Mike's Forums

Versatronics RV series Pick & Place machines => RV Hardware => Topic started by: arvydas on April 16, 2016, 11:55:36 AM

Title: Power supply issues
Post by: arvydas on April 16, 2016, 11:55:36 AM
So I have this very old RV1S with toroidal transformer and veroboard based power supply circuitry. If you remember I mentioned that I have issues with random rotation of placed components. Been placing about 12 panels yesterday with about 200 components each and most of them had random rotation issues especially with 0603 caps. Came in today and the machine has been placing 4 5 panels so far with 0 issues and correct component angles. The only difference between yesterday and today is that I am working alone in a rather large office building.

Mike mentioned in one of his post that toroids work just fine unless mains voltage is unstable and I think I do have unstable mains when office building is full. What would be the best option to mitigate this issue? I'm thinking of either replacing the toroid and veroboard with a couple of high quality switch mode PSUs of just buy a high quality UPS that would also act as backup power in case of power failure.

I would probably prefer a UPS solution as it's very easy to install and I wouldn't have to bother with PSU rewiring. From what I've read on the internet, I need a high quality PSU that would also stabilize the mains power. Would any of you have suggestions on what I should purchase?

Thanks in advance for your help!

Arvy
Title: Re: Power supply issues
Post by: Mike on April 16, 2016, 06:12:59 PM
Might be worth replacing the electrolytics first.Also beefing up the internal supply wiring - someone mentioned the supply is wire point-to-point through all the driver boards with the crappy IDC connectors - may be a simple case of star-wiring back to the caps  with better connectors.
 For UPS check it's happy driving a big transformer - you'd probably need a proper sinewave one, online so it acts a a voltage stabiliser.
 
Title: Re: Power supply issues
Post by: arvydas on April 16, 2016, 06:26:30 PM
Already replaced the electrolytics on the power board and did the rewiring, but that didn't help much. Placed almost 4000 components today with minimal rotation issues. Yesterday with identical setup had componwnts rotated all over the place...
Title: Re: Power supply issues
Post by: phonoplug on April 16, 2016, 09:35:59 PM
Personally I think you're barking up the wrong tree. I'd check the air hole through the tool is completely clear. Any small obstruction that reduces vacuum pressure can result in random rotations, and I've found this primarily affects ceramic capacitors (I work with 0603 mostly).

I use one or two (if they fit) strands of 7/02 wire to clear out the hole.
Title: Re: Power supply issues
Post by: Mike on April 16, 2016, 11:37:39 PM
Wouldn't hurt to stick a DMM on the DC rail on min/max record.
Seems like the rotate axis is the one least likely to be affected by power issues as it's carrying no real load.
If the stepper is slipping, you'd also see tool unload failures.
 
Title: Re: Power supply issues
Post by: arvydas on July 13, 2016, 11:56:04 AM
Decided to get to the bottom of this as I have been using the machine a lot more recently. I still have this annoying buzzing sound as mentioned a while back especially when the machine goes full speed. I beefed up all power cables (like to an insane level), replaced all electrolytics, checked all the wiring, tested hybrids with multimeter and everything seems in a solid shape however the buzzing just wouldn't go away! Hooked up main power rail to a scope and just as Jason reported in one of my other threads I have a nice 4V ripple and a voltage drop of 7V on occasions just by running warm up procedure. Can't hook it up to a bench PSU to test the theory as mine goes only up to 20V. I want to completely get rid of the toroid and the crappy veroboard and replace them with proper switch mode PSUs.


Thanks for all your help!
Title: Re: Power supply issues
Post by: phonoplug on July 13, 2016, 11:26:51 PM
The power supplies are long obsolete. I checked them out a while back. Made by Lambda, part number ZWS120PPF-36. I'll attach the datasheet. No doubt you can find something similar but the only thing to watch out is how well any replacement handles the surge requirements the motors may need. From experience that's not something you can glean from datasheets, you just have to try it and see.

The machines that use them do indeed have two. From what I can tell each one powers one high power drive (presumably X and Y) and one low power drive (presumably R and Z) but I don't know that combination it is. I may have something sketched on paper somewhere.
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 09:59:44 AM
phonoplug, thanks! You are amazing :)

