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Tektronix 4052A Screen CRT dead

tomeucapo

tomeucapo

Member
Joined
Jun 17, 2018
Messages
31
Location
Campanet, Spain
Hello at all!

I try to find schematics documentation from Tek 4052A but only I found Technical Manual without all schematics. I have 4052A with death CRT, and I checked logic board appears goes because accept commads throw keyboard. I check all power supply fuses and 3 fuses of 3A are death, i replaced but blowup again! I try to check Display Board I think any component are shortcircuit or bad.

Any ideas?
 

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There are several 4052 schematics in this post:
https://forum.vcfed.org/index.php?threads/tektronix-4052-intensity-issue.1244122/post-1330220
and I think you would be interested in the entire thread.

I'm still searching for an older thread that had 4052 schematics.

All of the 4052A ALU, MAS,MCP and I/O boards are the same as the 4054A.
The 4052 and 4054A shared the same Display board as the 4051 - so you can look at the 4051 service manual volume 2 for the Display board schematics.
 
As this is your first post, welcome to VCFED.

Yep, the schematics are around and we can help you out!

You will be under moderation for your first 10 posts, so we will have to take things slowly at first to give time for your posts to appear.

You have a few pointers above from Monty to start with to locate the relevant schematics.

Gut feeling is short circuit capacitors - but that is only a guess without any valid data points.

Dave
 
nikola-wan said:
There are several 4052 schematics in this post:
https://forum.vcfed.org/index.php?threads/tektronix-4052-intensity-issue.1244122/post-1330220
and I think you would be interested in the entire thread.

I'm still searching for an older thread that had 4052 schematics.

All of the 4052A ALU, MAS,MCP and I/O boards are the same as the 4054A.
The 4052 and 4054A shared the same Display board as the 4051 - so you can look at the 4051 service manual volume 2 for the Display board schematics.
Click to expand...

Hello and thanks for response

I read some posts in other thread here and read some TekWiki notes maybe can help or not. Because, I only had Tektronix 4052/4054 Technical Manual (Without schematics), and figureout issue with this documentation and some posts in similar threads as you write to. My issue is: The fuses of high voltage that power up CRT are blowup, then try to replace them put on and blown again only hight voltage fuses (the 5 volts are ok because logical board appears goes "well") The keyboard accepts any basic commands and can execute simple program as play simple sound or do loop because when RUN then BUSY indicator on and when break BREAK indicator off, maybe not very scientific method to test logic board but with little experiments of execute simple sound and do loop tested logic board "in part".

In other hand CRT no responses totally off and tube is off (obviously high voltage is off because fuses are blown). Now its time to figureout what is the reason of high voltages fuses are blowedup. Without schematics, I found one of deflection circuity from of one your past threads talks about 4052 failures.

Where found this schematics? I go to TekWiki but only found Technical Manual with some little schematics (not complet).

Thanks for advance.
 
daver2 said:
As this is your first post, welcome to VCFED.

Yep, the schematics are around and we can help you out!

You will be under moderation for your first 10 posts, so we will have to take things slowly at first to give time for your posts to appear.

You have a few pointers above from Monty to start with to locate the relevant schematics.

Gut feeling is short circuit capacitors - but that is only a guess without any valid data points.

Dave
Click to expand...
I think there are existing short circuit in some capacitors on Display board, and its very useful found the schematics of this board.

Sorry, yes its my first post on VCFED. I'm from Balearic Islands (Spain) and here there are not any groups like VCFed where share some technical questions about this serious old hardware :)
Its pleasure able to write on this forums.

Thanks for all
 
nikola-wan said:
There are several 4052 schematics in this post:
https://forum.vcfed.org/index.php?threads/tektronix-4052-intensity-issue.1244122/post-1330220
and I think you would be interested in the entire thread.

I'm still searching for an older thread that had 4052 schematics.

All of the 4052A ALU, MAS,MCP and I/O boards are the same as the 4054A.
The 4052 and 4054A shared the same Display board as the 4051 - so you can look at the 4051 service manual volume 2 for the Display board schematics.
Click to expand...
Thanks very usefull information :) I Try to check all caps marked in yellow as described on post as you refered.
 
I found 4 tantalum or ceramic caps shortcircuited between GND and different potential points like -20v and +20v.
Still check all other caps.
 

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I had similar bad capacitors in that same section on my 4052, replacing those capacitors made my display board work again. Before replacement the fuses in the power supply would blow just like you described.

I assume you have checked the voltages in the low voltage power supply section and they are all good?
 
nikola-wan said:
I had similar bad capacitors in that same section on my 4052, replacing those capacitors made my display board work again. Before replacement the fuses in the power supply would blow just like you described.

I assume you have checked the voltages in the low voltage power supply section and they are all good?
Click to expand...
Yes first when I seen high voltage section fuses are blowedup then replace and disconnect all connections to Display Board and then check voltages are good!

Now I now waiting to order new caps to replace it all in shortcircuit.
 
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Thanks for your help. Are very useful beacuse before I try to find into tekwiki or bitsavers and only had few manuals of 4054.
 
