[labnetwork] Dektak 3030ST: CRT Horizontal Sync Issue ? Seeking Advice and Service Manual

[Dennis Culver]

 Dear Yoji,
Hopefully, I can help you isolate this issue.  
In video # 1, (mixed video), the Dektak 3030ST sign-on screen is not scrolling, it is synced. Cycle the videokey to video only. If the image is stable, not scrolling, then the monitor is receiving sync. If you cycle tocamera only, if it is rolling, either the sync signal for the camera is missing or the camera is defective.If you unplug the BNC connector for the camera video, and the scrolling stops when you cycle through thescreen options, (video only, camera only, mixed), then we can deduce that the sync signal to the cameramay be absent or the camera is bad.
The Dektak video circuit is a modified NTSC; black & white horizontal sync is 15.750 khz.  The Dektaks needexternal sync as the horizontal sync rate is 15.735 khz, same rate as the color horizontal sync rate(?)  Youwill notice that both camera vertical (60.00hz) and horizontal sync are generated on the SHI PC card, schematicattached, from U17, connected to the camera cable through connector J-6 pin 3 for horizontal.  You willnotice that the raw H sync signal comes from the MEU to U22 pin 1.  The horizontal sync delay is to syncthe camera H sync to the monitor, to prevent horizontal scrolling of either image.
You can troubleshoot the sync signals using an oscilloscope.  TP-5 is ground and the signal can be viewedat connector J-6 pin 3 brown Methode style connector.  You will also notice the camera "auto iris" signal at J-6pin 6.  This signal is "white data" from the camera to servo lamp brightness when you zoom in/out or toadjust the lamp to the sample.  If the horizontal sync signal is present at J-6 pin 3, suspect the camera external sync input defective. If the signal is absent, follow the signal back.  If there's no H sync signal atU22 pin 1, there's an issue on the CPU board in the MEU.  (I'll try and locate the appropriate section of that CPU board for you).  With only the power connector on the camera connected, you can plug the camera cable into a composite monitor (75 ohm) and view the camera image as the camera will default to 15.750 khz, internally generated.  The lamp brightness should work normally using the brightness knob on the front of the scan head.  The Javelin cameras do fail in this manner.  Sadly, you can only replace the camera with the EXACT same model. 
Hopefully, this will help you get your Dektak back up and running!
Best Regards, 
Dennis CulverCulver Consulting3820 N. Ventura Ave.Ventura, CA 93001 USA



On Thursday, August 20, 2026 at 12:38:18 AM PDT, yyasuda at t-kougei.ac.jp <yyasuda at t-kougei.ac.jp> wrote:


Dear LabNetwork members,

  

I am a researcher at a university in Japan working in a thin film laboratory. I am currently experiencing a serious display issue with our Dektak 3030ST and would greatly appreciate any advice from members who have experience with this system.

  

--- Current Symptoms ---

1. The CRT screen image continuously scrolls horizontally and cannot be stabilized.

2. White and black screens appear alternately. see attached files.

3. A horizontal band appears from the top of the screen and drifts continuously to the left.

4. When the EXT SYNC cable is disconnected, the camera lamp remains on continuously and the camera image is displayed normally. However, the horizontal scrolling on the CRT persists.

  

Based on symptom 4, we believe the camera itself is functioning normally. We suspect the issue is related to the H-SYNC signal circuit on the CRT board, possibly caused by accidental adjustment of the H-HOLD or horizontal frequency trimmer.

  

--- What We Are Looking For ---

1. Has anyone experienced a similar issue with the Dektak 3030ST and been able to resolve it?

2. Does anyone have access to the service manual or circuit diagram for the Dektak 3030ST, particularly the CRT display and horizontal sync adjustment section?

3. Any guidance on which trimmer controls H-HOLD vs H-POSITION on this unit would be extremely helpful.

  

Thank you very much for any help you can provide.

  

Best regards,

Yoji Yasuda

Tokyo Polytechnic University
e-mail： yyasuda at t-kougei.ac.jp

  
_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu
https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20260820/e1f6fa0f/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 173779 (7 of 7).pdf
Type: application/pdf
Size: 1052831 bytes
Desc: not available
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20260820/e1f6fa0f/attachment.pdf>