Hi. I started having some trouble with my CH3-R during this summer. I didn’t have time to find out what it was and it has been lying on the shelf for a few months now. Just a few days ago I had some time on my hands and I started testing what the problem was.
What happened was; I was controlling the hex with my laptop and a USB to serial and it suddenly went limp. It struggled to stand on its legs and just gave in. Each time I switch it on the servos reacts a bit initially but then go limp.
I made a few searches on the forum here and I found a few topics with the word “limp†in them. Mostly they refer to the logic and the servos being powered from the same source causes short drops in the logic voltage and the microcontroller resets. Now I don’t think that is the problem here. I have always powered the VS and VL separately. VS is powered from a 6V 3300mAh battery and the VL from a 9V battery. And the VS=VL jumper is open(no jumper).
I disconnected the BotBoard II from the SSC-32 and connected my USB to serial cable directly to the SSC-32. I put back the TX and RX jumpers on the board. Changed the baud jumpers to 115.2k. I downloaded the Lynx SSC-32 terminal and changed the setup in the program to the right COM-port with 115200/8/1/none/none. I don’t know about timing settings so I have left them as they were. Next I started sending different commends to the SSC-32 like the All=1500 or commands like #5P1200S5000. The diode on the board blinks respectively but none of the servos move. I then changed the baud rate to 38.4k both on the board and the SSC-32 and tried again. This gave same results. The diode blinks each time I send commands but nothing happens.
Now at this point I think that there is some issue with the microcontroller. I thought I would upload the latest Firmware to it. So I downloaded the newest Firmware for the SSC-32 (non beta)version: 2-03XE.abl. The program reads the current version so something is working atleast. I tried to upload the new firmware to the board with the Lynx Terminal. This dident work and I get a message that reads “Unable to update firmware with the software method you may check the power supply, communication parameters and serial connection†and I basically get the same message from trying the “jumper methodâ€. Now since the program managed to read what version of firmware is on the board I think that the serial connection and the communication parameters are ok. And if it is possible to retrieve information from the board I recon the microcontroller is working.
So what next? I started measuring all the voltages on the board. All the logic has correct power applied to them. However, I measured the terminals of the battery and it is only 2V! So I disconnected the battery and suddenly the battery voltage is 6V again. Then when I connect the battery again the voltage slowly goes back down to 2V. It takes about 10 seconds or so. I have made sure the battery is fully charged when I test this.
Well, I have written a lot and I am trying to figure out where to go from here. If any of you have some idea what might be wrong I am happy for any help and suggestion of where to go from here. Next I’ll probably disconnect all the servos and connecting them one by one to see if there is some malfunction in one of them. Maybe one of them has burned out or something.
Actually I appreciate that you gave a complete description. The first things I always suggest is power, but so far it looks like you have done all of the things I would recommend, but I will through out a few things to try anyway.
Have you tried replacing your 9V battery?
I still wonder about your 6v battery. You say that it was fully charged and showed 6v? I had a spare 1600mah battery that I charged three days ago and it measured something like 6.8V. If yours drops from 6v to 2v in 10 seconds, my guess is either you have a bad battery or something is eating a lot of current, like maybe one of the servo wires has been crimped and shorting out. In cases like this, I have a tendancy to first recharge/replace all batteries, if it is still a problem, I try unplugging everything from the SSC-32 and see if the voltage still drops. If not add one or a few servos back. If it looks like they are OK, add some more back, until things go bad, in which case you have a pretty good idea of where the problem is.
Updating firmware. I think this may only work if you are running at the highest speed 115.2K. I have never had the jumper version work for me…
Have you successfully updated the firmware on the V2 SSC-32 to the GP sequencer? I’ve tried several times, different chips, different baud rates, good power, straight RS-232 cable (no USB, unless it’s internal). No success with either software or jumper download.
I just pulled out my spare that test things with. I plugged it into my AC Transformer. I have the baud rate set to 114 (both jumpers). I downloaded the 2.04 beta file and had no problem updating from 2.03 to 2.04.
I was trying all sorts of baud rates, but none up that high. Must it run at that speed for some reason? I’ll try that speed next. I even went so far as to use my bench power supply vs. the 9V battery.
Yes i tried changing the 9V battery. Same results. So that is not the problem. And yes, fully charged the battery is like 6.9V. I have been thinking about getting a second 6V battery anyway so I’ll pick one up later today. I guess I’ll just disconnect all the servos and measure again.
