Date   

Re: Tek 2467B Erratic Intensity controls

Siggi
 

On Tue, Dec 3, 2019 at 7:30 PM peter bunge <bunge.pjp@...> wrote:

I guessed that. Do you agree that the DAC Ref Adjust working means the DAC
is OK?

The best way to verify that the DAC is working correctly is to measure
the +1.36V and -1.25V references on the A5 board. If those are good, then
the DAC and a bunch of supporting machinery is working right. If those are
way off, then you're going to have all manner of problems, as this scope is
pretty much all drive-by-wire.


Re: Tek 2467B Erratic Intensity controls

peter bunge
 

I guessed that. Do you agree that the DAC Ref Adjust working means the DAC
is OK?
I am seeing O/Ps change when there is no pos going clock edge on U2210, a
74HCT273. I am triggering on clock pin 11 in chop mode (using another
'scope) and looking at the outputs pins. Pin 8 especially gives me a clear
picture.
I was suspicious because the Reset had been jumpered high instead of
connected to the other resets per schematic.
Maybe this was a temporary fix. However it worked for a few years.
I have to make sure because these are soldered surface mount chips.
I will send a photo privately.

On Tue, Dec 3, 2019 at 1:13 PM Chuck Harris <cfharris@...> wrote:

The DAC reference is a current. The DAC output
is a current... so, measuring voltage doesn't tell
you much.

-Chuck Harris

peter bunge wrote:
I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I
did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and
there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
The dV and dt switches take up to 10 seconds to display the dotted lines
and they arrive in sections and take many seconds to show fully.
I found a jumper between U2210 pin 1 and +5v. The wire had disconnected
from the bad solder joint. I tried connecting it then jumpered it to the
reset line as shown on the schematic U2310 pin 1. It made no difference.
There are obscure notes written with a broad magic marker on 1.5" purple
tape stuck over the A5 board. They say "Parm-OK, AC-bad, DC Bal-OK". And
on
a second piece "Repaired, CT 'Dac (maybe) sap tonpur id' (pretty well
illegible) kind of works with AC". However no sign of work except around
the DAC which I think is OK. The board is in pristine except for the
jumper
I mentioned, some soldering on resistors around the DAC and a jumper for
-15v to the DAC pin 17. I don't think this is where the problem is.
I will check the CPU clock but the address lines are certainly not
changing
at 5 second rate.


On Mon, Dec 2, 2019 at 10:31 PM Chuck Harris <cfharris@...> wrote:

Again,

There can be no delay in the DAC. It is simply
sent a byte of data. The processor has no way to
find out if the data was turned into voltage, or
when. There is no handshake signal.

The DV switch signals go into the CPU, are processed,
and then go out to the display generator.

Have you checked the CPU clock speed yet?

-Chuck Harris

peter bunge wrote:
Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in,
logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay
in
the DAC/ADC can also delay the logic but would that not mess
everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...>
wrote:







Re: Tek 2467B Erratic Intensity controls

peter bunge
 

I assumed they were current inputs, not V REF voltages as the schematic
implies. Normally pins marked Vref imply a voltage. Iref would imply a
reference current.
Anyway the DAC appears to be working so I did not bother pursuing it
further.



On Tue, Dec 3, 2019 at 12:57 PM Raymond Domp Frank <@Raymond>
wrote:

On Tue, Dec 3, 2019 at 06:21 PM, peter bunge wrote:


I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I
did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and
there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
Peter,
Read SM "Theory of Operation" > "Digital-to-Analog Converter (DAC)", page
3a-10 in my manual (070-6863-01). Did you spend enough attention to
understanding what's going on?

Raymond




Re: Tek 2467B Erratic Intensity controls

Chuck Harris
 

The DAC reference is a current. The DAC output
is a current... so, measuring voltage doesn't tell
you much.

-Chuck Harris

peter bunge wrote:

I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
The dV and dt switches take up to 10 seconds to display the dotted lines
and they arrive in sections and take many seconds to show fully.
I found a jumper between U2210 pin 1 and +5v. The wire had disconnected
from the bad solder joint. I tried connecting it then jumpered it to the
reset line as shown on the schematic U2310 pin 1. It made no difference.
There are obscure notes written with a broad magic marker on 1.5" purple
tape stuck over the A5 board. They say "Parm-OK, AC-bad, DC Bal-OK". And on
a second piece "Repaired, CT 'Dac (maybe) sap tonpur id' (pretty well
illegible) kind of works with AC". However no sign of work except around
the DAC which I think is OK. The board is in pristine except for the jumper
I mentioned, some soldering on resistors around the DAC and a jumper for
-15v to the DAC pin 17. I don't think this is where the problem is.
I will check the CPU clock but the address lines are certainly not changing
at 5 second rate.


