Date   
Re: 2445A calibration

maxim.vlasov@...
 

On Wed, Oct 17, 2018 at 04:58 PM, Harvey White wrote:


You used which disassembler to do this?
Harvey,

I used IDA (Interactive DisAssembler created by Ilfak Guilfanov. There is a Wiki page), you can see the section of photos in this thread for the screen capture. it's a semi-automated disassembler. You see the bytevector in front of you at the beginning and you manupulate it by instructing it to convert the byte vector to code/data/table of immediate data or vectors. The tool then will try to start from this, go and disassemble the rest. When it's blocked again you go, explore, instruct comment and give the tool a go. So it's an itterative work. It has a long list of features for signature searching in code, text, etc. I use IDA from the end of 90s. It's by far the only tool to re-create the source quality disassembly.

Re: 2445A calibration

maxim.vlasov@...
 

On Wed, Oct 17, 2018 at 02:08 PM, Siggi wrote:


Awesome, congratulations!
This has been one of the more epic repair threads I've seen here recently,
it was fun to see some of the firmware disassembled. Super-fun to see the
firmware matched my calculation to within 2/4096.
Did you measure the +1.36/-1.24V references after your repair (and DAC
re-calibration)? I'd be most interested to know what the final values of
those reference voltages were against the centered +1.25/-1.24 DLY REF
output.
Apparently 0.5% from the calculated value is too far out, but the -1.25V
value on the schematics is still 0.25% out - the truth is out there!
Thank you Siggi. I had no time to re-measure the test points, I'll do it today. But now DAC is centered (pin 13 J119) between -1.250V and 1.250V, which is quite amazing. I hope that the results will converge with the LTSpice simulated values. After changing the op-amp I have noticed that the OPAMP instead producing -8.1V started pulling the -1.25V line more -8.8V. And everything worked after that.

Re: Tek 2467B

jmtfungus@...
 

Just to confirm, a compatible NVRAM replacement for the 2467B (DS1225Y) is DS1225AD-150+? Thanks Jude

Re: Tek 2467B

Chuck Harris
 

Dallas/Maxim made a few variants of the 1225. The notable
themes are:

1) Speed, which is unimportant.
2) Temperature range, which is also probably unimportant to you.
3) Voltage tolerance, which is the whole ball game.

The two temperature ranges are: plain (0-70C), and IND (-40-+85C).
The two voltage tolerances are: +/-5% and +/-10%.
The available speeds are 70ns, 150ns, and 200ns.

Tektronix typically lets their 5V get kind of low in scopes,
and it centers around 4.9V on the A5 card. It is a really bad
thing if the DS1225 decides to go into power save too early,
as the CPU will keep on chugging well below a 5% drop. They
specify the temperature range for the scope to be: -15C- +55C.

I typically pick the IND temperature range, the 10% voltage
range, and the 150ns speed, so, I recommend:

DS1225AD-150IND

The 200ns speed works just as well. The motorala data sheets shows
235ns would work, and I have used either with no issues.

Be safe, get it from Mouser, never ebay or Amazon. It is only $25
plus shipping.

-Chuck Harris

jmtfungus via Groups.Io wrote:

Just to confirm, a compatible NVRAM replacement for the 2467B (DS1225Y) is DS1225AD-150+? Thanks Jude

Re: 2445A calibration

Max Vlasov
 

On Wed, Oct 17, 2018 at 02:08 PM, Siggi wrote:


Did you measure the +1.36/-1.24V references after your repair (and DAC
re-calibration)? I'd be most interested to know what the final values of
those reference voltages were against the centered +1.25/-1.24 DLY REF
output.
Apparently 0.5% from the calculated value is too far out, but the -1.25V
value on the schematics is still 0.25% out - the truth is out there!
I've measured the +1.36/-1.25V test points today with two Agilent 34401A. So, the results are the following:

