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B&W TV 1968 Philips T-Vette

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Jayceebee
(@jayceebee)
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Although this is a Philips diagram other manufacturers did it as well. This is something I really hate, grouping multiple connections into a sort of bus with lines having an ID, A23 for example. Also connections with just a number identifier, can drive you mad trying to find where they end up on unfamiliar circuits.

cct2

 

 

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Posted : 17/01/2022 9:19 pm
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Cathovisor
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Posted by: @jayceebee

Although this is a Philips diagram other manufacturers did it as well. This is something I really hate, grouping multiple connections into a sort of bus with lines having an ID, A23 for example. Also connections with just a number identifier, can drive you mad trying to find where they end up on unfamiliar circuits.

I used to see that on some car wiring diagrams of old.

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Posted : 17/01/2022 10:03 pm
WayneD
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Been redrawing the wiring diagram (ignore the colours) one huge benefit is I now have a better understanding of how the boards and transformer, switches etc go together. 

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I think I may dismantle the whole TV, lay all the boards out flat, run new wires neatly to each part and fault find from there.

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Topic starter Posted : 17/01/2022 11:53 pm
WayneD
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Redrawn the entire wiring diagram in the correct colours. Some of the positions of negative wires (the black ones) seem to vary between sets and I haven't put the aerial wires in but I'm sure it should be fairly easy to pick things up.

tvette diagram compr

The mains wires are a bit "interesting" shall we say, the live wire is just a couple of mm away from the housing of the UHF tuner. I wouldn't trust the single green earth wire going to the cabinet earth plate either.

Screenshot 20220119 200832 Gallery

I've decided to strip the whole set down, give everything a thorough check and probably replace all the wiring as I've noticed a lot of it is solid core and starting to break. Plus it would be nice to be able to take boards out without having to desolder the wires every time as well as be able to fault find.

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It's nakkid! 😮 

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Topic starter Posted : 19/01/2022 9:14 pm
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crustytv
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Loving the diagram, way better than the original. If you're OK with it, a copy for the library to go along with the Philips Sm would probably help others in the future.

Posted by: @wayned

[...] probably replace all the wiring as I've noticed a lot of it is solid core and starting to break. Plus it would be nice to be able to take boards out without having to desolder the wires every time as well as be able to fault find

Yep, another great feature I encountered on the G6, the dreaded “wire-ping”. Turn away and the blighters pop off, then you have a devil of a job trying to figure out where they came from. 

As for your latter comment about having to desolder wires just to get at a board to service it, this again was what I found with the G6 timebase board. It was unserviceable in situ with only the 45-degree angle of access given, all hard-wired in. The only board that can be unplugged was the IF, which is a luxury on the SS G6, on the DS G6 every board is hardwired. All easily resolved by using plugs but no, for some reason no plugs. My solution, although far from ideal, was to just extend the wires. At least this allowed me to run the TV, take measurements and make repairs.

The access, 45-degree, the board (outlined in white) under the CRT neck attached by short wires. Impossible to get at.

aggh1

My solution, not pretty, but at least I can now work on the timebase while powered now.

aggh2
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Sorry for taking the

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Posted : 19/01/2022 9:52 pm
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WayneD
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@crustytv yeah, if you want a higher quality version too that's fine. 

OH GOD! These bloody things:

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Yes, I know all about these wire pings! There's only five of them mostly in the centre of the IF board but man... 😡 

I tried extending the wires but quickly realised that some of them were starting to break and there seemed to be a few other underlying problems too.

I may just entirely do away with the mains side of things on this TV and make a new power connector panel that only accepts 12 volts. Or have something fully insulated at least.

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Topic starter Posted : 19/01/2022 10:24 pm
WayneD
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LOTS of wiring. It seems to be best to bundle the wires in groups of four. I *think* there was originally a logic to how the wires connect but it seems to have been lost when transferring to full production.

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Topic starter Posted : 23/01/2022 3:49 pm
sideband
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@wayned

If you want to bundle wires that's fine but be careful. If you bundle video leads with audio leads or video leads with timebase leads etc, you can end up with video buzz on sound or striations (patterning) on video, strange artefacts that weren't there before due to capacitive coupling between cables. Sometimes there is a method in the madness of apparent (or not) lead dressing. 

I restored a Pye TV some years ago and after a particular repair later, I noticed a buzz on sound that changed with picture content. It hadn't been there before. I hinged the chassis down to investigate, switched on and the buzz had gone! I then found that it was only there when the chassis was hinged up in normal position. Investigation showed that a cable from a choke in the line stage was draping across the audio section when the chassis was hinged up. There was a clip at the top of the cabinet to hook the cable as I discovered....When the cable was clipped up, it was held well away from the audio stages....no buzz when chassis hinged up. 

Be careful of cable dressing!

 

Also...watch those plastic clips that hold the aquadag earthing cable, particularly the ones at the top with the springs. They go brittle and break. It happened to mine. I just used twisted wire to fabricate a hook which a lot of manufacturers did anyway. They usually break after you've replaced the CRT and it was a bottom one that broke....the most difficult one to replace with the CRT in position!

 

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Posted : 24/01/2022 9:44 am
Cathovisor
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^^This. Absolutely this.

I bought some cheap SCART cables once and wondered why I could see the outline of a picture floating in the background. Answer? Unscreened cable in the cheap lead leading to HF crosstalk. Immediately binned and I made my own up using proper miniature 75 Ohm coax from work and screened twin for the audio. Net result? Perfect, no more crosstalk.

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Posted : 24/01/2022 12:04 pm
WayneD
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@sideband the bundling of cables is more to help me figure out where everything goes, if any interference does occur I can easily separate them as I'll be attempting to get this running whilst it's de-cased.  

I was expecting the plastic clips to break but I've been pleasantly surprised. 

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Topic starter Posted : 24/01/2022 7:08 pm
WayneD
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Just realised that I never uploaded a pic of this displaying a test pattern. 

Screenshot 20220324 085432 Gallery
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Topic starter Posted : 24/03/2022 10:15 am
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sideband
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Is that after the rebuild? Looks like it needs a tweak of the height and line linearity...assuming the 11V supply is correct of course....! Don't forget that the picture shift/centering rings around the CRT neck might need adjusting.

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Posted : 25/03/2022 3:24 pm
WayneD
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@sideband yeah, I realised after I took the pic! There's a whole load of pics I need to sort out for this thread.

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Topic starter Posted : 25/03/2022 3:45 pm
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