Recapping the Systems 9000 Control Head

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Systems 9000
Control Head
By Mark Tomany N9WYS

The Systems 9000 control heads, used with the Syntor and Spectra radios, have two surface-mount electrolytic capacitors in them. Like all other Spectra radios and control heads, these two caps will go bad, stop working properly, leak, and possibly damage the circuit board.

Here's a photo showing the front of the Systems 9000 head used on the Spectra.

The head is assembled from two halves, and two Torx T-15 screws (one at each top corner) hold them together, seen in this photo of the rear of the head.

You will not see the capacitors right away; you must remove the boards from the plastic covers to gain access to the components. To do this, you remove five Torx T-10 screws from the front (face) half of the head, and two Torx T-10 screws from the rear (back) half. The rear half also has a sliding tab along the bottom edge, which must mate properly with the toggle switch (power control switch) mounted on the rear circuit board. NOTE: Failure to ensure proper engagement when reassembling this half of the head WILL result in the inability to control whether the radio can be turned on and off, depending on what position the switch was in when you reassembled the head. You may need to use some finesse to remove the rear circuit board, as it fits within close tolerances in the shell half. I pushed my finger through the connector opening in the shell half to assist with the board's removal.

Once you remove the boards from the housing halves, turn them over and you will see the two electrolytic capacitors on the rear board. Also note in this photo, you can see the power control switch referenced immediately above. Fortunately, my head showed no evidence of leakage.

Each capacitor's position on the circuit board is marked for proper polarization, so it is difficult to install your news caps wrong. There is a "+" marked on the circuit board adjacent to the solder pad where the positive lead of the cap is to be attached. In the photo below, the positive end of the upper capacitor is towards the left, while the positive end of the lower capacitor is towards the 50-pin connector.

Performing a re-cap of the Systems 9000 (Spectra "A9" through "E9" radio) control head is straightforward. There are only two capacitors in the head, and both are 10µF 50V rated. Remove the old caps, clean the solder pads WELL with alcohol, and allow the board to dry. Solder in the new caps. I used leaded capacitors - rather than surface-mount - because I had them and they're easier to install.

Reassemble the head. Remember to make sure that you have the sliding switch tab on the rear head shell in the proper position to match the toggle lever on the power switch, or you WILL NOT be able to cycle the switch. And if you force it, you risk damage to the switch itself and the circuit board.

[Editor's Note: While you've got the head apart, now would be a good time to give all the plastic parts a good cleaning. Make a diagram showing where the various buttons are located, then remove the clear plastic from inside the front half and remove all the buttons. Soak everything in hot water with some dishwashing detergent, scrubbing the dirt from all the nooks and crannies with a toothbrush. Rinse everything well and dry all the plastic parts. Get all the water out of the inside of the buttons using compressed air or just banging them against a towel to dislodge the remaining water.]

I also took the time to polish the display lens before reassembly, since it was scratched and fogged. I used Meguiar's PlastiX^® polish for reconditioning automotive headlamp lenses, along with a foam rubber "Power Ball" in my cordless drill. I masked off all areas I did not want to polish - including the area where the "PRI" and "NON-PRI" markings were on the lens - with clear packaging tape. Once I finished polishing the lens, I removed the tape and washed the entire assembly in mild soap and water, and used my wife's hair dryer to ensure that I had thoroughly dried the head before reassembling the circuit board into it. When finished, it looked nearly new and the display is clearly visible in any lighting condition now.

Acknowledgements and Credits:

Spectra, Syntor, Systems 9000, and a bunch of other terms are trademarks of Motorola, Inc.

Contact Information:

The author can be contacted at n9wys [at] ameritech [dot] net.

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This article first posted 22-Aug-2011.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.