On the working o-scope the points are stable with a time (4 digits after the decimal point stay where they are, both meters agree).
TP-1.25 = -1.2498V (3mV off the simulation here: https://groups.io/g/TekScopes/photo/74577/0?p=Name,,,20,1,0,0 simulated 1.2468V, calculated -1.2469V, 0.24% off the target)
TP+1.36 = 1.3680V (6mV off the simulation. simulated 1.3619V. calculated 1.3620V, 0.44% off the target)

As highlighted before, the pin 13 of J119 is perfectly centered CCW=-1.250V, CW=1.250V

However, I haven't measured 14.2K and 13.0K resistors. They have bent legs, didn't want to damage or compromise them.

Re: 2445A calibration

Harvey White
 

On Wed, 17 Oct 2018 23:19:49 -0700, you wrote:

On Wed, Oct 17, 2018 at 04:58 PM, Harvey White wrote:


You used which disassembler to do this?
Harvey,

I used IDA (Interactive DisAssembler created by Ilfak Guilfanov. There is a Wiki page), you can see the section of photos in this thread for the screen capture. it's a semi-automated disassembler. You see the bytevector in front of you at the beginning and you manupulate it by instructing it to convert the byte vector to code/data/table of immediate data or vectors. The tool then will try to start from this, go and disassemble the rest. When it's blocked again you go, explore, instruct comment and give the tool a go. So it's an itterative work. It has a long list of features for signature searching in code, text, etc. I use IDA from the end of 90s. It's by far the only tool to re-create the source quality disassembly.
Ah, ok. They wanted money for that. Mine works the same way (all the
disassemblers that I wrote worked the same way as an option).

Mine runs on a GUI because I find GUIs easier to interact with.

In the tek code, I found a modified pascal string, where the first
byte 4 MSB are set to something other than 0 (I think it's a message
type tag) and the last 4 are the string length. MSB are set at times
in the characters in the string. Tek used this (in the DM5010) for
the 488 bus vocabulary.

Mine's not designed to put out source quality disassembly (some were),
but more as a tool for reverse engineering. The source quality stuff
is simply a matter of reformatting the output, so that's not a big
deal.

The whole nature of the thing is to be interactive, of course.

Ok, it was easier for me to continue work on the existing disassembler
than it was to learn and support python, and every other disassembler
was also command line driven, and I couldn't add features.

Thanks

Harvey





Re: Tektronix 551 Power Supply

johnasolecki@...
 

Fortunately I have the cable.
Thank you for the lead but an ebay search using various combinations of Tektronix, 551 and power supply failed to bring anything up. Would you have a link to it?


John

Re: Tektronix 551 Power Supply

Jerry Ingordo
 

Re: Tektronix 551 Power Supply

Daniel Koller
 

....and it appears that the lower fan isolation mount has turned to goo and melted, so the fan is not straight and is probably rubbing against the grille.   Or it was dropped, and the fan motor's inertia bend the mount.  Definitely argue for a better price.  Dan

On Thursday, October 18, 2018, 11:37:25 AM EDT, Jerry Ingordo <gjingordo@...> wrote:

Here is a link.  The asking price is out off wack.

https://www.ebay.com/itm/Tektronix-Type-551-Oscilloscope-Power-Supply-Parts-or-Repair-READ/302769747661?hash=item467e7bb6cd

Jerry
W2JI

Re: 7A13 relay substitution report

Fabio Trevisan
 

Thanks Dennis,

For the heads up and for the kind offer...

I think I`m covered, with the 10 x NEC EB2 relays I got, and the 2 OMRONs G5V-1.

What puzzled me more (until I gave up on the Tek ones) was that, when I removed the Tek relays and exercised them in my test jig, they seemed to operate quite well, even at 10 or so cycles / sec, the contact bouncing would still be less than 10% of the period, meaning that they would settle in less than 5ms.

