mar. 19 avril 2016

Tektronics 2445 scope PSU repair: part 3

After having mostly destroyed the PSU of my Tek 2445, I've decided to be a bit less foolhardy and I've subscribed to the yahoo Tek group. I discovered that such a failure has already been reported there, also after a full recap of the preregulator and regulator of the power …

dim. 17 avril 2016

Lambda LPD 422 FM Bench PSU

This post is a quick presentation and teardown of a small bench power supply I bought on ebay a few weeks ago for something like 40€.

The Lambda LPD 422 FM dual regulated power supply.

It's an old unit, not sure it's exact age, but the components inside the unit seem to have date codes around 1971/1972. So …

sam. 16 avril 2016

ZPB30A1 Electronic Load

A few weeks ago, I purchased a cheap electronic load from AliExpress (this one to be precise). It's a ZHIYU model ZPB30A1. It's specifications are:

  • constant current mode
  • max voltage: 30V
  • discharge current: 0.2A to 9.99A (+/- 0.7% + 1 digit)
  • max dissipated power: 60W
  • voltage measurement error: 1 …

dim. 27 mars 2016

Tektronics 2445 scope PSU repair: part 2

After a quick repair of the PSU of my Tek 2445, I've started a more systematic replacement of the capacitors.

Tek2445 PSU Caps being replaced.

But I was also a bit worried because of a dirty noise coming from the preregulator area.

After having replaced most of the electrolytic capacitors, the dirty noise became louder …

sam. 19 mars 2016

Building a bench 10MHz reference: part 2

This is a quick follow-up of the first part of this series.

I've received a few parts from digikey, including a couple of 22µH Sumida CLS62 inductors (I bought two of them in case I f**k up one of them trying to solder it with my Weller WS50 iron …

sam. 12 mars 2016

Quick overview of the HP5334A Universal Counter

The HP5334A is a decent universal counter. It has a two 100MHz channels. Some models come with an optional third channel (1.3GHz), an optinal DVM, and an optional oven controlled oscillator. Unfortunately, my meter has no option at all.

My HP5334A Universal Counter

There is a nice quick instruction set printed on the …

jeu. 10 mars 2016

HP8904A Multifunction Synthetizer Repair: 10MHz output

After having fixed the PSU of one of my HP8904A signal generator, I discovered that the other unit had its 10MHz reference output dead flat.

I've disassembled the main logic board, but unfortunately, the schematic of this later A2 board (as it is referenced in the servce manual) is notavailable …

jeu. 10 mars 2016

HP8904A Multifunction Synthetizer Restoration

What Is This About

I have a couple of HP8904A multifunction synthetizers for years (bought them on ebay around 2007 IIRC). One of them is working properly, but the second one had very inaccurate output levels, generating a non-symmetric signal when output level was set above 5V or something like …

jeu. 10 mars 2016

Building a bench 10MHz reference: part 1

Many electronics test equipment need an accurate time base. Most often, it's build on a 10MHz base.

For quite a while now, I have a used rubidium frequency and time reference (Efratom Model LPRO-101) waiting for a nice enclosure. I also have a small Extron Electronics video signal amplifier I …

jeu. 10 mars 2016

Tektronics 2445 scope PSU repair: part 1

I've recently took my good old Tek 2445 scope from the cellar (along with my {tag}HP8904A signal generator), and it showed signs of tired PSU: unstable display, noise, then the typical noise of a capacitor failure.

Here is the beast:

My old Tektronics 2445 scope

And some pictures of its womb:

The main analog board. Top view of the scope.

The PSU consists …

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