I ordered a 10A lab power supply yesterday just to test the theory that PSU is causing all my troubles. Have been shopping for a permanent solution around so thanks very much for the tips! I'm even thinking of getting 3 power supplies: one for X, one for Y and one for R+Z. My only concern is whether I need any additional set of circuitry which is on the veroboard between each PSU and motor drivers. I'm good at MCUs, but motor drivers and their power supplies is something new to me.
Title: Re: Power supply issues
Post by: phonoplug on July 14, 2016, 10:06:58 AM
I'm not entirely sure that that bit of veroboard circuit is exactly. I've got something similar in my machine though they did manage to progress to a proper bit of PCB by the time mine was built (hurrah!). What I would say is that the Sanyo-Denki motor control boards do all the clever stuff so I wouldn't worry too much. The power from your 36V power supplies goes straight to these drive boards so this little extra circuit is probably providing relatively low current power for other parts of the machine (quite possibly power for the arm control board and fid LED ring, but don't quote me on that).
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 10:30:35 AM
Yes, I think you are right! I'll reverse engineer the veroboard to make any sense out of the circuit.
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 12:56:15 PM
Ok, looked through the datasheets. One of the amazing features is "Low Cost!!" :) Wonder why just two exclamation marks? 8)

Anyway, found a few power supplies that should be suitable. They are rated at 9A nominal output current and have way more advanced features. The ones that originally came in your machine seem to have a feature for "Applicable to peak output wattage 200%" which sounds dodgy... There is also a limitation of 10s duration at peak current. I think that's why they are sort of suitable for the machine as all steppers do not run at 100% all the time and you just get power spikes when the arm moves around.

If I stick power supplies with nominal current way above required by the machine I think I should be on the safe side. Plus I'll be putting 3 PSUs instead of just two.

Having had so many power supply wiring problems with this very old model I just want to completely get rid of this issue and have the machine running at full speed reliably. I really like RV1S, just hoping that one day I can find an RV4S for an upgrade :)

Fingers crossed as I should be receiving a lab power supply today so should be able to check really quickly whether it's actually PSU problem. Will keep you updated.
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 02:36:21 PM
Just hooked up the machine to a lab power supply. To be honest, it's the first time I heard it running so smoothly! ;D
Title: Re: Power supply issues
Post by: Mike on July 14, 2016, 03:05:02 PM
Anyway, found a few power supplies that should be suitable. They are rated at 9A nominal output current and have way more advanced features. The ones that originally came in your machine seem to have a feature for "Applicable to peak output wattage 200%" which sounds dodgy... There is also a limitation of 10s duration at peak current. I think that's why they are sort of suitable for the machine as all steppers do not run at 100% all the time and you just get power spikes when the arm moves around.
Well sounds dodgy grammatically - Chinglish? Don't think I'd ever buy a PSU from a company that can't write proper specs... I usually use TDK-Lambda, and never anything cheaper than Meanwell.
There are some very good PSUs ( e.g. PULS) specifically designed to handle short peaks ( and with intelligence to enforce it by shutting down if exceeded for too long) - obviously this is for thermal reasons, but it indicates that the magnetics are working comfortably inside spec.
For this type of application I'd go for a PSU that is rated significantly over the required load to ensure that there's plenty of margin.  Something with active PFC is probably also a good idea as this ought to be able to deal with surges better.

For dual PSUs it would seem to make teh most sense to have aone hogh and one low load on each, to spread it evenly.

Quote
If I stick power supplies with nominal current way above required by the machine I think I should be on the safe side. Plus I'll be putting 3 PSUs instead of just two.
One, honking big PSU may be a cheaper and more effective approach. You're rarely going to get a peak draw on all loads at the same time.
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 04:08:37 PM
Mike, I was considering TDK-Lambda, but decided to try out Meanwell. Considering that TDK-Lambda are priced £200+ for the specs needed I ordered four RSP-320-36 for £44.50 + VAT each. They have PFC and with 8.9A max rating each they should be more than enough for the requirements of the machine. Here's the link to the product page with specs:

http://www.ecopacpower.co.uk/mean-well-power-supply-rsp-320-series-150w-320w-3-3v-48v-8693.html (http://www.ecopacpower.co.uk/mean-well-power-supply-rsp-320-series-150w-320w-3-3v-48v-8693.html)

They have higher spec alternative twice the price, however there is a 2-3 week lead time which I can't wait. I decided to go with multiple PSUs in order to distribute the load as I think it will be healthier for the motors to be on separate power supplies instead of just one. Motors are rated at 1.5A so it may seem like an overkill, but I want to upgrade the machine once and forget about it!

I really can't wait to see my machine working properly probably for the first time since I got it!
Title: Re: Power supply issues
Post by: arvydas on July 14, 2016, 05:09:02 PM
I think I've got the veroboard reverse engineered now. It's basically a DC-DC power converter that drops the 36V to 12V for the LEDs on the fiducial correction camera. That's pretty much it. The motor controllers essentially don't use any of this. They are powered like this:

Mains Power -> Toroid -> diode bridge -> 12000uF cap -> motor controllers

 :( :o ??? >:(

Mains power in the nineties must have been very stable when they were designing this machine...
Title: Re: Power supply issues
Post by: arvydas on July 15, 2016, 03:50:03 PM
Just installed new power supplies. Rewired pretty much everything power related ensuring that the PSUs get beefy supply wires and 20 AWG for the motors from PSUs.

