Author Topic: Passive Electronics Fix  (Read 343 times)

Offline jack_givdog

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Passive Electronics Fix
« on: October 08, 2019, 04:07:15 AM »
Hello again,

I was hoping someone would be able to shed some light on why my passive electronics seem to not be working in my 77' stage.

When I first had my rhodes the soldering was shoddy and the connection was faulty. The rhodes hadn't been properly played in years so the more I played it the worse it got.
I was going to buy a new passive electronics part just for something more reliable, but they are out of stock in the UK vendor. My short term fix (learnt on this forum!) was to replace the female RCA at the top left of the harp with the 1/4 jack port from the front of the piano and get a direct output from the harp. This worked! (Strangely enough only after prodding a couple of pickups with a screwdriver when testing for dead ones).

I was going to let whoever was going to service my rhodes fix the electronics, but having recently decided to do all restoring myself this is kind of the first thing I would like to get sorted just so I don't have to worry about it anymore.

https://imgur.com/a/n9SlIfO

This is where I am up to: After resoldering and wiring the passive electronics to exactly how they were when they were in working order I still can't get any output. I am using a new RCA as the original one seemed in very bad condition... maybe that is the issue? But I have used a couple of different RCAs and still nothing. In the pics I have attached with a link I am using new electrical wire (could actually be incorrect wire?) but I have set it up in the same way with the original wires and it didn't work then either. I know the issue doesn't exist on the harp as the direct from harp output worked. Please excuse my shoddy soldering I am new to this!

I was hoping it would be possible to diagnose the issue just by looking at some pics. There is also a pic of the original wiring back when it was all in working order (albeit a little unreliable (the pic with the orange jack in it)). Maybe it is something really obvious. Maybe it is the RCA port... but it was working fine back when I first had the rhodes a few months ago and at that point it seemed like the wiring that was the issue. Maybe it is my soldering. I have surfed through the forum in search for an answer but there is nothing that could specifically help me so any advice is greatly appreciated.

Thanks all,
Jack

Offline Tim Hodges

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Re: Passive Electronics Fix
« Reply #1 on: October 08, 2019, 06:14:40 AM »
Can you upload a photo on imgur showing it directly from the back? Slightly difficult to tell.

This thread is particularily useful, look at the first two images created by Sean.

https://ep-forum.com/smf/index.php?topic=9793.0
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Offline jack_givdog

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Re: Passive Electronics Fix
« Reply #2 on: October 08, 2019, 07:09:34 AM »
Thanks for your response. I think the second photo in the imgur should show the current setup from the back (I have rearranged them now so it is the first photo). Sorry if I am misunderstanding you!

I am very familiar with that thread, I referenced it a lot whilst trying my fixes.

Offline Tim Hodges

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Re: Passive Electronics Fix
« Reply #3 on: October 08, 2019, 07:34:27 AM »
Is that orange lead spanning the end and middle terminal on the bass boost? (It's hidden by the cap)
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Offline jack_givdog

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Re: Passive Electronics Fix
« Reply #4 on: October 08, 2019, 07:38:00 AM »
Yes it is.

Offline Tim Hodges

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Re: Passive Electronics Fix
« Reply #5 on: October 09, 2019, 03:36:10 PM »
If you want Jack I have a spare original stage preamp you can have for £25 inc postage.

If you do I’ll give it a once over and clean the pots and re-solder it to be safe.
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Offline sean

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Re: Passive Electronics Fix
« Reply #6 on: October 09, 2019, 05:39:29 PM »


Is the terminal on the volume pot that is soldered to the orange wire touching the back of the name rail?  That would kill it.
Similarly, is the uninsulated part of the green and yellow wire touching the name rail?

Also, there is a chance that your energetic soldering job on the volume pot ruined the pot.  You can check this by simply turning the pot to somewhere in the middle position (well away from the zero volume setting), and then using an aligator clip or pair of pliers to short the middle terminal to the terminal with the orange wire.  If this brings the piano alive, then the volume pot is fried.

This is how you have it wired right now:

Right?

Sean

Offline jack_givdog

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Re: Passive Electronics Fix
« Reply #7 on: October 10, 2019, 07:06:54 AM »
Thanks both for your messages.

Whilst I am tempted to take you up on your offer Tim I have actually fixed it for the moment and it seems to be pretty solid. I think it may have been the first thing you mentioned Sean, I had another go and it worked this time. Strong connections.

Thanks again for both of your time!

Jack

Offline Tim Hodges

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Re: Passive Electronics Fix
« Reply #8 on: October 10, 2019, 07:33:24 AM »
No worries Jack, glad to hear you got it fixed.
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