Invicta T105

[Hunts smoothing bomb]

Morning all,

Could anyone give me a rough idea how much one would expect to pay for the above set in unrestored condition? I've been told It was powered around 15 years ago and had frame colapse showing just a bright white line.

Cheers

[mark pirate]

Hi Lee, These sets are quite rare, so worth more than the Pye LV20.
I would say an unrestored set in good condition is worth around £75- £100.
I would happily give one a home for that sort of money.

Mark

[Hunts smoothing bomb]

Hi Mark, and thanks!

The opportunity has just come my way to possibly pick one of these up from an old friend!

Cheers
Lee

[beery]

Hi Lee,

I love these sets (on my wish list). They look quite cute (can I say that about a TV set?).
Bits of Pye B18T are in there, like the line output stage and bits of the Invicta T102 (also found in the PYE D16T/Invicta TL31) in the form of RF stages based on the PYE 45MHz Radar IF strip. By also using a metal rectifier mounted above the chassis, the whole thing ends up more compact than the B18T/LV20.

Do buy it, I'm sure you will enjoy it.

Cheers
Andy

[mark pirate]

I am with Andy on this one, grab it with both hands

By also using a metal rectifier mounted above the chassis, the whole thing ends up more compact than the B18T/LV20.

Although the B18Tand LV20 share an physically identical chassis, the B18T has a smaller cabinet. I only noticed this when I compared my two sets.

If you do get the Invicta, please post some pictures of it, it would be very interesting to see the differences between it and the B18T/LV20.

According to Jon's site, it was released in Dec1949, the LV20 was released three months earlier.

Mark

[Hunts smoothing bomb]

Morning guys,

The chap is coming round with the set around lunchtime so we will go off to the workshop to give the patient a "health check" before I decide to purchase.
One question though is that whilst looking at the data in the red Newnes book it mentioned that some of the EF50's needed to be special quality versions, some with silver pins and some "non microphonic"
Why is this and is it absolutely necessary?

Cheers

[Freya]

Hi lee,
I looked into the specially selected EF50 valves, it seems they were selected in these positions because their grid emissions were negative. After testing the specials and comparing there is a difference on a valve tester.
However if standard versions were fitted in place in the set, no discernible difference was seen. This was on Pye B18T.

[mark pirate]

Hi Lee, I believe the same applied to the B18T I restored. Some of the EF 50's had two black stripes across the top, I think these were the 'special' valves.
I just numbered them so that they could be fitted back in the same place.

There is mention that if these valves were replaced, the sent may have to be realigned.

When I restored one of my LV20's, the valves got a bit mixed up as I was working with two chassis: https://www.vintage-radio.net/forum/...d.php?t=116290
I just used the valves that tested the strongest from both chassis, it did not seem to make a noticeable difference though.

Mark

[Hunts smoothing bomb]

Thanks guys for the info,
I now own the set, the cabinet is a little rough but solid so no problem there.
The chassis is very clean but powering up under variac and limiter produces smoke. We agreed that £40 would be taken in exchange for the set.

The set in "as received" condition.

Cheers

[mark pirate]

Very nice, do you have the knobs for it?
I would be very interested to see photos of the chassis as well.
If it is like the Pye, there are just two screws at the back of the chassis.
The speaker just unplugs from the chassis.

BTW, the smoke may just be the power resistor under the chassis, or maybe the mains filter cap.

Mark

[Hunts smoothing bomb]

A pic of the chassis.
Cheets

[mark pirate]

That looks very clean indeed, I notice the sliders look much more accessible that the D18T/LV20. The speaker is different too, not the usual brown R&A.
It looks as if the chassis is steel rather than aluminium, as in the Pye sets.

You have certainl bagged a bargain, I look forward to seeing first light on it.

Mark

[Hunts smoothing bomb]

Some more pics of the chassis.
Cheers

[Hunts smoothing bomb]

I had a bit of a play with this set last night and I noticed that someone has been here before!
1. The metal rectifier has been replaced and is not the right type. (single type and too short so only held by one mount)

2. The main smoother has been replaced.

3. According to the Newnes books the frame osc T6 should connect to + through R7 (2.2k) In my set it is coupled directly to HT and by the way it is soldered, looks like it is original. (R7 appears to not exist!)

4. Despite C129 being original, it's clamp has been removed and never refitted for whatever reason.

5. According to the red Newnes books R8 anode load for V15 line osc on the Invicta T105 should be 820k. In my set it has been replaced by a 47k!! The resistor looks to be the same age as the others of the period so looks like it was done a long time ago, I thought it may have been a misprint so looked up the Pye B18T/LV20 and sure enough this resistor all be it R48A on this schematic is documented as 820k also.

The set can now be powered up, the smoke was caused by the failing mains bypass cap, this was snipped out. As it is at the moment I have no line whistle or EHT so need to investigate but was wondering if the value of R8 could be partly to blame.

I'm going to change the waxies as matter of course but what do you think about those differences to the scematic?

Cheers

[Hunts smoothing bomb]

I didn't get much done last night so planning on changing the leaky caps tonight in the line and frame stages to see if I can get any life into them.

I've noticed that all the valve pins are completley black and tarnished so will need to give them a clean also. I have found that scraping them very lightly with a scalpel blade brings them up like new, with the addition of a little de-oxit and a few insertions this should guarantee a good connection.

Cheers

[mark pirate]

all the valve pins are completley black and tarnished so will need to give them a clean also. I have found that scraping them very lightly with a scalpel blade brings them up like new, with the addition of a little de-oxit and a few insertions this should guarantee a good connection.

That is exactly what I do, it is very important to make sure those EF50 pins are making good contact. I use a sewing needle to clean the pin holders on the valve bases.

It is also worth checking that they grip the pins properly, a careful squeeze with needle nose pliers works well

I am looking forward to some under chassis photos, it certainly looks very different to the Pye sets on the top.

Mark

[Hunts smoothing bomb]

Thanks Mark,
I'll post some more pics tonight!
Cheers

[Hunts smoothing bomb]

Here's some pics of under the chassis to compare woth the B18T/LV20

Cheers

[Hunts smoothing bomb]

Well, there is life.
First light achieved! Still lots to do though!

Cheers

[Hunts smoothing bomb]

I'm not sure how good the CRT is as the getter doesn't look good.