Did you find a cable?

Nice collection,  more than most would have,  how long did it take to achieve such a large number . I have a few of the dual beam , only missong the 7844. Good luck with your collection,  i am sure there are many that may have questions. 
On Thu, Jan 31, 2019 at 7:55 PM, books4you@...<books4you@...> wrote: Hi. My name is John. I have just joined so I would like to observe for a bit to get the hang of being on here. My interests are 500 series restoration and repair. My google photo sight is

https://photos.app.goo.gl/vWHUhwHc74o7ed7Q9

I am looking forward to being a member of this group..

Welcome, John!  Very impressive collection!
Jim Ford


Sent from my Verizon, Samsung Galaxy smartphone

On Thu, 31 Jan 2019 18:35:46 -0000, you wrote:

I *seriously* have no idea what's going on, but I do have at least, a
question.

With the intensity at minimum, where are those intensity spikes coming
from?

1) could they be related to the readouts? (not sure, but changing
readout intensity ought to say something)

2) are they related to something breaking down in the intensity
circuits? (I'd expect anything on the CRT Z axis to spike and be
bright).

3) are they related to unblanking (in which case, I'd expect the
retrace to do something odd....)

Not sure what else is in there, since I don't have a 7854, although
I'd rather like one.

OK I just ran through the Z-Axis calibration and pretty much everything
looked just fine on the test scope.

which means that the relative voltage readings are fine, and the z
axis stuff is ok, but tells you little about the sources.

The following test was done with readout on the 7854 turned off.

Looking at the waveform at TP183 on the Z-Axis board: With the 7854
intensity set to minimum, the base line is at about 9.5V, and while a sweep
is running the voltage is about 20V. If I increase the intensity to
maximum, the voltage is about 80V, which is correct. The signal has a
flat top (no variation), and the variation in the peak voltage is linear
with the intensity control.

Then where are the dots (negative spikes in K-G voltage) coming from?

With the intensity set to minimum there is no obvious trace, but there are
very short bright dots at fairly random locations along the line where the
trace would be. As I increase the intensity to the 270 degree position
(dot on knob pointing to left) the dots disappear but no trace appears.

Hmmm, sounds odd, but what happens to the baseline K-G voltage or the
effective intensity modulation given to the CRT?

Nothing is then visible until the intensity control reaches just before the
90 degree position (dot on knob to right). At this point a somewhat out of
focus trace with intensity modulation along its length appears, and finally
with intensity to maximum the trace is a bit more out of focus and somewhat
brighter but still modulated. The modulation appears to about 1-2 cycles
per sweep division when the timebase in the 7854 is set to 10mS/div.

Then the modulation is still there regardless of intensity control,
and perhaps you're just seeing it?

At this stage I'm guessing it's probably some sort of problem in the HV
circuitry (possibly the cathode supply) or maybe the DC restorer, or even
the EHT supply to the anode? I suppose it might also be a dying CRT?

IF so, then I'd expect some variations in the voltages, HT, cathode
supply (where's it coming from) and grid supply (ditto).

If I didn't see any pulses at all (can you find a source?), then I'd
start to suspect the CRT.

Not readily, though.

I have scoped the cathode supply using a P6015 and it's close to -3kV with a
square wave ripple of about 0.5Vpp at 25.5kHz.

Then the HT is likely stable enough, and I'd start to probe the other
electrode voltages on the CRT.

Not sure you've gotten there quite yet.

From there, I'd look to see what causes it..

Elementary, of course, but completely looking from the outside in,
without any particular knowledge of the circuitry involved.

Just looking at this from an entirely logical viewpoint.....

Hope it helps... <grin>

Harvey

Harvey

Your thoughts most welcome ...

David
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C.
Partridge
Sent: 30 January 2019 18:30
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 display problem

Drat it - it still split the link!

<https://tinyurl.com/ycarxp3k>

David
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C.
Partridge
Sent: 30 January 2019 15:43
To: TekScopes
Subject: [TekScopes] 7854 display problem

OK when I powered this 7854 on fixing the PSU, if failed POST with a ROM
failure (dratted Mostek mask ROMs).

So as to be able to continue testing, I "borrowed" the ROM board
(670-5047-02) from my personal 7854 and put it in the patient.

