07-07-2013, 06:46 PM
Another plendid day. Baking hot, which keeps everyone out of my way, and no hope of doing anything in the garden. It was between 90 and 100 in the Garage, even with the fan running. Perhaps I'm a Lizard really 
So, what about the rest of the Controls? The only one that I couldn't turn properly was the A Channel Input Attenuator. The B Channel seemed to have loosened up overnight. At first glance it looks impossible to get at anything, but in practice it's quite simple. There's an Input wire - Resistor actually - from the Front Panel Connector and an Output wire - again a Resistor - from a Feedthrough at the back. It's a complete Module which is held in place by two screws into Bushes at the back and the usual Nut and Washer at the front. After removing them it comes out, with a bit of wiggling, as a complete lump. The application of PlusGas and oil, plus a bit of easing in the vice got it all working. So far, so good, but there's a couple of Hunts in there and it seemed a pity to get this far without changing them. One of them is the Input (AC) Capacitor and should be 0.1u (100n). However, I'd only got 0.22u at 630 volts so I used that. The other one is 0.01u (10n) in the Output circuit so I changed that as well for a 630volt one. Getting it back in was pretty straightforward apart from getting the Washers and Screws in being pretty fiddly. While I was at it I did the same with the B Channel as well. The Gods weren't entirely with me as I dropped another Grub Screw and this time I didn't find it.
There was one other job to do while it was upsidedown and that was to change a couple of 2M2s in the PSU circuit. I'd tacked in a couple of 1/4W ones when I was getting it going 'cause I hadn't got any big ones at the time. Fired it up and checked the voltages - all OK.
Now for a real test. Got it right-side-up, give it a Signal and twiddle the Controls. With a bit of fiddling a twiddling, a Sine Wave appeared
Before getting too excited a few comments:-
That's the B Channel. The Shifts work OK but the Gain Control does some very odd things. By the way, it's better than it looks in the picture, although it's only about 2kHz.
Switching to the A Channel produces a line and that's about all.
Just like the old Tek 'scopes - 545 etc - you actually only get the middle section of the Tube.
Alternate and Chop don't work, yet.
It attemps to Trigger but that's about all I can say. On the other hand I knew that the Trigger Amplifier wasn't working - it's riddled with Hunts.
After about 10 Minutes, maybe less, the Trace gradually faded away, and not even the Trace Locate Button would produce anything. Methinks one of the Tube Voltages has gone walkabout. However, switching it off, waiting a bit and switching back on got it back for a short time.
It's cooling down a bit now so I need food, a shower and some beer
Alan
So, what about the rest of the Controls? The only one that I couldn't turn properly was the A Channel Input Attenuator. The B Channel seemed to have loosened up overnight. At first glance it looks impossible to get at anything, but in practice it's quite simple. There's an Input wire - Resistor actually - from the Front Panel Connector and an Output wire - again a Resistor - from a Feedthrough at the back. It's a complete Module which is held in place by two screws into Bushes at the back and the usual Nut and Washer at the front. After removing them it comes out, with a bit of wiggling, as a complete lump. The application of PlusGas and oil, plus a bit of easing in the vice got it all working. So far, so good, but there's a couple of Hunts in there and it seemed a pity to get this far without changing them. One of them is the Input (AC) Capacitor and should be 0.1u (100n). However, I'd only got 0.22u at 630 volts so I used that. The other one is 0.01u (10n) in the Output circuit so I changed that as well for a 630volt one. Getting it back in was pretty straightforward apart from getting the Washers and Screws in being pretty fiddly. While I was at it I did the same with the B Channel as well. The Gods weren't entirely with me as I dropped another Grub Screw and this time I didn't find it.
There was one other job to do while it was upsidedown and that was to change a couple of 2M2s in the PSU circuit. I'd tacked in a couple of 1/4W ones when I was getting it going 'cause I hadn't got any big ones at the time. Fired it up and checked the voltages - all OK.
Now for a real test. Got it right-side-up, give it a Signal and twiddle the Controls. With a bit of fiddling a twiddling, a Sine Wave appeared
Before getting too excited a few comments:-
That's the B Channel. The Shifts work OK but the Gain Control does some very odd things. By the way, it's better than it looks in the picture, although it's only about 2kHz.
Switching to the A Channel produces a line and that's about all.
Just like the old Tek 'scopes - 545 etc - you actually only get the middle section of the Tube.
Alternate and Chop don't work, yet.
It attemps to Trigger but that's about all I can say. On the other hand I knew that the Trigger Amplifier wasn't working - it's riddled with Hunts.
After about 10 Minutes, maybe less, the Trace gradually faded away, and not even the Trace Locate Button would produce anything. Methinks one of the Tube Voltages has gone walkabout. However, switching it off, waiting a bit and switching back on got it back for a short time.
It's cooling down a bit now so I need food, a shower and some beer
Alan
