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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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29th Jan 2017, 5:57 pm | #41 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: Philips T-Vette
Exactly what happened, I now have a good 405 picture although there is terrible S-O-V and V-O-S. The fault is the contrast control that has given up, luckily it is still working up to about half way, from then the picture goes blank.
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29th Jan 2017, 9:38 pm | #42 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
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Re: Philips T-Vette
Hi.
That looks a very well defined picture on the 405 line standard. The CRT emission looks very good. It might be a good idea to check the system switching. This was often a source of problems, sometimes intermittent, on dual standard sets. The solid core wiring between panels could fracture during servicing so new faults could be introduced. Cleaning the turret tuner connections carefully might solve the SOV and VOS problems. Regards Symon. |
29th Jan 2017, 10:24 pm | #43 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Philips T-Vette
Can you say if that image of the pcb you posted is the view looking from above (as if you are looking through the pcb) or the track side view ?
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30th Jan 2017, 9:09 am | #44 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Philips T-Vette
The reason I ask the above question is that the AF125 has a lead out configuration
(going around clockwise starting from the emitter and viewed from below; e,c,s,b) that is not ideal to replace the AF115 (in a row e,b,s,c), and as I have suggested on other posts, the superior transistor to replace the AF11x series is the AF178 available on ebay or from Langrex etc, and they are even better for a television application (that they were designed for) where the frequencies are higher than in MW & SW radios. Lead out is e,b,c,s. If that pcb image attached is the top view, then the 4 leads of the AF178 will fit with a perfect orientation and none of the leads will need to be bent or cross either, and it will be slightly superior in performance, in this application and look like a more similar sized part to the original AF115. In addition the AF178 is more stable in RF/IF amplifiers because it has a lower feedback capacitance, only 0.8pF as opposed to the AF125's 1.5pF. I have suggested this before and used the AF178 as the superior replacement for whisker affected AF11x transistors for many years in all my vintage gear. Last edited by Argus25; 30th Jan 2017 at 9:14 am. |
30th Jan 2017, 9:59 am | #45 |
Nonode
Join Date: Jan 2004
Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area.
Posts: 2,965
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Re: Philips T-Vette
Excellent results. I get bad S O V and V O S on my BRC980 due to the very high output from the Aurora convertor, fitting 20-30db of attenuation to the Aurora output clears it.
I also have a T-Vette on my large to do pile and this is very encouraging. I must dust it off and have a go.
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Simon BVWS member |
30th Jan 2017, 12:51 pm | #46 |
Octode
Join Date: Feb 2010
Location: Leicester, UK.
Posts: 1,431
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Re: Philips T-Vette
Hi Symon,
The picture on 405 is extremely good, in fact it is honestly the best 405 picture I have ever seen, the CRT is definitely a good one. I will give the turrets a clean as they are causing all sorts of tuning trouble with the set. Argus25, the view of the pcb is the underside showing the view of the metal tracks. I read a few articles where people replaced them with AF125s and I just went with them. Transistors really don't interest me, I have had a few tranny radios but I never bother fixing them either, this is why I am completely clueless when it comes to them! Simon, thanks for the tip. I think it is definitely being overloaded by some amount although the sov and vos is being caused by the set. I am yet to work on the turrets for 405 although I am going to try it on 625 and see how that tuner fares, could be further in the circuit that the fault begins. Cheers Bren |