My Roomba does not detect connection to the docking base

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My Roomba does not detect connection to the docking base

Postby mechatronicsman » September 27th, 2008, 1:42 pm

I have a Roomba 560, and straight from the store, It was not able to correctly dock. It started with general charging problems, but after a full reset, the battery was able to correctly charge with the charger plugged directly into the Roomba.

When I press the dock button, it correctly finds the dock, and homes in on the charging contacts. But when it is in the dock, it just rubs back and forth, and does not sem to detect the contacts.


I have cleaned the contacts, and ensured that they come in contact with the contact plates on the Roomba. I have also manually placed the charging contacts on the contact plates, but it does not start charging.

As I live outside US, and bought the Roomba at Frys in Las Vegas, Irobot told me that the warranty was void

Has anyone had the same problem and found a solution?
Last edited by mechatronicsman on September 27th, 2008, 2:18 pm, edited 2 times in total.
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Postby mrniels » September 27th, 2008, 1:56 pm

Hiya

Are you sure that the home base is actually providing the roomba power via the two connectors ? Perhaps you can measure the voltage?

When you unpacked the roomba, did you have any problems with removing the piece of plastic near the battery ? (as indicated in the manual)

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Postby mechatronicsman » September 27th, 2008, 2:16 pm

Hi Niels,
I swapped home base with a friend that have the same Roomba. And my homebase works on his Roomba, and his (working) home base did not work on my Robot. So I am sure it is the Roomba and not the Homebase.

Yes the plastic was removed completely. Also charging works perfectly if I plug the charger directly into the Roomba, so I guess connection to the battery must be as it shoud.

-bjorn
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Postby vic7767 » September 27th, 2008, 3:03 pm

mechatronicsman, since you have no warranty on your 560 you might consider disassembly and see if possibly you just have a poor connection on the PCB.

Here is a URL to the disassembly process, just scroll to the bottom of the page and then scroll up.

http://vic7767-robotmods.blogspot.com/
Roomba and Neato Mods, come visit: http://www.vic7767.com/
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Re: My Roomba does not detect connection to the docking base

Postby Gordon » September 27th, 2008, 5:03 pm

mechatronicsman wrote:I have a Roomba 560, and straight from the store, It was not able to correctly dock. .... it correctly finds the dock, and homes in on the charging contacts. But when it is in the dock, it just rubs back and forth, and does not sem to detect the contacts.
Correct. It is not 'stimulating' the HB to up-switch charging power. If you were to follow through on Niels' suggestion, you would find a high source-impedance 4+ Vdc across those contacts. That, plus the following (for future trouble shooting -- since you have already switched out HBs to show no fault there): If you 'short' the HB's pads with a proper resistance, the voltage will up-switch to 22.5Vdc charging level, and be able to deliver 1.25A {revised} current. The "proper resistance" for a Disco-HB is in the approx range: 3k < R< 6k (I would have to look for the exact value range).
...Has anyone had the same problem and found a solution?
AFAIK, this is a new one!

I know you are an experimenter, so here is something you may try. Cautionary words first: I assume the 5XX charging control circuit to be quite similar to Scooba & Roomba-Disco's. Refer to Schematic_1 (concentrate on zones at upper left) for insight. There, you will see the two charging-input paths which diode-converge onto the common charging-control section. I'm assuming, that portion of the 5XX's main_elex is very much identical to Disco's.
By Q3 of 2010 we developed a more accurate picture of the 5XX charging control circuit. Find that discussion in this post {added 110311}:
viewtopic.php?p=81792#p81792
Hence, it is on that basis that I suggest you use your bench power-supply set to 22.5Vdc, with ~ 1.5A{revised} current limit, then apply that source to the 5XX's charging pads. I know I don't need to say to you how important proper polarity IS (but, another 5XX troubleshooter may pass this way in the future ;-) ). If you go inside the 5XX, as vic7767 suggested, you will be able to determine correct polarity from what you see. If you don't have the 5XX opened for inspection, the polarity may be determined from the HB's contacts.

When you apply that test power, Roomba should quickly go into Charging Mode, and after a brief battery examination (by the MCU & firmware) charging current should ramp up toward 1.3A{revised}.

If none of that happens, you are going to have to trace out where the 22.5Vdc gets to, and determine why it stops there. Good hunting!
Last edited by Gordon on March 11th, 2011, 5:08 pm, edited 3 times in total.
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Postby mechatronicsman » September 27th, 2008, 5:05 pm

Thanks for the link vic7767. Ill check this out. And try to probe around on the PCB with my oscilloscope to try to trace the signal from the home base.
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Postby mechatronicsman » September 27th, 2008, 6:34 pm

Thank you so much for the detailed posting Gordon. I will try this.

I have now stripped down my Roomba to the bare PCB just to check for obvious assembly errors during manufacturing. All looks good.

