RI-RFM-007B-30 Failure

Hello Wayne/David... we have operated many,many dozens of MB2+rfm007 modules continusiously 24 Hour a day 7 day a week for 12 to

+24 months and I can only account for 1-2 of them failing (Lightening strikes and board corrosion were to blame)... we cannot complain about reliability

I am "hoping" your failures are due to either operating the coils off-resonance or that you are using ferrite rod aerials which are being driven into magnetic saturation...both of these matters will cause "excessive" current drain and therefore Regulator-chip overheating into failure.

we too will be shortly getting 32  Readers....if in your 42 there are early failures...you can sense or shared concern.

I am "also hoping" you are not the recipient of a cluster of "factory faulty units"...because we could be next to see your failures...and we are about to buy a lot more of the MB6/RFM007 readers.

To guide us, can you tell us where and when you brought these faied units from... so as to clear the suspicion of faulty manufacture. (we are in Australia).

Another cause for overheating into failure can be if the coil is up against some metal conducting surface such that induction heating of that foreign surface is again causing excessive current drain, even if the coils were resonated in "free space".

Both of you are observing something that we have not seen and now we are worried...

We have seen failed units caused by moisture stimulating visible corrosion of PCB tracks...I have seen at least one failed Regulator chip...how can we help you pin-point the cause of your failures, it is in our common interest.

I assume you have not used S2-Utility to have excessive heating by long transmitt pulse durations with too short a gap in between bursts, ie duty cycle abuse. Is the reader-pair inside an enclosed box...are you in a hot desert environment????

Is you power supply "dirty" or shared by other electronics...are there induced "inductive spikes on the battery line????

Also, the RF duty cycle can be changed to also lead to overheating of the regulator. Are you using 12 or 24Volts (they work down to about 7Volts)....we use 24Volts always with no identifable failures.????

Can you better describe how you are using these modules?

Kind Regards

Ray

Sorry Wayne .... I may have been too hasty in suspecting "miss-tuning" as a cause for regulator chip overheating....it seems obvious this 5V regulator is supplying only the digital circuitry on the MB2/6 therefore the "fault" probably lies in the digital areas not the RF areas (ie the in with the push-pull FET drivers of the RFM 007..etc).

In all likelyhood you are seeing a fault condition on the MB6 board not the RFM007 board....maybe?....therefore it looks more now like some common faulty or weak component is probable and therefore our worst fears are taking hold.

I do not have a schematic for either board and have asked previously if TI would give me one....this is a difficult thing to diagnose faults a \t board level without a schematic...I suspect TI have issues with people copying or cloning.....

I assume because you have 42 modules for some application, that you are well familiar with both modules....perhaps you are one of the rare few who can decipher the blandness of S2-Utility ( I still need a Rosettastone to come to grips with S2)...I assume you are no novice and have a;lready have delved into cause and effect on this matter....this now makes me even more nervis.

Regards

Ray

My apology Wayne for being too persistent....like you we cannot afford to send out suspect product (which includes RFM007/MB6) to "far-flung-customers"....it is almost a business "death wish".

I will urgently get  +10 sets, and do some prolonged tests (switch on and leave on to failure...)

What I propose is to first only power up only the MB6 off 24V and let 10 sit on the bench and see if any fail...my thinking is towards a component weakness in the MB6, as before it the MB2 "seemed indestructible"

I will repeat this (or get more modules to fast track this episode) by adding now the RFM007 and again watch for failure...at least by this mechanism we can identify the culprit board.

How many minutes/hours/days/weeks did it take for each of your six boards to report faulty?...what voltage do you run them at?

Are you aware of many other users with this fault?

Regards

Ray

I would appreciate it if you too could do a similar thing with your remaining modules (if you have any left).

Hi Ray

I've tried the fualty RI-RFM-007B-30 on multiple MB6 boards and have the same problem. I then tried a known working 007B on the same MB6 boards and it works fine, so it seems the problem is in the 007B's. I'm using a 24VDC 2A power supply. The units fail after 60 seconds. These units were brand new out of the box.

I've tried using a 9VDC supply and attaching a heat sink to the back of the 7805 DC regulator to disapate the heat which stopped it from failing. But the regulator still got warm.

The modules that are drawing 20mA are fine. The ones that draw 40mA plus are the problem.

Cheers

Wayne

Thanks Wayne....the 7805 has internal current limiting and "thermal shut-down"....so, do/does the faulty RFM007 repair itself after it has had time to cool down?

Are there any distinguishing labels/pcb text on the faulty boards to correlate them with failure?

is the MB6 running on the default settings?

where/what country are you?

what does your supplier have to say?

what have TI had to say?..

I am obviously anxious to see if the new boards in Australia are infected with this issue.

maybe you can send me a "faulty 007" for a second opinion... though I am sure you know what you are doing.

if you remove the aerial does this still happen?

what aerial are you using?

what is the quiescent average DC current flowing from the power supply with MB6 indefault settings?

can you identify where these faulty boards were assembled, I think there is a sticker? ( I am away from the workshop here for a while yet)

Kind regards

Ray

Wayne

Just in front of the 7805 is a two prong jumper, if I recall it is for earthing the board to a metallic supporting leg...chasis grounding etc....it is possible if the 7805 is bent over for it to "nearly touch" one of the prongs.....I don"t know what it would do, but is that all away from touching.

