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.
How did you gain access to the board, it seems like the back panel is glued to the cabinet?
Hi Bob,
I pushed something through the vent port at the bottom. There is nothing in the way, and you can push the back off (after removing rear screws).
Cheers, Richie.
Would moving the caps into air actually help with heat issues especially in longterm?