Hardware

TSP #336 - A Fancy PID Controller! Keithley 2510 TEC Source-Meter Teardown, Repair & Experiments

The Signal Path
The Signal Path•May 10, 2026

Why It Matters

Restoring the Keithley 2510 saves labs significant capital and ensures continued access to precise temperature‑control capabilities essential for research and production.

Key Takeaways

  • •Keithley 2510 source‑meter powers TECs and measures temperature via PID.
  • •Unit powered on but supplied ±15 V rails were far below spec.
  • •Faulty opto‑isolator in DCDC converter caused all supply failures.
  • •Replaced hot SPDT switches and identified dead multi‑slope ADC chip.
  • •New O2‑version ADC may restore functionality after component swaps.

Summary

The video documents a detailed teardown and repair of a Keithley 2510 TEC source‑meter, an instrument that combines a programmable power supply with a PID controller to heat or cool devices while measuring temperature. The host demonstrates the unit powering up with a disturbing squeak, then discovers that its critical ±15 V rails read only +8 V and –12 V, far short of the expected values, indicating a deep power‑supply fault. Thermal imaging reveals hotspots up to 72 °C on a floating switching converter and several SPDT multiplexing switches, prompting a systematic voltage check and component isolation. By inserting a test socket and swapping an opto‑isolator in the DCDC converter, the host restores all rail voltages, confirming the isolator as the root cause of the failure. Subsequent replacement of the overheated switches eliminates excess heat, but a burned multi‑slope ADC (part 200802 AO4) remains dead, likely responsible for earlier switch stress. Key moments include the audible squeak linked to the switching supply, the measured 65 °C and 72 °C components, and the discovery that an O2‑version ADC, interchangeable with the original, can be sourced for under $100 on eBay. The host plans to install this replacement to fully revive the instrument, illustrating a pragmatic approach to legacy equipment repair. Successfully fixing the power rails and replacing the ADC would return the Keithley 2510 to full functionality, offering labs a cost‑effective alternative to purchasing new temperature‑control hardware. The repair also showcases how detailed diagnostics—voltage checks, thermal scans, and component swaps—can extend the life of high‑precision test gear.

Original Description

In this episode Shahriar attempts the repair of a Keithley 2510 TEC Source-Meter. This instrument is capable of delivering up to 60W of power to any TEC in both polarities. Furthermore, the instrument integrates a flexible temperature read-out capability with 4-wire interface. Lastly, combining both capabilities, alongside a fully customizable PID controller, a precise temperature controller can be realized.
This particular unit returns erroneous readouts in all modes: voltage, current, resistance & temperature. The unit is also generating "squeaky" noises which is indicative of a failing DC-DC converter. The block diagram of the unit is examined and the fault is ultimately traced to a damaged opto-isolator in the isolated switching power supply. Several other components are also faulty which are located via thermal camera. The output Class-D / buck converter circuit & block diagram are also examined in details.
Unfortunately, the custom IC at the heart of the multi-slope ADC is also damaged. The IC is de-capped, examined under a microscope, and compared with its predecessor CPLD counterpart. This Keithley component is sourced from an older high-speed power supply. The correct readout is then verified. Several experiments are demonstrated using the PID controller and a custom TEC setup.
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