 405 and nothing at all on 625. I suppose something may have came loose upon replacement of the AF115s? I will continue to take a look but I was extremely cautious with it so I don't think anything has detached itself. I've definitely opened up a can of worms now!
I remember a bizarre fault on a T Vette where they would be full scan on tuning in yet the frame collapsed on a blank channel or when tuning in between channels. I can't remember if the frame osc or output transistor was dry jointed but re-soldering cured the problem.

Still have the set which still works but has developed audio problems. Probably those transistors mentioned. Might get round to looking at it someday.
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Old 29th Jan 2017, 10:34 am   #34
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Default Re: Philips T-Vette

Make sure you have the lead-outs correct as obviously the AF125 is a different layout to the AF115.
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Old 29th Jan 2017, 1:35 pm   #35
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Default Re: Philips T-Vette

I'll admit transistors aren't my thing, I normally keep it simple and stick to valves! Right I have photographed the schematics and will upload them at the bottom of the post. I ordered AF125s in a TO72 case, searched the pin numbers for a TO72 online and it shown me (looking from the bottom, anticlockwise from the metal tag) 1:Earth 2:Collector 3:Base 4:Emitter, I checked pin 1 against the case of the transistor and it gave me a reading so I confirmed that was the earth. Fitting it to the philips involved crossing over the pins for the collector and emitter and soldering in place. From what I understand it is done correctly but someone please prove ne otherwise so I can correct it!
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Old 29th Jan 2017, 3:06 pm   #36
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Default Re: Philips T-Vette

http://www.semicon-data.com/pdf/SH/AF/AF125.pdf

?

Lawrence.
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Old 29th Jan 2017, 5:13 pm   #37
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Default Re: Philips T-Vette

Thanks Lawrence, looks like they were installed incorrectly after all. Reversing them to the correct way I now have sound although it is distorted, could be the output set to high on the aurora. Still it has frame collapse so I shall try and solder the transistor pins although I wonder if the invorrect fitting of these transistors have somehow caused damage to them.

Cheers
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Old 29th Jan 2017, 5:46 pm   #38
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Default Re: Philips T-Vette

A little more progress, giving the field output transistor (AD149) a tap I now have a raster back on the screen although still no image, the sound is now fine with no distortion. 625 produces a raster less bright and lacking slightly in width.
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Old 29th Jan 2017, 5:51 pm   #39
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Default Re: Philips T-Vette

Changing the line hold, vert hold and contrast has produced this...
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Old 29th Jan 2017, 5:54 pm   #40
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Default Re: Philips T-Vette

If that's a VHF 405 picture, then maybe all that's needed is to adjust the VHF channel selector's fine tuning control knob (the outer clear ring on the VHF tuner); push in and turn.
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