I got this Fluke 8030A digital multimeter for cheap. I'm sharing some pictures because there doesn't seem to be a lot of info online about this meter.
It was sold as non working because it didn't display any readings correctly and the battery didn't last long. Also it didn't had a power adapter. Since the displays seemed to work I took the chance and bought it, thinking the repair wouldn't be too difficult, I could always modify a power adapter for the multimeter.
As soon as I got it, I took the battery pack out and saw 4 1800MaH NiCad C cells from the late 70s, two of them didn't hold any charge and the other two were completely dead. I hooked 4 AA NiMh batteries to the battery pack terminals and the meter worked fine, so I just had to replace the cells.
Here i stumbled into some issues. The first one was to find the best replacement for the batteries, the local electronics shops didn't had any rechargeable C cells, and the AA cells with an equivalent power density were as expensive as the meter itself (also I would have had to order plastic adapters online or make some myself). If i wanted to use rechargeable C cells I would have had to order them online.
The other issue was the power supply. I could not find the correct adapter for the power jack, and because the power input for the batteries and the circuit were shared I would have to make sure to use the correct voltage and current for the circuit.
The schematics showed the power input of the meter as +5v, so I thought the best and cheapest replacement would be a USB power bank. The lithium cell could fit in one half of the battery pack and the electronics in the other. The only issue was charging, since the input and output ports on these power banks are separated, and the 8030 power input and battery output share the same line.
So I bought a $3 power bank from the supermarket, tore it apart and put it in the multimeter battery pack. I solved the separate power input issue by passing a couple of thin wires through the hole of a broken tab of the battery pack up to the case hole for the power input jack.
I attached a couple of pictures of the meter. SOme more pictures of the meter, and of the hacky battery pack mod, can be found in this Imgur album:
https://imgur.com/a/d3hkNVa.