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Old 24th Jan 2017, 8:53 pm   #1
EF80TVVALVE
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Default Philips T-Vette

Hi all,

Having picked this little transistor dual-standard portable from Aidan Lunn this weekend I couldn't wait to get the back off and see if i can get any life from it. The T-Vette has been on my list for a long time and this set looks lovely to begin work on. Firstly I did the usual with powering up these sets, I removed the back, removed the tube connector and gave it 12v through the battery terminal. I was met with a healthy 625 line whistle and a steady 10v on the CRT heater. I then connected it all back up and was met with a very bright clear raster. I have tried it on both 625 and 405, the 405 turret definitely needs a clean as it requires a bit of wiggling to get it to tune in. There is a problem with the linearity as can be seen in the photos, there is also no sound although turning the volume pot does make a crackle through the speaker.

I'm without a manual on this one at the moment so could anyone help on where to start with it? Anything I should look out for too on these little sets? I'm glad the tube was good, I've not seen a 405 picture as sharply defined as this although I suspect the size of the tube helps, the brighness is great though, perfect little candidate for restoration!

This will make the first transistor set I have repaired so let's see how we get on...
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Old 24th Jan 2017, 9:06 pm   #2
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Default Re: Philips T-Vette

Well done, I have one on my roundtuit list and a little inspiration helps a lot.
Greg.
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Old 24th Jan 2017, 9:09 pm   #3
Philips210
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Default Re: Philips T-Vette

Hi.

Nice to see another of these sets working again. I have two in my collection.

The service information was available from thevalvepage.com but the link to the T-Vette isn't working. You could try contacting Jon Evans (member Duke Nukem). If you have no joy then I could scan my manual and send it to you.

Regards
Symon.
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Old 24th Jan 2017, 9:47 pm   #4
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Default Re: Philips T-Vette

Hi
I may have a spare manual for one of these. Will look tomorrow,yours for the price of postage

Dave
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Old 24th Jan 2017, 9:58 pm   #5
EF80TVVALVE
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Default Re: Philips T-Vette

Thanks for the replies everyone, Dave if you happen to have one then that will be great, just drop me a PM if you find it. They're quite nice sets really, I don't know how many people will share that opinion with me but I really like the styling of them, you can really tell it's a philips! It is missing one of the antennas so I'll be posting a wanted thread now for one.
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Old 25th Jan 2017, 12:48 am   #6
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Default Re: Philips T-Vette

Mine was a good set... Then the CRT heater went o/c! Also, mine only has one antenna, looks like it has always been like that as there is a plastic plug in the hole where the other one could go, it's definitely never had one fitted there as there are no marks around the hole. Maybe some were supplied like that from new?

Regards,
Lloyd.
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Old 25th Jan 2017, 7:24 am   #7
dazzlevision
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Default Re: Philips T-Vette

Hello,

Lovely little sets these!

For no sound, but audio output stage working, I'd point the finger at the two AF11x transistors in the sound IF stages.

Regards,

Dazzlevision
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Old 25th Jan 2017, 4:42 pm   #8
SteveCG
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Default Re: Philips T-Vette

Does the UHF tuner dial turn - or has the dreaded hardened grease struck!

As others have said - a nice little set, quite sensitive too. Be aware that the audio output stage quiescent bias setting need to be correct otherwise the output transistors will have a hot and short life.
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Old 25th Jan 2017, 5:30 pm   #9
Philips210
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Hi.

The CRT heater is vulnerable if the 11-Volt rail rises excessively and I have read that some form of protection can be added using a zener diode. Can anyone recommend the best modification here that's known to be safe and reliable?

Regards
Symon
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Old 25th Jan 2017, 8:05 pm   #10
chriswood1900
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Default Re: Philips T-Vette

If you want as quick look at the manual you can download a copy from here,
http://www.thevalvepage.com/tv/phili...tte/tvette.htm also there was a very useful article in Television magazine back in the 70's covering a long list of its many fobiles here http://www.oldtechnology.net/documentation.html about 2/3 the way down.
Chris
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Old 25th Jan 2017, 9:08 pm   #11
Philips210
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Hi Chris.

