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that was supposed to be shifts and xors

This might be a dumb question, but why not get a different motherboard?

On Thu, Jul 15, 2021 at 6:46 PM David C. Partridge
<david.partridge@...> wrote:

I have a scope (not Tektronix or HP/K/A) that uses the BCM MX855 mobo with a
1.3 Celeron.

I'd like to give a late life performance boost and an told a Pentium M765
will do the job and maybe even an M780 (though that may depend on BIOS
levels).

Can anyone help? If you also have stick on PC2700/PC3200 1GB Ram that would
be great too!

Thanks
David

That sounds like a plausible theory, all though, what you described as a crc is really a checksum. A crc is similar but much more stringent. It is a polynomial with a characteristic divisor. In implementation is it is a bunch of shits and xors. None the less, that does not affect your theory, it works somewhat the same but the crc for target image must be calculated and then compared to the one in the last number of bytes depending on whether it is a crc8, crc16, or crc32. On the other hand the life time of those modules is 10 yr. About 30 yr ago I wrote a lot of 8051 code and designed a bunch of circuits to do all that. Back then 10 yr seemed like a lot of time. I think this scope is a mid nineties as its serial number is B4xxxx which is the later variety.

Anyhow I need to find out how up/download a new image. As I said above, I am getting an ieee 488 and I have an image I found posted. After that I can see if the same thing happens when power is removed, if so the module battery is bad. I would have thought running the SPC would have written a new freshly calculated crc. Seems like a flaw in the design. I always incorporated such features into my designs as I had an original IBM AT which used the original Mot chip the Dallas module was based on. The original design had a circuit bug that caused the battery to go dead regularly and so even though Dallas fixed the bug in the module, I always incorporated a convenient work around as sometime actions of users drained them. In the end the module was just a bad idea as can be seen now. Something custom that becomes obsolete changed out for something standard that will live seemingly forever.

Bert, Jeff, and Albert, thank you for the response.

Bert, I am planning on replacing the line caps. Seems to be the No.1 item to address during my research. Definitely not leaving that out! I have also heard that I should check the resistors in the focus string, that is also definitely on my list of things to do.

Jeff, I can appreciate that adage in certain situations, but I know that this scope was used in a university setting which makes me wager that it has a significant amount of hours on it. Not so much it is worn out, the interior is actually fairly clean, but in my (somewhat limited) experience, replacing electrolytics are a good PM measure especially when there is a fair chance they have seen some use (and have reached what many consider a ripe age).

Albert, on the topic of the pot, that is what I am thinking as well. I just want to see what kind of signal the two pots together send to the MUX. In regards to the screen at power up, I was not aware that this a cal screen. When the scope powers on to that screen, no control input gets me past it.. It could be related to my cursor control? Have not gone that far yet. But since the cursor control is essentially useless as it stands, I bet it has something to do with it. The few times I had traces, the cursor was so erratic that it made the scope seem to have a mind of it's own. Hopefully a good cleaning can get it working for the time being.

Again, thank you everybody for the help. I really appreciate the time you are willing to share with me.

On Thu, Jul 15, 2021 at 01:10 PM, sweetbeats wrote:

The rear interface output of the SG 502 will be connected to the rear
interface input of an AA 501A located adjacent to each other in the TM 504
frame. Is it necessary to use coaxial cable for this interconnect, or is it
acceptable to use standard stranded cable?

I used coax but even so the environment back there is so electrically noisy that the THD measured via the backplane is significantly higher than when connected around the front with BNC cables.

Beware that using pins on the righthand module can foul the module when inserted. I connected my SG505 on the left to an AA501 in the middle and an SC504 on the right of a TM515, and everything worked except the SYNC connection, which was shorting on the scope. Removed the pins and soldered the connection straight in and problem solved.

EJP

Can somebody come out with any reason for the CR3068 diode on VR 2nd Filter
Select board (left bottom corner on the schematic on page 185 of 494A/AP
Vol.2 Service Manual)?

There are 5 filters there, each having same exact switch on input and output
made from couple of diodes and a 2N2907 switch applying either +15V for ON
or -15V for OFF via 64uH inductor thus forward/reverse biasing those diodes.
Two switches per filter, on input and output so all inactive filters are
disconnected from both ends.

