Repair of a Mettler PL3000 Part 2

[@xabaer]

Hi Steve. Thanks for that video. I am just restoring a broken Mettler PC4400 which looks very similar. In mine some of the flat springs that hold the vertical column in place are broken by brute force. The "massive chunk of metal" as you named it is a permanent magnet. The vertical movement of the scale-column is transferred by the scale beam into a vertical movement of a solenoid coil which moves in the air gap of this magnet very much like the moving coil in a loudspeaker. In my scale there is an optical sensor giving the mechanical zero position. The electronic sets the current through this coil to zero if there is no weight. If a calibration weight "C" is applied, the coil is moved and the current - i.e. the magnetic force - increases to a value of "I" until the mechanical zero position is reached again. Applying an unknown weight W = x*C requires a current of x*I to reach the zero position again. Basically the current is measured and shown on the display.

[@stevestrivia-bystevewagner4852]

That's an extremely well done explanation! Thanks Steve

[@miland2000]

Hey @xabaer thanks for the explanation im currently trying to fix a PE400 with the same issue of broken flat springs. Have you succeeded in fixing it?

[@xabaer]

@@miland2000 Hi, I have a small milling machine and I managed to remake one of the springs from an old saw blade. But then other more urgent projects came across and I had to postpone the other two springs. So, please ask me again in 4 weeks. But I am quite confident.

[@miland2000]

@@xabaer pfew thats quite some precision work. Do you happen to have any of the service manuals or are these springs available for order to your knowledge?

[@xabaer]

@@miland2000 I do not have a service manual - just an operation manual with quite a bit technical information available on internet. I don't know about the availability of these springs. I doubt however that they are available. I think however that their parameters are not very crucial for the operation of the scale. they must be flexible enough in the active direction so that they do not hinder the necessary movement of the column and strong enough across to hold the column in place. You might even make them from bronze sheet metal using a fine hacksaw and some needle files.

[@jjustinengineer]

Nice job, Steve. I purchased the Mettler PL3000 on eBay for parts a while back. I wanted to use it to measure the weight of filament for my 3D printer before and after drying the filament to see how much water was removed from the filament. I couldn't get the unit to zero. But, the give away was a very almost imperceptible flicker in the display. I took off the cover and measured the ripple voltage across the caps with my scope. The ripple was OK on all the caps except for one of the 470uf caps. It had a 10 volt ripple on the 30V supply! I replaced it and it now the unit zeros out. I'll probably replace the other 4 caps at some point as well. Hope this helps someone. Cheers!

[@kenokoci9853]

Thank you. I have just bought used pj 400 but the 0.00g keep blinking so would not stabilize. I am not sure what may i cause it. I can not access menu also. Can you help. Thanks

[@trackie1957]

This was helpful! I have a PE 3600 that I bought for FIVE DOLLARS ten years ago and it just stopped working. I bet it’s either the limit switch or the relay, but ten years in a Florida garage might have taken its toll.

[@seabreeze555]

Enjoyed the video as always Steve - Nice repair! I also miss the Electronics Trivia mailbags.

[@KallePihlajasaari]

The level mechanism multiplies the movement but divides the force.

[@jameshauser1507]

Happy to see you back Steve.

[@cavellsit]

Hi Steve. Thanks for that video. i have an mettler ME204 which LCD display shows “temperature sensor defected" after power ON, What are the repair solutions available? many thanks.

[@JohnJones-oy3md]

Wouldn't use it for reloading, but that's once nice scale. Can't imagine what that must have cost new.

[@csn583]

Of course not, unless you were reloading a cannon!

[@zakariatalbi]

Hi Mr Steve, thank you for this interesting video. I have a Mettler BJ3600 scale where the pan does not keep its initial position (Perhaps, it is a problem of the strain gauge / Test body or the support). So, how can you help me (Video or manual)? All thanks

[@stevestrivia-bystevewagner4852]

Sorry, I have the manual (I think) for the PL3000, but Operation only, not Repair. Good Luck! Steve

[@zakariatalbi]

OK , thank you sir

[@kenokoci9853]

Hi Mr. Steve, I have pj400 and i have an issue. The 0.00g on display keeps blinking so not stabilizing. What would be the reason? Just purchased used and i dont know nothing about it. I try to access menu but the button works only for on and of so i dont have access to callibration also. Any idea what would be the cause? Thanks

[@stevestrivia-bystevewagner4852]

Sorry, I can;t help. Good Luck! Steve

[@kenokoci9853]

@@stevestrivia-bystevewagner4852 the technician said looks like a sensor problem. At least can you tell where is this sensor located if you know? Thank you anyway sir. 🖐

[@trackie1957]

It can be as simple as moving air. That’s why the more sensitive balances have a cabinet to shield against drafts.

[@kenokoci9853]

@@trackie1957 what do you mean by easy? easy to break or to adjust? can you help?

[@trackie1957]

Sorry, I’m not an instrument technician, but I do know that if you have drafts moving around the room they will not allow the balance to stabilize. If you can remove the drafts or protect from them, you might have better results.

[@saminac7062]

I have a mettler Toledo model # XS16001L it’s giving me an error “program memory defect” error. Do you have a Video or can you guide me how to get rid of the error.

[@stevestrivia-bystevewagner4852]

Sorry, I don't work on digitally controlled systems, only on digital display systems. Thanks Steve

[@KallePihlajasaari]

You can find a service manual at ManualsLib titled "Mettler Toledo XS Series Service Manual" but it simply suggests replacing the terminal PCB for that error so not too much help for DIY. Tiny chance that someone who does SMD soldering and repairs phones could replace the flash memory IC (check the part numbers for which one) but it is likely that it contains code or parameters that are corrupted so you would need to copy them from an identical working scale. You would probably need to do some sort of factory calibration after to update parameters for your scale if they are stored in teh Flash. You may be lucky and the flash has only code and the battery keeps calibration parameters but there is no way of knowing.