Date   

Re: TM 500 Front Panels

 

Nylon It an excellent material for something like this.
The important qualities it has are strength, resilence at the corners, stability over time, and many other things.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Michael W. Lynch via groups.io
Sent: Tuesday, June 09, 2020 7:55 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM 500 Front Panels

John,

Thanks for your comments.

Yes, PETG is my material of choice, at least for these prototypes.

I am thinking that ABS or NYLON would be a more durable material for the final product. Then again, the PETG may be perfectly fine, real world testing will be needed.

Layer height on these samples is .2mm. This yielded decent quality, detail and printing speed.

Another person raised the point of the many square holes on the various plug ins. These would need to be added to the STL design model and printed into the model.

It is possible that an "open center" design would be suitable.

I considered using a "Grid" or "Lattice" center, where the end user could simply snip out the required portions of the lattice to clear areas for the required holes and leaving the grid intact in other places. I will also explore this possibility.

Producing usable holes is a work in progress. There are several possibilities.

These are all problems and solutions that must be explored.

Keep the ideas coming.

Thanks!

--
Michael Lynch
Dardanelle, Arkansas





--
Dennis Tillman W7pF
TekScopes Moderator


New file uploaded to TekScopes@groups.io

TekScopes@groups.io Notification <TekScopes+notification@...>
 

Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the TekScopes@groups.io group.

Uploaded By: Doug <dmeek@...>

Cheers,
The Groups.io Team


Re: TM 500 Front Panels

 

I would not worry about it. As long as a flat head screw fits in the recessed hole it is fine. S drill bit turned by hand will clear out any leftover "flashing" in the hole

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Michael W. Lynch via groups.io
Sent: Monday, June 08, 2020 6:11 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM 500 Front Panels

Dennis,

I am working on improving the ragged edge at the mounting holes. These are covered by the screws, not visible once installed. This is something that requires experimentation to correct or minimize.

These fine details (and others) are the most difficult thing to duplicate with FDM printing. These holes will never be quite as good as the original IM parts. Overall, 3D printing cannot duplicate the fine finish of an IM part, at least NOT on the caliber of machines that I have. There are some very good printers out there (costing many thousands of $$$) that can get close to IM, but they are not quite there yet for the home hobby user.

The back side is recessed. See new picture posted in album. You can see the detail and the rougher surface. Again, covered by the inner panel and mostly not visible.

These are all printed from PETG, which is a good compromise of strength, flexibility and easy to print. Different colors of the same material. The white seems to print just a bit better, that cannot be explained, since they are the same material, by the same manufacturer, using the same printer and settings. . The only difference is the color

Once I have these and other small details worked out, I will try to fit one of these to a plug in that has the corners broken off.


More to come.

--
Michael Lynch
Dardanelle, Arkansas





--
Dennis Tillman W7pF
TekScopes Moderator


Re: TM 500 Front Panels

 

Hi Harvey,
This is a prototype being made for proof of concept" purposes. If it works for some plugins but not all then that is more than we had up until now.

Recessing the rear is not easy for a 3D printer to do and I know that. I predict a flat back will not be a problem for many plugins.
It is worth the effort to see if they are usable and under what circumstances they might not be usable.
I am willing to find out by testing the flat back samples Michael Lynch is making.

There may be a way to support the plastic being applied where the rear recessed area would be by placing a rectangular piece of thin material coated with mold release in that spot to provide a smooth support surface for the hot plastic the 3D printer is laying down there. Even better would be to place a piece of thin gauge aluminum, resting on another piece of material (to make up the total thickness of the recess). This way it will be good if the aluminum ends up really stuck to the plastic because there will be no need to reuse the original thin aluminum backing piece Tek uses. Youi simultaneously drill the necessary holes in both the front panel and aluminum sheet attached to it.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: Monday, June 08, 2020 5:47 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM 500 Front Panels

I took one of the prototype front panels apart. The actual plastic panel itself has an inset both in the rear and the front. The front panel of aluminum fits within the frame. It has (at the least) countersunk holes for the four mounting screws, a countersunk hole for the latch screw, and a slot for the latch screw.