On Mon, Dec 2, 2019 at 10:31 PM Chuck Harris <cfharris@...> wrote:

Again,

There can be no delay in the DAC. It is simply
sent a byte of data. The processor has no way to
find out if the data was turned into voltage, or
when. There is no handshake signal.

The DV switch signals go into the CPU, are processed,
and then go out to the display generator.

Have you checked the CPU clock speed yet?

-Chuck Harris

peter bunge wrote:
Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in, logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay in
the DAC/ADC can also delay the logic but would that not mess everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...> wrote:





Re: 5103N Comments, advice

Harold Foster
 

Yes, the manuals were acquired before the unit even arrived; both websites listed were very interesting and I'm sure that I will be referring back to them often.

I guess that what I was asking for were known issues or "gotchas" that *don't* show up in a manual - certain caps that go bad often, transistors that run hot and degrade, that sort of thing. I've been refurbishing TE (HP) for quite a while as a hobby and am familiar with the process - I just don't want to spend several hours to discover an issue that is undocumented but well known to those who have worked on this TE previously.

Thanks,

Hal


Re: Tek 2467B Erratic Intensity controls

 

On Tue, Dec 3, 2019 at 06:21 PM, peter bunge wrote:


I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
Peter,
Read SM "Theory of Operation" > "Digital-to-Analog Converter (DAC)", page 3a-10 in my manual (070-6863-01). Did you spend enough attention to understanding what's going on?

Raymond


Re: Tek 2467B Erratic Intensity controls

peter bunge
 

I am suspicious of the reset jumper on U2210. It is part of Pot Scanning
which is a clue.
I will look at the outputs.

On Tue, Dec 3, 2019 at 12:22 PM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
The dV and dt switches take up to 10 seconds to display the dotted lines
and they arrive in sections and take many seconds to show fully.
I found a jumper between U2210 pin 1 and +5v. The wire had disconnected
from the bad solder joint. I tried connecting it then jumpered it to the
reset line as shown on the schematic U2310 pin 1. It made no difference.
There are obscure notes written with a broad magic marker on 1.5" purple
tape stuck over the A5 board. They say "Parm-OK, AC-bad, DC Bal-OK". And on
a second piece "Repaired, CT 'Dac (maybe) sap tonpur id' (pretty well
illegible) kind of works with AC". However no sign of work except around
the DAC which I think is OK. The board is in pristine except for the jumper
I mentioned, some soldering on resistors around the DAC and a jumper for
-15v to the DAC pin 17. I don't think this is where the problem is.
I will check the CPU clock but the address lines are certainly not changing
at 5 second rate.


On Mon, Dec 2, 2019 at 10:31 PM Chuck Harris <cfharris@...> wrote:

Again,

There can be no delay in the DAC. It is simply
sent a byte of data. The processor has no way to
find out if the data was turned into voltage, or
when. There is no handshake signal.

The DV switch signals go into the CPU, are processed,
and then go out to the display generator.

Have you checked the CPU clock speed yet?

-Chuck Harris

peter bunge wrote:
Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in,
logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay
in
the DAC/ADC can also delay the logic but would that not mess
everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...>
wrote:





Re: Tek 2467B Erratic Intensity controls

peter bunge
 

I was surprised to find only 150mv on the Ref pins of the DAC but when I
tried the "Adjust DAC Ref (R2010)" page 5-3 it was almost perfect and I did
not adjust it. This tells me the DAC is working. I don't know what to
expect on the Ref pins. They show high impedance (7k?) power off and there
is about 9V at the top of R2013 but about 150mV at the bottom. I assume
this is normal or the adjustment would be way off.
The dV and dt switches take up to 10 seconds to display the dotted lines
and they arrive in sections and take many seconds to show fully.
I found a jumper between U2210 pin 1 and +5v. The wire had disconnected
from the bad solder joint. I tried connecting it then jumpered it to the
reset line as shown on the schematic U2310 pin 1. It made no difference.
There are obscure notes written with a broad magic marker on 1.5" purple
tape stuck over the A5 board. They say "Parm-OK, AC-bad, DC Bal-OK". And on
a second piece "Repaired, CT 'Dac (maybe) sap tonpur id' (pretty well
illegible) kind of works with AC". However no sign of work except around
the DAC which I think is OK. The board is in pristine except for the jumper
I mentioned, some soldering on resistors around the DAC and a jumper for
-15v to the DAC pin 17. I don't think this is where the problem is.
I will check the CPU clock but the address lines are certainly not changing
at 5 second rate.

