EMT 162 Plate Reverb, (Elektromesstechnik)
Repair & Upgrade
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Power Supply:
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The power supply input jack is a somewhat obscure, recessed, panel-mount, male, 4-pin connector by "switchcraft," accepting a female "A4F" plug. The use of this connector was apparently an expensive design-perception-flex, though, because only two terminals within it are utilized for its function.
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The original unit had no power switch, so I added a little SPST toggle for ON/OFF.
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Some information found, but not specifically for the Quad 477 model, referenced a 22VDC power supply voltage. After considering all of the info available and observing under different voltages, I settled on providing it with 19V DC. As an added measure of protection against damage to the circuitry, some of which is rare and nearly unobtainable anymore (more on that later), I outfitted it with a current inrush-limiting circuit, designed and installed off-the-cuff. It consisted of a good sized capacitor with a fairly-rapid-draining resistor. The capacitor always draws current at the initial transient of power-up and also some filtration for the inevitably-noisy switch mode power supply (SMPS).​
Top Board & Switch Replacement:
The replacement switch put here works, and is secured to the chassis of the fully assembled unit, as well as to the PCB, but next time I would look for new-old-stock of this switch. They are Japanese toggle switches, not made anymore. Some are DPDT and some are DP3T, but double check the specs yourself if you are working on one.
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Another switch that had a broken post / toggle was outfitted with a section of a bamboo shish kabob skewer, held invincibly to the plastic with some quality super glue. It turns out that supper glue bonds bamboo exceptionally well. The PCB-mounted switches were electrically functional.
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The faders were grimy, and not to be tampered with as far as most cleaning solution is concerned.​​ They functioned well enough once vacuumed, and their smooth sliding action is ruined by most liquid cleaning solutions. Use caution here because sticky faders are annoying.
Drum Triggers:
The back panel of the drum-triggers, the plastic bottom, is threaded. It screws into the "shell" of the drum. Righty-tighty, you know. A pair of channel-locking pliers used backwards is perfect to get enough torque into the rear-disk for it to unscrew. You put the handle-ends into the holes in the the disc and rotate it.
Inside each trigger is a simple speaker, connected to a 1/4" mono jack. There is foam on both sides of the speaker, which is probably disintegrating. The foam in these turned to dust upon a mere sideways glance.
Two triggers worked, one was weak, and the 4th was dead.
The dead one had its speaker magnet fall off, and the weak one had a dirty jack.
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I replaced all the foam with new and cleaned the jacks. Made them all nice and secure.
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Now to connect them all to the main unit with a custom made wire. This became art.
Drum Trigger Wire:
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The drum wire terminated into the main unit via a 6 pin plug that is male, the same outside / sleeve dimensions as a male XLR cable has, not a "1BL6MX" plug.
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If making (or using) a wire for the drum triggers of a Syndrum, some tips are as follows.
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- Keep the lead-wires separated from at, or as close to, the plug going into the main unit as possible. The voltages needed to trigger the synths are so low, and capacitive / inductive coupling occurs with these transient-voltages, and when the wires run parallel AND near each other in the path to the machine. A section of the wire I made is an Ethernet cable, and it works well, but I would not do it this way again for this reason.
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- If drum-trigger to synth-module mismatching, or bleedover-triggering is occurring (ie. you strike the trigger on module #1 and multiple modules sound, all, a couple, or just one that is not supposed to) then you likely have a compromised connection somewhere between the main unit and a speaker in a trigger, somewhere. This is what I have observed causes this. Meaning that you can not properly use, or test the Syndrum, without having all 4 drums plugged in, connected well, and in proper working order. The induction and impedance of the speaker windings may negate the effect of cross-talk within my Ethernet-incorporated custom-wire, though, leading to this effect in only my case. It is at least a consideration to make, if anyone else is doing the same thing.
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Pedal:
It connects with a standard 1/4" TRS cable. The switch-pedal engages total-mute, and the potentiometer-based pedal changes the synthesizer's decay-time for all modules.
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Final Remarks:
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Replaced all electrolytic capacitors. Replaced all SPST toggle switches. Cleaned all pots and connectors. Tended to every detail within reason. It is amazing to play!
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Servicing one of these in this condition is a time consuming (and expensive) thing to do. If you can justify it, though, the results are worth it in my opinion. I am grateful to my client for this opportunity. If you have a broken Syndrum I may want it, or be interested in servicing it.
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