Hi Bri, I can't find my notes on this, I had a quick look at the manual and D809 & D811 spring to mind. I emailed the manual to you last night, I hope I was successful. I found 4 diodes faulty as I said on the last one I did. I think they all stood together behind the STR. I found it easier to check them with the STR removed. My memory was never great and it is a couple of years since I saw one of these. Norman.