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Re: [xl7] Re: Replace PSU power supply in Command Station

2012-05-14 by Nathan Steele

RE: the front and rear power switches. The PSU is a switching type supply, the front power switch is a "soft" switch, when the unit is powered down via this switch the supply is in standby, which is not off, which means the supply is still somewhat stressed. The rear switch is a "hard" switch, it phsically interupts the AC power on the way to the supply, the supply is completely off, no stress, no heat. It could be argued that one way is better than the other, switching on from a hard off will cause some inrush current which is the most stressfull...VS leaving it in standby, generating heat.....I'd say if you are only turning it off a short time like an hour or two, either leave it on or put it in standby... long time, turn it off.

Me, my whole studio is on a master power switch so everything is "Hard Off".

Matt: Did they replace any capacitors when they repaired your supply or just the chip and resistor?

On 5/13/2012 5:00 PM, retroillumination wrote:


Glad to help! The one that was repaired is working just great, it gets switched on and off every day using the front panel switch and the rear switch is just left on 100% of the time now. The other XL-7 that hasn't had a repair yet, that still works fine too, but I just leave that fully powered on most of the time now.

So what happens when you use the soft button to power on/off?

Cheers,
Matt

--- In xl7@yahoogroups.com, "ackack1020" wrote:
>
> Hey thanks! That's great info, and much better and more detailed than I expected even. I'm no electronics wiz either, but that should be enough for someone who knows their stuff to have a starting point.
>
> Mine seems to do fine with powering on-off with a surge protector (hard power off), but only has issues when I turn it off with the soft switch on the front panel and leave power fed to it...
>
> We'll see, at least it's repairable... how's yours since it was worked on?
>
> --- In xl7@yahoogroups.com, "retroillumination" wrote:
> >
> >
> > Hi,
> >
> > I'm not an expert when it comes to switching power supplies, so I'm just relating some information I gathered during the course of the repair. So I'm not exactly 100% sure about all the details but below are some of the things I picked up.
> >
> > Before I say anything else, I must wholeheartedly recommend a Mr. Lazaros Papazoglou of Olympus Electronics, Wirral, UK. He did a great job at a superb price, and he was fast, a total pro. He specializes in repairing power supplies of all types.
> >
> > info@
> >
> >
> > The resistor in this case is a large resistor R7. This had failed and was too discoloured to identify. This is 120KOhm. I am not exactly sure of the power rating of this one, although there is speculation that the one in the Powdec PSU is under specified and should be 5 or 7 watts, it certainly appears to diisipate quite a bit of heat.
> >
> > Luckily we had another, working XL-7, so I could have a look at the PSU in that. In the working XL-7, that resistor R7 is again, very discoloured. Like it's had a good roasting. So no doubt, that will fail sooner or later too.
> >
> > The controller chip in question, as far as I know, is the PWM controller, which is a UC3842. This is a current part and can still be obtained easily, so I am told. I can't be more specific on that, I don't know exactly where that chip is or whether it is surface-mount or not. You are welcome to get in touch and send me some pics of the PSU and i'll have a look.
> >
> > It is said that that part of the circuit (PWM controller) is under greatest stress when you power on the machine. So I try to keep mine on 24/7 these days :) When the PSU fails in this way, all you notice is that it won't power on. It won't become intermittent, just stone dead :(
> >
> > Regarding the rear panel hard power switch, I can tell you that the machine described above, the one that failed, was always switched on using the rear panel switch so I don't know if that makes a big difference or not?
> >
> > Oh well, at least they can be fixed :)
> >
> > Cheers,
> > Matt
> >
> > --- In xl7@yahoogroups.com, "ackack1020" wrote:
> > >
> > > Please elaborate on the resistor and controller chip. I'm always scared of the PSU going out, and I'm sure this info would help a good amount of other CS users...
> > >
> > > Also, I've said it before, but I'm finding that using the hard power switch (rather than the soft front panel one) keeps the unit working well. Actually, at this point, I just switch all my kit on/off with one surge protector.
> > >
> > > -Sack
> > >
> > > --- In xl7@yahoogroups.com, "retroillumination" wrote:
> > > >
> > > > Hi,
> > > >
> > > > Some time ago I was looking for a replacement. Powdec say that the Command Station PSU was a one-off design made to Emu's specifications. That probably explains why there aren't many around now.
> > > >
> > > > That's not to say that another PSU could not be made to work in its place. If it has the correct voltages present, and can supply enough current at those voltages, and do all that without having to dissipate too much heat, there's no reason why it shouldn't work.
> > > >
> > > > But in the end it turned out that the old PSU had a fault which could be fixed relatively easily and cheaply, by replacing a dead resitor and a controller chip. Do you still have the old PSU?
> > > >
> > > >
> > > > --- In xl7@yahoogroups.com, "intrepidpete" wrote:
> > > > >
> > > > > Anyone replace the PSU power supply in a Command Station or Proteus 2500 in the last couple of years? If so, where did you order the PSU?
> > > > >
> > > > > I can find the old powdec/powergatellc/powersupplyemporium PTE43-XX-C 10-pin 43-watt PSU in cage listed here: http://www.powdec.com.tw/pages/pte43.htm
> > > > > but there does not appear to be any way to actually order one. Part not made any longer? No other supplier?
> > > > >
> > > >
> > >
> >
>

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