This article is a summary of a YouTube video "The PDP-11/23 Plus Works!" by Usagi Electric

Fixing the PDP 1103 Power Supply - Deep Dive into the Regulator Circuit

TLDRLearn how to fix the PDP 1103 power supply by understanding and repairing the regulator circuit. Discover how the circuit works and how to troubleshoot common issues.

Key insights

🔧The PDP 1103 power supply uses a regulator circuit to control voltage output.

💡The regulator circuit consists of a three terminal regulator, overcurrent protection circuit, and crowbar circuit.

🛠️Overvoltage issues may be caused by shorted diodes or other faulty components.

🔌Checking and replacing the 7915 negative voltage regulator may solve voltage regulation problems.

🧰Troubleshoot the regulator circuit by checking diodes, capacitors, and traces for any damage or shorts.


What is the purpose of the regulator circuit in the PDP 1103 power supply?

The regulator circuit controls the voltage output of the power supply, ensuring stable and regulated power for the system.

Why might overvoltage issues occur in the power supply?

Overvoltage issues can be caused by faulty diodes or other components within the regulator circuit.

How can I troubleshoot voltage regulation problems?

Check diodes, capacitors, and traces in the regulator circuit for any damage, shorts, or abnormalities.

What is the role of the 7915 negative voltage regulator?

The 7915 negative voltage regulator regulates and supplies the minus 5 volts necessary for the system's logic.

Can I replace the diodes and capacitors in the power supply?

Yes, replacing faulty diodes and capacitors can help resolve voltage regulation issues in the power supply.

Timestamped Summary

00:00Introduction to fixing the PDP 1103 power supply and rotating topics in YouTube videos.

00:43Explanation of why the Bendix video was postponed and the focus on the PDP 1103 power supply.

04:59Detailed explanation of how the regulator circuit in the PDP 1103 power supply works.

10:04Discovery of shorted diodes in the circuit and the impact on voltage regulation.

13:21Replacement of diodes and testing of the 7915 negative voltage regulator.

13:43Confirmation of successful regulation of negative voltages.

16:14Troubleshooting advice for voltage regulation issues in the PDP 1103 power supply.