"Gareth the Menace" ...

Here's a hi res picture of the opened module:

http://postimage.org/image/2qgigsn38/

What are those things?

** Here is the datasheet for the similar STK422-90.

http://datasheets.pl/S/STK/STK442-090.pdf

The 4 output devices are Darlington pairs and the SMD devices in the middle
of each pair are the bias stabilisers. The Darlingtons each have twin
emitter leads soldered to the PCB.

Looks an easy enough to copy the thing - just normal SMD board plus four
power chips on metal headers.

Older versions (made by Sanyo) had no SMD - but instead used transistor
chips and printed resistors directly on the board. They were known as
"hybrids" to distinguish them from regular ICs.

My local supplier ( WES Components) has the STK442-130 listed for A$22.50
each.

Littlediode in Surry offer them for 10 UK pounds + VAT.



..... Phil