TDS724D 7 segment diagnostic display - meaning?

[tkamiya]

I have just acquired a non functioning TDS724D, a Tektronix scope. 

First off, when powered on, all LED on front panel lights but nothing on display.  (This is a CRT, not LCD although it looks like a LCD unit)  Fan works and there is a faint one "click" on floppy drive.  Visually, I don't see any burned parts or exploded/leaked caps.  There is a 7 segment diagnostic display on CPU board.  It goes through iterations but gets stuck at top and bottom segment alternatively flashing.  I went through a service manual but there is no mention of what this means.

I have not tested the power supply, but I'm curious as to if anyone has a chart on the above mentioned 7 segment display. 

Anyone?

ps.  There are several threads on these units and they mention "diagnostic port".  Apparently, a special jig is required to connect to this port and then to RS232C.  But link on the actual document on this jig is all broken. 

[madao]

two  segment lights up alternating ->  firmware is good, someone of hardware is failed,  you need debug interface-Adapter
7-Seg Displays  meaning is only worth in bootloader-mode.

Here  two file, which i have saved from dead theard/link since time ago.

Gerber file (debug-interface.zip) , it  is mine design (has little fault,  you must put  him 180° to CPU board. )

[tkamiya]

Thank you for sharing!

I'm sorry, I am having trouble understanding what you are telling me.  I read the serial interface port and debug port does not share the same connection.  So a special adapter has to be made.  I think that is what your first two pictures are showing.  The 20 pin edge card connector is the debug port we are interested in, correct?

But I was not aware I needed a micro controller.  What does your board do?  I see isolaters, then I see it goes to TDS-TX and TDS-RX as well as flow control.  Or is this showing part of the scope hardware?  I'm sorry, I'm totally lost here.

[madao]

Yes,   20 pin edge connector  on CPU is  debug / console interface.
You put this  interface on CPU board and   computer.   It make log while boot up.  You can see, at which point are DSO hang up .
Terminal setting , i believe  9600 baud,  no flow control need.



Schematic, it is not mine, it is saved from dead theard. Most interessing parts is only   20 pin connector and  68681 UART Controller.

Here a picture of screenshot of result,  (a TDS754C doesn't start up complete)

[keystone]

Where can you get one of those premade boards?

[madao]

gerber files in ZIP-file is attached on my first  answers on you.  You can made it by jlcpcb (eevblog's advertisment    ),  5 pieces cost only 2 $, Quality  good.

I can sending  pcb with part to you, but  you must paid over $30 for only shipping , german post  . 

[Jwalling]

Where can you get one of those premade boards?

Have a look here: https://www.eevblog.com/forum/testgear/console-port-debug-adapter-for-tek-tds500-tds600-and-tds700-series-scopes/

Much simpler solution...

[tkamiya]

Ah, I understand now.  The Motorola chip is UART!  I thought it was a cpu chip. 
I also understand optional serial port already contains UART....  so it is possible to make an adapter for it.

I kind of prefer an independent solution, as I may have to use it for more than one machine which may or may not have the serial option.  These scopes are getting cheaply available now.

[tkamiya]

I'm seeing 68681 UART chip is no longer in production.  Digikey shows zero stock, Mouser does not even show one, and of course plentiful on eBay.  I should have kept those "serial adapter card' from 80s....  About 40 years too late.

[madao]

68681, i have buying two from china, it look like orginal.  (new, no  "used" with grinded surface ) and it works. Of coruse, i am careful by semicondutor from china.



Greetings
matt

[tkamiya]

Greetings....

Yes, I'm sure there are many genuine chips coming from China.  But it is also true some people do anything knowingly for money.  Fakes, factory seconds, used pulls, etc, etc, etc.  Unless necessary, I stopped buying semi-conductors from eBay.  It's just not worth the hassle.  Especially things that matter, I try to stick with known vendors.  Pay a bit more but I can be assured I get the right product.

[madao]

honestly, i want sending you a complete board.   Wait.. i look on DHL site... yes  i can ship him now for less than $30
Now, i can ship to you with 9€  (~$10.5 ) ship cost and  price for complete PCB, checked. Can you  wait over one months (sea shipping) ?

Greetings
matt

[ChuckDarwin]

MaxLinear XR68C681 (Mouser US) viable alternative? Or Philips SCC68681/SCN68681 (just saw that the SCN68681 is already noted in the schematic)

[tkamiya]

If cost makes sense, I'd prefer that, too. Can you work out a price and let me know via PM?

honestly, i want sending you a complete board.   Wait.. i look on DHL site... yes  i can ship him now for less than $30
Now, i can ship to you with 9€  (~$10.5 ) ship cost and  price for complete PCB, checked. Can you  wait over one months (sea shipping) ?

Greetings
matt

[madao]

MaxLinear XR68C681 (Mouser US) viable alternative? Or Philips SCC68681/SCN68681 (just saw that the SCN68681 is already noted in the schematic)

Yes, SCN68681 fit here, but also osbolent since long time ago

  XR68C681, i have checked datasheet,  yes it may fit !

Greetings
Matt

@tkamiya ,  offer is for you, i have sent a pm to you.

[tkamiya]

PM replied.  YES!

[keystone]

honestly, i want sending you a complete board.   Wait.. i look on DHL site... yes  i can ship him now for less than $30
Now, i can ship to you with 9€  (~$10.5 ) ship cost and  price for complete PCB, checked. Can you  wait over one months (sea shipping) ?

Greetings
matt

I would be interested in a board also.  Please PM me.  Thank you.

[madao]

I have only few complete board, my offer is for him.

But you can use gerber file  from my first answers, or you want complete , checked board ?
All information:  https://www.eevblog.com/forum/repair/tektronix-tds500-700-debug-konscole-interface/

Greetings
matt


Important: Pleas  delete old  gerber file (with file  date 13.02.2020 ) and  use gerber file with newer file date  30.05.2020.
First answer is  edited and old gerber file is already replaced.

Sorry !!

[keystone]

I want a complete checked board.  Thank you.

[coromonadalix]

@keystone   you have to make the board  ....  read the previous post before yours ....