It passed POST, but this is what the screen looks like: <
https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem.
MOV>

It sort of looks like it may be trying to display the normal Self Test
Complete screen, but it sure isn't right!

Any suggestions for likely culprits?

Thanks
David

Hi John-
welcome and wow unbelievable collection!
Renée

Thanks Oliver. I fortunately can’t say “I started two wives ago.” But I did start buying from eBay, swapmeets etc many years ago. Now I am working on repairs, painting and special projects such as that 551 with no high voltage. Sadly I never did become much good with transistors and the subsequent offshoots. But I still can work with tubes pretty well for 74 years young. Thanks for your interest.

The old HV issue , i have a 551 that had no power to crt it turned around when i replaced all Hv caps in fly back and replaced a tube diode or rectifier.  I have a 547 with a bad HV transformer that i one day want to rewind , first o will need info on number of turns and some good tips from others who already did a rewind. 
On Thu, Jan 31, 2019 at 9:25 PM, books4you@...<books4you@...> wrote: Thanks Oliver. I fortunately can’t say “I started two wives ago.” But I did start buying from eBay, swapmeets etc many years ago. Now I am working on repairs, painting and special projects such as that 551 with no high voltage. Sadly I never did become much good with transistors and the subsequent offshoots. But I still can work with tubes pretty well for 74 years young. Thanks for your interest.

1) Readout was turned off completely so no I don't *think* those spikes
relate to that.
If it had been turned on I believe I would've seen the RO Z signal mixed
with the main Z signal.

2) Maybe? I am befuddled.

3) Pretty sure not.

I don't think this is in any way related to the digital stuff.
If this were coming from there I'd see a crazy Z-Axis signal.

Cheers
David

On Fri, 1 Feb 2019 04:10:50 -0000, you wrote:

This would have been easier to follow had you interleaved this <grin>.

1) Readout was turned off completely so no I don't *think* those spikes
relate to that.

turned off or disabled so it didn't do anything? But I'd expect you'd
see something on the CRT unblanking.

If it had been turned on I believe I would've seen the RO Z signal mixed
with the main Z signal.

OK

2) Maybe? I am befuddled.

I'd think you should see this with an HV probe.

3) Pretty sure not.

OK, lets that one out.

I don't think this is in any way related to the digital stuff.
If this were coming from there I'd see a crazy Z-Axis signal.

Except.....

Have you looked at every digital input to the Z axis (and X and Y) to
make sure that they were correct (or at least, off) when you got that
dot?

You're seeing intensity variations in the trace.

Either....

1) it's on the Z axis (and if random, why not on the readouts?)

2) it's on the X axis (stopping the sweep)(yeah, how?)

3) on the x and Y axis (in a time where the beam is not multiplexed
for readouts... possible


4) I don't get this, but I *do* think it's something to do with the Y
axis (and perhaps X) that the Y axis ought to be doing something and
isn't. you can argue the x axis....

Harvey

Cheers
David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey
White
Sent: 01 February 2019 01:18
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 display problem

On Thu, 31 Jan 2019 18:35:46 -0000, you wrote:

I *seriously* have no idea what's going on, but I do have at least, a
question.

With the intensity at minimum, where are those intensity spikes coming
from?

1) could they be related to the readouts? (not sure, but changing
readout intensity ought to say something)

2) are they related to something breaking down in the intensity
circuits? (I'd expect anything on the CRT Z axis to spike and be
bright).

3) are they related to unblanking (in which case, I'd expect the
retrace to do something odd....)

Not sure what else is in there, since I don't have a 7854, although
I'd rather like one.

no I have not found one yet. I am all ears

Take a look at my photos. You can see one that I made using connectors and hookup wire. Let me know if that would work for you as well. It is just about impossible to find just the cable as few people would recognize it for what it is.

https://photos.app.goo.gl/vWHUhwHc74o7ed7Q9

I will be contacting you as soon as I get my money. I am owed it and it is coming. I want MANY probes, as well as the probe parts we discussed months ago.

I'll catch you offlist. I want a BUNCH of them. As soon as I am able we will do business.

