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Chris55000 · 9th Oct 2021, 10:05 pm

Hi!

The fault on it is a total lack of anything on the CRT whatsoever, not even a dot or anything!

There is a faint buzz from the mains transformer at switch–on, but the 160mA mains fuse is fine!

The two ECC83 valves on the main PCB are both fed with 12.6V across pins 4 and 5, the "hct" on pin 9 left unused, and I measured 13 V across here!

There was 245V and 305V at the anodes of the horizontal plate amplifier valve, (the base of the vertical one is covered by a screening plate) altho' I didn't try the horizontal shift control, I suspect it's not doing much!

The CRT base is awkward to get at without a lot of dismantling, and I've received two spare DG7-32 CRTs, (allegedly n.o.s!), but I'm not going to poke about any further – I'll complete my circuit diagrams and parts lists first and then see what the CRT cathode, (but NOT grid – I'll do that by checking the cathode voltage and then ohms tests on the grid circuit!), anode and plate voltages are like when my documents are completed!

Oh yes, the CRT heater hasn't gone, neither is the 6.3V winding on the transformer at fault!)

Chris Williams

9th Oct 2021, 10:05 pm	#4
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,870	Re: O.U. Generatorscope HK/2A Hi! The fault on it is a total lack of anything on the CRT whatsoever, not even a dot or anything! There is a faint buzz from the mains transformer at switch–on, but the 160mA mains fuse is fine! The two ECC83 valves on the main PCB are both fed with 12.6V across pins 4 and 5, the "hct" on pin 9 left unused, and I measured 13 V across here! There was 245V and 305V at the anodes of the horizontal plate amplifier valve, (the base of the vertical one is covered by a screening plate) altho' I didn't try the horizontal shift control, I suspect it's not doing much! The CRT base is awkward to get at without a lot of dismantling, and I've received two spare DG7-32 CRTs, (allegedly n.o.s!), but I'm not going to poke about any further – I'll complete my circuit diagrams and parts lists first and then see what the CRT cathode, (but NOT grid – I'll do that by checking the cathode voltage and then ohms tests on the grid circuit!), anode and plate voltages are like when my documents are completed! Oh yes, the CRT heater hasn't gone, neither is the 6.3V winding on the transformer at fault!) Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!