On the back is a similar recess that is for a panel (thin gauge) of aluminum. The front panel in these plugins, at least the ones I have, is therefore three layers. The back layer, the plastic, and the front panel.

The problem with the back happens when you consider how 3D printing works. In this case, you have a rim and an inset on both top and bottom. The printer starts with the part of the plastic that touches the base. It prints that. Now the rest of the panel is slightly, (say
1.64 mm or so) above the printer base. The printer does not necessarily provide support (it can), and extrudes a filament in the air from one side to another. This filament tends to sag. When enough filament is piled on top of the recently printed filament, you get a surface that's flat enough that the remaining layers look flat.

What you end up with is something that looks good from the top (say the front of the panel), and is stringy at the back.

It is possible to print the back with supports, but they will be very thin and perhaps difficult to remove. The supports are thin, and made so that the amount of filament that is in free air is minimal (and you can therefore print it without too much sag). This will have to be removed before the panel is utilized. Haven't tried that yet.

Harvey


On 6/8/2020 8:23 PM, Dennis Tillman W7pF wrote:
Hi Michael,

These look very good in the picture. Unfortunately I can't see much of the detail and that detail matters a lot.
I will be able to make a better assessment when I can hold it in my hand and get a sense of its mechanical properties.
The first real test will come when I make a plugin with them. For that test it would be good to have one each from each different material you used to make them.
The corner holes in the gray one look ragged.
Color isn't important. I don't think Tek panels were always the same color. Either that or as they age their color changes in completely different ways and I am sure some of their final color had to do with the environment they were in, for example - smoking, exposed to chemical vapors in the air, used outside or where they could be exposed to sunlight.

Some I have are gray, some are a dirty brownish-gray, and most are the sand color that Tek switched to for compatibility with the color of HP instruments. When Tek switched from blue to the HP color it sparked an uproar within the company.

Is the backside completely flat or does it also have the recessed area in the entire middle area?

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Michael W. Lynch via groups.io
Sent: Monday, June 08, 2020 4:49 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM 500 Front Panels

All:

Working on the TM 500 Blank Face plate that was being discussed recently.

I have now printed a couple of prototypes. The THINGIVERSE item listed above IS NOT dimensionally accurate. I have modified the STL file to match the dimensions taken from the actual TEK part.

I have posted some pictures of a new original TEKTRONIX part and then two 3D Printed prototypes.

https://groups.io/g/TekScopes/album?id=248278

Printed one part in white, since this material was already loaded in the machine. The gray one in the center, is a second iteration, with some slight modifications. The tan/gray one to the left is the original TEK Part. Color is close enough for me to run with it.

The quality of the front of the printed part is good, the back side is slightly rough, but this is not what you are looking at when the part is installed.

The rim of the original part has some "draft angle" built into it, so it appears slightly tapered toward the top of the rim. It is not possible to duplicate this draft angle with the FDM printing method, so the sides of the panel are perpendicular. This makes the rim of the part a little wider, but it should still fit.

These are not Injection molding quality, but they are not expensive to print. My next task is to try to fit this to one of my plugins that has the broken corners.

Comments and questions are welcomed.

More to come.




--
Dennis Tillman W7pF
TekScopes Moderator


New file uploaded to TekScopes@groups.io

TekScopes@groups.io Notification <TekScopes+notification@...>
 

Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the TekScopes@groups.io group.

Uploaded By: Doug <dmeek@...>

Cheers,
The Groups.io Team


Re: AM700 Resurrection

Siggi
 

Hey Juri,

I've never seen one of those before, but TekWiki has a full service manual
for it (http://w140.com/tekwiki/wiki/AM700). I find this pretty
interesting, as this device is from a time when Tek (and others) had pretty
much stopped issuing component-level service manuals for their devices. You
have a copy, I hope?

