Discussion Category:  Scintillation Counters

Power Supply and LED Startup Sequence Trouble

Hello all,

I have an LS6500 that I'm trying to get up and running.  According to stories, the power supply failed.  I had a new power supply installed, connected all the leads and here is where things go wrong.  The machine has a single S+/S- connector, while my PS has two, labeled V1 and V2.  The guy who installed the supply told me just find  way to connect both the V1 and 2 connectors to the S+/- lead and I'll be good to go.  I have created a connector to do just that, but have also tried just connecting on or the other V to it.  Either way, with the connection in place, it won't start.  The PS cuts out almost as soon as the switch is flipped.

I though maybe since it's just supposed to make sure the right voltage is applied to the wire, I could get away without it and here is my second issue.  Without the S+/- connector on, the machine seems to start up.  I don't see anything on the terminal, but the LED startup sequence begins.  but it seems to sit at the front end board test, and then reset.  It runs through the same sequence as before, somewhere in that sequence, the terminal beeps, and then it sits at the board test again.

Any ideas on what could be wrong and if I can get past this without paying someone to do it for me?

Many thanks in advance!

avatar placemark

Asked by

cbarback
Report this Post
avatar placemarkReply by
dpkleessr

Please attach pictures of what you are dealing with.  Was this a Beckman Coulter engineer that told you that or a 3rd party engineer?  I worked on the LS6000/LS6500 counters for over 20 years and even I'm not sure exactly what you are dealing with but I will try to help as I actually was a factory trained engineer as well as an instructor for teaching on the LS6500.

Don

Report this Post
avatar placemarkReply by
cbarback

Hi Don,

Thanks so much for the reply.  Regarding the engineer, he was 3rd party.  Since it seemed like a quick swap of the power supply, we decided not to go direct to Beckman Coulter.  As for pictures, I hope the following will help.

This is the S+/- connector coming from the LS6500.

And here is the connector on my new power supply.  YOu can see that there are two S+/- positions, V1 and V2.

Next, here is the board with the startup sequence LED's.

And here is a closeup of the LED's in question.  The startup sequence LED's are on the right, and the left is a bank on which ones for Run and DIAOP are steadily illuminated.

This is the sheet on the inside of the front panel, listing out the meaning of the sequence.

The sequence of lights from startup is 1, 2, 5, 6, 6&1, 6&2, beep, 7, hold for a while, reset.  I interpret this as: U52-53 ROM Test #1, U26-27 RAM Test #1, U52-53 ROM Test #2, DSP Init & Test, DSP ROM U2-U3 Test, DSP RAM Test, beep, Front End Board Test, hold, reset.

There is another set of LED's on another board that lights up, steadily indicating Right Trigger Flash, Left Trigger Flash, Live Time Running, and Count Running.  I have pictures of these LED's and their info sheet, too.

I hope this is useful.  Please let me know if there is anymore information I can provide.

Thanks,

Chris

Report this Post
avatar placemarkReply by
cbarback

Anyone have any ideas?  Thanks, all!

Report this Post
avatar placemarkReply by
dpkleessr

Sorry but I have been involved in a bathroom make over but I will take a look at what you sent and try to help you out later tonight.

Don

Report this Post
avatar placemarkReply by
cbarback

Thank you so much, Don!

Report this Post
avatar placemarkReply by
dpkleessr

I'm waiting on a callback from one of my former coworkers about the wiring on the new power supply assembly that you now have.  Do you see the LED's on the relay board mounted on the power supply indicating the you have +/- 15 volts and +5 volts?  The +5 volts is obviously there as the diagnostic startup LED's are working but not sure about the other LED's.  It is also not uncommon for the diagnostic LED's to sequence a time or two but they usually end up with a pattern that can be interpreted once they stop sequencing.  Whatever that pattern is will tell you what the defective component is and from what I reread it appear you may have a front end problem but please correct me if I am wrong.  The loss of the +/-15 volts would definitely cause a front end issue.  I will get back to you once I hear from my friend and please respond to my questions.

Don

Report this Post
avatar placemarkReply by
cbarback
Thank you, Don! I'll check those things as soon as I get into the lab in the morning.
Report this Post
avatar placemarkReply by
cbarback

I just checked on the LED's you asked about.  The +5 and +15 ones are fully illuminated, but the -15 and also the +24 appear to be only partially illuminated, about 50% as bright as the other two.  No other LED's on that board appear to be lit.  The sequence of lights on the other board remains unchanged, but the DIAOP LED no longer lights up.  RUN still does.

And yes, the sequence hangs and restarts the front end board position.

Thanks, as always,

Chris

Report this Post
avatar placemarkReply by
dpkleessr

Do you have a DVM to actually measure the voltages?  If what you are seeing is indicative of a problem with those voltages then you may still have a power supply issue and that would stop the FRONT END from starting up properly.  The DIAOP LED should NOT be on all of the time.  That would indicate that the diaphragm assembly would be open all of the time.  The ONLY time that LED should be on is right before the elevator is getting ready to raise or lower a sample into the detector assembly.

I am curious as to why the 3rd party engineer did not install and verify the operation of the LS counter after replacing the power supply before leaving your lab.  That is very unusual.  Still waiting on a callback so I will get back to you as soon as I hear from him but let me know about the actual voltage readings.

Don

Report this Post
avatar placemarkReply by
cbarback

Sorry for the delay, I had to find a multimeter from another lab.  I'm not very well versed in these things, so hopefully I did this right, but I tested the voltages between the specified voltage terminal and COM terminal on the PS.  The -15V read at -13.5V, and the +24 read at +22.8V.  I tested the others, too, and they were all pretty close to what they were supposed to be.  I'm not sure what the tolerances are for these things, so maybe that's not close enough.

As for why the engineer left without checking it, the answer is a mix of money and expertise.  He was contracted only to find and install the PS, since that is what my PI thought the problem was.  It seemed correctly installed, so he said he could try to diagnose the problem, but it would cost us just as much again and he wasn't even sure he could identify the problem.

It's not a great situation, I have to admit.  Hopefully we'll learn something from it...

Anyway, I hope this info helps!  Thank you!

Report this Post

Page 1 of 3