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

GW Instek

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 heard inside the instrument during power on.
Teardown of the unit reveals a modular design with PCBs on all sides. The instrument comprises 6 different modules and 3 complete power supplies in parallel. The controller circuit is powered from the middle power supply module. Examination of the boards reveals three separate failed devices.

More details on The Signal Path site.

Check out the video after the break.

HP 8566B Spectrum Analyzer “YTO unlock” repair

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Kerry Wong did a repair of an HP 8566B Spectrum Analyzer “YTO unlock” and documented the repair process on his blog:

While I was making a video on how to use HP 8671A as the frequency reference for an improved version of my simple DIY tracking generator for my HP 8566B spectrum analyzer, my spectrum analyzer suddenly decided to call it quits and displayed the dreaded “YTO Unlock” message. Although it wasn’t the first time it had done so — other times the “YTO Unlock” message only appeared once in a blue moon and rarely affected any measurements — this time however the problem seemed to be permanent and the error message wouldn’t go away.

Check out the video after the break.

HP 8620C sweep generator repaired

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Kerry Wong did a repair of an HP 8620C sweep generator we covered previously:

In my previous post, I did a teardown of an HP 8620C sweep generator along with an HP 86245A 5.9 GHz to 12.4 GHz RF plugin. A few of the plguin boards in the 8620C had leaked capacitors and also there seemed to be some sort of mechanical issue as no power was delivered to the transformer regardless of the power switch positions. So what I planed to do next was to restore the power to the unit and replace those bad capacitors and see if I could bring this sweep generator back to life.

See the full post on his blog here.

Check out the video after the break.

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

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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 it powered on and there was no sign of life whatsoever. So before I start troubleshooting and repairing the unit, I thought I would do a quick teardown to see what’s inside and if I could spot anything obvious that was out of the ordinary.

More details on his blog here.

Check out the video after the break.

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

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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 through the mechanism. The reader has a small amount of logic, but instead of transistorized circuits, the logic is implemented with electromechanical relays.1 Timing signals are generated by spinning electromechanical cams that generate pulses at the proper rotation angles. This post explains how these different pieces work together, and how a subtle timing problem caused the card reader to fail.

See the full post on his blog.

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

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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. To fix this we had to delve into the depths of the computer’s core memory circuitry and the power supplies.

See the full post on his blog.

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer from The Signal Path:

In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.

More details at The Signal Path homepage.

Yaesu FT-1000D receiver repair

Alan Wolke (a.k.a W2AEW) writes,  “A local ham radio friend dropped off his Yaesu FT-1000D transceiver for me to take a look at. He said that the receiver was “dead”. This video documents my debug process and the repair and final check out.”

 

Teardown and repair of an Agilent E3632A DC power supply

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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 is applied to the unit after the fuse replacement. It is clear that a short is present somewhere in the instrument since even at 10V AC the instrument consumes more than 1A.

See the full post at thesignalpath.com.

Check out the video after the break.

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

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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 module is a module components and upon measurements shows no activity.
The power supply is a simple switching architecture with functioning input rectifier and capacitor filter. By using an oscilloscope it is clear that the power supply PWM controller attempts to start. However, the main power supply pin shows unstable voltages indicating inadequate charge retention on the rectifying capacitor. Replacing the capacitor revives the startup condition and the power supply function returns. The PWM controller and main switching transistors are also replaced with new ones. After this repair the unit powers on and passes all self-tests. The unit can successfully measure signal frequencies and power.

More details at The Signal Path.

Check out the video after the break.