Plus, there is a switch bank on the board, the one with "switch 1" for programming (or was it on the MB6?) any how ....I ever only toggle SW1 ....look to see if the accompanying sw2,sw3 are in their default positions.....by the way I have often wondered what sw2 and sw3 actually do...do you know?

Yes, without a schematic we are doomed to fly blind....it would be nice to know a bit more.

Regards

Ray

Ray

I'm in Australia. My supplier referred me to TI and they then referred me to these forums.

Disconnecting the aerial (RI-ANT-G02E)  makes no difference.

The boards were made in Thailand.

"Switch 1" is on the MB6. No idea what Sw2 and Sw3 are for. I set it to default and made no difference.

I tested the MB6 alone. It drew 60mA. With the 007B mounted it drew 400mA. (Just realised i made a typo in my original post with amps reading)

I checked that the 7805 wasn't touching the jumper behind it. It wasn't.

Cheers

Wayne

Wayne

Does the board reset itself after cooling down?....is a failure irreversible?

Did the addition of a heatsink fix the problem into infinite time?....at least 24 hours continuous

With your "heat-sink" fix, did you notice any reduction in detection range? .... (is it low emitted power or low receiver sensitivity?

Can you monitor emitted field strength....(with some crude crystal-set detector)...for a comparison against what comes out of a good RFM007?

Put an old  AM Radio next to the reader and "listen" to the RFM007....try a good one then a bad one....compare what you hear.

David Thio reported this problem almost a ear ago...have you spoken to him...is he still here?....what came of his case?

See a thread below by Tayfun Onbasioglu....he is trying to replace the MB6 with PIC board...God help him if he has a faulty RFM007

Is your supplier ElectroCom?....will they replace your faulty boards...yet this still is a poor response to a potentially disastrous situation.

Perhaps we/I am your competitor.... no worries... this is like the blind leading the blind

What are you contemplating next?

Regards

Ray

Wayne

Sorry mate , I'll give it a rest soon.

This may be silly, but I have to ask.

Please confirm you are "testing" by alternating two different tags while the MB6 is in it's default "Normal Mode"

the green read led should acknowledge the proper crc checked tag BUT if you are using "Putty or Docklight or the like, to see the RS232 output then if you only have one tag to test with then after the first detection no more Ascii outputs will be seen...this is the same if you are in "Gate Mode".

Please confirm it is not "whoops! finger problems" you have, but a real apparent component fault...I had to ask.

Regards

Ray

Hi Ray

I've had another chat with Electro-com and they've asked me to send all the faulty units back. I'll keep you up-to-date. Thanks for your help.

Wayne

Hi Wayne,

sorry to hear that you are having trouble with this product. It is hard to make a long-distance diagnose so assuming you have done testing back-and-forth with the other working modules I would recommend to start an RMR process and return them through the distributor you bought them through.

Cheers,

Klaus

Hello Wayne/David/Klaus

Wayne, if you still have (42-6) FM007 modules, could use a hot-air -blower to overheat the remaining 36 (while they are running)...and report if any more fail or worse still do they all fail....can they be "pushed over the edge?"

It is cold here, and I still cannot be certain the failed few here share your "temperature correlating" problem, that is, you say the cooling by a small heatsink seems to fix the problem (faulty 7805?)... when I return we will also use an elevated heat cycle to pre-warm the boards.

ps. we we on the verge of getting the next 32 module sets from ElectroCom...thanks for "taking a bullet" for us...we are loyal to the TI product range, it has served us well...this is just a passing distraction

Klaus...do you know of a history behind this issue and what does RMR stand for?

Anxious Regards

Ray 

I experienced dealers are not eager to go for the RMR , I had to ask 5 times where to send the board to and all together it took me 4 months to get the module replaced under warranty. 

I never got any feedback about the modules under failure.  (DC/DC 7805 which heats up)

I can advice to buy the modules from RS-components or Farnell. They will replace faulty units without delay and they are even cheaper than my local sales agent in Belgium.

My conclusion is that the RI-RFM-007B-30 is not a module you want to use in any field tests!

I decided to use Agrident readers which have proven industrial stability. (but can not read MUSA tags)

David.

Ray,

thanks for your comments. I am not aware of any such problems in the past. Sorry.

RMR stands for Return Material Request, a term commonly used for returning faulty products.

BR,

Klaus Seiberts

Thanks Klaus.

"We" ...cannot bell this cat just yet.....I assume you are finding out who in TI is "aware" of this problem, and what caused it and what is being done to "fix" it....

Please find a quick way to reassure me about TI quality control ...our new designs using these modules are well advanced...we need certainty.

While I am waiting your reply....can you point me to where I can learn more what the "DIL Switches" on both the MB2/6 and RFM007 do....perhaps a comment on schematics could be also mentioned?

Kind Regards

Ray

Hello Ray,

I was checking the specs on the 78XX series regulators... the recommended maximum input voltage is 25 volts DC (for the 5 volt reg) whereas the others in the series can handle 35volts , in the past I have had issues with 5V regulators running hot on high input voltage, so maybe use a regulator that has a higher recommended input voltage?

Cheers

PK