In the service manual, there's a table with the CPU's memory map, which
claims this about the afflicted range:
0E00 0000 – 0EXX XXXX I/O Processor Shared Memory/Registers

I took a quick look at the service manual, and my guess is that this'd be
referring to the memory that's shared with the front-panel processor. In
the Theory of Operation it says "The address bus to the front panel
processor shared
RAM is buffered by bidirectional data buffers on diagram 7", so maybe those
could be at fault?
The processor's data bus seems to be pulled high, so if you have a bad
output driver, you'd get a stuck-hi bit.

Siggi

On Tue, Jun 9, 2020 at 3:11 PM Juri Ghisio via groups.io <yurighisio=
iol.it@groups.io> wrote:

Hi,

I' am try to back to life an AM700.
After changing capacitors, washing pcb, check for corroded track the unit
boot up and enter diagnostic mode. After solve some issue I dropped in a FP
RAM error, I have posted a a screenshot in photo album AM700 folder. Anyone
could help me to decode this error?

Best Regards

Juri




Re: 2445 woes

 

On Wed, Jun 10, 2020 at 05:47 PM, Ondrej Pavelka wrote:


Any idea what the failure mode is? They are quite expensive and I wouldn't
want the new one to last one week?
AFAIK, if these break down, they do so spontaneously, no overheating or the like.

Raymond


Re: Telequipment D34

David Tucker
 

Now that reminds me.

When I was repairing my Telequipment D61A, I needed the exact same JFET for the input amplifier - 151-1076-00.
I tried a few different JFETS, but the one that worked perfectly for that source follower was a J113. I bought 10, and most of them worked perfectly.

I know that this application is different, but if you have any J113s to hand, it might be worth a try.

Of course, a better way of doing it would be to follow Jim's advice - characterise TR104, then perhaps compare it with the datasheet for J113.

David

On Wed, Jun 10, 2020 at 02:56 PM, Jim Tibbits wrote:


what I would do ...since tr104 is the same type, i would remove tr104 and
measure its Idss...Match Idss with measured random different fet ..replace
tr104 with original, replace tr302 with matched Idss fet
that should at least get you in the ball-park
(the same type fet is used in the D32 and the D61 if you know anyone who
has parts unit)


Need advice on removing an SC503 broken vertical knob/shaft assembly

 

I accidentally pushed my lab chain into a rack mounted SC503, and sheared off the skirted part of the vertical knob/shaft assembly.
after much searching, I did get a replacement from a kind list member. at last, restoration is at hand!

The problem is that the plastic keyed shaft is stuck inside the attenuator rotating cam assembly, and I just can't get it out to replace it. A check
of the manual just says "pull the knob/shaft out. hah! if only I could... I can push it back a bit, but I can't pull it out. I can't see any kind of locking device to anchor the knob shaft in place, so I am baffled as to why it won't come out.

any suggestions to offer? I am SO close to restoring this beauty.
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.


Re: 2445 woes

Ondrej Pavelka
 

Exactly this is happening but only at the top of the screen, so I need to
buy U400 hybrid.

Any idea what the failure mode is? They are quite expensive and I wouldn't
want the new one to last one week?

On Wed, 10 Jun 2020, 17:09 Raymond Domp Frank, <hewpatek@...> wrote:

On Wed, Jun 10, 2020 at 03:59 PM, Raymond Domp Frank wrote:


Viewing a sawtooth waveform centered over 7 - 8 vertical divisions shows
it
quite clearly.
I guess I should explain that: Since the compression becomes stronger when
further away from the horizontal, the sawtooth loses its linearity and
becomes sinewave-like near the upper and lower edges of the screen.

Raymond




Re: Tek 4041 GPIB Controller

 

On Wed, Jun 10, 2020 at 03:59 PM, Gary Robert Bosworth wrote:


At the present time, I am trying desperately to find a power supply
schematic for the 4041 DDU disk drive. Please let me know if you ever come
across one. My DDU makes a high-pitched whistling sound which makes me
think the feedback loop has a problem.
Without a schematic, it's probably not too difficult and therefore worthwhile to check DC voltages and Al and Ta caps for shorts and opens.

Raymond


Re: 2445 woes

 

On Wed, Jun 10, 2020 at 03:59 PM, Raymond Domp Frank wrote:


Viewing a sawtooth waveform centered over 7 - 8 vertical divisions shows it
quite clearly.
I guess I should explain that: Since the compression becomes stronger when further away from the horizontal, the sawtooth loses its linearity and becomes sinewave-like near the upper and lower edges of the screen.

