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Dead RX-360

Measured low resistance both ways (ie switching probes on anode and cathode) using a DMM out of circuit. Can I assume the zener is open and I need a new one?
 
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jhart said:
Measured low resistance both ways (ie switching probes on anode and cathode) using a DMM out of circuit. Can I assume the zener is open and I need a new one?
Click to expand...

Low ohms both ways--shorted or semi-shorted..BAD!
 
Replaced D26. Q42 voltages where they should be. Took voltages at Q13 and Q10.

Q13:
E 5.6 __5.548
B 6.2 __6.261
C 10.5 __11.03

Q10:
E 5.4 __5.389
B 6.1 __6.06
C 11.3 __11.37
 
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I checked a few transistors for proper voltage - Q6 & Q7 to be exact, and when I turned the power off using the power button, I notice that there is still power to these transistors and a few more that I checked that were on PCB #1. There was no voltage on the power transistors on PCB #2. I notice on the schematic that there is a standby function in the power switch. Is this normal behavior i.e. the unit doesn't shutdown completely when you push the power button off? Just wondering.
 
After power on. and relay clicks. Measure the DC voltage at the speaker connections.Check all plug in connections inside the unit for loose connections or cracked solder connections where they solder to the circuit boards.Especially around IC501,IC9 and LCD V501.
 
Carefully measure pins 56 & 58 of IC501 for the 5 volt VDD power supply voltage and pin 64 of IC9 for the 5 volt VDD power supply voltage.
 
Checked plugin connections as prescribed and remelted a handful that look suspect. Voltage readings were as follows:
IC501
Pin 56: 4.97v
Pin 58: 4.98v
IC 9
Pin 64: 4.698v
When you say measure DC voltage at speaker terminals, do you mean across the terminals? If so, I'm getting 14mV on the left and 34mV on the right.
Still nothing lighting up.
 
When you say measure DC voltage at speaker terminals, do you mean across the terminals? If so, I'm getting 14mV on the left and 34mV on the right.
Click to expand...
Yep. Those values are OK...:thmbsp:
Appears the IC chips are getting power as well.:scratch2:
 
I checked some voltages on the pins of V501, the LCD display. All the ones I checked are reading at least 2.4 volts. According to the schematic, only pins 1 & 2 should be reading that high. The rest should be 1.9 volts. Is this OK?
 
I'll post voltages from IC9 later today, but in the meantime, I've attached a photo of the LCD display board, V501. As the photo shows, there is an irregular pattern of bumps on the surface of the display. These don't look good to me. Are these heat related and is this display a goner?
 

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  • LCD V501 (640x427).jpg
    LCD V501 (640x427).jpg
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Disregard my last. Replaced 10ufd cap on LCD board that had a marginal ESR reading and all is well. All systems are fully functional except pilot light. Avionic -thanks for your time and effort helping me get this unit up and running. My troubleshooting skill and knowledge have taken a quantum leap forward as a result. Thanks again.
 
:banana: Sa weeeet! Good job..:thmbsp:


The pilot lamp is a 14.5volt @ 80ma. contact Dave at dgwojo.com for the correct replacement.

Dave
 
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