Here is the problem, this radio wouldn't program, the head programs fine but not the radio. Also, the radio transmits but without audio.
I did some digging and it turns out the Mic HI line is at nearly zero volts. I don't have a X9000 service manual so i don't know the voltage this line should be at without tearing apart another one of my radios and it's too darn cold and windy to do that right now!
Anyone have schematics of the HLN4925D personality board?
Or does anyone know of any common failure to cause the Mic HI line to go dead? I'm assuming a failed component or shorted cable at one time? I checked connections from the drawer pin 27 to the control head and everything is fine, so it's not a control cable problem. The voltage is nill at pin 27 of J1 on top of the personality board as well!
X9000 Mic HI line is dead??
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X9000 Mic HI line is dead??
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"I Reject Your Reality And Substitute My Own!" - Adam Savage
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This may have absolutely nothing to do with you X9000, but the Spectra mobile has a setting for Mic audio: current or voltage. I suspect when set to current, it will supply current/voltage to the mike for use with carbon buttons or preamp/DTMF mikes. If set to voltage, it might get rid of the DC on the mike audio line. Although, since you need to ground it for programming purposed, I'd think it would need DC there all the time.
Time to look at the schematic.
Bob M.
Time to look at the schematic.
Bob M.
There was a previous post with a similar problem. Maybe you could contact him to see how he fixed it.
http://batboard.batlabs.com/viewtopic.php?t=42822
http://batboard.batlabs.com/viewtopic.php?t=42822
DJP126, Yes there is a diode before J1. And it was blown.
POST EDITED...
I wanted to get the exact description on here in case anyone else comes across this problem.
I think they were using the mic high line to control something externally, there was a 10k resistor from the Mic HI line to an unused pin on the VIP connector. Not sure why, best I can figure is the way the head was setup it would cause the pin it was jumpered to through the resistor to go low, maybe it was some kind of external transmit indication or switching they needed. Evidently something further was done in the radio this head was originally intended for since this head caused the damage. I don't think it was merely the resistor that did it, after all shorting the Mic HI line to ground for programming doesn't cause damage. The control head had a lot of various jumpers and components added to it, i removed everything to get it back to a stock configuration.
I started ohming it out, from the Mic HI pin 8 to pin 27 on the solder side of the personality board was ok so this just left the radio itself. The Mic HI line is not influenced in any way by the control head, there is a trace from pin 8 of the mic connector to pin 12 of the control cable connector and then it just routes through the control cable to pin 27 on the radio's connector.
So you can rule out the control head as a cause of the TX audio problem if all those connections are good. Also, try another mic, I have one here that transmits but the mic element must be bad since it only hums when I transmit with it.
From pin 27 on the personality board there is a trace that goes to a small chip resistor in the center of the connector pins, the small area with no ins coming through, then it goes to the left between all the pins and ends at a Zener diode (CR100), there is three of these diodes going left to right just left of the main connector J1 on the bottom component side of the board. On mine the chip resistor was bad and the diode was bad. All three of those Zener diodes are fed by another diode (VR500) that is near the front edge of the board behind the upright mounted hybrid. If VR500 was bad there would have been more problems than just the mic audio since all three of the circuits being fed would be dead. I didn't trace out the other two Zeners since they were good, so I don't know exactly what they feed without taking the time to check or getting a schematic.
End of the story, everything works, programmed on the first try and the Mic audio is perfect.
POST EDITED...
I wanted to get the exact description on here in case anyone else comes across this problem.
I think they were using the mic high line to control something externally, there was a 10k resistor from the Mic HI line to an unused pin on the VIP connector. Not sure why, best I can figure is the way the head was setup it would cause the pin it was jumpered to through the resistor to go low, maybe it was some kind of external transmit indication or switching they needed. Evidently something further was done in the radio this head was originally intended for since this head caused the damage. I don't think it was merely the resistor that did it, after all shorting the Mic HI line to ground for programming doesn't cause damage. The control head had a lot of various jumpers and components added to it, i removed everything to get it back to a stock configuration.
I started ohming it out, from the Mic HI pin 8 to pin 27 on the solder side of the personality board was ok so this just left the radio itself. The Mic HI line is not influenced in any way by the control head, there is a trace from pin 8 of the mic connector to pin 12 of the control cable connector and then it just routes through the control cable to pin 27 on the radio's connector.
So you can rule out the control head as a cause of the TX audio problem if all those connections are good. Also, try another mic, I have one here that transmits but the mic element must be bad since it only hums when I transmit with it.
From pin 27 on the personality board there is a trace that goes to a small chip resistor in the center of the connector pins, the small area with no ins coming through, then it goes to the left between all the pins and ends at a Zener diode (CR100), there is three of these diodes going left to right just left of the main connector J1 on the bottom component side of the board. On mine the chip resistor was bad and the diode was bad. All three of those Zener diodes are fed by another diode (VR500) that is near the front edge of the board behind the upright mounted hybrid. If VR500 was bad there would have been more problems than just the mic audio since all three of the circuits being fed would be dead. I didn't trace out the other two Zeners since they were good, so I don't know exactly what they feed without taking the time to check or getting a schematic.
End of the story, everything works, programmed on the first try and the Mic audio is perfect.
Duct tape is like the force, it has a dark side and a light side and it holds the universe together.
"I Reject Your Reality And Substitute My Own!" - Adam Savage
"I Reject Your Reality And Substitute My Own!" - Adam Savage