Mackie SRM1801

[Enzo]

I don't recall a loading necessity. Seems to me they will run naked. I could be wrong.


Pull that shorted rectifier, load disconected, and see if the SMPS will fire up without it. In general, I find shorted rectifiers on the secondary to be fairly common as SMPS failures go. And they don;t seem to do much collateral damage. One way or another, that diode will have to be replaced, so why not see if that is all it needs.

And of course, check the power amp for shorts.

[Brian Swatton]

Thanks Enzo, I was planning to try and replace the diode first and fire up alone, but haven't found specs for it yet. Yes, as long as primary side power limiting is effective then rectifier failure often isn't too disastrous.

I did want to have a look on the rail to the other boards in case something else has caused this, I thought it might be quicker to identify it with a circuit than trying to trace the board.

I've been on something else while waiting on Mackie, but I'll probably try what you suggest in a little while, assuming the current job is done and dusted before packing up time, nearly done.

I have been over the rest of the PS and amp for shorts btw, no signs.

[Brian Swatton]

try
techmail@mackie.com for schematics
they seem to be getting easier to deal with lately IMO.

They certainly are, I've just got drawings from them. I'll have a peruse this evening and crack on with that in the morning. It's later than I thought.

[Brian Swatton]

Just realised I forgot to update the thread.

Replaced D24, which was for the -15v, and all was well. I confirm the supply board can be powered up alone too.

[clintronics]

anyone ever get a list of voltages for the TPs? I'd love to know the voltage on TP42 and is that using TP47 as ground?

[rf7]

I'm seeing +15Vdc on TP42 and TP43, on a unit that is not working. That seems reasonable as C50 is only a 25V cap.

Yes, you can use TP47 as a ground. Or TP6, which is easy to clip onto.