[sdiy] Siel OR400 Transformer needed

ASSI Stromeko at nexgo.de
Sat Jul 27 12:56:45 CEST 2013

[sorry if you get this twice, mail client is acting up]

On Saturday 27 July 2013, 05:05:33, M Maeghan Skala wrote:
> The voltage readings I gave off were from the spare PSU board.

Thanks, that explains a lot.  So, the board is slightly dodgy from age or 
abuse, but it is likely that the IC are still functioning.

> I went to my local electronics store tonight and purchased some new
> components … frankly, i wouldn't mind building a whole new power supply.
> I got some LM317's and LM337's and some bridge rectifiers, since I didn't
> have any adjustable regulators in my inventory or any bridge rectifiers …
> i know off the top of my head the sill cruise uses lm317's, and LM337's to
> supply +12/-12, and +6/-6 VDC to the board … maybe I could copy that
> circuit????

That would probably work, but I'm not familiar with that circuit.

> this would be a quick and easy re-build if it wasn't for the µA79MG &
> µA78MG voltage regulators being 4-pin … can i make the current board work
> with  connecting some leads? or should i start drawing up a new PSU board
> to etch later today?

If you go for a new board, then maybe you can find one that you only need to 
wire the connectors for.  But given your spare board, I'd try to salvage it 
first: Check if the regulator IC are still functioning by putting a 100k 
resistor in parallel to each resistor Ra3..Ra10 (with small croco clamps or 
micro-hook clamps so that you have your hands free) and check that the 
respective output voltage changes by about 5% to 10%.  Do this first with no 
load and then load each output and do it again (the loaded voltage should 
only be slightly smaller).  If that works, simply get a new bridge rectifier 
(the schematics show a 80V/1A most likely, you can substitute a 2A model in 
the same package, but don't go for much higher voltage), the load caps 
(1000µF/35V or 50V axial, same size) and the filter caps (1µF/25V radial) 
plus all the resistors Ra3..Ra10 (as 1/2W metal film and better than 5% 
precision).  If you replace these you should then have a good as new PSU 
board.  Be careful when unsoldering the old parts and double check the 
poarities of the parts.

+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Wavetables for the Waldorf Blofeld:

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