8Bit-Homecomputermuseum

Retrocomputer, Heimcomputer und Videospiele der 80er

Grundy NewBrain PSU repair (blown capacitor replace)...

If you need help repairing a Grundy NewBrain, feel free to contact me :-)
I received 2 Grundy NewBrain Power Supplies to repair.

On arrival both PSUs are "dead".

One has a blown Capacitor and the other has allready undergone a repair-try and the (also blown) capacitor has been removed.
I meassured the Inputvoltage on the one with the blown capacitor and it was "0V", after a little searching i found, that the fuse inside the powerplug had been removed...
Luckily i alway keep a few spare fuses...
Fuse inserted and cables newly cut / stripped and tinned.
Now i had to remove the blown capacitor. The process of removal is not very easy, because the capacitor is soldered on 3 points and its legs are twisted around the transformer pins.

So you need to "soldersuck", twist, pull, and wiggle until the capacitor is removed...
As it is impossible to find an exact replacement (the same case) i replaced it with this (it has the same electrical values, only another case).
After fitting it into the PSU case (rather tight)...
All the voltages are present!

=> 1. PSU working!
On the second PSU the thin wires connecting the transfomer had been left unsoldered...

I connected them, added the new capacitor and fitted everything back in its case.

=> 2. PSU working!

Autor: Thomas Gutmeier