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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

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Old 13th Feb 2020, 5:29 pm   #41
dave cox
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Default Re: Tektronix 585A issues.

Does this scope have XY display ?
It'll be simpler to think things through in 1 dimension at a time !

I would be trying to prove to myself that the 'deflection plate' drivers can swing enough voltage, driven by the input channel(s) to start with then driven by the timebase ...

dc
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Old 13th Feb 2020, 6:31 pm   #42
MotorBikeLes
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Default Re: Tektronix 585A issues.

Andy, have you trried checking the voltages on the X plates? If you set to a SLOW scan speed, you can watch the X plate voltages with an Avo. If each one goes to the same max and min voltages, you have a tube fault. Well worth checking as that could be game, set and match if you don't have a spare.
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Old 14th Feb 2020, 8:59 am   #43
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Default Re: Tektronix 585A issues.

"Does this scope have XY display ?" Not as such but it does have a hor input which doesn't work AFAIK, I remember trying to use the scope in XY mode. "It'll be simpler to think things through in 1 dimension at a time !" Agreed, it's confusing.

I'll check the voltages on the CRT and do some more reading of the manual.

Andy.
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Old 14th Feb 2020, 9:40 am   #44
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Default Re: Tektronix 585A issues.

Went into the WS and went to familiarise myself with the connections to the CRT...hello, what's this, a wire off, well I'll be. Popped the wire back on, turned on the mains SW...BANG!! What the flegnog! Main fuse blown but all's well as it had touched the chassis being a temporary fuse holder to save on blowing big 63mm fuses. Put another in, THUMP!! Pigeon landed on the WS roof, made me jump, last thing you need is loud noises when messing with HV. Switched on, scope started, then cut off. Mains on SW now iffy, so jumpered it out. Scope finally on, trace is a good un, hoorah : )

Electronics eh, from euphoria to heart attack in 30 seconds, then embaressment for not checking the obvious. However I now need to check the scope over, neon B171 still not lit, this is the case with several neon pairs, EG one lit, tother not.

Andy.
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Old 14th Feb 2020, 4:52 pm   #45
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Default Re: Tektronix 585A issues.

Andy,

If you are still considering a main transformer replacement, I have a TEK585 sulking on the floor of my room at the moment. I got it with no HT supplies which was fixed by getting the time delay to work after finding a resistor that had gone high value. The K600 timer was working but R6000 in series with the K601 coil had gone from 33R to 60R and K601 would not pull in to turn on all the DC rails. I think I had to change a 6080 and 6AU6 as well to get them all in spec.

Anyway, managed to get a trace (or two) and found the 82 plug in was more or less working but after a few minutes the trace disappeared due to the well known EHT transformer problem. It would return after powering off for a while but I've effectively given up on it as I have a 544 working quite well and I'll use the 585 for spares where appropriate. I haven't checked precise details of the differences between my 585 and your 585A but I would imagine the transformer will be the same. It will weigh a ton and I imagine the post would be high but the offer is there...

I had thoughts about using the magnificent transformer (T601) in a high voltage PSU for a linear amplifier but will probably never get round to it. I'm sure it is fine. Pretty sure the CRT is too but wouldn't want to post that!

Ian
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Old 14th Feb 2020, 6:46 pm   #46
dave cox
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Default Re: Tektronix 585A issues.

From what Craig posted earlier the 585 and 585A have the same trafo.

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Old 14th Feb 2020, 8:06 pm   #47
Craig Sawyers
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Default Re: Tektronix 585A issues.

That is what the Tektronix Transformers Replaceable Parts Registry says.

Craig
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Old 15th Feb 2020, 7:52 am   #48
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Default Re: Tektronix 585A issues.

Thanks Ian, That's a very kind offer, will drop you a PM.

Checked the scope over yesterday and it's working better than it was before it went bang. Still haven't found what caused the original fault, it's a puzzler.

Re B171 & B167 can anyone confirm whether they are supposed to be lit at the same time? It looks to me like they're there to keep the grids of V173 at 60v. On my Hickok 545 clone they're both lit AFAIR.

Andy.
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Old 15th Feb 2020, 12:37 pm   #49
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Default Re: Tektronix 585A issues.

I'll be replying to your PM Andy.

Ian
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