HP 34970A Data Acquisition Unit - part 2
This is quick follow up of my previous blog post on my attempt to fix my recently acquired HP 34970A.
In my hurry to replace the failing FRAM (FM24C04) chips, I also replaced the FRAM chip on one of my 2 plugin modules.
Bad idea: the module then provoques an …
HP 34970A Data Acquisition Unit
I recently "scored" a HP 34970A with the DMM included and 2 plugin cards (HP 34901A and HP 34907A) for less than 200€. The plugins should be in working condition, but the main switch unit was almost "given" with the plugin modules since it is non functional.
It's in very …
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 …
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€.
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 …
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 …
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.
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 …
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 …
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.
There is a nice quick instruction set printed on the …
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 …
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 …