Re: Baird T5 restoration project.
 

Hi David,
I've been following your progress with this restoration with great interest! At least with the cabinet in that bad a state, the decision to replace most parts of it is made rather easier.
It must have been a very satisfying project so far. Of course, when you come to the veneering, things will get even more difficult! Have you much experience of doing this?
Well done on progress so far.

All the best
Nick

Re: Baird T5 restoration project.
 

Hi Nick,
fortunately there is not too much veneering work required for this job.
The CRT screen panel, the new control panel and the front panel will need veneering. The side panels are furniture grade plywood and have very nice wood grain patterns. The new panels can be stained and polished before final assembly. The mirror lid is in good condition and requires little attention other than stripping off the old lacquer and a few minor repairs to the veneers.

The screen aperture has a 30 degree chamfer around the edges. That part of the job went well, see second picture. However, things didn't go well when it came to routing out the 5mm recess for the implosion glass. The router tool kinda went wild and ruined the panel. So that panel will join the woodworm damaged parts. Scrap!

DFWB.

Re: Baird T5 restoration project.
 

It will be possible to repair the damaged CRT display panel but instead I will make a new one which will be constructed from two pieces of 6mm plywood glued together.
I'm now on the lookout for veneer for the front panels.

DFWB.

Re: Baird T5 restoration project.
 

Great progress David, the skills that you possess in cabinetry I find nothing short of amazing!

This is going to be a super set when finished.

Cheers

Re: Baird T5 restoration project.
 

Hi Lee,
The cabinet reconstruction is progressing very well. The control panel is the last cabinet part to be made. I'll attempt to do this later this week. In the meantime let's take a look at the vision receiver. Signals are supplied direct to the mixer, no RF amplifier. This was a common practise in early TV receivers. Because the intermediate frequency is low the four stage amplifier should provide excellent gain. The Mullard TSP4 pentodes have a gm of 4.2ma/V which is a good figure for early television RF pentodes. Because the set employs a large CRT a full wave demodulator is employed in order to avoid a fine dot pattern appearing on the screen. A Mullard 2D4A double-diode is used as the vision detector. A TSP4 is used as the video amplifier.
Positive going video is supplied to the CRT grid via a capacitor. No DC restorer.

DFWB.

Re: Baird T5 restoration project.
 

Come on, David, let's have an up-date. The suspense is killing me: have the woodworm eaten you?

Re: Baird T5 restoration project.
 

"have the woodworm eaten you?" Hi Pillenwerfer,
But they have made a good meal of every plywood panel. The control panel is the last cabinet part to be made and it is proving to be a bit difficult replicate but I will have something show on the forum by the weekend.
The vision receiver and the power supply units are on the bench for servicing. We'll soon find out the intermediate frequency and the passband characteristics of the IF amplifier.


DFWB.

Re: Baird T5 restoration project.
 

Testing the power supply unit. The 16mfd reservoir capacitor and the 24mfd main smoothing capacitor were found to be useless so for the time being two 8 + 8 mfd capacitors will be used until the correct components can be found.

Under no load and with only 150VAC supplied from the variac the smoothed HT voltage is 300V. Later today the vision and sound receivers will be connected to the power supply.

DFWB.

Re: Baird T5 restoration project.
 

Good to hear that your steadily progressing.

Re: Baird T5 restoration project.
 

In fact as the picture shows I've little choice but to make a new control panel.

DFWB.

Re: Baird T5 restoration project.
 

Wow, only just seen this thread & the first thing that springs to mind is that episode of The Young Ones... "Vivien, eat the telly!" :o

Right, now I've got that off my chest I shall go back and continue reading. It looks like one heck of a project and I doff my hat to you for taking it on.

Re: Baird T5 restoration project.
 

Hi David,
I'm loving the progress by the way.
I've uploaded a photo of how the vision unit would have looked with the original capacitors. The electrolytics in the one you are restoring have been very neatly fitted, so I would say definitely a manufacturer's post war overhaul.

Another thing I have noticed by looking at photos of other surviving T5 sets is that sometimes the speaker is on the other side of the cabinet. I can't see any reason why moving it to the other side would help really, so maybe it is just random...

Cheers
Andy

Re: Baird T5 restoration project.
 

Today's report is about the good progress I'm making with the sound and vision receiver units. The oscilloscope trace shows the negative going video present at the grid of the TSP4 video output valve. Despite having no RF amplifier the vision receiver has high gain. It has been established that the vision IF amplifier is aligned to the upper sideband which means there is a deep "trough" between the vision and sound passbands. The vision IF is 13mc/s, much higher than I thought it would have been.
Much more work needs to be done on the vision receiver but the results so far are very encouraging.

DFWB.

Re: Baird T5 restoration project.
 

Today the new control panel was test fitted.

The panel is canted back 35 degrees which made it necessary to adjust the angle of the cutting disc on that scary saw bench.

DFWB.

Re: Baird T5 restoration project.
 

Hi Dave.

Got one of those saws myself,not my favourite tool.

Nice to see your progress on the T5. I remember you saying that you were enjoying this restoration. Hope the problems you have encountered haven’t changed your mind.

Keep up the good work, Anthony.

Re: Baird T5 restoration project.
 

Hi Anthony,
The restoration of the Baird T5 is progressing well. Just two more jobs to do before the wood veneers are applied to the surfaces of the cabinet front panel, the control panel and the CRT screen panel.
First task to do this weekend is make the specially shaped beading fitted between the control panel and the upper panel, see the attached pictures. It might be possible to use ordinary stock beading available from B & Q. Again, the saw bench will cut out the 30 degree chamfer.

The second task is to make the cut out in the front panel for the door to access the timebase controls.

DFWB.

Re: Baird T5 restoration project.
 

The cut out in the front panel for the timebase controls door was made today.
The front panel is now ready for the surface veneers to be applied.

DFWB.

Re: Baird T5 restoration project.
 

I see you have included a cat sized fire escape via the speaker aperture...

Re: Baird T5 restoration project.
 

All the interior surfaces of the cabinet are matt black and of course the best paint for the job is that used for blackboards.

DFWB.

Re: Baird T5 restoration project.
 

Decisions, Decisions. The attachment shows two CRT support panels, the one on the left is the original and the other is the newly made replica.
The CRT panel was the only plywood part in the set that wasn't totally destroyed by woodworm, only one corner of the panel had been invaded by the worms.
So, the question is, in order to maintain some originality should the refurbished panel be used in the reconstruction or, should we play safe and fit the replica part?

DFWB.