Raymond


Re: 2445 woes

 

On Wed, Jun 10, 2020 at 02:29 PM, Ondrej Pavelka wrote:


There is a common part for both the channel 1&2 level drop as well as
readout shaking which is the U400 hybrid.
A well-known problem of vertical compression results from the failure of U400, the Channel Switch. It only affects CH1 and CH2.
Viewing a sawtooth waveform centered over 7 - 8 vertical divisions shows it quite clearly.

Raymond


Re: Tek 4041 GPIB Controller

Gary Robert Bosworth
 

The verification tape worked perfectly. Thank you Monty. I was wondering
how you make copies without a dual slot tape deck? If you ever make other
debug tapes for the 4041, please let me know.

At the present time, I am trying desperately to find a power supply
schematic for the 4041 DDU disk drive. Please let me know if you ever come
across one. My DDU makes a high-pitched whistling sound which makes me
think the feedback loop has a problem.

Gary Bosworth

On Wed, Jun 10, 2020 at 5:01 AM Monty McGraw <mmcgraw74@...> wrote:

Gary,

Did my copy of the System Verification tape work for you?

Monty



--
Gary Robert Bosworth
grbosworth@...
Tel: 310-317-2247


Re: Telequipment D34

Jim Tibbits
 

what I would do ...since tr104 is the same type, i would remove tr104 and
measure its Idss...Match Idss with measured random different fet ..replace
tr104 with original, replace tr302 with matched Idss fet
that should at least get you in the ball-park
(the same type fet is used in the D32 and the D61 if you know anyone who
has parts unit)

Jim

On Wed, Jun 10, 2020 at 2:09 AM Ondrej Pavelka <info@...>
wrote:

The problem I have with the random J-fet I used is following.

Scenario 1, channel 2 is OFF

I only get trace for high frequencies, on low frequencies it shrinks to
left side gradually up to the point I only see dot which moves up or down

Scenario 2 channel 2 is ON and no signal present

I get trace for low frequencies, then I get the problem mentioned above
with screen shrunk to one side and then if I am on high enough frequencies
I see the whole trace again.


I think what I am seeing is unblanking issue?




On Wed, 10 Jun 2020, 08:54 Jim Tibbits, <ab7vf1@...> wrote:

stuck a schematic redrawn for tr302 in d34 folder...looks like a constant
current regulator for the unblanking circuitry to me, but ...

Jim






Re: 2445 woes

Ondrej Pavelka
 

There is a common part for both the channel 1&2 level drop as well as
readout shaking which is the U400 hybrid. It is also possible that since
both channel 1&2 dropped their level equally and 3&4 are ok the U170 mux
could be causing the problem and U400 or the transistor arrays U475 and
U485 be the cause of the shaking.

I have ordered some MC3346Ps and I'll try to swap the 4051 to see if it
helps



On Wed, 10 Jun 2020, 11:00 Ondrej Pavelka, <info@...>
wrote:

So I am pretty sure the problem is with readout vertical. Output should be
very much stable pulses +3V -3V, at least that's what's in the manual

I have this instead

https://photos.app.goo.gl/MnJRpvRuy9WPmjZF6

This is readout vert out, pin 7 of the opamp



I have some pulses 3V and some just 2V give or take.

I can already see the level differences before the mux on the TP29.

https://photos.app.goo.gl/E4fEuLYAdMntkooP6

Am I right to assume the oscillations cause the blurriness and the level
drops cause the readout to jump up and down ? On the other hand I can't
really make it worse by moving the trace up and down so possibly this is
normal?

The fact that it is interference with trace makes me think this problem
could be elsewhere in the circuit which mixes the readout and trace
together ?









On Wed, 10 Jun 2020, 01:30 Chuck Harris, <cfharris@...> wrote:

The 2465B manual is 100% the same on the A5 board, HV supply, and
power supply, but about 95% the same on everything else. There are
a couple of extra trimmers on the A1 board, that relate to transient
response.

