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Tektronix 4054A HoLLyWoOD Syndrome

stepleton

Experienced Member
Joined
Jan 1, 2020
Messages
295
Location
London, UK
Exclusive photos reveal Hollywood secrets!

cracks1.jpg
cracks2.jpg

That's a problem right there. This connector conveys power from the "low voltage power supply" to the display circuitry. In the top photo, from left to right, are pins carrying

+490V unregulated
+290V regulated
+175V unregulated
Ground
-15V flood gun filament
+15V flood gun filament

In the bottom photo, from top to bottom:

Ground
-15V
+5V
+15V
Ground
-9V

So the joints were cracking at the edges at least, and on the obviously impacted pins, those voltages (+490V, +290V, -15V, +0V of course) are all critical for the display. I did go ahead and replace the capacitors that I had been abusing earlier (this board is a bear to extract from the machine, so might as well do it), but in all likelihood the connector here is the main culprit. Either way, it has to be fixed. I reflowed the cracked joints... and the rest of the joints, and the joints on all the other plug connectors on the board. Plus the joints at the other end of the cable that connects to this connector.

After running with the lid on for a while and noting no jumpy text, I'm hopeful that the Hollywood saga is concluded with long odds of a sequel. The process of disassembling the display circuitry also made me feel a bit more brave about undertaking the imposing calibration procedure that hopefully might improve display quality --- although it still sounds like a pain! In any case, thanks for the thoughts --- let's hope this was it!
 

nikola-wan

Veteran Member
Joined
Mar 7, 2018
Messages
968
Location
Texas, USA
Exclusive photos reveal Hollywood secrets!

View attachment 1241702
View attachment 1241703

That's a problem right there. This connector conveys power from the "low voltage power supply" to the display circuitry. In the top photo, from left to right, are pins carrying

+490V unregulated
+290V regulated
+175V unregulated
Ground
-15V flood gun filament
+15V flood gun filament

In the bottom photo, from top to bottom:

Ground
-15V
+5V
+15V
Ground
-9V

So the joints were cracking at the edges at least, and on the obviously impacted pins, those voltages (+490V, +290V, -15V, +0V of course) are all critical for the display. I did go ahead and replace the capacitors that I had been abusing earlier (this board is a bear to extract from the machine, so might as well do it), but in all likelihood the connector here is the main culprit. Either way, it has to be fixed. I reflowed the cracked joints... and the rest of the joints, and the joints on all the other plug connectors on the board. Plus the joints at the other end of the cable that connects to this connector.

After running with the lid on for a while and noting no jumpy text, I'm hopeful that the Hollywood saga is concluded with long odds of a sequel. The process of disassembling the display circuitry also made me feel a bit more brave about undertaking the imposing calibration procedure that hopefully might improve display quality --- although it still sounds like a pain! In any case, thanks for the thoughts --- let's hope this was it!
You might try to run my new ICE RACES program for the R12 Graphics Enhancement ROM. This program replaces the Option 30 CALLs with R12 CALLs which are in your MFM. This program draws the two race cars in refresh mode - so they should show up in orange, like the cars in the Option 30 version. Just create a new directory on the MicroSD card - I named my directory "ICE RACES" and extract the zip file in the github folder for ICE RACES into the ICE RACES folder on the Flash Drive. Then PRINT @5,9:"ICE RACES" to change the Flash Drive to that directory and FIND@5:1 followed by OLD@5: and run that program on the 4054A. I would pick "2" for the car image to reduce the flicker of R12 refresh graphics between the two cars.

You can then compare my R12 version with the original Option 30 version to see if the Option 30 board is working properly.
 
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