I'm nipping down to Swindon one day next week, anyone in the East Mids want any bringing back but you will have to collect from me.
I'm not shipping out.
Price is Ģ12.99 for the PS, no other costs.
Printable View
I'm nipping down to Swindon one day next week, anyone in the East Mids want any bringing back but you will have to collect from me.
I'm not shipping out.
Price is Ģ12.99 for the PS, no other costs.
Aargh,
Cheers for the offer John, I would've done but paid for mine earlier. In fairness he only charged Ģ12 shipping for 2 units so it's all good.
John
Pop on in if for a mug of tay and knobs if you do, and i might even get some of those things you like so much in as well.
Will do and send a PM when I get a reply on times and dates.
No, I cant find it again either... but if memory serves (and I'll have to look when I get home) I didnt find it before but a near match - enough to give pinout and reference circuit clues... but I dont recall offhand what it was or where I found it...
*edit* might have been a typo.... UCC2895 datasheet
thank you anyway.
An older part perhaps? There is certainly enough info on the, what I suspect to me similar, ucc2884, 3884.
If I can track down a comparator feeding the opto-isolators then the switching chip may be irrelevant. You mention a second opto, could this be for over-voltage?
Output -> voltage divider -> comparator -> opto... if nothing else the feedback circuit could be replaced.... heh... maybe :)
Guessing again, the comparator - in custom chip or not - is running from +5v or +12v, so there must (-ish) be a voltage divider external to the custom chip/comparator etc.
Anyway, we know these are good for 42v.
Drivers that can cope with the full 56v are not so expensive (?)
On a personal note, if the worst comes to the worst, I now have the makings of +/-56v psu @ 500w which will make for a stonking sub-base amp :)
Some initial investigation:
PWM controller : http://www.digchip.com/datasheets/pa...C2895N-pdf.php
The interesting parts on the surface mount board are, guessing here as I've not buzzed things out or even applied power yet!!! :
Op-Amps : lm224 equivalents
Comparators: lm239 equivalents
Now I guess the fun can begin :)
well I got as far as setting up my test bed again yesterday to restart the investigation but got sidetracked (watching TV while probing 400V isnt a good idea)... This link gets you to datasheet and applications notes.
probing 400v at any time is not a good idea imo!
Anyway, that daughter board is a nightmare, everything is way to small and the board would be trouble to remove: I think I have the comparator outputs to the 2 optos, via 2 transistors so looks good :) The bad news is all the fun gubbins for this is behind the capacitor bank making it almost totally inaccessible :(
Undeterred, lol, I moved on to the inputs to the daughter board and here I may have hit the jackpot... maybe.. The op voltage is divided down by a factor of ten and fed to the daughter board. Yay. These dividers are on the main board and not surface mount. Yay. The bad news is there are two voltage dividers and I have no idea what the second one is for, then again I have no idea which of the 2 we need anyway.
Divider 1 feeds op div 10 (measured) to daughter board pin 12
Divider 2 feeds op div 10 (measured) to daughter board pin 8
You should be able to trace the resistors I'm talking about from these pin numbers.
If I'm right about the lm224 equivalents then pin 12 feeds to a unity gain op amp, pin 8 feeds to a different opamp that actually 'does stuff'. I've no idea what it does but it's not unity gain.
So, why two dividers and two opamps ? 1 to catch the default 42.9v and the other for the variable feature? I don't know. Do I need to change both? I don't know.
These boards were not made for easy disassembly so I've measured the divider resistors in circuit, of course the values measured this way do not match the values required for a div 10 series pair. Ho-hum. One resistor in each pair is big and easy to see - they are not quite under the heatsink and just behind the output coils, I can't see a ref number now the thing is back together :( -, so if you have reasonable colour vision perhaps you can let me know the value?
Anyway, before I risk life and limb by snatching the soldering iron from the coals (should be hot enough by now) I'd like your opinion on which of the two possible modifications would be most suitable...
1) Configure the psu so the variable range works over, say 43v to 47v (ish)
2) Configure the psu so the 'non-regulated' voltage can be set to XXv and the variable input can be ignored.
I'm off to try and find a zener...
Where did you think the optos are?
Ideally would want to be able to force the voltage down further, tho that might not be viable...
Where were you going to put the zener?
Since I've fried this board anyway I think I'll pull it to bits, get easier access to the parts....
