[EchiDna]

well in over 5 years (I think) of AKSA ownership, my 100n+ has never missed a beat... until today when switching it on gave a drone of gawd awful noise from the speakers - I took it off the speakers and checked the DC across the speaker terminals - about 500mv on both channels, or about 3 times what it was when I built it...

any thoughts on why/how this could suddenly "appear"?? rectification proceedure?

thanks in advance,

EchiDna

[AKSA]

Glen,

Disconnect the power supply from the modules, and measure DC voltage on the filter caps.

I think you may have blown a diode on the rectifier bridges.

First things first..... then we will look at the modules.

Cheers,

Hugh

[EchiDna]

perhaps caused by a lightning strike? my building's earth is somewhere, somehow tied into the lightning protection system (don't ask, I dunno why either).

will be right back with an answer to your suggestion

[EchiDna]

ok Hugh, I've disconnected all three leads from each module and so far I've confirmed that I am getting about 37V ac out of the traffos and I get about 3 Vdc on one side and 8Vdc on the other (between the two output tabs on the power supply, not WRT earth)

[AKSA]

Glen,

I'm sorry to tell you that you've blown the power supply diodes.

You will need 6 x BYV32E, or equivalent.  Replace all of them for good measure, they are no longer expensive.

I can send you some of course, but you should be able to get some in the DIY stores of Singapore.

I'm sorry to hear this;  power spike maybe, this happened on some of the early supplies with the underrated diodes.  The ones quoted are 10A, not 5A like the BYQ28Es.

Hope this helps, let me know what you'd like to do,

Cheers,

Hugh

[EchiDna]

Thanks Hugh, pretty much as I surmised 

anyway, I should be able to pick up the offending items quickly enough to get the trusty 100n+ back up and running, so thanks for your offer, but no need for you to go to any extra effort at this point in time.

as always, you are quick, accurate and most helpful when needed!!

 

where is the latte's emoticon? lol!