On Mon, Dec 2, 2019 at 10:31 PM Chuck Harris <cfharris@...> wrote:

Again,

There can be no delay in the DAC. It is simply
sent a byte of data. The processor has no way to
find out if the data was turned into voltage, or
when. There is no handshake signal.

The DV switch signals go into the CPU, are processed,
and then go out to the display generator.

Have you checked the CPU clock speed yet?

-Chuck Harris

peter bunge wrote:
Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in, logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay in
the DAC/ADC can also delay the logic but would that not mess everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...> wrote:



Re: Tek 2467B Erratic Intensity controls

Siggi
 

On Mon, Dec 2, 2019 at 10:31 PM Chuck Harris <cfharris@...> wrote:

Have you checked the CPU clock speed yet?
While you're in there also look at the interrupt generator counter. On my
2467 schematic it's designated U2640 on schematic <1>. This should be
generating a regular interrupt every 3.3ms, and there's a testpoint #3
where you can take a look. This interrupt is the "metronome" for the pot
scanning and DAC refreshing routines in the firmware.


Re: OT: floppy disk head

BW
 

Having had one of these failures myself, from what I recall researching it at the time, the failure cause was simply bad/porous sealant on the head coils, which lead to corrosion and eventually open-circuit in corrosion-prone environments.

I still have the affected drive in a box here somewhere... I swapped out the mechanism with an ALPS one at one point but kept the D500 both out of future interest and parts for my still functioning D500 1541.


-BW


Re: 533A powering on after long storage

simoniep
 

Hello

Just to tell you that I am still alive and that the 533A is working.
Still some work to do like replacing most of the capacitor and perform a calibration.

Thanks for help


Re: Changing Color

Richard Knoppow
 

Which e-mail program do you use? Probably has a setting in it for header font and color.

On 12/2/2019 8:50 AM, Karin Johnson wrote:
Is there any way in Groups.io to change the color of the header test in the messages?
Karin
--
Richard Knoppow
dickburk@...
WB6KBL


Re: Tek 2467B Erratic Intensity controls

Chuck Harris
 

Again,

There can be no delay in the DAC. It is simply
sent a byte of data. The processor has no way to
find out if the data was turned into voltage, or
when. There is no handshake signal.

The DV switch signals go into the CPU, are processed,
and then go out to the display generator.

Have you checked the CPU clock speed yet?

-Chuck Harris

peter bunge wrote:

Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in, logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay in
the DAC/ADC can also delay the logic but would that not mess everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...> wrote:


Re: OT: floppy disk head

snapdiode
 

The price for 360K or worse 170K single-sided 5.25" mechanisms is much higher than that, I'm afraid. Besides, I am looking at specifically the Newtronics D500 mechanism used only in the Commodore 1541 and 1541-II drives.
You can't really just swap in another type of mechanism in there since the front is different and it's not a PC interface.
I'm not the only one where the head failed with an open coil.
https://retrohax.net/commodore-1541-floppy-drive-fixing-chaos/

I was really looking at how the heads are built, with what materials, specifically the potting. I'd like to see how far down I can dig into the problem. I don't have a source of cheap PC 5.25" 360K drives either to experiment with, and in any case I'd guess they're all slightly different and you can't just swap in the head rail assembly across brands.


Re: Tek 2467B Erratic Intensity controls

peter bunge
 

Thanks J-P; yes I have suspected that area. Washing with Iso made no
difference and the area looks clean but I have not ruled it out.
I have taken a break to study the manual and use logic.
Why are the dV and dt SWITCHES delayed. That is straight logic in, logic
out and whatever they control to turn on the dotted lines.
I am tracking this because it is simpler than the ADC. However a delay in
the DAC/ADC can also delay the logic but would that not mess everything?
I will take another look at the DAC area tomorrow. Good idea on the DAC
calibration procedure.
Peter.

On Mon, Dec 2, 2019 at 4:28 PM Jean-Paul <jonpaul@...> wrote:

Hello all

Wonderful thread with Chuck and other super 2465 mavens giving us the
benefits of long experience.

I would not assume replaced A5 board smd lytics exonérate the board of
corrosion damage.

Reading the entire thread my gut instincts is A5 in the DAC and DAC
référence area.

A careful inspection with strong light and magnifying glass might révèle
the problem.

Try the DAC référence cal proceedure near the start of CAL.

Just the ramblings of an old retired EE

Jon





Re: 5103N Comments, advice

 

Hi Hal,
Congratulations.

