Date   : Fri, 21 Nov 2003 20:57:24 -0000
From   : Andrew Hancock <Andrew.Hancock@...>
Subject: Duff Power Supply Fixed! SUCCESS!

 
Hi All

Just wanted to thank members of the list for help and advice in fixing this
power supply, which was duff in my Beeb.

To summarise, power supply was outputting all the correct voltages, when
disconnected from the BBC, but under load, connected to the BBC the voltages
fell to 1 - 2 volts.

Many people commented, it was the chopping transistor BU208A, I replaced
this with a BU208D - WRONG - (because my electronic engineer friend told me
this was an up rated version of the BU208A - WRONG), but after fitting I got
ZERO supply voltage.

Maplins only stock a BU208D, but I finally managed to order a BU208A from RS
(also available from CPC and Farnell).

I've replaced it today, and the BBC power supply is working well again. I
also took the trouble to replace the capacitors as suggested for high
temperature caps.

Thanks to Sprow, Jules Richardson, Mike Tomlinson, Pete Turnbull, Michael
Foot, and if you are not mentioned by name, thanks also!

Regards

Andrew