The container says it is general use flux paste it does not say specifically for plumbing or electrical. And no, the pin 7 voltage does not change when keying up. Pin 6 after checking it again does fluctuate a little bit more than originally posted. Slowly anywhere from 2 to 2.45v. Edit: the light on the front does not flicker red anymore it stays on solid green now.
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Galaxy DX2517 Troubleshooting Help
- Thread starter Junkyarddog76
- Start date
I have been sitting here since my last reply and have left the radio on and I tried keying up the radio again for the hell of it and now all of a sudden it keys up, the light switches to all red, and pin 7 drops to 2.66 volts when keyed. I dont know if poking around the pins with the meter lead disturbed it into working or what, but is this correct now??
Sounds correct, except for the unpredictability of it. Might you have a bad connection in the mic cable or socket? Hold the key down and wiggle the mic plug wire while watching the light color.
You're right, since my last reply I've been rechecking and now it doesn't want to switch to red all the way and sometimes it won't switch at all. one minute it will work than the next minute it wont. but the voltage still drops to 2.66 every time. I've tried a different mic, pushing around ic7, and the q33 area and wiggled around the wires at the mic connector on the face of the radio and nothing seems to make much of a difference. Could using 3 series diodes instead of 2 with around a 1.7v drop instead of 1.2v for d71 be causing this? I could try changing it back to 2.. and now as im hitting send on this reply it is keying up normal again.
Looking at the 2517 schematic, D71 is a KB362 (the 3 indicating the number of junctions). When I made that simplified switching schematic, I must have glanced at D72 (a KB262, a 2 junction device). This means D71 in my drawing is wrong and should be a 3-junction device.
Give me a minute to think about this further.
Give me a minute to think about this further.
In post 46 you reported that the voltage was not dropping when keyed, but post 49 you say it does now. When conflicting statements are made, I like to recommend double checking. If the voltage at pin 7 drops every time it is keyed, the issue is after the op-amp. If the voltage only drops when it is working right, the problem is at or before the op amp.
I just double checked and even when the light only partially turns red or not at all it still drops to 2.66 everytime. I can still hear the static pop or whatever from the speaker when it switches from rx to tx. The light just doesn’t come on red all the way most of the time now.
I just noticed when I push around on q31 it seems to affect the red light and make it work a little. It has been replaced with a c1815 from Amazon that Google said was a newer substitute. The traces are also not in great shape in that area from the traces lifting and having to repair some of them. Maybe I should spend time seeing if the traces could be improved or try putting a 2sc945 back in it?
Q31 is the RX switches buffer, it should not be affecting the red light.
Is the green light staying on when the red light struggles to come on or does it switch off cleanly leaving only a weak red?
Edit: I will be away from the computer for about 45 minutes.
Is the green light staying on when the red light struggles to come on or does it switch off cleanly leaving only a weak red?
Edit: I will be away from the computer for about 45 minutes.
Okay, the last 10 minutes it has been cleanly switching to only red like normal again but when it does intermittently act up it will still light up mainly green but you can see a little red on simultaneously through the green light a little.
Is green/partial red condition while keying or without keying?
I know I ask a lot of questions, but it is important to narrowing down the problem remotely
Assuming the green shuts off every time it is keyed...
The op amp supply (and therefore the regulator voltage) is at 9.25v. The high state at pin 7 is 8.53v, a difference of .72v. That voltage difference in RX should completely prevent D71 and Q33's junctions from conducting because it would require 4 junctions to be forward biased (something that cannot happen with .72v across them). So either those diodes are leaky (but you replaced them already, so thatis unlikely) or something else is back-feeding the TX rail.
Pulling Q33 and measuring the voltage at the collector's pad would tell us if that were the case. It could be as simple as a bad diode somewhere else but we need to get there one measurement at a time.
The op amp supply (and therefore the regulator voltage) is at 9.25v. The high state at pin 7 is 8.53v, a difference of .72v. That voltage difference in RX should completely prevent D71 and Q33's junctions from conducting because it would require 4 junctions to be forward biased (something that cannot happen with .72v across them). So either those diodes are leaky (but you replaced them already, so thatis unlikely) or something else is back-feeding the TX rail.
Pulling Q33 and measuring the voltage at the collector's pad would tell us if that were the case. It could be as simple as a bad diode somewhere else but we need to get there one measurement at a time.