The switches are driven from an open collector 74LS145. Same filter is
inserted for 1MHz and 3MHz (it is a pass-through with only gain adjustment
potentiometer -- it is SECOND stage filters so actual filter is implemented
in the first stage). To make it happen they tied 'LS145 pins 2 and 9
together so either one would pull the 2N2907 switch bases low thus inserting
that bypass "filter" for corresponding BCD code.

The 100kHz/10kHz/1kHz filters are all separate so 'LS145 3/4/5 pins each
control their own pair of switches.

Then, 10Hz/100Hz share the same filter, exactly like 1MHz/3MHz, but this
time it is an actual filter. That means 'LS145 pins 6 and 7 should be tied
together to implement wired OR exactly like it is done with pins 2 and 9 for
the 1MHz/3MHz one.

Tying OC outputs into wired OR is perfectly fine when active level is LOW,
it is done all the time and this is what 1MHz/3MHz have. However for
10Hz/100Hz they put a DIODE between corresponding pins that is equivalent to
a short pulling the Q2020 and Q8035 bases to ground when either pin 6 or 7
is low.

But that is not all -- all switches are identical with 3.3K resistor to -15V
EXCEPT the one implemented with Q2020 that has 2.2K instead of 3.3K with
everything else EXACTLY identical. That also doesn't change anything as all
those switches are DC-blocked by 10nF capacitors on both sides of each
diodes/transistor switches. Diodes are also identical so there is absolutely
no reason for 10Hz/100Hz part to be any different from 1MHz/3MHz one.

Am I missing something?

---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*

I have the following CPU's spare if any of these will be of use:

1x SL6F9 - M705
1x SL7EG - M725
1x SL7SA - M740
2x SL7EN - M745
1x SL7V3 - M765
1x SL7VB - M780

I'm sure I could send one or two vaguely in your direction for the cost of shipping etc. :) (I'm in Japan, but it shouldn't cost too much for such a small parcel if you can't find anything locally)

David, here is the chip data. Lots of info to be found using a search. I have several Dell desktops and HP laptops from that era but you need to state if it is a desktop board or a converted laptop. The Dell desktops did use an M series processor even tho it was meant for mobile.?

Hi David I have 8 Pentium, 4 Pentium 3 and 2 Pentium 4. But none
have a M in their markings like M765 or M780.
Have a couple 1 gb 2700 and 1 3200, several 512mb of this speed.
Have 5 AMD processors also.
But I am across the pond from you it seems.
Gary G

Looking at what I think is going on, it's possible that the processor was in the middle of writing to NVRAM and corrupted the process.? (it's write, and then write a checksum to validate the data).? *if* that happened, then the NVRAM should be electrically fine, but might have corrupted data.? In theory, the NVRAM itself is not likely bad, but the data could be corrupted.? A CRC is (one crude method), add all the data up to make a number, chop off part of it, then find a number that when added to what you have, makes the result zero.? Write that number into the last locations in the NVRAM.? When the processor checks it, the sum of all the data (corrected for the part you lopped off....) should be zero.? Not, and there are errors.

It's perhaps rare that this process could be interrupted, but it is possible.

Harvey

FIXED!

"DJI ZH3-3D Damping Rubber Set (Part 42)", less than $10 at ebay.
This is four bags of four different isolators, for an RC helicopter camera mount, one of DJI’s “Zenmuse” series.
The ridged ones are too soft.
The ball shaped ones (two bags, gray marked "A40" and white "30")
are, as far as I can tell, *perfect* drop-in replacements.

From my repair notes:

These are 348-0007-00.
348-0087-00 plus 361-0113-00 (used in 1A6 and 1A7) might work too.

One of the three replaced way back
when is now severely crazed. Bad batch of rubber?
I tried Julian Bunn's fan mount rejuvenation procedure
(see "Another interesting Tektronix web site" at Tekscopes
at groups.io). Soak in olive oil 1/2 hour, boil in water
5 minutes. No effect, must be a different rubber.

Original part 348-0007-00 is a hollow rubber ball approx
15mm dia across equator, with a 12mm OD flange at each end.
Rubber is about 1.5mm thick. Neck OD 9mm, neck to neck 11mm.
Clearance hole for #8 screw. Chassis holes are 5/16" (8mm).

