Yaesu FT-1000MP Transmit Relay Replacement
What do you do when your Yaesu FT-1000MP, your main base HF rig, that’s been a trusted partner for over a decade, just doesn’t want to transmit? As if antenna problems weren’t enough, now I have to perform surgery on my old friend. Fortunately, this is a story with a happy ending.
For a while now, I’ve been experiencing some difficulty tuning my Yaesu FT-1000MP. I’ve been trying to figure out how to resolve this problem, but was still able to operate reasonably well, so I carried on. Anyways, on certain band segments, the internal tuner would hunt around for a long time but wouldn’t be able to tune the antenna for the frequency. Sometimes, tuning up or down the band, letting the tuner lock in and then coming back would work, but it was annoying. Recently, that changed completely. The radio would no longer tune at all. Instead, it would just show an infinite SWR and the protection circuit would cut output power to milliwatts, as designed. This is what happened when the radio was tuned to the antenna resonant frequencies, so it isn’t a mismatch issue. (Yes, I know that most internal tuners only function if the SWR is 3:1 or less.)
Time to do some troubleshooting. With the assistance of Alan, AB4OZ, we opened the radio up and started checking signal paths and function. To make a long story short, we found a relay that had failed. RL-6016 on the LPF board was getting a trigger signal, but simply wasn’t functioning. The radio has been in service for about 12 years, and this is really the first major issue that it has exhibited. (The only other repair that I have had to make was to resolder the center connection between one of the antenna SO-239 connectors and the board to which it was attached.)
We also traced the signal path on the schematics from the PA through the LPF board and out to the SO-239. As an additional diagnostic, we identified an internal coax connection downstream of the PA and the SWR coil, but before the relay in question, disconnected it and attached it directly to a dummy load. (If I can remember which one, I’ll edit it in later.) Once we did this, the radio would key up normally, the power levels would go to expected values, and the internal SWR meter would show expected measurements, near 1:1 for a dummy load. We also verified that the trigger voltage was normal going in to the relay, and verified that the relay was actually not engaging. That’s relay RL6016 – the black one in the picture.
OK, so the (hopefully, only) problem has been identified. I called Yaesu on Tuesday, after the holiday, and spoke with some very friendly people in both the parts and tech support groups. I got the impression that this is a fairly common problem. I explained the symptoms to the tech support rep and they very quickly told me that my diagnosis is probably dead on. These relays do wear out over time and a simple replacement usually resolves the issue. Parts followed suit by dropping a relay in the mail the same day. I had the relay in hand via USPS First Class Mail on Friday afternoon. Total cost, about $15. Thanks for the quick answers and the fast delivery.
What I haven’t mentioned is the nitty-gritty of getting into the beast in order to diagnose and replace anything. Opening the cover is the easy part. Knowing what to do next is not for the novice. At first glance, it is intimidating. This radio is fairly tightly designed and assembled. However, Yaesu appears to have used a modular approach. There are numerous boards, interconnected with cables and connectors, and well shielded. A roadmap here helps immensely. In other words, if you’re going to open this radio up to do anything, it is best to have a copy of the service manual, if for nothing else, to have the disassembly instructions!
For my project, it was fairly straightforward. First caution: pay attention to the locations and positions of all cables, cable ties, copper ground fingers, etc. Now, if you’re ready to start, remove the cover, remove the six screws holding the big heat sink and the fan from the left side of the radio, flip that over, remove the main shield (one screw in the center), and expose the board with the bad relay. In the photo at left, the board in question is on the left.
Here are photos of the LPF unit, after it has been repaired. Relay RL6016 is the large black lump at the right end of the board.
In the trace side photo below, the relay is located just to the left of the two copper grounding fingers at the center. Note the four pins in a square and the three pins located to their left in the red box. These had to be desoldered to remove the old relay and to install the new one.
Of course, removing that board was a little more complicated. All of the connecting wire harnesses appeared to be permanently attached to this board and had to be disconnected at the other ends. Add about 5 mini push-in coax connections on the board too. My advice here is to be very careful and patient, and mark every connector with the connector number on the board where it attaches. (Ex: J6006, J6015, etc.) It will make it easier. Fortunately, almost every connector is unique in number of wires or color code.
To disconnect everything, you’ll need to start by removing the speaker, held in place with 4 screws. Don’t lose the bushings around the screws. Lift it up and set it aside. Next, remove the screws holding the frame that supports the SO-239 antenna connectors and the board to which they are attached. Note the positions of the grounding fingers. Slide the board slightly towards the front of the radio and rock the frame upward toward the center of the radio to get it out. Expect to have to cut some of the zip ties holding the cabling in bundles. Yaesu left enough wire and cable that you can get room to work. The automatic tuner is on the underside of this frame.
You’ll have about three wire harnesses on this frame to disconnect. Two go to one of the boards on the top and the third goes to the auto-tuner. label them as you disconnect. You’ll be glad you did later. For the two on top, it’s easier to remove the three screws holding the pc board to the frame first. It gives you room to work around all the other wire bundles.
Once everything is disconnected, replacing the relay is pretty basic. The board looks like it is a single layer board and not too densely packed. Use good desoldering technique on the relay, be careful to use low soldering heat – don’t burn the board or the traces, and swap out the relay. It’s the big black one on the end. Be careful not to damage the two copper grounding fingers on the bottom of the board. Many thanks to Alan, AB4OZ. He did a masterful job of swapping out the relay – so good in fact, that I couldn’t tell that anything had been changed on the board! Of course, he does that kind of thing every day. I suppose I could have done it myself, but it wouldn’t have been as clean on a good day. And have you ever tried to focus on desoldering electrical components from a PC board with a massive headcold where you can’t focus on the aspirin bottle in front of your face???
Back to work – time to put everything back together. Just reverse the process and put everything back. ;-) Yes, I know, easier said than done. Actually, it is fairly easy. It’s tedious to do all this, but it is fairly easy, if you’re just careful and patient. Be sure to pay attention to placement of copper grounding fingers, cable paths, etc. Long ago, I learned the difference between “difficult” and “tedious.” The former is a challenge of knowledge and skills; the latter is a challenge of patience. Another plus – no alignment process necessary. Once I finished the reassembly, everything worked perfectly!
For this job, it looks like Yaesu made it something that a reasonably skilled ham can accomplish. The board is fairly easy to get to and appears to be a single layer, the traces aren’t too small, and as long as you’re patient, you might even be able to just unmount and flip the board over to do the work. On the other hand, if the auto-tuner module has problems, I’m not so sure. It’ very tightly assembled, and I couldn’t figure out how to disassemble that one, but I didn’t try very hard. Guess I got lucky there.
So, the FT-1000MP is back in one piece and working as well as it did a decade ago! Looks like it’ll be ready for Field Day!
Now, if I can just figure out where that leftover copper ground finger goes…..
If you have any questions or comments, leave them below…..