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Thank you everybody for the feedback so far. Sorry I have not responded sooner. Just to be clear, my primary interest is in the isolation characteristic of the differential probe as a safety precaution. I already do a lot of things for lab safety... I have an isolation transformer and a current limiter that I typically plug into. But, I also watched how Dave on the EEV blog has recommended differential probes at the end of his video () on how not to blow up your oscilloscope. I'm not desperate for one. Between my current lab set up and my best practices, I think I've got things pretty well covered. But, I occasionally see the entire P6046 kit come up for sale and was wondering if it's worthwhile for its isolation capabilities and if it's easily adapted into a regular (CRO?) probe.

Good job Jeff. I told you that the group could help you. :)

Hello the Forum, I was once told these connectors have a limited life, don't know for sure. How many
insertions? For someone who repeatedly configures with spectrum plugins, dual channel verticals,
curve traces, differential amp, ...
Perhaps its best to have multiple scopes. what do you say??

Well, I have most 7000-series scopes and plugins, some of which several times over. And I have never
seen any evidence of degradation of plugin connectors.

Craig

Epilogue,

I consider it done for now.
...
The End.

Congratulation Jeff!
Albert

Epilogue,

I consider it done for now. When I get some more JB Weld I will try to fix the variable controls, but I am satisfied for now. Then it was time for calibration, which is close enough but not done according to Hoyle.

First was the amplitude. Since channel 1 was untouched I used the main "VARIABLE" control for that and the other channel fell into line. The slight compression at the top was also gone. I couldn't do the frequency compensation because I actually lack a 50 ohm resistor (got a 47, no problem). So I was using banana ended wires from the generator to both scopes. At 1 KHz it looked great, at 10 KHz it had some rounding and at 100 KHz there was pronounced ringing. My generator (Wavetek 111) has an output marked with ?|_ 10 ns and if I recall its output is 50 ohms. All I need is the right cable and to terminate it then I can do the rest. It is not a huge priority. It read the same as the other scope (elcheapo 72-720) so I think it is very close, with the fact that both channels read identical.

On to the timebase. Was pretty close once I figured out what I was doing. HA, I was getting readings that said it was so far off it is ridiculous. I actually checked to see if the time base knob was on right. Then I see the other scope reads the same. I rocked the generator to 60 Hz and the frequency counter read 18 Hz or so. Duh ! I wasn't using enough signal and adjusting the input level on the counter (HP 5314A) fixed that. Once I got that straightened out and adjusted it with the sweep calibration control the ranges were closer and the linearity was better than the other scope.

The calibrator was just a dirty tube socket and level switch. The switch was really filthy, I had to use a typing eraser on some of it. Even LPS2 didn't work immediately like it usually does. I didn't calibrate it, I'll do that once I am sure of the gain of the input stages.

I am calling it a day, thanks all. Your tips and calling out my faux pas' here and there made it possible, or at least not take much longer. No, possible, if it was too long I might have given up. Too bad my Uncle isn't alive to see it. He gave it to me in the 1980s when it was about 25 years young. It has been in a fire and a very moist and moldy environment and I am surprised it turned out this well. Wish they built things like that now. And rest is odds and ends,

The End.

pretty much good advice. for a s/a a 3 hole with a large crt. 7603 ?

On Tue, Mar 27, 2018 at 10:03 AM, Richard Solomon <dickw1ksz@...>
wrote:

Buy a second (or third) scope and
dedicate it.

73, Dick, W1KSZ

On Tue, Mar 27, 2018 at 10:02 AM, brasscat <brasscat@...> wrote:

Hello the Forum, I was once told these connectors have a limited life,
don't
know for sure. How many insertions? For someone who repeatedly configures
with spectrum plugins, dual channel verticals, curve traces, differential
amp, ...
Perhaps its best to have multiple scopes. what do you say??

Thanks, Stan KO6YB

Buy a second (or third) scope and
dedicate it.

73, Dick, W1KSZ

Hello the Forum, I was once told these connectors have a limited life, don't
know for sure. How many insertions? For someone who repeatedly configures
with spectrum plugins, dual channel verticals, curve traces, differential amp, ...
Perhaps its best to have multiple scopes. what do you say??

Thanks, Stan KO6YB

Likely problems include shorted epoxy dipped solid tantalum
capacitors.

On mine one of the 7475 4-bit latches was bad so I replaced it and the
rest of the TTL logic with LS TTL logic but this is probably an
uncommon failure.

Hi to All,

Dave couldn't find these anymore in his files. Anybody who will send the original pdf's to him? Then I can order them again.

Greetings to All,

Egge Siert

PG506 came today. Serial #B059196. Looks like someone has been inside messing with the group of dale resistors. Some of the leads are bent and it looks as if some flux is left behind on the board. Never seen anything come that way from tek. So I'm assuming someone has been monkeying around. Anything I should look at/out for before I fire it up? The 504 mainframe wont be here until Wednesday or Thursday.