Dave Wise

From: David Wise
Sent: Monday, June 21, 2021 5:12 PM
To: [email protected]
Subject: RE: [TekScopes] Another interesting Tektronix web site

Maybe 275-1N or 7110-0.5 or 7110-1.0 .? The latter can be had for $8 each at .

Dave Wise

From: [email protected] [mailto:[email protected]] On Behalf Of stevenhorii via groups.io
Sent: Monday, June 21, 2021 3:52 PM
To: [email protected]
Subject: Re: [TekScopes] Another interesting Tektronix web site

All on this thread,

There are Barry mounts which come in various sizes and damping abilities:



Scroll down the pages of this distributor’s Web site until you get to “Ball
mount series” which sounds like what you are looking for.

I have no conflict of interest with this company. I have seen Barry mounts
used quite a bit in various pieces of equipment when isolation from
vibration is important.

Steve Horii



On Mon, Jun 21, 2021 at 14:34 Dave Wise <david_wise@...> wrote:

Thank you, Daniel, for your research and ideas.

The natural shape is a hollow ball. It must have been molded.
The screw plays no role in normal use; it limits motion extremes to keep
the cushions from tearing or coming out of the mounting holes.

I replaced all the cushions in my D and H, maybe ten years ago, with
new-old-stock I bought from Stan Griffiths. (They all have the same orange
paint stripe.) Most are fine but one is a mosaic of cracks. I’ve read
that making rubber is not 100% science. I figure there was a bad batch.

A solid ball with a hole through the middle would be too stiff unless the
rubber was exceptionally soft.

Another TekScopes member created a photo album, "541 Flip-flop fan
mounts", in which he created fan mounts from the sole of an old sandal. It
seems to me that I could combine that with your tubing idea.

- Long screw or stud, nuts, washers
- Thick-wall latex or silicone tubing, with 5/16” outside diameter (slip
fit in the mounting hole) when the screw is in
- Three foam rubber disks with 5/16” hole

- Put screw through tubing
- Thread first disk onto it
- Slide into first mounting hole
- Thread second disk onto it
- Slide through second mounting hole
- Thread third disk onto it
- Add washer and nut just snug

The foam rubber disks cushion axial motion, the tubing cushions radial
motion, and the screw holds it all together.

I will look around for an old mouse pad. Cut into disks with scissors and
hole with a paper punch. This just might work!

Dave Wise

From: [email protected] [mailto:[email protected]] On Behalf Of
Daniel Koller via groups.io
Sent: Sunday, June 20, 2021 5:42 PM
To: [email protected]
Subject: Re: [TekScopes] Another interesting Tektronix web site

Hi all,
I took a look at my D. My shock mounts are not gray - they are black.
They are just so oxidized on the surface they look grey, but they darkened
up with rubbing.
They have the consistency of latex surgical tubing, which makes me
wonder if A) that is what they are made of, and B) maybe that is what they
can be made of. I think if allowed to expand fully, they would be closer
to "I" shaped - a tube with flanges on the ends, rather than "ball
shaped". They take on the ball shape because they are compressed in their
mounts. You might be able to approximate them with surgical tubing. I
don't know if latex can be formed like thermoplastics, but if so, you could
try heating a section of tubing and blowing into it to bulge it out.
Donno. But making a flange would be hard. That might have to be molded.
Regarding molding hollow things - maybe mold the solid part, then
freeze it and drill out the center in a drill press? Keep it frozen in the
mold until drilled. Might be able to cast it in RTV that way. But the
resulting part will still be stiffer, in my opinion, than the original,
just based on poking at the ones I have on the chassis.
Another possible option is to 3D print. I have been playing with a very
soft thermoplastic polyeurethane (TPU) in my 3D printer. One needs a
special extruder with very little clearance between the extruder gears and
the feed tube, OR a direct extruder that goes right into the print head, in
order to be able to "push" the plastic through. But it does work, and I
have successfully printed lens caps and gaskets. I have not yet tried
stand-offs and vibration mounts, but I do plan on printing a door bumper
for a car, which has some of the features of the D's mounts. In the end,
the consistency will be a bit stiffer than RTV I think. There is
"Ninjaflex" TPU available, which is even softer, but I have not tried it
yet.
Ok, and lookie here:

<

Rubber balls. You still need to put a hole through them. The
dermatologist can provide the answer. Just go have a mole removed and ask
them for the hole-punching razor tool they use to circumscribe the mole.
I saved one or two and they are about 3 and 5 mm in diameter or so, with
various sizes available. This is cheap if insurance pays for the
service. Otherwise, you can get biopsy punches on amazon.



