So I started the repairs of the newly arrived PSUs with the apparently simplest of them (and easiest to repair), the Conrad PS-302A.
![](https://i.imgur.com/2vtGLJs.jpg)
A quick test showed that it was mostly working. However, the meter behaved erratically after mid scale. Also, the output did not reach 30 volts but maxed out around 28.
From behind, it was clear that the device had had some kind of incident involving mechanical stress ...
![](https://i.imgur.com/aRG44tj.jpg)
Maybe that incident was also causing damage to the meter?
Without the hood, a slight bending of the chassis could be seen, but there seemed to be no more damage. It could also be seen that this PSU couldn't qualify as a "laboratory" supply. I'd classify it as "hobbyist".
![](https://i.imgur.com/YtNqX8U.jpg)
Removed the meter, found it to need 1 mA full-scale and having a resistance of about 300 Ω.
40 years ago I built my own power supply (from the magazine "ELO"). I had bought meters also, but never used them. One of them had a 30 V scale and 30 kΩ resistance. Bingo! So I took it apart to get rid of the series drop resistor. This turned out to be a 30 kΩ/5 % affair. The meter claimed to be class 2, though. The remaining resistance was 100 Ω - that might cause some problems.
Here's the meter's box, still with price tag. Per chance it comes from the same company as the PSU.
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
![](https://i.imgur.com/CMgAEyy.jpg)
Both meters had the same size. While the original had a flat front face, the replacement (definitely the older one here) had a slightly konvex one. Alas, the frame was just a tad different, so the flat window would not snap onto it.
I decided to keep the original scale, which was glued on. Getting it off resulted in some bends and wiggles, which I straightened out as best as I could. Removing the nasty hardened glue required sanding. Then I had to cut off a few millimeters from the bottom and drill 2 holes before it could be fastened to the "new" meter.
![](https://i.imgur.com/3spjRh8.jpg)
The replacement does not fit exactly, but it was good enough for this device. Voltage readings were fine, but current was, as expected, way off. Twiddling with some of the trimmers, I was able to adjust the readings and also the max output voltage to the spec'd 30 volts.
![](https://i.imgur.com/OvbjRUs.jpg)
Gave it to a friend, who'll put in in his attic ... likely to never be used again.
![Tongue :P](https://www.eevblog.com/forum/Smileys/default/xtongue.gif.pagespeed.ic.J5mTe0A2NA.png)