You can go back through the amsat-bb archives and find many of the same problems that are being talked about now. Yaesu rotor problems are not new and are re-discussed from time to time.
I have a G5500 on my Arizona station. It was installed in 2013 and it was a used rotor at the time. It worked ok for several years. I had it tracking Funcube 24x7 for many months and that was probably not a wise decision considering the potential problems. A few years ago I started to experience what is being talked about now. The azimuth readings started to be erratic. The LVB tracker would give up trying to move the rotor and since I was not there to manually move it, I would use the park command in SatPC32 to try to get past the intermittent areas. That would work for a while but soon I could not park the rotor from about 100 degrees back to zero.
So the best option for me was to buy a replacement azimuth rotor (no control box or elevation rotor). This was a catalog item at many ham radio supply houses. So last December my son and I replaced the azimuth rotor with the new Yaesu unit. I thought I would be good for a few years but that would not be the case. I planned to repair the original az rotor by replacing the pot and have it available if the rotor should fail in the future.
In August the rotor started showing signs of the same problem. I noticed that the actual azimuth was lagging behind what SatPC32 was sending to the LVB tracker. Eventually it would get past the bad spot and movement would be normal until it got to another bad area. So the new rotor only lasted 8 months and I wasn't tracking and downloading data on any satellite.
So what is different about Arizona? For one thing the temperature gets to 120F and when the sun shines, as it does most every day, the dark cclor of the rotor absorbs the heat and the temp inside the rotor is likely sky high. Could that be a reason that the potentiometer is failing? Maybe and maybe not.
Several years ago I ordered replacement pots from Yaesu. The shaft on these pots is metric so 1/4" American made pots will not fit. You are stuck with metric components. The part number on the replacement pots is RA25Y25S B501. You can look it up on the web. The specs for this pot are 15,000 cycles and 100 degrees C. I doubt if the temp inside the rotor exceeded 100C so it should have held up in the Arizona sun. 15,000 cycles is a lot and you can do the math.
The next question is what is the part number of the pot in my new azimuth rotor? Did Yaesu change suppliers over the years and what are the specs of the pots they are using now? Once I disassemble the old rotor which is in Arizona, I will know if the part number is different than the replacement pots I purchased. I could send the new rotor back to Yaesu under warranty and have it repaired, but why do that if the same pot is used to repair the unit and will likely fail again?
I thought I was alone with this problem but after asking around I found that that might not be the case. KB6LTY is experiencing the same problem with a new G5500DC that she purchased not long ago. There appears to be a systemic problem here. Changing the pot may work for a while but you can't be taking things apart every year just to have the same problem occur shortly thereafter. K3RRR reported similar problems and his story should be told here as well.
Last year Yaesu changed the model number of the G5500 to the G5500DC. There was no announcement and ham radio dealers knew nothing about the change. EA4TX who makes replacement control boxes was also unaware of the change. The motors in the rotors are now DC rather than AC. The controller is different, but Yaesu did not publish the schematic in their instruction manual as they did with the G5400/5500 series. One satellite operator noticed that when SatPC32 sent a command to move the az and the el at the same time, the control box would go into a fault condition. Apparently the control box detected an overcurrent condition due to a high startup current and shut down. I'm not sure if that issue was resolved by Yaesu or by a software change. Just another thing to be aware of if you have a new DC model.
Another thing to be aware of is that there are meter amplifiers in the the control box that are used to isolate and control the output voltage to interfaces like the LVB tracker. These meter amplifiers can become erratic rendering the interface unusable. The meters in the control box are separate so if they are reading properly and don't jump around, erratic readings going to the computer interface are likely caused by the meter amplifiers and have nothing to do with the pots in the rotors themselves.
If you have experienced these kinds of problems and have or have not resolved them, please post so that we can determine how widespread these issues are and possible fixes.