<

I think careful use of one of those punches can put a neat hole through
a rubber ball, and rubber washers seem to be available in plenty of sizes
on the interwebs! Good luck.
I'd be curious to know how you replace these. My 503 has latex
isolation mounts in parts of the circuitry. I'm betting they are getting
pretty dried up.
Dan

On Sunday, June 20, 2021, 04:16:31 PM EDT, teamlarryohio <
larrys@...> wrote:

Been far too long, but the ones I used were the same type generally as the
fan mounts. Otoh, McMaster has a huge variety of hardware bits.
G'luck!
-ls-

Dennis,
in the affected regions is no power, no internet, no water, no food.

So it will take some time to reach the people.

Peter
==============

Last winter we had a power outage where the power co would turn power on for 15 min ever hour or so. The scope was soft turned off by the front button. Since then I have been getting the error message above. I ran SPC but that didn't change anything. Looking at the log there are lots of (loosely quoting) nvRam crcc errors. I am getting a gpib interface from Prologix that someone wrote a nice interface for that I found searching this topic. I also got a copy of the nvram file.

Should I be able to fix this by writing a new file, or will the nvRams need replacing? I assume that if I don't cycle power, the SPC should not have that error after uploading new image?

This seems to be a common problem. Anyone have any comments advice?

If you are in the region affected by the flooding in Germany, Brussels, or
The Netherlands pleased contact me (dennis at ridesoft dot com) if there is
anything I can do or TekScopes can do to help.
Dennis

And Cordwainer Bird is still collecting residuals.....

Harvey

My deepest condolences on your loss, Gordon.? ?It's hard enough to have to put a dog to sleep, as we did last weekend, but to lose your wife wow, I can only imagine!? Feel free to PM me if you want to talk.? ? ? ?Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone

On Thu, Jul 15, 2021 at 07:48 AM, Tom Norman wrote:

Tek used something called Kellite in their wash station

Nope.
It was Kelite (not Kellite)... lot's of stuff pops up including the logo "Scientific Cleaning Through PH Control."
Anyway... it was just a buffered alkaline detergent... nothing special.

--
Roy Thistle

I use Simple Green all the time when giving a rig a bath. It doesn't always get rid of tobacco stench, but if followed by another rinse with ammonia everything smells great. I collect water from my dehumidifier or central air conditioner, filter it, and use it for a final rinse. After removing motors, loudspeakers, and meters, I have never damaged anything in forty years of cleaning rigs this way. I dry everything with several hours in a hotbox heated with a blow dryer blowing hot air through.

??? Bruce Gentry, KA2IVY

On Wed, Jul 14, 2021 at 10:03 PM, stevenhorii wrote:

look
for "Io" (as in Jupiter's moon) on Netflix

Yup... humanity escapes a toxic Earth (where it's still possible to live) to go to Io to die for certain... where the razor thin atmosphere is almost all sulphur dioxide, and Jupiter's intense radiation will cook you.
Harlan Ellison is somewhere throwing up.
--
Roy Thistle

Hi All,
For cigarette smoke smell and tar removal, I can most enthusiastically recommend Simple Green. My dearly departed wife was a 2 pack a day smoker (Yep, the smoking was the root cause of her passing away) and left our home a smokey mess. After finding out I was allergic to smoke tar (I have always been a non-smoker and having smoke allergies can happen to people who live with smokers or are around tobacco products) I have been slowly decontaminating the home. I have seen smoke/tar covered items literally drip off the smoke/tar from their surfaces after being sprayed with Simple Green. It works far better than soap and water. In the case of electronics, I believe that Simple Green can be slightly corrosive to the components if left on, so a liberal rinse with water and DI water afterwards with internal pots protected from the Simple Green I think would be called for. YMMV. Gordon