And no, when the battery voltage drops there is no somke or funny smells.
On a sidenote though; The battery I have is pretty new. Only charged like 10 times or so. What could make it go bad anyway?
Allen you must be at 115.2kbaud for firmware update. This is stated in the manual, in the Firmware Upgrade in the first sentence…
Firmware Upgrade.
Updating the firmware is an easy straight forward task, but can only be done at 115.2k baud. Unlike simple VER or servo move commands, updating the firmware requires fast bi-directional serial communications. If you are experiencing problems with this please check over the serial port troubleshooting guide to ensure your serial port and or USB to serial drivers are optimized.
I’m sorry to have to be the one to tell you, your 6vdc battery is dead. Well more accurately one of the cells are bad. Think about it. You charge the battery (lots of current goes in over a relatively long time) you turn it on and all that current goes away in like ten seconds… If nothing is hot, then the pack has a dead cell and I doubt it’s really charging… The evidence screams bad battery to me. Sorry…
Like anything that is manufactured, you have what’s called manufacturing defects. It is very possible one of your cells rolled off the assembly line defective. Even if it worked before, its integrity was prolly teetering on the edge of failure until it just quit.
Thanks for all the responses. I finally got around to disconnecting the servos last night. And reconnected them one by one. The fully charged battery(same one as before) handled this very well. I used the same command set and same port on the SSC-32 to test all the servos one by one. I tested the movement in both directions and all the servos responded well. Except one. One of the servos only works in one direction. Can a servo shortcircuit/burnout in just one direction? Anyone experienced this before? The servo is definitely broken right?
Could this have made my battery go bad? Or just make the servo draw too much power and results in a voltage drop?
I thought about measuring the current the servo uses, but my measurement equipment doesn’t support 1A+ current.
I’ll pick up a new servo and a new battery today i think.
I have definitely seen a servo burn out half the h-bridge. Tried to do a payload lift test on an AH3-R and it couldn’t do it. The result was a burned servo. This did not result in a large current draw, but yours certainly could have. If it truly is the servo that drew the battery down it must have been smoking hot!
I had a servo work in only one direction before and it was a defective controller board inside the servo case. It went for working fine one day to erratically in one direction the next day. I was using a cheap wall adaptor that had selectable outputs and I am sure I killed the board from excessive voltage. It held up to the abuse for a long time before giving out. I now only use a 2 amp 6v Lynxmotion wall adaptor or the 6.0vdc Ni-MH 1600mAh battery pack.
I changed to 115.2K, and of course it programmed the first time! I’d guessed that it would have had to be slower, if there was a problem. No worries! Luckily I was not in a hurry, just trying to learn a little more.
I re-checked my PDF copy of the SSC-32 manual (favorite), and the info is not there. I did immediately find it (of course) in the on-line manual after reading your post!
Hi Allen, Where are you finding this PDF of which you speak? We don’t host a PDF of the manual. If someone else is, it’s not Lynxmotion approved, nor is it a good idea for obvious reasons.
PDFs are often quicker and more convenient for me to call up and view if I’m working on something. I realize it’s not the most up-to-date. Maybe it’s something about the layout of the document I like (just used to it?). Maybe you could make PDFs of the new manuals?
I’ll bet you could even make a book of all of the tutorials, etc. And sell them in a loose-leaf binder. Sherline does that for their manuals and tutorials, about $10 as I recall. I’d buy that. A CD would be appropriate for the release of a set of PDFs, although I do realize that LM is constantly re-writing, adding additional papers and updating them (I’d buy that too!).
Ah I see. Well there’s no problem here. I thought you were linking to it from somewhere else. We are removing them from our server for obvious reasons. lol
I haven’t gotten around to test the CH3-R with the new battery and servo. I have been swamped with papers due last week and this week. I think my teachers are deliberately trying to keep us from having a life besides school.
Alright. I finally got to change both the battery and the faulty servo. Everything works now… sort of…
I replaced the faulty servo with a temporary servo from the local RC store. It was a cheap FUTUBA servo i think. Problem is that it rotates the wrong way. (Its not mounted the wrong way. Just rotates opposite of the Hitec)
So now i got one leg doing opposite of what it should…
Is this an easy fix in the BotBoard program?
The FUTUBA servo is just temporary and i don’t want to go ahead and use time on fixing this if it is more than two lines of code needed.
