So, one of my Tannoy Reveal 502 speakers kept blowing its T500mA fuse. I purchased some replacements, tried a new one, and pop. Something was obviously wrong.
The cabinet was a bit awkward to open, but I needed to get in there and have a look. The outer screws removed I poked something soft(ish) through the front port and ‘persuaded’ the back panel to come loose.
After a quick visual inspection I noticed that C11, a 100nF decoupling? capacitor, looked very hot and burnt. I did a quick check at this point and sure enough there was a short somewhere on the +ve and -ve rails.
Out with the soldering iron, I removed C11 and C6. C11 disintegrated as it was being de-soldered, and was obviously defective. I also removed the two 3300uF caps and gave them a quick test, they seemed fine. With those two re-soldered as they were ok, I replaced C11 and C6 with some 104’s (100nF) ceramics, and ran some tests with a new fuse in place. All seemed to working fine, sounding great. I left C6 and C11 on long legs to move them into some free air to try and reduce the chance of over heating. The yellow ‘hot snot glue’ was a nightmare to remove and was more like epoxy.
I must say, the ‘psu’ board did not seem to be of high quality. It looked as if it had been put together on a Friday afternoon, caps at all sorts of angles, rectifier twisted, just shoddy workmanship. I didn’t remove the amplifier/filter board so I can’t comment on that.
Anyway, a simple fix and I once again have a right speaker ! Happy days.