IC-7000 Driver Board Replacement How-To

This post is a how-to guide on how to fix a blown driver board in an Icom IC-7000 radio transceiver. You can permanently damage your radio while working on it and I am not an authorized Icom repair technician. You are responsible for all damages to your radio.

Service manual download: hamradio.online.ru/ftp3/Serv_Manual_IC-7000.pdf


Is the driver board bad?

There is a lot of talk on the internet about the "driver board" in the IC-7000 failing and while this is true, it may not be your specific problem.

Symptoms:

• radio receives normally
• HF power output reading is 0
• VHF power output reading is 0
• UHF power output reading is 0

The driver board is the final amplifier before the amplifiers for each band. If only one band is broken, this isn't the guide for you. Let's take a look at the block diagram for the transmitter.

Transmitter Block Diagram

As you can see, IC504 is the driver board. You can easily see why if this part goes bad you'll experience the above symptoms. The part in the driver board that will most likely go bad is the transistor and is part number Q504.

If you have access to an oscilloscope you can test this part with the bottom chassis cover removed before tearing the entire radio apart. Check the service manual to find the input and output on the driver board. If you see signal in but no signal out, your driver board is blown.

Disassembly

Remove the top and bottom chassis covers. Take note of where the little rubber pads were because they have a habit of falling on the floor. Start on the top side with the fan and remove the items attached to the back side.

1. note the grounding clip position

2. disconnect the coax

3. disconnect coax

4. remove copper foil tape and free coax from cable channel

Now it's time to remove the bottom board. Give it a quick once-over to make sure there aren't any other obviously blown up parts. Look for cracked transistors or charred circuit board. I've marked all the points to be unscrewed, unsoldered, and unplugged in this image. Once all these points have been removed the board should pop out easily. If it feels like it's still attached to something double check all these points.

I made the mistake of unsoldering the power connector instead of just disconnecting it from the chassis. Each side of the connector to squeeze from the top and bottom. Before lifting the board out make sure you watch for the ribbon cable attached to the front of the board. Push the connector through and lift the board up from the rear. Find something to prop the board against so the ribbon cables don't get disconnected.

The driver board is now fully exposed. If your driver board is blown the transistor (the little chip) on it should look obviously broken. Mine had a large lengthwise crack in it. If you don't see any obvious damage at this point stop now, you'll need to take it to someone with an oscilloscope to diagnose the problem.

Unscrew the driver board from the chassis. Did yours have heatsink compound under it? Mine didn't and it was an early model IC-7000. I suspect this may be the "ic-7000 driver board problem" everyone talks about.

Replacement

You'll need to order another transistor. The part list in the service manual says Q504 as a MOSFET PD55015. I ordered mine through digikey "IC TRANS RF PWR LDMOST PWRSO-10" (http://parts.digikey.com/1/parts/1234780-ic-trans-rf-pwr-ldmost-pwrso-10-pd55015-e.html). 

Once you've replaced Q504 follow the steps in reverse but make sure to apply heat sink compound in the locations outlined in the previous image. This includes under the driver board, even if it didn't have heat sink compound there before.

Be careful when placing the bottom board back on so that you don't bend any of the pins on the driver board. Once you have the driver board pins lined up, put a couple of the bottom board screws in to hold it in place. It's a bit tricky getting the solder to stick to the pins and the solder pad. I found that bending the pins closer to the pad helped. Also, don't heat the pins too much or you'll have solder run into the board underneath. If you're still having problems here, just take a small piece of wire and lay it across the hole then solder around that.

Contact me if you have any questions, suggestions or helpful steps you think I should add to this guide.