Roland TR-77 power supply upgrade

[Big Chris]

Hi folks!

I read about the TR-77 power supply upgrades, and decided to attempt it myself. I bought the same internal power supply from eBay, and set about installing it using the original two core fixed power lead in the TR-77. However, when I powered the machine up the internal fuse blew. Annoying, as it's soldered into the TR-77. I decided to do a proper job at this point, so I removed the fixed power lead and used the hole in the case for a panel mounted fuse holder. I then used the slot left from removing the redundant voltage selector as a starting point to cut a hole for an IEC socket. I soldered everything together, and happily the TR-77 fired up again - but only temporarily. The 500mA fuse blew again when I switched the mains on from the wall socket this morning. I put a 630mA fuse in, and then repeatedly switched the mains on and off. It hasn't blown again, so it looks like the 500mA fuse was only just sufficient with the upgraded power supply.