It’s my fault, I fiddled.
Radio was working fine, then I attempted to DIY a remote head cable as they can’t be purchased any more.
I left it for a couple of days, trying it again each morning, in the eternal hope that by some magic or via electrical fairy helpers, it would spontaneously start working again. I kept telling myself things like “Perhaps the capacitors need a little more time to fully drain. Yes. that’s why it hasn’t started working again.” For a hyper logical person like I am, it’s amazing the flights of fantasy we can summon in times of need. I even offered a little prayer, while all the time knowing that in the grand scheme of things, there were more worthwhile causes to which God’s attention could be better addressed.
Checking the schematic, there are no fuses in the head or protection diodes that I could see to check.
I did find one post on the net where some poor chap had the same issue after a dog ate through the extension cable, but he didn’t mention how or if he fixed it.
Well, after a degree of panic and stress, I managed to fix it with the help of the VKLogger community.
The culprit was R513 (check the service manual). This little sucker here:
It’s a 1Ω resistor. Not knowing it’s purpose, I asked and was filled in by Peter as follows:
“it would be a cheap way to fuse the line and by the look of it, it’s purpose was a success as it has sacrificed its life to possibly save the rest of the radio. having low ohm resistors in vulnerable rails (exposed to humans) has become a common way to provide protection that does not cause the tracks on a PCB to burn up. In years gone by it was common to have to repair a PCB track after an incident like you experienced but that is hard work and very messy and sometimes it was a terminal event for the radio.”
Well there you have it. I was lucky enough to have a 1Ω surface mount resistor in my box of tricks, so replaced it, and…
Before I close off this post, a word to the wise. I was going to just jumper the bad resistor with a piece of wire when I thought I didn’t have the correct resistor at hand, before I was offered this piece of advice…
…don’t put in a wire jumper unless you have a death wish
So I didn’t.
Thanks again to Adam, Barry, Dion and Peter.