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FBC-7 Eliminator


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May 7, 2013
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This is the original thread.

I decided to start a new thread because the scope of the mod has exceeded the duplication of the AMC-4.

Heres what the FR-7 after the mod:

<ATTACHMENT filename=FR7Mod_01.jpg index=0>

You can see (from left): MIDI out, MIDI in, 24VDC jack, and (2) charging jacks. I need 2 jacks for charging because there are 3 wires: positive, negative, and temperature sensor. I have considered other connectors (e.g. 1/4 stereo connector) but finally decided on using 2 power jacks. The two charging jacks, besides being color coded, are of different sizes to eliminate the chance of reverse polarity. Initially I didnt plan to add the MIDI in connector, but adding it didnt really take much additional time, I did it anyway.

Heres the accordion with the 24VDC adapter. It is a used copy of the Canon CA-CP200 (24V, 2.2A), abundantly available from eBay for about $10. During testing the FR-7 with a bench power supply, I found supply current rarely exceed 0.4A and never go above 0.5A. The Canon adapter, rated at 2.2A, is more than sufficient.

(Note that the plug of the Canon adapter is positive-center. But I made a mistake in the harness and decided that it was simpler to fix that mistake by reversing the plug of the adapter).

<ATTACHMENT filename=FR7Mod_02.jpg index=1>

For charger, I decided on the Tenergy 12-24V 0.5A charger. It will take a long time to fully charge the Roland 4.5Ah battery pack. But I normally charge the battery when its low (not necessarily exhausted), and leave it charged overnight anyway. The battery can be charged inside (with the adapter cable) and also outside of the accordion (plugged directly to the charger).

<ATTACHMENT filename=FR7Mod_03.jpg index=2>

Heres what the battery compartment looks like. The harness electrically sits between the battery and the accordion. Physically, except for the connectors visible in the battery compartment, the harness resides inside the accordion. The additional connectors make the battery compartment very crowded and thus closing the battery cover is a bit fussy. But I dont expect to mess around with the battery cover very often.

<ATTACHMENT filename=FR7Mod_04.jpg index=3>

I havent been able to eliminate the FCB-7 yet. But I think I can from now on leave it home most of the time.


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Been here for ages!
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Feb 16, 2016
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Montreal, Quebec, Canada
Good job on figuring things out and implementing this solution! I especially like that you chose a slow charger. Though recharge times will be slower, the benefit is a more complete charge and your batteries will last a lot longer thanks to not overheating (cooking) them. I also believe that the charger that you chose is an intelligent one, meaning once the full charge is reached, the charge current is reduced oe eliminated.

Well done! :)


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May 7, 2013
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Thanks, Jerry.

You're correct. I chose the Tenergy for its slow charging. I think that's better for the battery pack. Besides, if I need fast charging, there's always be the Roland FBC-7 :p Besides monitoring the temperature and the voltage to stop charging when the battery is full or when the temperature rises above 60 (or 65?) degrees, the Tenergy also has a 15 hr timer. It will turn off after 15 hours no matter what.

I forgot to state in the original post that when the charger or the power adapter is plugged in, the battery is isolated from the accordion. In other words, when the charger and the power adapter and the battery are plugged in:

- only the power adapter provides power to the accordion.
- the battery is charged by the charger.
- the battery and the charger are isolated from the accordion and from the power adapter.


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Feb 10, 2014
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What a superb mod job for the FR7 and 7x! In my case, I had a midi output installed in my 7x by a local Roland certified technician. How handy the midi output is as I use a wirless MIDI system and a Bluetooth midi system. I would really like the ac adapter to power the 7x and the charging system.


Very good job, and thank you to share it !
I want to do the same mod on my "old-new" Fr7b
Please, how do you connect the Tenergy T° sensor with the Roland battery connector (and the 3nd pin) ? I'm not sure to understand
Best regards
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