29-04-2013, 02:02 PM
That intermission lasted longer than expected due to all sorts of other things getting in the way. The valves actually came last Tuesday - very good service from http://stores.ebay.co.uk/Tube-shop-UK?_t...7675.l2563.
So, step one was to replace the two duff valves. That only entailed a small loss of hair due to the limited access.
Then the big switch on - nothing
OK, lets try it with the 5763 actually pushed into its socket - I'd previously half pulled it out to measure on the pins.
Try again - faint trace on 'scope which got a lot better with the probe actually clipped on. Well over 400v p-p.
Next measure voltages on various Outputs - nothing. Try again with AVO Negative clipped to Chassis.
Some voltages but not very impressive. Perhaps it would be happier with the Focus wire on A5 and not A9. And Lo, big voltages all over the place.
Next reconnect the Resistor from the Transformer to V505 etc. This time it didn't kill the Oscillator and there's a glow on the screen - hallelujah.
There's no scan because I've still got the Blanking connected to -150v, but it looks promising. I'll have to do some tidying up cause the wire connections have got a bit scruffy with all the unsoldering and soldering.
I'll also have to try to measure the Output voltages, and hopefully set them using the Pot. I'm only good for 3kv on the AVO and I haven't got a meter which will read higher. However, a few weeks ago I spotted a High Voltage/High Resistance String on ebay - see attached. I was surprised that they didn't make much. They measure OK so I'm ging to give them a try. I've also bought some EHT Cable as recommended in another Thread so provided I keep my hands in my pockets and stand well back I should be OK. In time I'll make a High Voltage Probe.
Finally, I was pondering on the differences between this one and the Manual and it dawned on me that the Manual refers to TF1331A while this is a TF1331, so presumably it's earlier. That's logical as there's less valves and no Pot in the A Version.
Alan
So, step one was to replace the two duff valves. That only entailed a small loss of hair due to the limited access.
Then the big switch on - nothing
OK, lets try it with the 5763 actually pushed into its socket - I'd previously half pulled it out to measure on the pins.
Try again - faint trace on 'scope which got a lot better with the probe actually clipped on. Well over 400v p-p.
Next measure voltages on various Outputs - nothing. Try again with AVO Negative clipped to Chassis.
Some voltages but not very impressive. Perhaps it would be happier with the Focus wire on A5 and not A9. And Lo, big voltages all over the place.
Next reconnect the Resistor from the Transformer to V505 etc. This time it didn't kill the Oscillator and there's a glow on the screen - hallelujah.
There's no scan because I've still got the Blanking connected to -150v, but it looks promising. I'll have to do some tidying up cause the wire connections have got a bit scruffy with all the unsoldering and soldering.
I'll also have to try to measure the Output voltages, and hopefully set them using the Pot. I'm only good for 3kv on the AVO and I haven't got a meter which will read higher. However, a few weeks ago I spotted a High Voltage/High Resistance String on ebay - see attached. I was surprised that they didn't make much. They measure OK so I'm ging to give them a try. I've also bought some EHT Cable as recommended in another Thread so provided I keep my hands in my pockets and stand well back I should be OK. In time I'll make a High Voltage Probe.
Finally, I was pondering on the differences between this one and the Manual and it dawned on me that the Manual refers to TF1331A while this is a TF1331, so presumably it's earlier. That's logical as there's less valves and no Pot in the A Version.
Alan
