This is a discussion re the bad Accel, Gyro and Baro values that we're seeing with ArduCopter-3.1. The increase in the SPI bus speed from 500khz to 8Mhz has exposed a hardware problem on some boards. That hardware problem is that the 3.3V regulator has been blown so all sensors are running at 5V instead of the intended 3.3V.
How have these regulators been burnt out?
- Attaching a radio receiver or MinimOSD to the APM while the APM is only powered through the USB (see video below)
- Some clone boards seem to come from the factory with blown regulators. 3DR boards might also come with blown regulators although they do a specific check of the regulator as part of the regular QA process.
- It is not (as far as we know) actually caused by the AC3.1 software itself, it just exposes the problem. You could prove this to yourself by checking the 3.3V regulator (see video above) before and after the upgrade.
How can we fix the regulator?
Option #1: If it's a new board (so that it's less likely you burned it out yourself) you could report the problem to the retailer that sold you the board and ask for an replacement. If it's 3DR it's called an "RMA".
Option #2: if you're handy with a soldering iron you can replace the regulator yourself. On the APM2.5.2 (and higher) boards it's not that difficult. On the APM2.5 it's far more difficult.
For APM2.5.2 : TPS79133DBVR
For APM 2.5: MIC5219-3.3YML TR
How can I stop it from happening again?
Do not connect any devices such as a radio receiver, MinimOSD, GPS, etc while the APM is powered especially while powered only through the USB cable.
Attaching a 100uF capacitor across any of the APM's radio input's 5V and GND pins will stop the regulator from being blown by plugging in a receiver. video here!
There are very few reports of regulators being blown twice and no reports of it ever failing in flight.
Below are some graphs of the types of values that we are seeing on these boards.
Replies
Well there will always be a few buyers. Seems he sold 2 already:)))
It seems good to me. I found a capacitor that is similar to what you show in town but it was saying "Tantalum" on it. So that's why I decided to order mine online.
I got bunch of extra though. And I should sell the extras to other members...
Hello.
Unfortunately I also got a clone board with blown voltage regulator.. I am looking for voltage regulator in the UK but shipping for single regulator is 12-20 GBP :\ I think I have found an alternative, could someone verify that this regulator will work with APM 2.6? ebay link
Cheers!
If your original 3.3V reg is the same TPS79133 as the APM 2.5.2, which it probably is being a clone board, then no, it won't work.
The TC1017 regulator you link to needs pin 3 held high for operation, while the original TPS79133 needs pin 3 held low. The TC1017 will be in shutdown all the time on the APM 2.5.2 & 2.6 boards.
Paul
Paul,
thanks for mentioning TPS79133. I was able to find this regulator on ebay using this keyword. Finally reasonable shipping price!:)
Could anyone verify that this one is okay?
John -
If you're goinfg to go to the trouble of rewiring a non-original regulator in there, might as well do my LM1117-3.3 Regulator Mod and get a known more durable part. ;)
Linas -
That is the original part per the APM 2.5.2 spec; look on your board. MANY clone boards being sold right now are just a 2.5.2 with the internal compass omitted. If it has "2.5.2" screen-printed on the bottom, then it's one of those and this regulator will work. I'd have to do some research to find out for sure if the 3DR APM 2.6 uses that same regulator for sure. I'm in the middle of doing my Taxes, so sorry, that's a higher priority.
Not trying to pop your balloon, but the questions you're asking indicate that:
A)Your level of electronics repair knowledge may not be up to the delicate rework & soldering required, AND
B) You haven't even bothered to read the main article at the top of this forum. Yes, right up THERE, at the top of THIS and every page in the thread. ;)
You might be better off taking your board to someone with a bit more electronics repair experience. ;)
Paul
Yeah, thanks I have found the 2.5.2 mark.
My soldering skills are definitely too low to resolder this board, I am just looking for the correct component to pass my board with to some tech-repair guy ;)
I did read entire topic and the regulator advised in the top of the topic is called TPS79133DBVR and the one I linked is called TPS79133DBVT. That's the reason why I just wanted you guys to verify this.
Peace :)
Understood. Sorry, I think I came off a bit more brusque than intended. I guess I've gotten a little jaded after 30 years in the repair industry; let me tell you a little story...
I'm at work in my shop, and a teenage kid comes in with a list of parts and asks if I have them. I look over his list; it's all the parts to repair a common failure in the power supply in an Emerson VCR; there are a whole family of them known for it.
"Fixing an Emerson power supply I'd guess." I say, making small talk while I pull out a kit I keep on hand for them; a friend of mine sells the kits online and he lets me have them for a 10% markup over cost. I quite him a price that'll pay for two of them; still less than he could get them himself anywhere else.
"So... you need any solder or flux to finish the job?"
"Naahhh... there's plenty on the board already; I'll just heat it up and let it flow around the new parts."
I raise my eyebrows at that statement, then ask him "Yeah, you know your soldering iron can't transfer the heat properly unless you tin it with fresh solder, right?"
"Oh, that's no problem; I'll just use this...
...and heat up the whole board so it all flows back where it should be." he answers, grinning like he'd just got one over on the old TV technician.
I immediately put the parts back under my counter and answer "Go home, get all the bits of your VCR together and take it to someone who knows how to fix them before you burn your whole house down. And be GLAD if they quote you a price that's less than a new one, after the damage you've likely done."
Now.... consider this: I used to see at least one or two "customers" like him EVERY WEEK.
So please, forgive my crusty old repairman demeanor; I try to keep it in check, but I'm not always successful. ;)
mnem
"Yes, you may touch it."
Hey Paul, that was quite a quote...
Must be the grumpy English teacher in me ;-)
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