A couple of hi-res images if needed ...
http://www.i2net.me.uk/files/cnc/min...oard-hires.JPG
http://www.i2net.me.uk/files/cnc/min...oard-hires.JPG
Back of the board showing the 2 optos (2 x 4 pins), the track feeding pin 20 (Error Amp) on the PWM and the 4 res making up the 2 voltage dividers. (ignore the pencil marks, they may or may not be correct!)
http://www.i2net.me.uk/files/cnc/min...0-Markup-1.jpg
Top of board, only 1 of the optos is visible.
http://www.i2net.me.uk/files/cnc/min...OptoMarkup.jpg
Close-up of output coils, one of the two large voltage divider resistors marked (R34). The large resistor from the second divider (R11) is right next to it.
http://www.i2net.me.uk/files/cnc/min...-ResMarkup.jpg
The zener is just so I can set up your test circuit... still not found one :(
My idea is to modify one or both of the voltage dividers by fitting parallel resistors, this is a nice easy modification and so long as we don't ask for the impossible the whole of the control circuit should play along with us :)
Example:
In fixed mode the op voltage is 42.9v and the voltage at the centre of each divider pair is 4.29 volts. This 4.29 is the critical voltage in fixed mode, the control circuit will do every thing it can to maintain 4.29 volts at the centre of the divider pair. If we reduce the value of the lower resistor in the divider then this resistor will drop fewer volts and the divider ratio will effectively increase. If we select a value that gives us an 11:1 divider for example, in order to maintain 4.29v the output voltage would have to be 47.19 volts. Yay, in theory :)
Reducing the value of the upper resistor in the pair reduces the divider ratio which should allow us to modify the output voltage range in variable mode.
What I don't know for certain is the value of the resistors in the pair, my colour vision is not so good so I can't read the value of R34 or R11.Once we know the value of one of the resistors we can calculate the rest :)
OK, going to whip the heatsink and daughter board off this dead one so i can get a good look... be back later...
Right, decimated the board lol
Attached is circuit diagram for the wiring to the daughter board. Q1/Q2 are the opto, the 6-way connector to the top left is the connection to the output connector. Also attached are pics of daughter board, will start tracing that through later this evening/weekend, and main board after decimation.
On the 6way, pin 1 is the control volts Ucr, pin 2 is SYSOUT, pin 3 is the 50v rail internal to the PSU (via temp compensation so can be used to control output voltage on load in a system), pin 4 and 5 I suspect are +/- voltages to the control board and pin 6 is common.
It is likely as ecat says that R11/R12 and R33/34 are the dividers providing upper and lower voltage control limits, why there are two isn't clear. Adjusting either R11 or R33 may not change the output voltage, but merely adjust the levels at which the SYSOUT function changes state... some experimentation needed there... but getting closer...
I was getting worried that you had probed the 400v line again!!
You have been busy. Indeed, R11, R12, R33, R34 are the ones I'm looking at, 9.1k and 1k make the 10:1 divider. Lovely. So, I'll stick a 10k resistor across R11 and or R12 and we'll see what happens. Why 10k? As my old man said one day 'it's always 10k', in this case it may, or may not, give us a fixed output of 47v. Good enough for you?
:)
501 1j in the middle od the daughter board is a variable resistor, I may twiddle it if I'm feeling brave.
All I know about the daughter board...Err, from memory :blush:
http://www.i2net.me.uk/files/cnc/min...arked%20up.jpg
Note to self: Work out how to do thumb nails
It's alive!!! Muhahahahhahaha
Whenever I put something back together I'm always delighted if it still works, from that point everything else is gravy :)
Ok, in fixed mode I now have 47v output :naughty:
First attempt was across R12, I don't know what it is supposed to do but it doesn't affect the fixed mode voltage.
Second attempt I used 9k4 in parallel with R34 and the result is close enough to my calculations. Always a good sign. Why start with 9.4k? Simple, I found a bag of 4k7s.
Calculations:
Top divider resister is 9.1k
We are changing the value of the divider resistor, call this value x.
Desired output voltage is op
Ratio is the ratio of the divider
These calculations are based on k ohms
op = 4.29 * Ratio
Ratio = op / 4.29 : Required Ratio
Ratio = (9.1 + x) / x
x = 9.1 / (Ratio - 1) : Required resistance
As we are creating the value x by placing a resistor in parallel with the existing 1k resistor we need a bit more maths. Lets call the parallel resistor rp.
x = 1 / (1/rp + 1/1)
rp = x / (1 - x)
N.B. In the case of THIS power supply, the existing resistor is 1k. As x is the value resulting from paralleling a second resistor, x will always be less than 1.
Ok, now to work through for my measured 47 volts:
47 = 4.29 * Ratio
Ratio = 47 / 4.29 = 10.956
x = 9.1 / (10.956 - 1) = 0.914
rp = 0.914/(1 - 0.914) = 10.63
Hum, 10.63k is not the 9.4k we expected, lets work the calcs the other way:
rp = 9.4
x = 1 / (1/9.4 + 1/1) = 0.904
Ratio = (9.1 + 0.904) / 0.904 = 11.07
op = 4.29 * 11.07 = 47.49v
Less than 0.5v difference, maybe my calcs go wrong somewhere or my meter is worse than I thought, but I think the result is close enough.
yes... but it could equally be setting the current limit! might be worth twiddling....