The first thing you should do is download the Service Manual for the 5103 and read it cover to cover. It will teach you how to use the scope, how it works, how to fix it, how to calibrate it, and what it is capable of, and lots of other things.
The Service Manual is the "Bible" for any Tektronix product.

The names of the 5103N and D10 were later changed to 5110N. You can get the 5110 service manual at:
http://w140.com/tekwiki/wiki/5110

Another thing you may be interested in visiting is the most comprehensive web site devoted to the Tek 5000 Scope Series. It was created by Christian Weagle. It will give you a lot of information about plugins you can use in your scope. It is at:
http://www.i9t.net/5000_scopes.html

Dennis Tillman W7PF

-----Original Message-----
From: Harold Foster
Sent: Monday, December 02, 2019 11:40 AM
Subject: [TekScopes] 5103N Comments, advice

All:
I just bought a 5103N with 5B12N, 5A20N and 5A22N plugins for a very good price, planning to use it for checking power supply PARD since it has the differential inputs. I have not really done anything with it other than turn it on - squiggles on screen - and plan to work with it further this weekend.

So: Is there anything in particular I should be on the lookout for when I start? Hints & Tips? This is the first Tek equipment I will be restoring and am not familiar with the Tektronix way of doing things and, as such, very much would appreciate any input anyone has.

Thank you,

Hal




--
Dennis Tillman W7PF
TekScopes Moderator


Re: Changing Color

Jim Ford
 

"header text", maybe?Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Dennis Tillman W7PF <@Dennis_Tillman_W7pF> Date: 12/2/19 1:55 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Changing Color Hi Karin,I don't understand what you mean by the "header test".What format do you receive your TekScopes posts in?Dennis Tillman-----Original Message-----From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Karin JohnsonSent: Monday, December 02, 2019 8:50 AMTo: TekScopes@...: [TekScopes] Changing ColorIs there any way in Groups.io to change the color of the header test in the messages?Karin-- Dennis Tillman W7PFTekScopes Moderator


Re: Changing Color

 

Hi Karin,
I don't understand what you mean by the "header test".
What format do you receive your TekScopes posts in?
Dennis Tillman

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Karin Johnson
Sent: Monday, December 02, 2019 8:50 AM
To: TekScopes@groups.io
Subject: [TekScopes] Changing Color

Is there any way in Groups.io to change the color of the header test in the messages?

Karin





--
Dennis Tillman W7PF
TekScopes Moderator


Re: OT: floppy disk head

 

Hi Snapdiode,
Why would you want to fix a bad floppy drive head when, at the time these were current technology, you could buy a replacement floppy drive for less than $25?

The Tek heads may share a few of the same concepts but they are very different.
A floppy disk head is reading the magnetic orientation of iron oxide particles on the SURFACE of the floppy disk. The only considerations are the proximity of the head to the surface of the floppy disk.

The Tek current heads are measuring the magnetic field generated by a current passing through the area of a plane (the opening in the probe head). To do this the head must consist of two precisely lapped surfaces which mate together perfectly since the magnetic flux lines (from the current passing through the wire) must be uninterrupted. The flux passes through the surface of a Hall Effect Device to measure DC currents and/or through a multi-turn coil built into the probe head to measure AC currents.

The current probe heads (except for the CT1 and CT2) consist of two pieces. These two pieces are precisely lapped to mate with each other and have the lowest magnetic reluctance (the opposition to magnetic flux) to the magnetic flux being generated. You cannot combine the probe head pieces from different probes.

Dennis Tillman W7PF

-----Original Message-----
From: snapdiode via Groups.Io
Sent: Monday, December 02, 2019 12:46 AM
Subject: [TekScopes] OT: floppy disk head

Just wondering if in the collected knowledge pool here if anyone has any information on how floppy drive heads were manufactured?
Specifically the 5.25" drives. It's very similar to a P6042 head I guess, there's awfully fine wire, a core, some potting compound, polished surfaces, and built-in self-destruct mechanisms.
For example, the Newtronics D500 mechanism used in Commodore floppy drives has a failure mode where a winding for the read coil goes open circuit.
How can you fix that? It's not very likely to be repairable.




--
Dennis Tillman W7PF
TekScopes Moderator


Re: Tek 2467B Erratic Intensity controls

Jean-Paul
 

Hello all

Wonderful thread with Chuck and other super 2465 mavens giving us the benefits of long experience.

I would not assume replaced A5 board smd lytics exonérate the board of corrosion damage.

Reading the entire thread my gut instincts is A5 in the DAC and DAC référence area.

A careful inspection with strong light and magnifying glass might révèle the problem.

Try the DAC référence cal proceedure near the start of CAL.

Just the ramblings of an old retired EE

Jon