On Mon, Mar 26, 2018 at 01:31 pm, Bob Koller wrote:

Bad multiplier? Not an uncommon problem in general on Tek scops.

Or on anything that uses them. We changed tons of them in TVs way back. Actually when Sony used them they fed them with sine waves to supposedly go easier on them.

On Mon, Mar 26, 2018 at 09:26 am, David Hess wrote:

I do not think the CRT can short the power supply but the high voltage
multiplier sure can.

Actually I think it can but it would be rare because that would mean a dead short in the CRT. It can happen but usually there is some sign of the HV trying to start.

I checked the 15 volts like I said and it was 14.95, even Tektronix isn't so picky that would do this.

Well, I'm glad I took your advice and tried to fix the variable control. Couldn't fix it, there is a cracked nylon piece. Of course I did channel 2 because that is the one that has been tampered with. So failing that I decided to leave it out, along with the shaft and the knob. As such of course I had to jump it out electrically.

Remember I said I hadn't bothered to check the deflection yet ? Well with it wired across it had much more gain than channel 1. At first I am like WTF. (don't mean to sound like a valley girl here but...)

Turns out both pots were crudded up so badly that they were totally open. They are 575 ohms, open is no good. Channel 2 had no hint of clipping, and when I jumped out the same pot on channel 1 the same thing happened, I got a ton more gain. (a ton is approximately 20 dB or so in this case)

So now I have both channels, chop and alt, and no clipping. I went back and readjusted the DC balance again, it seems to drift a bit but then you are supposed to wait before adjusting anything. It is not that bad. One thing is the centering goes off about a division when using the add mode, but I can live with that.

I had rocked the 10 mV and 20 mV gain controls on channel two only to see if they were dirty, they are OK, they were a bit but rocking them fixed it. I put in the usual hand signal and set it to add and invert one channel and set it to null. It nulls as perfectly as you could want, even when in 10 mV where it is severely overdriven.

Now it does not jibe with my other scope, reading amplitude too high if the other scope is right. that is a matter of calibration and I'll get to it. There is a bunch of HF hash on the finger signal and it nulls perfectly as well so the frequency response is probably close. I will still check it but that is after the gain is set. I'll go through that later, soon though. I might see about fixing the calibrator, since it is totally dead and seems open circuit it might be something simple. I van take care of that and then get ready fo r the calibration. I am not buying all these old text fixtures obviously, but I have an accurate frequency counter, an accurate voltmeter, a source of good square waves and if not I got diodes to make one. And I have my second 422, I have found those to be very accurate. Between all that I should be good to go.

So I will take a quick look at the calibrator tonight probably. After that I get ready for the rest. Then I will want to find some of those screw thingies that hold the side covers on. those are broken and or missing and the duct tape just doesn't have that pro look :-)

Thing is I can actually use this scope for most audio work.If not I will fire it up from time to time and give the caps a charge. And it's old enough for a pension.

I'll keep you "posted".

Hi all,

After several more rounds of trial fittings, we have finished the 335 scope replacement feet project. Many thanks to Lee Houde for great photos and feedback. The feet are available on my website, www.n0dy.com, and on ebay (search for "Tektronix 335 feet"). They should also fit a 314, but the test fit on that scope hasn't yet happened, but should in the next week or so.

I'm also open to developing replacement feet for other models. PM me if interested.

Regards,
Jeff

On Mon, Mar 26, 2018 at 3:07 PM, John Griessen <john@...> wrote:

Does anyone have Tek 7xxx 4 pin probe power plugs to sell? (The cable part
that comes with a probe)

Well, Lemo does, if you don't mind paying the price:

Does anyone have Tek 7xxx 4 pin probe power plugs to sell? (The cable part that comes with a probe)

Bad multiplier? Not an uncommon problem in general on Tek scops.

Oh, I didn't mention, I think there is no grid current at the front end. The trace does not move at all when going through the ranges. The only time it did was on 10 mV/div before I adjusted it. Now it stays put at all settings.

The clipping however, goes away or at least off screen at the 10 mV setting, which kicks in more gain in a later stage Q 234 & 244. That is why I think it is before that.

But of course I will check everything.

Hmmm. So it sounds like if I don't get anywhere with the 15 volts maybe I should try switching those tubes ?

if this doesn't prove anything I am going to have to break out a signal generator or fix the calibrator so I can feed a constant level into it, So far the test signal has been my finger.

In fact a square wave won't do as well as a sine or triangle wave so I guess I have to fire up the old Wavetek.

In fact I'll have to use it anyway to be sure of the frequency response. The amplitude should be no problem, I can compare that to a DC voltage as long as it displays an accurate square wave at very low frequencies. At least I think so, correct me if I am wrong.

Also I guess I might as well put a probe on the frequency counter and check the time base while I am at it.

But that is all after the current problem is resolved. I hope it's not the tube(s). Not only are they hard to get, those look like something that really should be replaced as a pair. Maybe I should see if the ten buck one is still on eBay.