HELP.. no treble! Ideas welcomed!

I have a problem… I wonder if anybody can offer any advice?

I have a 500 active system… two 500 amps, a 552 preamp, SNaxo 242 crossover, CD555, ND555, LP12, NAT05, with appropriate Supercaps etc, into a pair of SL2s

All was brilliant until we had a recent power cut. On going to my music room to check everything, a number of my boxes were dead. I found that the fuse in the wall plug had failed. Changed that and everything came back on. I left it to warm up again, and then found I had nothing from the tweeters, whatever source I used. Mid/bass cones are fine.

I took out the tweeters to test, thinking they might have blown when the power cut was over, and connected each one up in turn to a small radio. Plenty of sound… just nothing when they are in the HiFi. I opened up the SNaxo, thinking there might be a blown fuse on the treble side, but no fuses in there to fail.

I am utterly mystified. Something in the preamp? Can’t see that the power amps or Supercaps would have a bearing on this.

Any ideas Guys?

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Which boxes had the mains lead fuse blown? SNAXO?

@Richard.Dane may be able to offer advise here. :slightly_smiling_face:

I guess you are using one NAP500 to drive both treble units and the other to drive both mid/bass units. If so, it sounds to me like the NAP500 that drives the treble units isn’t working. You might want to look at the equipment fuse for that NAP500 PS.

Also while it’s off I would unplug and replug in the burndy lead between the Supercap and the SNAXO, just to clean the contacts. Also I assume the Supercap equipment fuse is OK? These equipment fuses are next to the power lead on the back of the relevant unit and if you prize the holder out to see the fuse, there should be another of the right value which you get by pulling the fuseholder out a bit further.

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The blown fuse was in the plug at the wall socket. This lead goes to the first of three WireWorld extension bars. They were all okay.

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Yes but why did it blow? Maybe you have an equipment fuse gone too.

To add to David’s post, if you get no joy with his recommendation then go back to passive (provided you have the PAXOs) and from there try each amp, then reintroduce the SNAXo and PSU to try to narrow down the issue.

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Many thanks for your replies. I’ll have a go at all this tomorrow. Yes, I do have the PAXOs. Just to clarify… I’m assuming that if a box lights up, it should be working, or am I being naive here?

Should, yes, but may be not working fully.

@mjkent just to add to the other posts.
Active user myself - one further suggestion.

Before you follow the tips suggested, might I suggest, if you haven’t already, label absolutely every cable; all of them.

It makes troubleshooting on multiple boxes that much easier.

Roll of sticky labels is useful and label carefully - so when you try to read it sometime later…(been there!) That will enable you to swap around cables where you can, keeping a table so that you try every combo.

You suggested you have supercaps - plural. One will be on snaxo, if you also have one for phono (superline most likely), then try a swap, recording the serial nos, so you know which is which, or again label. As you know the signal goes via the s-cap, so if cables don’t reveal the issue, the snaxo s-cap would be worth checking.

Many thanks for all your suggestions. Re labelling the cables… absolutely… with a million black boxes and cables I made sure every one is labelled so that I know where it goes. However, in haste, and because I have to connect up while looking over the top of the kit, I suspect I may have connected a couple of cables up wrongly when I dismantled after the power cut.
Anyway, a sigh of relief, thankfully the problem now sorted.


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