PSU1 - X axis
PSU2 - Y axis
PSU3 - R + Z axis

What a difference! The machine runs smoothly and so quiet now! I used to get annoying buzzing just by using test controls to move the arm by 1500 and now it's gone.

Need to sort out the LED power supply and all should be done and dusted. BTW, the veroboard powered the LEDs both for fiducial correction and vertical facing static camera.

Thanks for all your help! Will be doing board placement next week to put the machine to a real test.
Title: Re: Power supply issues
Post by: Mike on July 15, 2016, 06:23:36 PM
I think I've got the veroboard reverse engineered now. It's basically a DC-DC power converter that drops the 36V to 12V for the LEDs on the fiducial correction camera. That's pretty much it. The motor controllers essentially don't use any of this. They are powered like this:

Mains Power -> Toroid -> diode bridge -> 12000uF cap -> motor controllers

 :( :o ??? >:(

Mains power in the nineties must have been very stable when they were designing this machine...
The motor drivers should work in constant-current mode, so supply voltage variation shouldn't be a big deal as long as it is high enough.
Title: Re: Power supply issues
Post by: Mike on July 19, 2016, 12:22:18 PM
Mine has 2 big toroids, maybe this was the solution they used to improve things. During motion the voltage doesn't drop below 33v
Title: Re: Power supply issues
Post by: arvydas on July 19, 2016, 12:37:55 PM
Mike, I noticed your two toroids in one of your videos. Guess if it works for you then there is no point in upgrading.  :)

Replaced the veroboard with a proper 12V power supply for the LEDs which seems to work great. Doing final update to the machine and installing fast blow fuses as per your recommendation in one of the threads. Measured all axis power draw and here are the MAX readings:

Z - 0.97A
X - 2.32A
Y - 2.23A
R - 0.90A

Bought a bunch of fast blow fuses from Maplin with the following ratings: 1.6A, 2A, 2.5A, 3.15A, 4A and 5A. Which ones would you recommend placing on each axis? Don't want to go too low in case my measurements were incorrect, but would also like to be on the safe side in case of a short to ground like you had. Going to be placing fuses on each axis separately.

This actually raises anther concern. Let's say one of the fuses on Z axis blows for any reason. Then the whole Z axis will drop and the head could start smashing into anything on the machine while X and Y are still operational. Same thing applies pretty much on any of the axis. Is there any way to detect that a fuse has blown and there is not power supplied for the controller in order to shut down ALL axis immediately?
Title: Re: Power supply issues
Post by: Mike on July 19, 2016, 02:02:59 PM
A crude but effective way would to be to put a relay powered by the fused Z supply and have the contacts disconnect the step inputs to the X & Y axes.
TBH i'm not sure I'd bother with fuses, especially with a switchmode supply, as that  will shut down pretty quickly if overloaded.
The only reason I added fuses is that I had a blown hybrid that looked like it was probably caused by a wiring short but I never found the root cause, so it was just insurance against that. Also at the time I didn't have the stock of replacement hybrids I have now.
I'm not aware of enyone else seeing blown hybrids , so adding a fuse could actually be more risky, unless you add protection to stop the other axes. 
Title: Re: Power supply issues
Post by: arvydas on July 19, 2016, 02:24:28 PM
Hm... wish I had your advise before I installed the fuses :)

I currently have 1.5A on the R and Z each and 3.15A on X and Y each. Just ran the warmup procedure and all seems well, but the risk exists. Will try to find out if I can find some sort of safeguard to shut everything off automatically if any of the fuses blow. I'm currently looking into using an Arduino with three relays. I would rather have the fuses in place just because each PSU is rated at 9A and the total drawn from each one looks like not going to be more than 2.3A. If I understand correctly when there is a problem, PSUs would shut down only after the current reaches 9A and I certainly don't want that!

Title: Re: Power supply issues
Post by: Mike on July 20, 2016, 12:12:58 PM
Hm... wish I had your advise before I installed the fuses :)

I currently have 1.5A on the R and Z each and 3.15A on X and Y each. Just ran the warmup procedure and all seems well, but the risk exists. Will try to find out if I can find some sort of safeguard to shut everything off automatically if any of the fuses blow. I'm currently looking into using an Arduino with three relays. I would rather have the fuses in place just because each PSU is rated at 9A and the total drawn from each one looks like not going to be more than 2.3A. If I understand correctly when there is a problem, PSUs would shut down only after the current reaches 9A and I certainly don't want that!

Why the arduino ?
Keep it simple - just use relays to interrupt the step signals. make sure you use relays designed for signal levels and not power.
Title: Re: Power supply issues
Post by: arvydas on July 20, 2016, 12:48:35 PM
Interesting idea. Mine was pretty much the same, except I wanted to cut the power with relays to each VCC-X, VCC-Y, VCC-RZ. Is this what you have in mind?

