X9000 HCN1033D VIP Ground Trigger Problem

[jmr061]

A dept has a HCN1033D control head that won't trigger ground on any of the VIP outputs (ie horn ring transfer for the siren). Any common causes for this that can be easily repaired. If it can't be fixed they will be in the market for a cheap used control head for the X9000.

Thanks

Jason

[kf4sqb]

OK, lets start with the obvious first:

Is the head properly programmed for the desired VIP functions? Was this a working install that recently developed this problem?

[jmr061]

Ah.....yeah thats all been checked. It's a control head issue.

Jason

OK, lets start with the obvious first:

Is the head properly programmed for the desired VIP functions? Was this a working install that recently developed this problem?

[kf4sqb]

OK then, into the guts of the head we go. From the way you have your subject line worded, I'm assuming that you have your relay wired correctly (one side of the relay's coil wired to a hot, preferably pins 18, 19, or 35 in the VIP plug, and the other side tied to pin 1, 2, or 34 in the VIP plug).

Pins 1, 2, and 34 are "sinking" inputs, grounded by three NPN transistors. Pin 1 is connected to the collector of Q29, pin 2 is connected to the collector of Q30, and pin 34 is connected to the collector of Q28. The emitter of all three transistors are connected to ground, while the base of each transistor is connected to a separate pin of U3, which is a CMOS shift register. Q28's base connects to U3 pin 11, Q29 to pin 12, and Q30 to pin 13.

To activate a VIP pin, the pin on U3 that goes to that VIP pin's transistor should go "high" (app. +5vdc), which biases the base of the corresponding transistor on, which "sinks" the transistor's collector, along with the corresponding VIP pin, to ground through the transistor's emitter. Check to see if this sequence occurs when the correct sequence of events occurs to activate a particular VIP pin. If the pin of U3 goes high, and voltage appears on the base of the corresponding trasistor, but the transistor doesn't switch, try replacing the transistor. If the pin of U3 goes high, but no voltage appears on the base of the transistor, there is an SMD transistor in line between U3 and the base of each transistor that may be bad. These resistors are located on the opposite side of the board from the transistors, and the resistor related to each transistor is directly behind it. If the pin of U3 doesn't go high, either there is a programming problem, or U3 may be bad. If the transistor proves to be bad, check the load thats tied to it. It is designed to pull a small relay, with no more than a 300 ma draw. If the relay tied to it has the correct current range, but doesn't have a suppression diode built into it, you may want to add one externally, as an un-suppressed relay coil can cause a large enough voltage spike when its turned off to kill a transistor.

I'm looking at the insides of an HCN1033 as I type this, and all the above-mentioned parts are labeled via silk-screening on the board. With the two halves of the head's housing seperated, and the board in the rear of the housing removed from the housing, look at the rear of that board (the side that the control cable plugs into) with the switch in the upper right corner. You should see four TO-92 package transistors in a vertical row along the right-hand edge of the board. Starting at the bottom of the row and going up, you should have Q28, then Q29, then Q30. The top one should be Q33, and isn't related to this part of the circuit. You will probably have to pull the orange "gasket" thats around the control cable plug back (it shouldn't be glued) to see the labels on these transistors. U3 is located in the lower left corner of the board, between the flex cable going from the rear board to the front board, and the metal shield that houses the EEPROM and microprocessor.

Be aware that the inverter for the vacuum-florescent display is also on this board. Its in the area of the small transformer located to the right of the above-mentioned flex cable, and the parts to the immediate right of the transformer. It puts out in the neighborhood of -40 vac, which probably wouldn't be lethal, but will probably be enough to bite you.

Best of luck, and feel free to ask if you need any more info, or any clarification.

[jmr061]

None of the VIP outputs work so it more than likely is a common componet to all 3.

Jason

[kf4sqb]

I've just layed out the whole VIP output circuit for you. If its not anything I've layed out for you, it would have to be in the data bus, or the microprocessor. Just because all three outputs are affected doesn't mean that its a part common to all three outputs. It is certainly possible that all three transistors failed at or near the same time. Try troubleshooting as I've layed out for you, and see what you get, then post back.