I've identified all the parts on the daughter board with the except of U102 and U105 which are just above the variable resistor, marked A012. All the other transistors on the board are generic NPN (1Bp = BC846) and PNP (3Dp = BC856) but these are designated like ICs - I have a suspicion they might be band-gap current sources or something...i dont think they are mosfets as these are designated 'Q' types elsewhere and diodes are 'D' (there are 6 generic small signal types and 2 zeners).
I've imported the diagram into Visio and populated it... now just putting in the links.... see attached WIP...
Guys, all this electrickery is terrifying! :confused::smile:
Keep up the good work!:beer:
That's some mark-up irving, thank you :)
It could be the current limit, it could be almost anything, lol. I'm just looking at the system as a black box controller and I'm especially trying to avoid that daughter board, I suspect it may be more clever than I am ;)
The current limit should be quite easy to trace. R30 is used to sense the current, this feeds to daughter board pin 7. I have no idea what d13 is doing in there.
That big daughter board VR has me puzzled, but you know what curiosity does to cats and ecat is especially suspicious of the intentions of the 400vdc lines.
@Tom,
Thanks for your support.
k, I'm off to kill some zombies :)
Hi,
How long it takes when yours power supply arrived?
I ordered a supply three days ago and nothing yet happened.
Usually ebay seller has sent message when you buy something, but he hasīnt sent anything.
Well its holiday season, he may be away. You are in Finland, he may have to sort out additional shipping. Why not contact him on eBay and ask?Quote:
Originally Posted by hmaki
Yes I have asked shipping time on eBay,but he have not answered yet.
iīm so impatient because that is last part and then I can test my machine.
You sound like Chinese origin,Hmaki...where abouts are you?
Have you emailed the seller? he could be on holiday/have problems??
Oops! pays to look at the last post.
Finland it will take at least 4 to 5 workin days to et to you...or more?
Ahh now that power supply looks familier to me, is it because that communications company i work for uses them to generate the 50v dial tone you hear every day when you pick up the phone (assuming you are not on cable that is, lol)...
Rick
Well its a Mineaba supply for telecoms, c 1995/96... no longer manufactured...Quote:
Originally Posted by Ricardoco
I knew it!! and maybe its not manufactured any more but they are still used, remember this comapany still has bakalite fixtures because they believe "if it aint broke dont fix it because the shareholders need the cash), they do replace them with farnell units when they go bang though....lolQuote:
Originally Posted by irving2008
Dont suppose you'd have any documentation on them?Quote:
Originally Posted by Ricardoco
Im not back at work till next week so i will have a look for you then (if there is i will have to send you some scans) although small there is a chance.. :)
Rick
I can see lots of rubbing of hands and faces being lit up here. :heehee:Quote:
(if there is i will have to send you some scans) although small there is a chance.. :)
I finally received my supply.Quote:
Originally Posted by Ricardoco
Now I wait instructions how I can rise supply voltage:)
It's early to bed for me tonight and a long day tomorrow, I'll see what I can do. I've tested a range of voltages BUT I cannot test at anywhere near full load so cannot comment on when the current trip will kick in. What voltage are you looking for?
Hi,
Irving:
Can you explain me how that schematic works on your first post in this thread?
Also I like to know what is this value on potentiometer.
I want to rise my supply voltage to 57V thats why I asking these questions.
BR
Juha
Juha,doyou know what you're doing? sorry for that but the pot is lablled as 1.5k variable.
Hi Juha,
I'm not great at electronics, but the usual way to write these things is to put the 'K' in the middle e.g.:
1.5K = 1K5
7.5K =7K5
I suppose this avoids costly mistakes if the small dot '.' is missed. My knowledge ends somewhere there . . .
I can't understand why he doesn't connect the suppy to whatever he wants 57volts for? the supply according to the pics Irving has posted,the first pic is showing the voltage output as 50v to 57.6 peak so it should be adaquate for his needs?
Hi!
It makes me little confused because I read that value 1V-5:redface:
But now voltage divider is almost ready.
Thank you very much Routercnc!
Can the voltage output of this unit be droped to <30vdc for use with the TB6560 driver board, Unto I upgrade to PM752 Drivers?
Would it be safe to put a few of these power supplies in parallel? Maybe put small resistors / diodes(?) in to balance the load.
I ask because it's occured to me that these are the right voltage for my big 48V brushless motor/spindle. It claims to take over 100amps but obviously I'll never need anywhere near that amount! I think 3 PSUs in parallel would be plenty.
@Mad Professor
<30v humm, possibly or possibly not. I'll review my notes and maybe give it a try :)
I got my power supply this morning, so now looking at how to drop the voltage for my TB6560 driver board.
Back on page6 you said you adjusted the value of R34 to adjust the voltage out the PSU when in safe mode.
So I am looking at removing R34 (9K1) and in it's place putting a 10K multi-turn pot + a 2K resistor.
Do we know yet what the 2nd voltage divider is for?