When inserted into the 7A13 however, as a general rule they would all perform well upon power-up, but after three or four minutes (sometimes up to 10) they would start acting...
But on the first 5 to 10 minutes, we cannot even use the plugin because it's still warming up and the 7A13 takes sometime until we can set the Var Balance, the Step Atten Balance and X10 balance.

The way how the relays are used on the 7A13, being kept all the time on or all the time off, depending on the range, makes their coil heat up considerably... and it seems the material the armature is made loose magnetic properties as they heat up (I'm not even sure if that can happen... I know magnets lose power with heat, but not quite sure about electromagnets) and the magnetic pull gets weaker.
There's also the PTC effect on the coil wire contributing to the diminishing of the magnetic pulling force.
Since the armature actuators are split into two opposite ends, and each one may "see" a slight different opposing force (from each of the contact springs), this causes sometimes one contact to remain actuated, while the other can give up altogether, not only breaking contact sometimes, but even enough to make a poor contact back to the N.C. contact (so half of the relay is make, the other half is break)..
It doesn't help either that the pivoting point is not very precise and plays somewhat, which allows one of the ends to "break" while the other side is still on "make".

I wasn't being able to go through the input attenuator's compensation adjustments until it started acting up, and that's what made me give up.
I would love to keep it original and even thought about getting some of them from Sphere or Qservice... But how to be sure they would also not fail in no time?

It's so unfortunate that no current relay share this same symmetrical / mirrored layout of the Tek ones, because wiring the new ones to the old pinout is never straightforward.
For each relay I`m having to draw 4 different combinations of positions and contact choices, to chose the one that has the shortest connections and less cross-overs.
So far I have been lucky to make most of the connections bridge no more than 2/10ths of an inch and no more than one signal cross-over but still, I'd guess there's at least 1/2 inch of added signal path and some added capacitance too.
Given the difficulty to get the wires routed the shortest path even counting on the 3D space between them, I doubt that making adapting boards won't make it even worse so, I won't even try it.

I`ll keep posting the results as I move on.

Rgrds,

Fabio

On Wed, Oct 17, 2018 at 05:32 PM, Dennis Tillman W7PF wrote:
Hi Fabio,
I think we will all benefit from your adventure into replacing the Tek relays.
If you get stuck and cannot find an appropriate substitute at any point
contact
me off list at dennis at ridesoft dot com and I will try to help however I
can.
Dennis Tillman W7PF

TDS5104 versus TDS7104?

dnmeeks
 

Hi Team Tek -
I am considering upgrading my scope. There are a bunch of TDS5104s and TDS7104s on Ebay, and other than the OS, I can't see any difference in their specs. Does anyone know how these two compare?
Thanks
Dan

Re: TDS5104 versus TDS7104?

Harvey White
 

On Thu, 18 Oct 2018 19:24:45 -0700, you wrote:

Hi Team Tek -
I am considering upgrading my scope. There are a bunch of TDS5104s and TDS7104s on Ebay, and other than the OS, I can't see any difference in their specs. Does anyone know how these two compare?
Looks like the 7104 has 10 Gsamples/second, while the 5104 has 5
Gsamples/second. May be the only difference.

Harvey


Thanks
Dan


Re: Tektronix 551 Power Supply

johnasolecki@...
 

Thanks for the link & the information. I have found another which hopefully is in much better condition. I'll keep this one in mind as a possible backup.

John

Re: 2445A calibration

Mark Litwack
 

On Thu, Oct 18, 2018 at 10:52 AM, Harvey White wrote:
...
Ah, ok. They wanted money for that. Mine works the same way (all the
disassemblers that I wrote worked the same way as an option).
...
Hi Harvey,

Are your disassemblers available somewhere?

I've been using this one for the 6800:

http://www.seanriddle.com/willy3.html#dats

It can be explicitly told where data sections, routines, etc. exist, but it's a bit hard to use. It's all CLI driven, which is fine, but it's not much more than a byte to opcode converter.

