I bought a Höcherl & Hackl PL506 DC electronic load just recently. It’s a nice piece of equipment to test switch-mode power supplies (SMPS) or any DC power sources like solar modules or batteries. I will need few of those for Tektronix SMPS repairs. As far as I can tell, DC electronic loads are rather rare and expensive units. So I grabbed one on an auction site for a very decent price compared to current offers (which is crazy, they ask 600…1000 EUR for such unit).
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_134814-700x394.jpg)
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_134959-700x394.jpg)
After unboxing and shaking the unit, I noticed a strange noise. Since it’s easter holidays here in Germany, I thought it was some kind of a “Kinder Surprise Egg” time!
But no, I was disappointed. No easter eggs 🙁 It was the fan which broke off. I looked for other damaged parts and defects but there were none. No signs of burned parts, bad electrolytic capacitors etc. Looking good inside!
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_140128-700x394.jpg)
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_135920-700x394.jpg)
The vibration isolators probably became brittle over the years and broke during the transport. The fan fell off and had to be reattached. The front panel buttons are a bit crusty, too and will need to see a maintenance one day. The heat sink could need a clean-up, too. Build-up of dust and dirt diminishes heat transfer and can cause either performance issues or overheating of power dissipating MOSFETs.
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_140332-700x394.jpg)
I was looking for a suitable replacement in my electronics parts bins but found nothing. I used zip ties to reattach the fan to the heat sink. The unit was fixed in less than 10 minutes.
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_145113-394x700.jpg)
A quick test with a random 13.8 V SMPS was successful. I was able to load 19.9 A at ~13.4 V which corresponds to ~267 W output power of the SMPS. This DC electronic load is capable of dissipating 500 W continuously or up to 900 W short-time. This was a short-time test with 4 mm banana cables since I didn’t have proper high-current cables at hand.
![](https://physik.co-i60.com/wp-content/uploads/2024/03/20240330_212442-700x394.jpg)
Very nice addition to the lab. Hope this will be useful for future repair and maintenance projects!