Author Topic: Dead Pianet N  (Read 259 times)

Offline theseacowexists

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Dead Pianet N
« on: July 23, 2018, 03:24:12 PM »
Since it had worked wonders on removing the remaining background noise on my Cembalet N, I decided to replace all the resistors on my Pianet N (version II).  I recapped the Pianet when I got it a few months back, but it seemed that the hiss and static was increasing a bit, so I thought I'd be able to take care of it by replacing the reistors.  Well, I plugged it after replacing the resistors to be greeted with a loud hum.  Shut it off, removed the lid, and smelled a distinct burning smell...but no sign of anything burnt.  The only problem seemed to be that the ground pin on the volume pedal socket broke off.  Reconnected that again, turned it on again, this time with the lid off.  Everything working fine.  Replaced the lid.  The hum was back, so I figured that the lid must be shorting something out.  The only thing that looked like it would be touching the lid was the metal case of one of the transistors.  Moved that out of the way, replaced the lid, everything worked fine again.

...Except the vibrato depth was weak.  So I went back in to tweak the vibrato depth level, and as I adjusted it one way, the bulb started to slowly dim out, and the power for the entire Pianet shut off too.  The fuse blew - easily replaced, as I had a direct replacement lying around.  Turned it on again, played well for about 10 seconds, and the bulb began to dim out as the sound faded out to be replaced by a hum.  Shut it off and turned it back on again two more times, same thing.  Although the third time I took the bulb out to see if that would change anything - it didn't.  The fourth time I powered it back up, I got nothing at all. 

After letting it sit for a few minutes, I tried it again.  This time it worked for about a minute before fading out, fading back in, and ultimately fading completely out again.  The unit is still getting power, because the mains light stays on even after the sound disappears.

Any ideas what I should be looking for to bring it back to life?  I guess the moral of today's story is to just deal with the hiss... :-[

Offline theseacowexists

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Re: Dead Pianet N
« Reply #1 on: July 25, 2018, 07:06:34 AM »
I ended up bringing it over to our local amp genius, and he found two things that likely caused the problem.  First, the bridge rectifier was what had smoked.  He replaced that, then found a broken trace on the board between the photocell and the transistor before it.  Once those were fixed, it was up and running again!  Best part now is that the volume level doesn't drop when the vibrato is switched on, like it did before.

One small (unrelated) problem remains though.  Has anybody every attempted to re-magnetize a reed?  There's one note that is still super quiet after ruling out all mechanical causes.

Offline conke

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Re: Dead Pianet N
« Reply #2 on: July 25, 2018, 10:34:10 AM »
Sick man. You should post some vids of those N models.

I have remagnetized reeds before. You sweep in one direction with a little (but strong) magnet a bunch of times. If it gets worse instead of better, then sweep the other way. I removed my reeds before doing this so I could have better control and not mess with neighboring reeds.

Edit: It just occured to me that the Pianet N is electrostatic, in which case the magnetism shouldn't matter(?)
« Last Edit: July 25, 2018, 10:38:45 AM by conke »
Hohner Pianet T
1977 Rhodes Mk I

Offline theseacowexists

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Re: Dead Pianet N
« Reply #3 on: July 25, 2018, 11:02:02 AM »
It just occured to me that the Pianet N is electrostatic, in which case the magnetism shouldn't matter(?)

That's what I figured too...but according to a former Hohner tech who used to post on the clavinet.com message board, the N reeds were magnetized.  He says something about it in this post: https://www.tapatalk.com/groups/clavinetdotcommessageboard39332/viewtopic.php?f=3&t=917&p=3019&hilit=magnetize#p3019

Even Aaron who runs clavinet.com recommended re-magnetizing the reed.  So there must be something to it. 

What I don't understand is how my cleaning the reed with a wooden-stick cotton swab would suddenly cause the reed to lose it's magnetism, because the note was fine before I did this.  Last I checked, wood and cotton weren't magnetic!  Stranger things have happened I guess...

I have a gig with it this weekend, so I'll wait to mess with it until after the gig.  I'll let you know how it goes.  I'm skeptical about unscrewing the reed too, as I heard those screws are prone to break.  But maybe a squirt of liquid wrench on the screw might help it come out easily.

Offline conke

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Re: Dead Pianet N
« Reply #4 on: July 30, 2018, 05:06:40 PM »
Hey how'd your gig go? And any luck fixing that bum note?
Hohner Pianet T
1977 Rhodes Mk I

Offline theseacowexists

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Re: Dead Pianet N
« Reply #5 on: July 30, 2018, 09:04:46 PM »
The gig went pretty well, I even brought the Hohner Symphonic organ out too!  Never paired those two before, but it worked.

I never got around to reopening the Pianet to mess around with the reed.  Here's the funny thing - I brought the Pianet to the rehearsal on Wednesday, and it seemed like the note (middle G FWIW) was back to normal.  Compared it against the neighboring notes, and it didn't notice any difference in volume.  And it's been fine since!  Wasn't an issue at the gig, and I've been playing it at home with no problems. I can't explain what happened, but I'll take it.  Any anyway, I now have a nice set of small strong magnets (thanks Amazon) in case I do need to re-magnetize any reeds in the future, either on my N or my T.

Offline conke

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Re: Dead Pianet N
« Reply #6 on: July 31, 2018, 03:30:48 PM »
Haha, awesome. Amazon always delivers.
Hohner Pianet T
1977 Rhodes Mk I