560 charging Err 3 or 27mv 0ma charge for Err 5

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560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 5th, 2013, 5:09 am

I have a 560 that I bought second hand.

The first time I tried to charge it i got err 3 but randomly it would Recovery charge or the full time and work perfectly for a couple of days.

I then bought a new battery and psu. Still the same issues.

I have a sci connection and when it trys to recover charge it reads out 27mv 0am 494c for 72 minutes and then err 5s.
My battery is reading 16.5 V 8 .87k on the thermistor


Attached are some pics of the motherboard.

U8 looks like it has some corrosion?

Also the metal can looking capacitor looks a bit crispy?

Can anyone point me in the direction of any additional diagnostics I could run or even the part names that i could replace from digikey?

Any advice would be appreciated thanks!
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby mfortuna » July 5th, 2013, 6:34 am

I can't really make out what is wrong with U8.The second picture shows a crystal, it is probably fine. The residue is probably adhesive used to hold the crystal down.

You could get some electric parts cleaner at an auto or hobby store and clean around U8.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 6th, 2013, 11:49 pm

Here is a better picture of u8

ahh crystal doubt that would effect charging.

Any ideas on what u8 does? or if i can test it?
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby mfortuna » July 7th, 2013, 6:10 am

U8 looks to be a ST micro 324 part which is a quad op-amp. The amount of resistors (which are used to set gain) around it adds to the possibility it is an op-amp. It could be used in the charging circuit. You would have to figure out how it is connected to determine what the outputs should be doing.

http://www.mouser.com/ProductDetail/STM ... 30nDj04%3d

It's cheap enough that you could try changing it. I would first clean around the area with electric parts cleaner and a brush
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby Gordon » July 7th, 2013, 3:50 pm

justinkau wrote:Here is a better picture of u8 ... Any ideas on what u8 does? or if i can test it?
I think we only know what one of the amplifier sections in U8 does for the R3-Roomba. See here:
viewtopic.php?f=1&t=16402&p=110710 to see what rr-members did to reveal what U8-A3 does.

I claim you can test that section by performing some stimulus input changes to Roomba while monitoring charging data via the SCI jack. In addition to your DMM, you would need a few assorted clip leads, a safe means to connect the battery's cell terminals to Roomba, but not connect the battery's thermistor contacts to anything, and several fixed resistors (or a variable resistance equal to the max value, or not much greater) spanning 2k ohms through 10k ohms.

But three other amps in U8 remain to be understood so their functions may be tested.

About two years ago I attempted to determine the functions that U8 supports, but gave up at that time after encountering too many tracks hidden by SMD packages, or chasing tracks to internal copper--where following becomes difficult.

But, this morning I compared U8's amplifier usage with a particular LM324 in the R2-Roomba and picked up some ideas to explore. If I can work in some electrical tests in the next couple days I will report any pertinent discoveries.

If you have not as yet fetched a datasheet for the LM324, you should do so.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby vic7767 » July 7th, 2013, 4:29 pm

When you enlarge the picture a bit, it appears that U8 did not get surface mounted very well. There are a couple of pins that look suspect for solder continuity with the surface or the board.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 9th, 2013, 4:00 am

I checked continuity on the pins and the surface mounts and it all seems good. I did put in a order for a new lm324.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby Gordon » July 10th, 2013, 2:54 am

I am now confident that the four amplifiers in U8 are assigned the task of signal conditioning sensory input voltages that are too large, too small for the MCU to handle, or may be subject to electrical noise.

Aids Sensing Total System Current:
U8-A1 and A4 condition the voltage analog of sensing total system current. A4 is connected as a differential amplifier 'measures' the tiny voltage developed across the system-shunt resistance of 0.05 ohms, and A1, adds positive offset to A4's output.

Aids Sensing Battery Voltage:
U8-A2, wired as a voltage follower, accepts a small fraction (~17.3%) of voltage VBAT and outputs the reduced signal.

Aids Sensing Battery Temperature:
U8-A3, wired as a voltage follower, conditions (buffers) the analog of battery-thermistor resistance and outputs the signal.

I think the only function in U8 that could contribute to causing err3 would be if the A1/A4 pair misbehaved in a manner that greatly reduced the reported current level.

