I was just waiting to see how long it would take you to spot that...... Ah-hem. ?
To understand the black art of electronics is to understand witchcraft. Andrew.
Hi Andrew
The loudspeaker is positioned above the sound chassis. I've decided to replace the front panel. There's fears that there might well be woodworms in the plywood just waiting to attack the cabinet again in the spring.
Till Eulenspiegel.
Probably best, the little beggars have certainly feasted on the plywood.
Frank
Quite a task Till but you are attacking it with gusto! That cabinet reminds me of the first Decca 1000 I ever got, the worm was as bad as that. Worse still someone had taped over the damaged/holed area with white "Fablon", you know that sticky 70s stuff. As I pulled it off the damaged wood section just peeled away and the wriggling larvae could even be seen to fall out so it was definitely active. I think the Baird is one of the more attractive pre war sets in my humble opinion. Interesting that the lower ribbed section of the Baird reminds me a little of the Decca cabinet style! Eventually I disposed of the cabinet as I needed the parts for other projection sets, a luxury you cannot afford with this set.
The rotten front panel was removed yesterday. Superficially, woodworm holes apart, it looked like a solid panel but was in fact just like the other plywood panels - it resembled a Weetabix biscuit. Crumbled into dust. The cabinet framework is sound, worm free and can be reused.
Till Eulenspiegel.
After quite a few adjustments the new front panel was test fitted yesterday. The next stage of the front panel reconstruction will be to cut out the aperture for the timebase controls. After I'm entirely satisfied the panel is a perfect fit it will be veneered and the original trim parts refitted.
Till Eulenspiegel.
This week I'll have to make a decision what to do with those cabinet sides. They are solid enough but as the pictures show are full of woodworm holes. No doubt with the use of wood filler the holes can be made to disappear but there's always the possibility there could still be nasties in the plywood.
Worth taking a chance or make new panels? Bear in mind the set does not belong to me and I don't wish to disappoint it's owner when those tell tale holes appear again on the cabinet.
The side panels are easy enough to replicate. Use 9mm grade AB plywood.
There's nothing special about the side panels, no book matching of the veneers and as long as the best wood grain pattern on the new plywood is chosen there will be no problems with the final finish of the replacement panels.
But before a final decision about the fate of the cabinet sides is taken, let's find out what the views of other forum contributors are about the matter.
Way back in 2008 I carried extensive repairs to a woodworm damaged HMV 2851 TV receiver, even got up early to do the work because the shop was still fairly busy then.
Later on the bad news! The woodworms returned with vengeance. Subsequently, the cabinet had to be destroyed.
So I'm taking no chances with the Baird T5.
Till Eulenspiegel.
After all that work with the HMV it must have been hearbreaking. More woodwork for you next week then.
Frank
Hi Frank,
It was a great disappointment because it was an impressive looking set. Although it was made in 1949 it was in construction terms very like a pre-war set. Mains EHT, full wave HT rectifier and like all early EMI sets over-engineered.
Link to the topic: https://www.vintage-radio.net/forum/showthread.php?t=33173
Till Eulenspiegel.
But before a final decision about the fate of the cabinet sides is taken, let's find out what the views of other forum contributors are about the matter.
Till Eulenspiegel.
Till,
I think replacing the sides is the correct decision.
Peter
Hi Peter,
The owner of the T5 has given me the go ahead to replace the side panels. Fortunately the internal framework has been untouched by the worms so at least there will be some original parts in the cabinet. But that's not the end to the problems. The control panel with it's unique "Televisor" emblem is in a bad state. From the wood working point of view it's an easy enough task to replicate the panel but we'll have find some means of saving the badge.
Till Eulenspiegel.
Hi Till,
Is there enough strength in the control panel that it could just be immersed in worm fluid for a while and the holes stuffed?
Peter
What about putting the control panel through a thicknesser to remove half the thickness from the back side, then glue a new thickness to make up to the original again. Assuming the panel will come off without damage.
Either that or soak the veneer off to be reapplied later using a suitable section containing the badge as an insert in the new veneer.
Hi Peter, Hi Freya,
It's an easy part to replicate except for one item, that "TELEVISOR" emblem which must be preserved or an exact copy made.
I'll give all your ideas consideration. The panel is strong and immersing it in wordworm fluid should kill off any nasties. Freya's idea of skimming of a few layers of the plywood on the reverse side is also valid. In 2012 I did something similar to certain parts of the woodworm infested HMV 900 cabinet.
Yesterday evening the signal generator was connected to the sound receiver unit. The sound receiver is not a superhet as the vision receiver is, but is in fact a TRF, fixed tuned to 41.5mc/s. The receiver down in sensitivity. Supplying the unit with a channel B1 signal direct from the Aurora gives insufficient output from the loudspeaker. According to the oscilloscope the oscillator in the demodulator is operating at 783kc/s.
The sound receiver unit is identical to the one fitted in my Baird T23.
Till Eulenspiegel.
A replacement right side panel was made yesterday and test fitted. A few slight adjustments required to achieve a perfect fit.
The circuit diagram of the sound receiver. Noteworthy is the demodulator which employs a Mullard FC4 octode. The oscillator is an essential element for the operation of the circuit.
Till Eulenspiegel.
The attachment shows the condition of the original left side panel. After removing the lower batten serious woodworm damage was found. The panel is scrap. A replacement was made today.
Till Eulenspiegel.
I was looking at the sound demod circuit the other day and couldn’t get my head around it.
After some thought and a whisky I think it’s a super regen circuit. I have replied on the UKVRRR forum to that extent.
Having put my head above the parapet I wait to told how wrong I am. ?
Any worms left in that panel will go hungry by the look of it, not much left.
Frank
Till causes global catastrophe: ☹️
We know to blame then. Yes I read that story.
Frank
And to compound my guilt the CRT screen panel will be replaced and the original burnt along with all the other woodworm infested parts.
Till Eulenspiegel.
