Four-pin/five-pin halfbreed.

Started by vpalmer, May 20, 2004, 09:22:28 PM

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vpalmer

Hello,

I have a 1974 model suitcase Rhodes and am trying to order a replacement cable.  All parts on the keyboard are original.  I have a problem -- the jack on the amp is a four-pin, and the jack on the piano itself requires a five-pin female end.  The person I am trying to order the cable from told me this is not normal -- can anyone help?

-Vanessa

Anonymous

Hi :-)
The fact is that you can't connect a 4-pin Cabinet to a 5-pin Piano preamp. The 5-pin version has a different power supply concept. The 4-pin uses a single 24V supply, the 5-pin version uses a dual +/-15V supply. So sadly, your problem can only be solved by searching for a 4-pin Piano top.

regards, Jens :-)

vpalmer

I've been told that the 5-pin keyboard and 4-pin amp are "incompatible" by a number of different people.  Here's the weird part though: all of it was purchased as a set and works fine -- you can hear it in action at www.purevolume.com/ininkplease.  I have a cable with a five-pin jack on the keyboard end and a four-pin jack on the amp end -- so it is already functional.  The keyboard, amp, and connecting cable were purchased together at a music shop in Sidney, Montana in the mid-70s by my band director, who sold everything to me two years ago.  I have never had any problems with my current keyboard (abnormal though it may be); I just wanted a replacement cable for the road.  Is it possible I have the product of some kind of factory slip-up?  Ideas, anyone?

-Vanessa

Jenzz

Have you ever checked the innards of the Piano preamp?

Seems that somebody modded the circuit to make it work at single 24V supply...this can be done, although its a bit difficult.

regards, Jens
Rhodes tech in Germany
www.tasteundtechnik.de
www.spontaneousstorytelling.net

VintageVibe 64 ACL + DOD FX25B, Tone City Sweet Cream, EHX SmallStone, Mooer e-Lady

Adams Solist 3.1 Vibraphone

In the Past:
Stage 73 Mk1 (1977)
Stage 88 Mk1 (1975)
Stage 73 Mk2 (1980)
Stage 73 Mk2 (1981 - plastic)
Suitcase 73 Mk1 (1973)
Suitcase 73 Mk1 (1978)

vpalmer

I've only ever opened up the amp to solder some wires; never the keyboard.  What would I be looking for?

The person from whom I was originally trying to buy a cord makes them himself; maybe I'll just try a four-pin cable but with a five-pin jack on the tacked on the keyboard end.  One of the sockets won't be connected to anything in the cord, but it might work.  Suggestions?

Jenzz

Hi :-)

Look for a circuit like this:
http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/virtual.htm

This forms a virtual ground circuit with Vcc/2 being the ground terminal.

With this circuit, you can derive a +/-12 V supply out of the single 24V supply of the 4-Pin cabinet.

regards, Jens
Rhodes tech in Germany
www.tasteundtechnik.de
www.spontaneousstorytelling.net

VintageVibe 64 ACL + DOD FX25B, Tone City Sweet Cream, EHX SmallStone, Mooer e-Lady

Adams Solist 3.1 Vibraphone

In the Past:
Stage 73 Mk1 (1977)
Stage 88 Mk1 (1975)
Stage 73 Mk2 (1980)
Stage 73 Mk2 (1981 - plastic)
Suitcase 73 Mk1 (1973)
Suitcase 73 Mk1 (1978)

Jenzz

Hi again :-)
While searching for some other things i came over this conversion kit schematic on the Super Site:

http://www.fenderrhodes.org/rhodes/ch11/fig11-16.jpg

This one makes it possible to connect a 5-pin Piano to a 4-pin cabinet by using an external / additional power supply only for the Piano


regards, Jens
Rhodes tech in Germany
www.tasteundtechnik.de
www.spontaneousstorytelling.net

VintageVibe 64 ACL + DOD FX25B, Tone City Sweet Cream, EHX SmallStone, Mooer e-Lady

Adams Solist 3.1 Vibraphone

In the Past:
Stage 73 Mk1 (1977)
Stage 88 Mk1 (1975)
Stage 73 Mk2 (1980)
Stage 73 Mk2 (1981 - plastic)
Suitcase 73 Mk1 (1973)
Suitcase 73 Mk1 (1978)