[IC-7000] IC7000 Front panel kills 8 Volt series resistor
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The filter electrolytic caps on the 8-volt line in the head are famous for shorting.
Sent from my Sprint Samsung Galaxy S7 edge.
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From: "jeter.d.barron@... [ic7000]" <ic7000@...>
Date: 10/3/17 12:31 PM (GMT-06:00)
Subject: [IC-7000] IC7000 Front panel kills 8 Volt series resistor
I have two IC7000 bought at an estate sale and bot were DOA when tested.
I found on one unit the series 4.7 Ohm resistor was bad and replaced it and turned the unit on after replacing it blew again. The 7808 was OK so I fed it a second resistor and tried the front panel from the second radio and the unit quit clicking and shutting down an booted up.
This panel has a bad headphone jack and has no audio out.
I tried the other panel and "tested" the resistor again.
I wonder if anyone else had had experience with this.
The DC resistance on the 8 volt line is 980 Ohms and clipping the lead on the 7805 makes no difference.
Any other thoughts?
By the way to troubleshoot this problem I added two wires to the working front panel to be able to read the 8 and 5 volt levels at the 7805 in that panel.
The bad one zapps the regulator resistor before one can check anything of course.
Any particular parts to look at and save some hacking about?
Thanks for the info.
They are not shorted, but the resistance on the line is lower than the other one and does not "charge" like the other.
I ordered replacement 7805 but the case is larger than the one I thought I was buying.
The 7808s I bought were correct
I need a few more parts from Icom for the head as well.
At least the other head is working and it doesn't smoke the 4.7 ohm resistor on the main board.
I am checking out the rig and antennas and getting back on the air after many many years off the air.
I had a simular problem with a 7k I bought, it was DOA.
On turning it on I noticed the back light on the mic was very dim if plugged into the head, if the mic was plugged into the back it was much brighter but was only on for a moment before the cpu would sense a fault and shut down,
The fix was replacing the large Chip filter caps on the front panel one had gone short and was pulling the rail down, I replaced both of them, Good luck Tom VK4DDG
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