That is the same website that I mentioned in post #3 but trying to open the file tvette.pdf [2.3MB] leads to a blind alley. Unless I am doing something wrong to access the file, then the link is broken. About 10 years ago when I first accessed that link it worked fine, so at the time I managed to download the manual without problems.

Can anyone confirm that the link doesn't work?

Regards
Symon.
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Old 25th Jan 2017, 9:49 pm   #12
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Default Re: Philips T-Vette

Hi All
Link is definitely broken

Rgds
John
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Old 25th Jan 2017, 9:52 pm   #13
Philips210
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Thanks for confirming that John. I wonder if Jon Evans will reinstate this?

Regards
Symon.
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Old 25th Jan 2017, 10:31 pm   #14
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Default Re: Philips T-Vette

Just sent an email to Jon so we will see what happens re downloads....
I was able to download last time I tried a couple of years (or more) ago.
Peter
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Old 25th Jan 2017, 11:08 pm   #15
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Default Re: Philips T-Vette

Ok here.
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Old 26th Jan 2017, 12:08 am   #16
chriswood1900
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I had previously downloaded OK but it now seems broken, if anyone wants a copy I have it on my PC. Please PM me with an email address and I can send it on.
Chris
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Old 26th Jan 2017, 12:30 am   #17
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Default Re: Philips T-Vette

Many small transistorized sets of this era which run from low voltage power such as 12V had a similar assortment of problems affecting the scan linearity. Special yoke windings were used on the H scan side of things with double bifilar or quadra-filar windings (and sometimes 6 wires in parallel) to help keep the resistance of the H scan coils very low. The peak yoke currents were higher in these sets than those in sets with higher voltage supply rails and the resistive component of the H coils adversely affects the H scan lineartiy. Even with the series S correction or H yoke coupling capacitor, often the H scan was stretched on the left side somewhere (as you can see the round part of the test pattern is egg shaped to the left). I don't have the schematic of this set, but some sets had a magnetic saturable reactor coil in series with the H scan coils to help adjust this error out. In American and Australian sets of this type/vintage the horizontal output transistor was a 2N3731 germanium type with its companion 1N4785 germanium damper (energy recovery) diode. In European sets usually an AU prefix transistor. But I'm not sure in your set if they had gone to Silicons here yet.

The frame scan linearity is invariably problematic with age on early transistor sets and the raster nearly always gets compressed with line crowding towards the bottom (this zone corresponds to the peak current in the vertical scanning coils) as shown in the photo of your test pattern. The usual cause is aging of the electrolytics with increasing ESR, especially the output coupling electrolytic to the Vertical yoke coils. If however, with all new electros in the Vertical output stage, the problem won't adjust out on the V linearity control, then sometimes the vertical output transistor needs replacing.

On the other hand I think the early transistorized tuners in these sets worked amazingly well, there is usually plenty of gain and they could often pull in and sync lock weak signals on rabbit ear antennas.
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Old 26th Jan 2017, 4:27 pm   #18
EF80TVVALVE
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Default Re: Philips T-Vette

Thanks for all of the help and replies so far everyone, looks like these are well loved sets within the forum! The UHF tuner still turns nicely and hasn't siezed up although I now have noise bars on VHF which I think is something to do with the turret that they fitted. I have adjusted the height and linearity controls and the picture is now looking great, I believe if it can still be adjusted with the controls then I don't really see the point in changing components, I'll leave that for when they can't be corrected via the pots. I've ordered some AF125s for the audio IFs and that should hopefully sort the sound.

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.

Regards
Bren
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Old 26th Jan 2017, 4:29 pm   #19
EF80TVVALVE
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Default Re: Philips T-Vette

Forgot to add the pic of it tuned to Channel 2
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Old 26th Jan 2017, 4:34 pm   #20
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Default Re: Philips T-Vette

An operational thought:

Given the age of the set it might be wise not to change line-standard whilst the set is on. This is to avoid arcing etc (c.f the BRC 2000 colour TV weakness).
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