Thanks,

-mark

Re: 2445A calibration

Harvey White
 

On Fri, 19 Oct 2018 07:11:53 -0700, you wrote:

On Thu, Oct 18, 2018 at 10:52 AM, Harvey White wrote:
...
Ah, ok. They wanted money for that. Mine works the same way (all the
disassemblers that I wrote worked the same way as an option).
...
Hi Harvey,

Are your disassemblers available somewhere?
Generally not, however, you can contact me off list if you want and we
can see if what I'm doing will be of use to you.




I've been using this one for the 6800:



http://www.seanriddle.com/willy3.html#dats

It can be explicitly told where data sections, routines, etc. exist, but it's a bit hard to use. It's all CLI driven, which is fine, but it's not much more than a byte to opcode converter.
Well, mine does execution tracing, so that makes it a bit more
complex.

Got a situation now where they set up a pseudo stack and execute it
with an RTI. Not sure if I need a feature for that or what.

Harvey




Thanks,

-mark


vintageTEK museum microfiche index

Dave Brown
 

Our volunteers are busy indexing the museum's microfiche. They are less than half way through but we have compiled an interim partial index of instruments included in our microfiche. Duplicate instrument numbers mean that we have multiple sets of microfiche. We do not know if they are duplicates or differ in content or date but merely that we have sets in multiple drawers. A PDF of the index-to-date is available at https://vintagetek.org/printed-and-microfiche-manuals/

vintageTEK

Tektronix 475 Possibly DM or other optional board ???

Craig Cramb
 

Does anyone have the parts details on a A9 board possibly in a 475 series that calls out the Part #670-2239-24. All the 475 manuals I have stop at extension -12 and don't indicate this specific board extension -24. as to what is specific about it. This is a Tektronix built board replacement board in a package not out of a scope.

Craig

Re: Tektronix 475 Possibly DM or other optional board ???

Jim Olson <v_12eng@...>
 

Craig,
I have a listing for that board in the service manual I have it is an option 7 only main board for the B250000 and up 475 scopes. So if you need any specific parts #'s I can supply them.

Jim O

On October 19, 2018 at 6:46 PM Craig Cramb <@Manfromtrane mailto:@Manfromtrane > wrote:


Does anyone have the parts details on a A9 board possibly in a 475 series that calls out the Part #670-2239-24. All the 475 manuals I have stop at extension -12 and don't indicate this specific board extension -24. as to what is specific about it. This is a Tektronix built board replacement board in a package not out of a scope.

Craig


Re: Tektronix 475 Possibly DM or other optional board ???

Craig Cramb
 

Thanks Jim,
My manual is a B25000/up rev Apr 1982. I see the -24, but the part number is changed for this extension it shows the manual 670-2339-24 which is maybe a typo. But in my manual from -12 and up the part number is changed. The board actually has the part # 670-2239-24 printed on it.

Craig


Craig,
I have a listing for that board in the service manual I have it is an option 7 only main board for the B250000 and up 475 scopes. So if you need any specific parts #'s I can supply them.

Jim O

Re: Tektronix 475 Possibly DM or other optional board ???

Jim Olson <v_12eng@...>
 

If you can send me a picture to my email I can compare it to the 475 A9 boards I have in the scopes to see if the parts layout is a match.

Jim O

On October 19, 2018 at 8:09 PM Craig Cramb <@Manfromtrane mailto:@Manfromtrane > wrote:


Thanks Jim,
My manual is a B25000/up rev Apr 1982. I see the -24, but the part number is changed for this extension it shows the manual 670-2339-24 which is maybe a typo. But in my manual from -12 and up the part number is changed. The board actually has the part # 670-2239-24 printed on it.

Craig


Craig,
I have a listing for that board in the service manual I have it is an option 7 only main board for the B250000 and up 475 scopes. So if you need any specific parts #'s I can supply them.

Jim O