There are a couple of slight differences in the calibration routines
to accommodate the missing/extra trimmers.

All the hybrids are nominally the same... the 2465B used some that
were selected for better performance...

-Chuck Harris

Ondrej Pavelka wrote:
So here's a update, I have completely rebuilt the impacted sections of
A5 board, added a socket for the Dallas chip but unfortunately that didn't
really had impact on neither of my issues.

I can see the switch scan matrix working fine, all the mux and demux
works correctly and reference voltages are what they should be -1.25 and
+1.36

I am starting to suspect vertical amp to be the reason for low vertical
amplitude because the problem is across all the channels.

The instability of the readout is still there and I noticed while
readout is shifted slightly down.
Where is the readout positioning on the screen? Is that separate board?
I only have 2445 manual and 2465B. Can't find the 2445B manual anywhere.
Is it ok to go by the 2465B manual for the suspected issues as well or
is it not so easy?







Re: Tek 4041 GPIB Controller

Monty McGraw
 

Gary,

Did my copy of the System Verification tape work for you?

Monty


Re: Telequipment D34

Ondrej Pavelka
 

The problem I have with the random J-fet I used is following.

Scenario 1, channel 2 is OFF

I only get trace for high frequencies, on low frequencies it shrinks to
left side gradually up to the point I only see dot which moves up or down

Scenario 2 channel 2 is ON and no signal present

I get trace for low frequencies, then I get the problem mentioned above
with screen shrunk to one side and then if I am on high enough frequencies
I see the whole trace again.


I think what I am seeing is unblanking issue?

On Wed, 10 Jun 2020, 08:54 Jim Tibbits, <ab7vf1@...> wrote:

stuck a schematic redrawn for tr302 in d34 folder...looks like a constant
current regulator for the unblanking circuitry to me, but ...

Jim




Re: 2445 woes

Ondrej Pavelka
 

So I am pretty sure the problem is with readout vertical. Output should be
very much stable pulses +3V -3V, at least that's what's in the manual

I have this instead

https://photos.app.goo.gl/MnJRpvRuy9WPmjZF6

This is readout vert out, pin 7 of the opamp



I have some pulses 3V and some just 2V give or take.

I can already see the level differences before the mux on the TP29.

https://photos.app.goo.gl/E4fEuLYAdMntkooP6

Am I right to assume the oscillations cause the blurriness and the level
drops cause the readout to jump up and down ? On the other hand I can't
really make it worse by moving the trace up and down so possibly this is
normal?

The fact that it is interference with trace makes me think this problem
could be elsewhere in the circuit which mixes the readout and trace
together ?

On Wed, 10 Jun 2020, 01:30 Chuck Harris, <cfharris@...> wrote:

The 2465B manual is 100% the same on the A5 board, HV supply, and
power supply, but about 95% the same on everything else. There are
a couple of extra trimmers on the A1 board, that relate to transient
response.

There are a couple of slight differences in the calibration routines
to accommodate the missing/extra trimmers.

All the hybrids are nominally the same... the 2465B used some that
were selected for better performance...

-Chuck Harris

Ondrej Pavelka wrote:
So here's a update, I have completely rebuilt the impacted sections of
A5 board, added a socket for the Dallas chip but unfortunately that didn't
really had impact on neither of my issues.

I can see the switch scan matrix working fine, all the mux and demux
works correctly and reference voltages are what they should be -1.25 and
+1.36

I am starting to suspect vertical amp to be the reason for low vertical
amplitude because the problem is across all the channels.

The instability of the readout is still there and I noticed while
readout is shifted slightly down.
Where is the readout positioning on the screen? Is that separate board?
I only have 2445 manual and 2465B. Can't find the 2445B manual anywhere.
Is it ok to go by the 2465B manual for the suspected issues as well or
is it not so easy?







Re: Telequipment D34

Jim Tibbits
 

stuck a schematic redrawn for tr302 in d34 folder...looks like a constant current regulator for the unblanking circuitry to me, but ...

Jim

28541 - 28560 of 196458