In Fast Rise mode, the output tubes provide base drive to the Fast Rise circuit. See SW242A on the schematic.
SW242B bypasses the AMPLITUDE control in Fast Rise mode, jamming it to maximum. So don¡¯t leave it running for hours in Fast Rise mode unless you have lots of spare 7189A¡¯s.
Dave Wise
From:
[email protected] <
[email protected]> On Behalf Of Stephen via groups.io
Sent: Tuesday, March 01, 2022 9:15 AM
To:
[email protected]Subject: Re: [TekScopes] Type 106 Saga (Again)
On Tue, Mar 1, 2022 at 05:55 PM, Albert Otten wrote:
Interleaved.
Broken switch SW242A? In High Ampl mode you should measure R99 600R at the GR
output plug.
What would happen when R55 is open?
Is the output 0V or some constant negative voltage?
Thanks Albert,
Interesting¡. I didn¡¯t think of a broken switch. I check that out when I¡¯ll get beck home later.
I¡¯ll check again, but from memory all of the outputs are pretty close to 0V. I¡¯ll check that again.
I¡¯ll also check R55.
I don't think this is weird. The -20 V on top of "A" supplies the grid and
trigger circuits. The 4x output tubes anode currents flow in a separate
circuit from GND to "A", regulated by anode-cathode voltage, not by grid
amplitude.
Ok, but the 4 output tubes only supply the High Amplitude section, if I understood correctly.
Why would all outputs be out? That must be caused by something they all share in common.
Maybe the switch¡
Albert