I see a R79 missing. Could be one missing intentionally, or maybe one fallen off during soldering, and not detected by production final test. Need to check that further.

I will try your suggestions and se if I can hunt down any large bugs.. Just need a couple of hours precious (but oh so wasted) hours of sleep first.
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Postby mechatronicsman » September 27th, 2008, 8:31 pm

Impossible to sleep with Gordons tip running around in my head. So I went back to my workshop, and actually managed to find the problem!!! :D

The 22,5 V applied to the charging probe connector on the PCB just seemed to disappear immediately after the intake fuse on the ground wire.

The Roomba 560 has three wires on its charging plug (the one for direct plugging of the charger), one red (+22,5V), one Black (ground) and one brown. I found out that the ground of the home base charge pads led to this brown cable, and nothing else.

The brown and black wire are supposed to be connected inside the power connector of the Roomba when there is no charger plugged. And as soon as the charger is plugged this connection is broken. This ensures that plugging a charger directly, while the Roomba is charging in its home base, will disconnect the homebase charge circuitry (removing its ground connection).

However on my charge connector, this mechanism did not work, and the connection was permanently broken, even when the charge plug was removed. Therefore the home base charger input circuitry never had ground connection..

A little surgery, opening the connector, bending the parts into correct position, and closing the connector using epoxy solved it all.

So thanks for your tip for fault finding method Gordon. It saved my night (and my Roomba) :cheers:

PS! The shematic you made does not apply for the 500 series. I thought for a second I should make a revision, valid for the 500 series, but being a 4 layer PCB, totally covered in white paint, I found the task to be too difficult.

PPS!!! FANTASTIC work done on that shematic Gordon. I am extremely impressed
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Postby mechatronicsman » October 27th, 2008, 3:02 pm

In case anyone are interrested, or ever comes into the same problem, I have made a description of the repair process here:
http://hobbymechatronics.com/component/content/article/27-robotics/18-debugging-and-repairing-the-roomba.

-Bjorn
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Postby Gordon » October 28th, 2008, 2:40 pm

Bjorn, I must apologize for my lack of response these last 30 days! For some, unknown reason (quite often, a notification from the php-maven fails to reach my in-box), I lost track of your thread just after you posted about having...
mechatronicsman wrote:...I have now stripped down my Roomba to the bare PCB ...I will try your suggestions ... Just need a couple of hours... of sleep first.
..., so a month elapsed before I browsed back into it, last night, after you moved the thread from obscurity back to top-of-heap by posting your fault-finding and subsequent repair tactics. Top marks for that work, I'd say!

Not only were you able to sleuth out the manufacturing fault in that coax-power jack, but, by doing that, and, showing the jack to contain a user-activated switch-element, you have shown that iRobot chose to switch from diode-OR'ing of charging current, to mechanical-switch OR'ing!

Now, why would the Company do that? I had to ask myself.

After pondering the "why", for a few minutes, I could not discern any particular electrical advantage for making that engineering change. One may safely plug a second SMPS into a 4XXX's charging-jack, while a 'first-applied' SMPS is powering Roomba's Home Base--to which it is docked. Whichever SPMS outputs a higher voltage will be the one doing charging. If both SMPSs' output voltages happened to be well matched, the one powering the HB would fall back into idle mode (due to a small dV loss going through the HB) while the rear-connected SMPS takes over.

I then began thinking that cost of parts might have driven the change. I thought 'perhaps the cost of adding a switch to the power-jack would be less than the cost of the OR'ing diodes', so I set out to see if I could find that differential part's cost--jack with SW vs. jack sans SW.

Some googling was done, and I ended at a very nice site (http://www.cui.com) for anyone interested in these cheap, power / audio jacks & plugs, that are now so ubiquitous. Eventually, I converged on one that looks very much like the one you repaired. Here it is:
___________________ Image
...and a pdf Spec-Sheet of it is attached which shows pin-outs and internal switching.
PJ-009BH.pdf
(22.03 KiB) Downloaded 1331 times

DigiKey stocks that PJ-009BH at $0.48 (1 to 9 pcs.) {EDIT: P/N corrected, to provide 2.5mm dia. center pin, not 2.1mm -- apologies to all former down-loaders!}. So, that is one price I needed. But, try as I may, I could not find any CUI-power-jack without an internal switch!

Now *that* issue got me thinking down a side-path. That 5XX charging jack looks a whole lot like the jack used on all 4XXX Discos! Could the same jack configuration have been used on those machines?

After digging one out of the parts-box, then doing a few continuity measurements on it, the answer is YES!! Its the same bloody part! The switch-pin lug penetrates the small PCB affixed to the jack, but that lug is not soldered to anything (in the older Roombas).

