A friend dropped by yesterday with a 1971 vintage 24" Pye T26 (all solid state) with no picture.

This "chassis" (if you could call it that, it's just a single flip-down PCB attached to a metal bracket that contains the power and EHT transformers) is not a model I used to see very often, both because they were very reliable and because Pye sold them with 4 years free service. Pye's own service department did any service that might be needed.

This particular TV had never had the back off it in 50 years!

I noticed that there was actually a picture, but only the brightest bits lit the screen.

CRT G2 measured 350 volts, so it's not that.

G1 was low even at max brightness setting.

The Brightness pot is supplied from the 450v rail via two 820k 1 watt resistors in series. One of these measured 3 megohms....

Replaced resistor, perfect picture. Perfect geometry. Nothing to do but screw the back on!

The T26 was known for rock-solid performance and reliability. A credit to its designers. No wonder they could afford to offer 4 years free service! But the service trade hated Pye for doing it.

The T26 service manual says it is "the first fully transistorised large screen television chassis designed in Australia".

Did you recall which particular model this TV is?

The transistor list has two columns showing both Philips & Fairchild types. I heard somewhere that Fairchild transistors were less reliable than the Philips types. Was this the case?

I wish I'd taken some pics. But it was in and out in an hour or so.
The manual is definitely correct on that first. I was told once that it was the first large-screen all solid state TV to go into production anywhere.

Yes I seem to recall having to replace the occasional Fairchild transistor. HMV used them as well. Hard to say if one was less reliable than the other, failures were not common and the company I worked for at the time did new warranty service..

Now the Anodeon transistors were the ones with reliability issues. Someone at some stage convinced Kriesler to use them in their PT1 portable.

Philips Australia made the OC9xxx series of transistors to compete with Fairchild.

Astor solid state sets used the Anodeon transistors and they were a disaster.

One of the issues with those transistors was that the faults were usually intermittent.

AVE made VDAs in little blue-grey boxes that were used in large numbers in TV studio fitouts in the early 70s. Most of these used Anodeon transistors.

You might recall seeing a disasterous episode of a current affairs program on the ABC where any attempt to cross to anything resulted in an out-of-sync picture. That was caused by one of those VDAs failing.

In short order the ABC ripped them all out.

Sorry for being a bit out of touch Ian.
But what was AVE? and what's a VDA?
Lance

Sorry about that Lance.

AVE were Audio Video Engineering, I think they were located in Rydalmere.

A VDA is a Video Distribution Amplifier. It takes a composite video input and splits it out to typically 4 or 6 outputs. Composite video must be 1Volt peak to peak into 75 ohms so an amplifier is needed.The amplifier must have a flat frequency response curve from DC to 5MHz.