I received an offline email from Christian Servais who suggested that the
control grid connection inside the CRT was open resulting in the intensity
signal being capacitively coupled. It wasn't that but the problem was
definitely related to capacitive coupling ...

As I swung the Z-Axis board out to gain access to the HV board, I noticed
that pin 1 of P83 wasn't connected even though I had connected it when I
opened it up earlier. This pin is the one that carries the Z-Axis signal
from the Z-Axis board to the HV board.

The connector wasn't a good fit on the pin, and consistently came off when
the Z-Axis board was closed up to its normal position!

Once I removed the plastic cover, "tweaked" the locking tab, and
re-assembled it, all was well!

It's so nice when the problems are reasonably simple! Even if it drove me
slightly nuts trying to work out what could be causing it!

Cheers
David

Sorry, try again.

RL

The cables for the 551 and the 555 are the same. They are listed as inter-unit cable 012-032 for both units in the 1965 catalog and as inter-unit cable 012-0032-01 in the 1967 catalog.

Hi John,

I like the the 500 series as well but I have a few less than you do!
Thanks for the photo gallery, it will be a tremendous asset for me to show my wife when I drag another Tek scope home: "What? I don't have that many; take a look at THIS!"

John

Do you have a part number or source for the connector you used to make up the cable? I just dug my 551 out of the garage where it has been sitting for about 25 years.

Joe/N8JM

I am attempting to do a full calibration on a 466 and am getting confused/irritated by the Storage calibration. I *think* I have managed to do the Variable Persistence mode adjustments, but the Fast mode I am not too sure that I am understanding correctly. There are two phases to this - the first requires pushing the erase button and waiting 15 seconds, the second requires a longer wait of 1 minute. Both of these procedures require the sweep to be triggered by adjusting the TRIG LEVEL control after the waiting time, and then immediately pushing the ERASE button. The manual then states:

"CHECK - Minimum fade-up or fade-down (brightening or dimming)".

I cannot understand whether this relates to a comparison of the screen between the sweep after the waiting time and triggering, or simply the fade-up or fade-down after the second sweep has been triggered. Does anyone have practical experience of this procedure and can clarify it for me?

It has already been mentioned on this Forum that the 466 has three different manuals, but there are also a number of Revisions, too. The big differences between the early scopes and the later ones deal with the triggering being done by tunnel diodes or by discrete components - I understand that. My Tek original manual is noted as being first printed in May 1974 and contains some pages marked as "REV. B, OCT 1974". I have also two pdf manuals which have some pages marked as "REV. B, JAN 1976", "REV. C, JULY 1976", "REV. C, JAN 1977", "REV. D, JAN 1977", "REV. D, APR 1977" and "REV DEC 1981". Comparing these, I find myself confused because there are different pre-adjust settings for the Front Mesh and the Fast Prep levels. In one case, the pre-adjust settings were completely wrong and the rest of the calibration couldn't be completed. These come from 070-1753-00 (my Tek original), tek-466-early.pdf and 070-1753-01.pdf. I would really like to get this 466 working as well as I can, but this is frustrating my efforts.

Any help/clarification/ideas will be gratefully received and may be of use to other owners of 466s.

TIA, Colin.

Problem
----------------
The problem is related to a TEK 2430A in good used conditions. It worked well up to some days ago, when I saw that the scope acquisition was frozen, not working controls on the front panel.
At the restart I saw with an extended diagnostics 5300 error version-check.
At successive restarts different other problems mostly in 7000, 8000, 9000.
At successive restarts the 5030 error disappeared but the scope was completely uncalibrated.
I did an external cal and then a autocalibration at the scope restarted to work but after twenty minutes the system stopped the acuisition and was uncalibrated.
Checks
The BT800 does not present external leaking, the voltage is 3.6 volt.
Test 4700 battery-status passed.
Test 6000 OK passed
I reseated some connectors and the PROM U480 and U490.
The voltages on A13 seems to be OK, the +8 is just 7.8 V
Any suggestion ?
Many Thanks to all
Marco

Thank you, sir

On Fri, Feb 1, 2019 at 9:19 AM boid_twitty <legg@...> wrote:

Sorry, try again.

RL



--

Sent from a Mobile iAnnoyance thingy, please pardon any typos