Each of the three sections can be tested. Some hints for doing those tests, and other U8 details are now ready to view in this thread.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 11th, 2013, 12:01 am

ok heres what i am getting with a battery at 16.1 V and PSU connected showing charging err 3

U8
PIN NAME Voltage
1 A1Out 1.24V
2 A1IN- 1.24V
3 A1IN+ 1.24V
4 Vcc 7.91V
5 A2In+ .7V
6 A2In- .7V
7 A2Out .7V

14 A4Out 1.28V
13 A4IN- .1V
12 A4IN+ .1V
11 GND
10 A3IN+ 2.6V
9 A3IN- 2.6V
8 A3IN+ 2.6V


I was unable to get the roomba into charging mode. Do these voltages make sense?
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 11th, 2013, 12:04 am

oh and 9K across the battery thermistor
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby Gordon » July 11th, 2013, 1:18 am

justinkau wrote:ok heres what i am getting with a battery at 16.1 V and PSU connected showing charging err 3

U8
PIN NAME Voltage
1 A1Out 1.24V
2 A1IN- 1.24V
3 A1IN+ 1.24V
4 Vcc 7.91V
All good to this point; and, then BAD A2; but wait, is A2 bad or might the voltage divider in front of A2 be in trouble? All three A2 pins show the same voltage, and that suggests the amp is still operating as a voltage follower. Perhaps the R207,R208 voltage divider's tap is at 0.7 volt. If so, that would divert the failure from U8 to the divider components, one or both.
5 A2In+ .7V
6 A2In- .7V
7 A2Out .7V
A2 voltages should have been ~2.78V for a VBAT of 16.1V (assuming my derived factor of 0.173 is correct). Regarding A4, if you compare your three voltages with what I measured on my 560's PCA (-12@0.09V, -13@0.09V, and -14@1.32) the differences are in hundredths of a volt. I think A4 might be telling the truth.
14 A4Out 1.28V
13 A4IN- .1V
12 A4IN+ .1V
11 GND
10 A3IN+ 2.6V
9 A3IN- 2.6V
8 A3IN+ 2.6V
I was unable to get the roomba into charging mode. Do these voltages make sense?
A3 values look right, considering 'thermistor' resistance is 9k ohms.

I reckon that charging mode got inhibited by a (an apparent) too low battery voltage. 0.7 / 0.174 = 4.02 V for VBAT.

Before dismounting U8, I would dismount R207(475K) so its resistance and that of R208(100K) could be measured. Then calculate the division ratio based on those as-measured values.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 11th, 2013, 2:36 am

so i am waiting on some new solder tips in the mail and will remove and measure r207 and r208 hopefully in the next couple of days.

So it sounds like U8 is functioning but something is sensing a way too low of voltage on the battery, which totally makes sense because the robot would die mid clean saying it needed to be charged but then turn back on and run for a half hour.

What other components are involved or possibly involved in sensing battery voltage?

I would just like to throw in a digi key order for any suspect parts since shipping takes a bit of time.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby Gordon » July 11th, 2013, 1:00 pm

justinkau wrote:...What other components are involved or possibly involved in sensing battery voltage?...
I do not know for certain. I would only be able to guess based on what has been seen on the R2-Roomba's main_PCA. IOW, it is you that will have to explore the IN signal path to U8-5. In addition to the two resistors under suspicion, there is a ceramic bypass capacitor, C87, connected to their junction. I can't imagine any other components connected to that input line.

U8-7(OUT) could be traced all the way to an MCU pin. You might find a series resistance (say 1k) followed by a ceramic cap that can shunt noise to SYS_GND.

An argument can be made that IF the amp is still functioning as a closed loop voltage follower, then the problem with this circuit is confined to an input signal that is too small rather than, say, a heavily loaded output pin.

OTOH, it is also possible to make an argument claiming that U8's IN+ (pin-5) has (somehow) lost its high input resistance characteristic (tossing the fault back at the LM324) and now has an input resistance that is substantially less the the 475k ohms that R207 is supposed to exhibit. Naturally, a time drifted R208 value (to less than its nominal 100k ohms) will give the same effect. Live testing of A2's action could be done if you have on hand something like a 500k ohm potentiometer.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby justinkau » July 21st, 2013, 12:49 am

Ok finally got my soldering iron.. R207 was ~475K and R208 was ~100K.. i think ill try to swap in another lm324 later tonight to be safe and since i do not have a 500k pot.
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Re: 560 charging Err 3 or 27mv 0ma charge for Err 5

Postby Gordon » July 21st, 2013, 1:15 am

justinkau wrote:Ok finally got my soldering iron.. R207 was ~475K and R208 was ~100K.. i think ill try to swap in another lm324 later tonight to be safe and since i do not have a 500k pot.
While you have U8 dismounted it would be a good idea to brush the pads & area with 91% IPA to clear away the debris that could be seen in your photo. Also, a picture of copper tracks hidden by a mounted U8 might be useful.
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