73, John K8YSE
BTW, although John's probably is probably not this (since the issue seems to be around the control box), I did have a problem with mice chomping at the control wire too :-)
On Mon, Oct 5, 2020 at 2:08 PM john--- via AMSAT-BB [email protected] wrote:
You can go back through the amsat-bb archives and find many of the same problems that are being talked about now. Yaesu rotor problems are not new and are re-discussed from time to time.
I have a G5500 on my Arizona station. It was installed in 2013 and it was a used rotor at the time. It worked ok for several years. I had it tracking Funcube 24x7 for many months and that was probably not a wise decision considering the potential problems. A few years ago I started to experience what is being talked about now. The azimuth readings started to be erratic. The LVB tracker would give up trying to move the rotor and since I was not there to manually move it, I would use the park command in SatPC32 to try to get past the intermittent areas. That would work for a while but soon I could not park the rotor from about 100 degrees back to zero.
So the best option for me was to buy a replacement azimuth rotor (no control box or elevation rotor). This was a catalog item at many ham radio supply houses. So last December my son and I replaced the azimuth rotor with the new Yaesu unit. I thought I would be good for a few years but that would not be the case. I planned to repair the original az rotor by replacing the pot and have it available if the rotor should fail in the future.
In August the rotor started showing signs of the same problem. I noticed that the actual azimuth was lagging behind what SatPC32 was sending to the LVB tracker. Eventually it would get past the bad spot and movement would be normal until it got to another bad area. So the new rotor only lasted 8 months and I wasn't tracking and downloading data on any satellite.
So what is different about Arizona? For one thing the temperature gets to 120F and when the sun shines, as it does most every day, the dark cclor of the rotor absorbs the heat and the temp inside the rotor is likely sky high. Could that be a reason that the potentiometer is failing? Maybe and maybe not.
Several years ago I ordered replacement pots from Yaesu. The shaft on these pots is metric so 1/4" American made pots will not fit. You are stuck with metric components. The part number on the replacement pots is RA25Y25S B501. You can look it up on the web. The specs for this pot are 15,000 cycles and 100 degrees C. I doubt if the temp inside the rotor exceeded 100C so it should have held up in the Arizona sun. 15,000 cycles is a lot and you can do the math.
The next question is what is the part number of the pot in my new azimuth rotor? Did Yaesu change suppliers over the years and what are the specs of the pots they are using now? Once I disassemble the old rotor which is in Arizona, I will know if the part number is different than the replacement pots I purchased. I could send the new rotor back to Yaesu under warranty and have it repaired, but why do that if the same pot is used to repair the unit and will likely fail again?
I thought I was alone with this problem but after asking around I found that that might not be the case. KB6LTY is experiencing the same problem with a new G5500DC that she purchased not long ago. There appears to be a systemic problem here. Changing the pot may work for a while but you can't be taking things apart every year just to have the same problem occur shortly thereafter. K3RRR reported similar problems and his story should be told here as well.
Last year Yaesu changed the model number of the G5500 to the G5500DC. There was no announcement and ham radio dealers knew nothing about the change. EA4TX who makes replacement control boxes was also unaware of the change. The motors in the rotors are now DC rather than AC. The controller is different, but Yaesu did not publish the schematic in their instruction manual as they did with the G5400/5500 series. One satellite operator noticed that when SatPC32 sent a command to move the az and the el at the same time, the control box would go into a fault condition. Apparently the control box detected an overcurrent condition due to a high startup current and shut down. I'm not sure if that issue was resolved by Yaesu or by a software change. Just another thing to be aware of if you have a new DC model.
Another thing to be aware of is that there are meter amplifiers in the the control box that are used to isolate and control the output voltage to interfaces like the LVB tracker. These meter amplifiers can become erratic rendering the interface unusable. The meters in the control box are separate so if they are reading properly and don't jump around, erratic readings going to the computer interface are likely caused by the meter amplifiers and have nothing to do with the pots in the rotors themselves.
If you have experienced these kinds of problems and have or have not resolved them, please post so that we can determine how widespread these issues are and possible fixes.
73, John K8YSE _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
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