Clarification: my text is incorrect for the two links in my previous post - they are August 1983 070-2829-01 4052/4052A Parts and Schematics manual in two sections.
https://w140.com/tekwiki/images/0/0e/070-2829-01_sections_1-6.pdf
https://w140.com/tekwiki/images/e/e1/070-2829-01_sections_7-9.pdf

The May 1983 070-2839-03 4054/4054A Parts and Schematics link is a completely separate manual:
http://www.bitsavers.org/pdf/tektro...ervice_Manual_Parts_and_Schematics_198305.pdf

The Nov 1982 070-2840-03 Technical Data Manual with theory of operation covering BOTH 4052/4052A AND 4054/4054A is here:
http://www.bitsavers.org/pdf/tektro...054A_Service_Manual_Technical_Data_198211.pdf
 
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nikola-wan said:
Clarification: my text is incorrect for the two links in my previous post - they are August 1983 070-2829-01 4052/4052A Parts and Schematics manual in two sections.
https://w140.com/tekwiki/images/0/0e/070-2829-01_sections_1-6.pdf
https://w140.com/tekwiki/images/e/e1/070-2829-01_sections_7-9.pdf

The May 1983 070-2839-03 4054/4054A Parts and Schematics link is a completely separate manual:
http://www.bitsavers.org/pdf/tektro...ervice_Manual_Parts_and_Schematics_198305.pdf

The Nov 1982 070-2840-03 Technical Data Manual with theory of operation covering BOTH 4052/4052A AND 4054/4054A is here:
http://www.bitsavers.org/pdf/tektro...054A_Service_Manual_Technical_Data_198211.pdf
Click to expand...

Hello again.

I replaced shortcircuit tantalum capacitors at Display Board (669, 668, 672 and 671) and put new fuses at power supply, now there are not any shortcircuit "apparently" because when put on all fuses still are good!
But, next:

1) Powerup and screen also in black
2) Create 8's test program and RUN -> BUSY goes ON, but nothing on screen (press BREAK and then BUSY goes OFF)
3) Press HOME PAGE key and screen flashes but still not show any character on screen.
4) When poweroff screen flashes and shines and fades

Then next re-check all powersupply voltages but I think something strange voltages values for example 20v are in +26.48v and on says P22.1 and P22.4 at schematics says +20v and have -26v.


1722873925335.png
 
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nikola-wan said:
The Nov 1982 070-2840-03 Technical Data Manual with theory of operation covering BOTH 4052/4052A AND 4054/4054A is here:
http://www.bitsavers.org/pdf/tektro...054A_Service_Manual_Technical_Data_198211.pdf
Click to expand...
Note that this manual has some corrected pages in later editions, which Monty has scanned:

github.com

Tektronix-4051-4052-4054-Program-Files/070-2840-03_Oct_1983_4052-4054&4052A-4054A_Technical_Data_updated_pages.pdf at master · mmcgraw74/Tektronix-4051-4052-4054-Program-Files

Archive of Tektronix 4051 4052 4054 and A series computer programs - mmcgraw74/Tektronix-4051-4052-4054-Program-Files
github.com github.com

Monty, would you consider scanning this entire doc? It would be handy to have it all in a single PDF, even though most pages are identical.
 
Thanks guys!

My Tektronix 4052A works! :)

Replaced capacitors as described above and verify grid voltages disconnecting high voltage from Display Board to confirm as described on top of CRT case.

Now I try to copy programs from PC to 4052A via serial port, if is possible (I don't known).

Thanks for all :)
 

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Well done.

>>> Now I try to copy programs from PC to 4052A via serial port, if is possible (I don't known).

Everything is possible 😀!

Dave
 
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tomeucapo said:
Thanks guys!

My Tektronix 4052A works! :)

Replaced capacitors as described above and verify grid voltages disconnecting high voltage from Display Board to confirm as described on top of CRT case.

Now I try to copy programs from PC to 4052A via serial port, if is possible (I don't known).

Thanks for all :)
Click to expand...
Congratulations! Another operational Tektronix 4052!

Have a look at my README file on my github repository for "Tektronix 4050 BASIC programs" for my instructions on how to transfer programs from a PC to a 4050 using the serial interface:

https://github.com/mmcgraw74/Tektronix-4051-4052-4054-Program-Files

Finding working DC300 (or newer versions up to DC6250) data tape cartridges at this time is very difficult. My last purchase of ten NOS (new-old-stock) DC6250 tapes from the early 1990's (around the time production stopped on quarter-inch tape cartridges) only yielded 5 working tapes. The most typical problem I find with these tapes is the drive band inside the tape cartridge is broken and sometimes both broken and moldy :cry: When these drive bands break - they also tend to pull oxide off the tape on both tape reels - which has prevented me from recovering programs on many old 4050 tapes.

I designed an Arduino based emulator of the Tektronix 4924 GPIB Tape Drive with the help of my collaborator @WaveyDipole that I call "Flash Drive" that plugs directly into the 4051, 4052 and 4054 GPIB connector and stores 4050 BASIC programs and data files on a microSD card in multiple separate directories - one for each set of 'tape' files.

See my Flash Drive thread in this forum for more details:

https://forum.vcfed.org/index.php?threads/tektronix-4050-gpib-flash-drive-now-available.1238891/post-1396821
 
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tomeucapo said:
Thanks guys!

My Tektronix 4052A works! :)

Replaced capacitors as described above and verify grid voltages disconnecting high voltage from Display Board to confirm as described on top of CRT case.

Now I try to copy programs from PC to 4052A via serial port, if is possible (I don't known).

Thanks for all :)
Click to expand...
Is your drive belt working in the tape in your photo?

If you gently try to move the tape capstan wheel with your finger - do both tape reels move smoothly?

You must execute a FIND command prior to executing the MARK command.

Try this:
FIND 1
MARK 3, 2000

Then run TLIST
It should find three files starting with file 1 of 2K size followed by a LAST file.

Without a LAST file, the 4050 cannot work properly with the tape.
 
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