Teardown and repair of an GW Instek PSW80-40.5 1080W multi-range programmable power supply

Teardown and repair of an GW Instek 1080W power supply from The Signal Path: In this episode Shahriar investigates the failure of a GW Instek 1080W power supply capable of providing up to 80V and 40A of programmable output voltage and current respectively. The power supply does not power on. However, relay noises can be […]

Capacitor plague? Inside an HP 8620C sweep oscillator and HP 86245A RF plugin

A teardown of the HP 8620C and HP 86245A by Kerry Wong: I just picked up an HP 8620C sweep oscillator with an HP 86245A 5.9 GHz to 12.4 GHz RF plugin on eBay. This time around though, the unit does not work. While it was advertised as a working unit I could not get […]

Repairing the card reader for a 1960s mainframe: cams, relays and a clutch

Ken Shirriff writes: I recently helped repair the card reader for the Computer History Museum’s vintage IBM 1401 mainframe. In the process, I learned a lot about the archaic but interesting electromechanical systems used in the card reader. Most of the card reader is mechanical, with belts, gears, and clutches controlling the movement of cards […]

Repairing a 1960s mainframe: Fixing the IBM 1401’s core memory and power supply

Ken Shirriff wrote a great article describing the repair process of  the vintage IBM 1401 mainframe computer: The problem started when the machine was powered up at the same time someone shut down the main power, apparently causing some sort of destructive power transient. The computer’s core memory completely stopped working, making the computer unusable. […]

Teardown and repair of an Agilent E3632A DC power supply

Teardown and repair of an Agilent E3632A DC power supply from The Signal Path: In this episode Shahriar & Rosanah investigate an Agilent power supply which does not appear to power on. It can be quickly observed that the fuse has failed on the unit. Using an isolation transformer a small amount of AC voltage […]

Teardown and repair of an Agilent 53152A 46GHz microwave frequency counter

Agilent 53152A 46GHz frequency counter teardown and repair from The Signal Path: In this episode Shahriar investigates a faulty Agilent 53152A 46GHz frequency counter. The instrument does not power on and shows no sign of internal voltage presence. Teardown of the instrument reveals a large PCB where all analog and digital circuity is contained. The power supply […]

How Scotty made his own iPhone in China

Over the past two months we’ve been super excited to follow Scotty’s adventure recycling/refurbishing an iPhone 6S in the used cell phone market just south of Huaqiangbei, Shenzhen, China. Scotty finds all the bits and pieces from various sellers and then follows the iFixit instructions, backwards, to build his own recycled franken-phone. Despite living in […]

Teardown, repair and experiments with a Tektronix RSA 6114A real-time spectrum analyzer

Tektronix RSA real-time spectrum analyzer teardown from The Signal Path: In this episode Shahriar attempts a difficult repair of a Tektronix RSA real-time spectrum analyzer. This well-equipped instrument reports several error messages during startup POST including LO Unlock as well as Signal Path failures. The service manual of the instrument does not provide any detailed […]

Teardown, repair and experiments with the Anritsu 37347A 20GHz Vector Network Analyzer

Here’s another great video teardown from TheSignalPath: In this episode Shahriar repairs an Anritsu 37347A 20GHz Two-Port Network Analyzer. The unit does not boot up and as a result its internal state is unknown. The boot fault is traced to a bad RTC module which has a built-in integrated battery. A replacement unit is located […]

Teardown, repair & calibration of a Valhalla 2701C Programmable Precision DC voltage standard

A teardown and repair of a Valhalla 2701C Programmable Precision DC voltage standard from The Signal Path: In this episode Shahriar examines a faulty Valhalla 2701C Programmable Precision DC Reference instrument. Valhalla Scientific’s 2701C Programmable Precision DC Voltage Calibrator delivers ultra-precision, ultra-stable DC voltage from 100 nanovolts to 1200 volts. This unit does not have a working […]

Repairing a Marconi Instruments 2955A Radio Communications Test Set, part 1

Mikko has written an article about Marconi 2955A repair: First off, I decided to see what was the deal with the CRT. I have never worked on CRTs before, I have understanding of how the picture is formed by steering the electron beam using the deflection coils but that’s about it. I know a charged CRT […]

Teardown, repair & analysis of a Rohde & Schwarz FSH3 3.0GHz portable spectrum analyzer

A teardown and repair of a Rohde & Schwarz FSH3 3.0GHz portable spectrum analyzer from The Signal Path: In this episode Shahriar examines a faulty R&S FSH3 100kHz – 3.0GHz Portable Spectrum Analyzer. This exceptionally dirty unit does not power on and is missing a power supply and battery. After verifying the correct operation of […]

Teardown & repair of the Siglent SHS810 100MHz 1GS/s portable oscilloscope & multimeter

Here’s a teardown & repair of the Siglent SHS810 100MHz 1GS/s portable oscilloscope & multimeter from The Signal Path: In this episode Shahriar examines the failure of a Siglent SHS810 100MHz 1GS/s portable oscilloscope and multimeter. The instrument’s multimeter inputs are functional, however the neither of the oscilloscope inputs display the correct waveform. The displayed […]

Teardown and repair of an Agilent E4433B ESG-D synthesized signal generator

Teardown and repair of an Agilent E4433B ESG-D synthesized signal generator: In this episode Shahriar repairs an Agilent E4433B ESG-D Synthesized Signal Generator. This 4GHz unit shows the “UNLEVEL” error for all frequencies and at all output power levels. After a close look at the system block diagram the fault is traced to the main […]

Reviving 80’s arcade, Super invaders

Stian did restoration of 80’s arcade. He wrote a post on his blog detailing the process: I did a visual inspection the board looking for shorts or burned out components, and replaced a few 100nF ceramic capacitors that literally had cracked and/or fallen off. I then examined the on-board power supply. It consists of four voltage regulators, […]