At about that point in my detective-work I decided about the only thing to do now, is to see what those steering diodes cost. On the 4XXX PWBs, they are D30 & D32, 1N5401, and the largest diodes (DO-201AD) used in any Roomba.

Re-visiting DigiKey, I see the 1N5401 to be somewhat expensive: $0.65 (1 to 9 pcs.). Gol-lee! Its a no-brainer decision: Not only will $1.30 parts-cost (holding comparisons to unit pricing, since I have no idea what lot-sizes iRbt may procure) be conserved per robot, but some PCB-area (ca., 0.5" x 0.5") will be freed for other 5XX needs! The PJ-009BH jack causes zero cost-impact, its switch-function is already paid for!

----------------------------------------

On Schematic1, Bjorn, glad you liked it! There are ~10 others, which detail other Disco-Roomba-functions. I feel comfortable in saying 'iRobot designers were probably so time-strapped to develop RF & 'sonar' (I think) capabilities, that, minimal resources were allocated to re-development of functions which were known to work well. Surely, there may have been some beefing up here and there, many value changes will be found, and most all part-markings on the PCB will differ, but, the general schematic diagram for each section should hold fairly constant'. Hence, I think posted schematics "SchematicN", where 1 < N < 12 may provide better guidance to 5XX/4XXX common sections, than none at all! :-)
Last edited by Gordon on June 20th, 2010, 3:09 am, edited 2 times in total.
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Re: My Roomba does not detect connection to the docking base

Postby ribar » January 20th, 2010, 4:23 am

Tack BJÖRN!

I had the same problem with my Roomba 560.
I used your instructions to fix the problem.
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Re: My Roomba does not detect connection to the docking base

Postby trumperl » April 2nd, 2010, 9:29 am

OK, I have the same problem. I bend the connector and this fix the situation for a couple of days. BUt after that the problem is still there. Could you show how is the bending procedure to be more effective?
Would be interesting if you show what do you need to dissasembly only to repair the connector.
thanks
Luis
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Re: My Roomba does not detect connection to the docking base

Postby mfortuna » April 2nd, 2010, 10:12 am

I assume you fixed the jack to make the roomba work on the base. Have you plugged anything into the jack after fixing it?

Maybe you didn't quite bend it enough and vibration caused it to open.
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Re: My Roomba does not detect connection to the docking base

Postby trumperl » April 2nd, 2010, 10:21 am

mfortuna wrote:I assume you fixed the jack to make the roomba work on the base. Have you plugged anything into the jack after fixing it?

Maybe you didn't quite bend it enough and vibration caused it to open.


No I didn´t use the external connection. yes I guess is the vibration. So I want to access the connector to bend it better or glue it. What I need to dissably to access the connector?

thanks
luis
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Re: My Roomba does not detect connection to the docking base

Postby trumperl » April 2nd, 2010, 10:54 am

OK, I have the connector but it´s a black sealed box? How can I acces the inside where the contacts are? Or may be mechatronicsman break it?
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Re: My Roomba does not detect connection to the docking base

Postby mfortuna » April 2nd, 2010, 11:39 am

You can probably use an xacto knife to cut away some plastic so you can get to the bent piece.
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Re: My Roomba does not detect connection to the docking base

Postby TechGuy » April 2nd, 2010, 12:02 pm

trumperl wrote:OK, I have the connector but it´s a black sealed box? How can I acces the inside where the contacts are? Or may be mechatronicsman break it?

I had the same problem a few weeks ago. But I did not disassemble my Roomba. The contact can be accessed from the front where the charger plug goes in. I used a small jewelry screwdriver to go behind the curved spring and move it a bit toward the center pole. It was 6 weeks ago and my quick fix is still working!
Charging battery directly: 400 Series, 500 Series,. How to Desolder
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Re: My Roomba does not detect connection to the docking base

Postby trumperl » April 2nd, 2010, 12:17 pm

TechGuy wrote:
trumperl wrote:OK, I have the connector but it´s a black sealed box? How can I acces the inside where the contacts are? Or may be mechatronicsman break it?

I had the same problem a few weeks ago. But I did not disassemble my Roomba. The contact can be accessed from the front where the charger plug goes in. I used a small jewelry screwdriver to go behind the curved spring and move it a bit toward the center pole. It was 6 weeks ago and my quick fix is still working!

When you say to the center pole you mean to the plug or opposite to the plug?
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Re: My Roomba does not detect connection to the docking base

Postby Gordon » April 2nd, 2010, 12:47 pm

trumperl wrote:OK, I have the connector but it´s a black sealed box? How can I acces the inside where the contacts are? Or may be mechatronicsman break it?
No. He did not "break" the housing to get inside.

