Re: Tek 577 D1 storage adjustment questions.


Eric
 

From having been through the adjustment process. I can say the dimmer tube that I have the brightness control does not appear to do anything for the over all brightness of the tube. I have checked the transistors in the oscillator circuit and they test ok. No further troubleshooting has been done yet. From that I have been able to gleen from the manuals is when you ordered a tube from tek it came with a card that said set the voltages to “this” and those seem to be unique to each tube and were established at the factory. So I am not sure what the manufacture tolerances were. I would have to assume that the storage functionality works the same as it did with the scope tubes. Though the curve tracers are a REALLY low bandwidth tube >2Mhz on mine the brightness does have an effect. At full brightness with a comfortable trace intensity the tube will store. At low brightness the trace will only store around the edges. The history of this tracer is odd. It has been doodled on the front with settings like b.p and a few other terms. It also has a “hospital” grade plug on the end the cord was cut and a different plug attached. So I believe that the unit was used in some thing medical or bio med but for the life of me I have no idea what it would have been monitoring especially at 100 V/div and 350 VDC collector.

If a video of the units side by side would help let me know and I can get one posted.

On 11/16/2020 12:48 PM, Dave Voorhis wrote:
On 16 Nov 2020, at 17:08, Eric <ericsp@gmail.com> wrote:

I am working on some 577’s D1 storage curve tracers. I am trying to get a 178 working. So I need the storage tubes up and running. I do not have much experience with storage tubes hence the noob question. I think one of these units has been miss adjusted pretty badly, my problem Is I do not know which one. When I do the 6 minute startup as called for in the manual both units will get some glow bloom on the tubes. One is far dimmer then the other but both tubes have really good brightness so I do not believe that it is a tired tube. If I hit erase on both tubes they will blank as expected but the bright one will again go to full glow. At the full brightness the tube will not actually store anything as it looks like the glow is too bright. On the dimmer tube after the initial power up the tube will not bloom any more in storage mod and it will store a waveform however the “brightness control” must be all the way up. At minimum storage brightness it will store but it will only store at the edges.

So having minimal exposure to storage tubes is this normal behavior or is one or both miss adjusted? I can take some pictures if it will help. In the service manual it talks about adjusting the tubes but it does not say where the brightness control should be during the adjustment curious if anyone has insight on that as well.
I have a 577 D1 which is rather similar to your dimmer tube. It originally had an obviously failing CRT — dim to barely visible in non-store mode and double-peaking — but storage mode worked surprisingly well despite the dim trace.

I replaced the CRT with a used spare that came with the curve tracer. Now it’s bright and sharp in non-store mode but despite multiple attempts at tuning the storage settings per the service manual, it will only store if the intensity is turned up to be uncomfortably bright and the brightness control doesn’t appear to affect storage sensitivity, only the brightness of a stored trace.

I suspect either the replacement CRT has worn-out storage gubbins or is in some manner mismatched to the drive circuitry, or I’ve somehow repeatedly failed to correctly follow the service manual instructions.

Sorry, that’s obviously no help at all, but I’m hoping someone will chime in with knowledge that will help both of us.



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