IN - signal wires coming from the connector to the computer
OUT - signal wires going into the Sanyo-Denki boards
VCC1, VCC2, VCC3 - separate PSUs I have
VCC-X, VCC-Y, VCC-RZ - power supply wires to Sanyo-Denki control boards

(http://agileinnovative.co.uk/other/versatronics-relays.png)
Title: Re: Power supply issues
Post by: Jason on July 22, 2016, 07:14:55 AM
Why not just put the relay output in series with the door interlock?
Title: Re: Power supply issues
Post by: Mike on July 22, 2016, 10:14:59 AM
No need to do anything with the R axis.
I suggested interrupting the step line rather than the power to the drivers to avoid anything that might cause power issues or contacts sticking.
Totally forgot about the interlock (has anyone not bypassed this ? ) Not sure what it controls - it can be overridden by the software for setup so probably not ideal.
Title: Re: Power supply issues
Post by: arvydas on July 22, 2016, 02:15:19 PM
Jason, mine has only a switch for the front door which lifts up to access the pick and place area and that only slows the machine down, but does not stop it so not ideal. It does not have any other door interlocks.

Mike, makes sense regarding contacts sticking. I would go with very high quality relays anyway.

On a side note, placed more than 6000 components yesterday with absolutely perfect placement at full speed! Had so many issues and now they are all gone: I can just start the machine and leave it to do it's job while I'm working on other stuff instead of constantly standing next to it and monitoring.

I have a few things still on my list to do:

* Rewire the connector on the box for feeders. The 220V wires going inside the box directly to the feeders are just too thin. I think the whole machine was wired with something like 28AWG for power and data wires. Already received the parts and crimps from RS so that's going to be my next mod before working on the next batch of PCBs.
* Feeders need servicing. Already received new O rings suggested by Mike so hoping that it will improve the performance. Will do some cleaning too. Feeder disassembly is a bit of a pain. Will see how they perform after I rewire the connector though. Current symptoms are: failing to pull back the cover tape, jumping back after index.
* Do the power shut down mod when fuse or PSU fails.
* Not sure if needed, but I would like to add a few PC cooling fans inside the box to cool down stepper motor drivers. They do seem to get very very hot... Machine works fine though.

BTW, this is how the main wires to the diode bridge looked like before I decided to start modding the hell out of that box...

(http://agileinnovative.co.uk/other/versatronics-wiring.png)
Title: Re: Power supply issues
Post by: Jason on July 24, 2016, 09:26:23 AM
Totally forgot about the interlock (has anyone not bypassed this ? )

Hehe, mine is bypassed so I forgot it's only a slowdown not a stop.
I would suggest in series with the emergency stop but then the Z is likely to drop.
Breaking the step lines might not help in a overcurrent situation.

I'm just about redo all the power on mine as I'm still not happy with it.
Title: Re: Power supply issues
Post by: trev on February 17, 2019, 03:38:15 PM
Read this thread after troubles with my vacuum and thinking that maybe I could do with a power supply upgrade anyway.

Have many people replaced the power supply in their RVs?

Trev
Title: Re: Power supply issues
Post by: Cubik on February 18, 2019, 02:01:46 PM
I have an RV4S that you could buy if you are interested..

I intend to sell it serviced and haven't started it yet but will get on with it if you are interested. PM me.

Paul
Title: Re: Power supply issues
Post by: trev on February 18, 2019, 02:25:33 PM
Hi, I did PM before and you said you did not receive it. I also sent you an email but was wondering if that hit your spam? Maybe you could send me an email at and see if that works?

trevor AT tswelectronics DOT co DOT uk

Thanks

Trev

Title: Re: Power supply issues
Post by: spiyda on February 19, 2019, 12:20:34 AM
On my twin toroidal power supply, I had some problems with supply to the house dropping below the legal voltage
Once it dropped below 200V, which was unacceptable and caused all sorts of issues.
so I fitted one of these APC Line-R 1200VA Automatic Voltage Regulator - LE1200I
It solved that problem instantly
Since then western power faitted a voltage monitor and within a few weeks of seeing the readings, dug the road up and fed our place from the other end of the line and voltages are all within spec so I guess that bit of kit is redundant.
Title: Re: Power supply issues
Post by: trev on February 19, 2019, 12:32:48 AM
Thanks for the info.

My unit is a twin toroidal so sounds like I do not need to worry at this stage about a new power supply. I may well measure the 12V line and see how it looks.

Trev

Title: Re: Power supply issues
Post by: Mike on February 19, 2019, 11:09:57 AM
Probably wouldn't hurt to replace the 20+ year old electrolytics