I see you have left a message for Bjorn at his site, hence, I am surprised that you ask how he opened the housing! IOW, you read all that he wrote about the process, before asking the question. Looking at his photos of the opened connector, it is easy to see that he 'hacked' his way inside. I think using a rotary-file, powered by a Dremel Tool under good hand control would be the way to cut away nearly half of the jack's housing.

Certainly, there is no decent way to bend any interior contacts until you have total access to them. Here are a couple pix for me to talk about:
JackCutaway.jpg

The above pic is a snippet from Bjorn's site -- clearly showing the hacked plastic, while the following pic is from the jack's mfr (CUI) data-sheet:
PJ-009B_CktDIagr.jpg
PJ-009B_CktDIagr.jpg (12.78 KiB) Viewed 56099 times

The data-sheet view (I trust you can mentally do a horizontal flip to make the drawing match Bjorn's photo's left-to-right condition) is useful to us because it numbers the contacts and shows the Normally-Closed condition of contacts #2 & #3. Those contacts are not touching in your faulty connector.

That view is important to us because I can more easily identify which contacts are immovable, and which one flexes. Of course, it is contacts #1 & #3 which are fixed, and only #2 flexes.

The difficulty in correcting the open-gap situation between #2 & #3 is the spring-arm of contact #2 must be deflected beyond the tip of #3 in order to permanently bend the arm of contact #2 -- to give it a firm electrical contact with #3. I am very surprised that TechGuy was able to gain success with his orthoscopic/jewelry-screw-driver trick!

Referring now to Bjorn's photo, IMO his red arrow slipped a bit to the left, since I think it should be pointing closer to the mid-point of the steeply angled region of spring-arm #2. You can see the straight contact #3 approaching that point from your left (in fact, in that photo #2 & #3 seem to touch!).

IMHO, I think what must be done to do a corrective bend of arm #2 is to first bend that straight blade #3 toward pin-#1, to provide some over-travel room for deflecting #2. Then bend #2 (at a point close to where it emerges from the plastic housing) towards pin #1. Finish by bending blade #3 so it is straight.

Check for pins' #2 & #3 continuity, and if OK, that is about as good as you can do,
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Re: My Roomba does not detect connection to the docking base

Postby trumperl » April 2nd, 2010, 1:34 pm

Gordon wrote:
trumperl wrote:OK, I have the connector but it´s a black sealed box? How can I acces the inside where the contacts are? Or may be mechatronicsman break it?
No. He did not "break" the housing to get inside.

I see you have left a message for Bjorn at his site, hence, I am surprised that you ask how he opened the housing! IOW, you read all that he wrote about the process, before asking the question. Looking at his photos of the opened connector, it is easy to see that he 'hacked' his way inside. I think using a rotary-file, powered by a Dremel Tool under good hand control would be the way to cut away nearly half of the jack's housing.

Certainly, there is no decent way to bend any interior contacts until you have total access to them. Here are a couple pix for me to talk about:
JackCutaway.jpg

The above pic is a snippet from Bjorn's site -- clearly showing the hacked plastic, while the following pic is from the jack's mfr (CUI) data-sheet:
PJ-009B_CktDIagr.jpg

The data-sheet view (I trust you can mentally do a horizontal flip to make the drawing match Bjorn's photo's left-to-right condition) is useful to us because it numbers the contacts and shows the Normally-Closed condition of contacts #2 & #3. Those contacts are not touching in your faulty connector.

That view is important to us because I can more easily identify which contacts are immovable, and which one flexes. Of course, it is contacts #1 & #3 which are fixed, and only #2 flexes.

The difficulty in correcting the open-gap situation between #2 & #3 is the spring-arm of contact #2 must be deflected beyond the tip of #3 in order to permanently bend the arm of contact #2 -- to give it a firm electrical contact with #3. I am very surprised that TechGuy was able to gain success with his orthoscopic/jewelry-screw-driver trick!

Referring now to Bjorn's photo, IMO his red arrow slipped a bit to the left, since I think it should be pointing closer to the mid-point of the steeply angled region of spring-arm #2. You can see the straight contact #3 approaching that point from your left (in fact, in that photo #2 & #3 seem to touch!).

IMHO, I think what must be done to do a corrective bend of arm #2 is to first bend that straight blade #3 toward pin-#1, to provide some over-travel room for deflecting #2. Then bend #2 (at a point close to where it emerges from the plastic housing) towards pin #1. Finish by bending blade #3 so it is straight.

Check for pins' #2 & #3 continuity, and if OK, that is about as good as you can do,


Welll, you are right. I discover after dissasemble my Roomba the text where he explain how opened the housing:)
I don´t have tools and I ám not too much skilled to open this housing withut break it.
And it seems a lot of people correct the problem with screwdrivers. I tried but I fixed only temporarily
I wonder if casino guy ( I have just sent it an email) sell this part alone.
Thanks Gordon for your detailed explanation

Luis
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