ebay power supply

[irving2008]

Just some thoughts around the 55v 9.9A power supply I bought off ebay for £22 inc postage as a result of this thread

The two questions being asked were, how do you connect to it and how can the output voltage be reduced below 50v.

The first is easy, standard 4.8/0.5mm LUCAR connectors fit perfectly, so no need for an expensive socket.

The second less so... but I'm working on it. The attached datasheet shows that the Inhibit line must be between 5.5v and 11.5v approx which controls the output voltage between 50 and 57v approx. As the inhibit line drops below 5v the output volts is fixed at 42v until at some point (to be determined) the output is turned off. At 42v the supply is out of regulation (but exactly what that really means is open to experimentation). The circuit diagram below shows one way to set the output voltage.

In the meantime here are some pics.. these are quality supplies..

Pic 1 shows the unit, Pic 2 the connector block.

Pic 3 shows the two main circuit boards when stripped out of the case. Note the substantial heatsinks.

Pic 4 shows the input RFI filter - a sign of quality

Pic 5 shows the daughter board which is a separate switch mode supply to provide internal intermediate voltages. The adjustment does not control the main output volts.

Pic 6 - another sign of quality - a temperature sensor on the main input bridge rectifier heatsink. The 25A bridge rectifier below it converts 240v AC to 330V DC

[Tom]

Hi Irving,

I was just logging on to PM you that I'd received my PSU this morning, when I found this thread! Thanks for the review!

Looks like a nice unit - I've had the covers off, but didn't get it down to the same state of undress as you...

The datasheet shows that if the inhibit line is left at 0V the PSU will sit at 42.8V (out of regulation). You also mention that it might turn off at some point, but I can't see that mentioned in the data - is this from experience? I'm thinking of just trying (leaving it plugged in in the corner) it to see what happens... You'll probably remember that I need 50V max for my drivers (aiming at 42 to 45V).

Need to get some 4.8mm spade connectors first though - I only have 6.3mm and they're not secure on the terminals...

Tom

[irving2008]

...The datasheet shows that if the inhibit line is left at 0V the PSU will sit at 42.8V (out of regulation). You also mention that it might turn off at some point, but I can't see that mentioned in the data - is this from experience?

No I haven't tried it - but whats the point of an 'Inhibit' that doesn't? Need to put a 100mA load on as well for test so need to find a 470ohm 10W resistor...

...
Need to get some 4.8mm spade connectors first though - I only have 6.3mm and they're not secure on the terminals...

Maplin's do them N35CY (Blue) and they do red as well...

[HankMcSpank]

No I haven't tried it - but whats the point of an 'Inhibit' that doesn't? Need to put a 100mA load on as well for test so need to find a 470ohm 10W resistor...
Maplin's do them N35CY (Blue) and they do red as well...

or if you're nowhere near a Maplin a pack of 25 for £1.99 delivered.....

http://cgi.ebay.co.uk/4-8mm-blue-fem...lenotsupported

(PS I've emailed Minibea UK on the off chance they have a schematic)

BTW If there's any interest in the from other living here in the Great Smoke, (ie a 'group buy')...he saying he can give more discount - plus I can use my own courier (£7.50 for up to 25kg in weight - which should get about 7 of these in there!). So each could work out as low as £13 ...which for that spec of PSU is just insane.

[Robin Hewitt]

Looks wonderful, but... :naughty:

All the cheapy stepper drive boxes clack out just passed 50 volts to protect themselves and you really don't want one axis to pause waiting for the volts to come down a tadge

[irving2008]

Looks wonderful, but... :naughty:

All the cheapy stepper drive boxes clack out just passed 50 volts to protect themselves and you really don't want one axis to pause waiting for the volts to come down a tadge

Which is why I am working to figure out the mod to control the volts down to 35 - 45 instead of 50 - 57. It may be as simple as changing the resistor controlling the current sink device in the feedback loop...

[Robin Hewitt]

Which is why I am working to figure out the mod to control the volts down to 35 - 45 instead of 50 - 57.

Aha ! :clap: :heehee:

[HankMcSpank]

Top quality PSU at a great price! I think it will be set to 45V soon.....Just keep giving Irving a prod...or a

If you're setting up a group buy put me down for 3....might come in handy :)

I think the group buy would only work for those that can collect from my place here in North London ...ie savings to be had from lumping the one delivery together (or they could be collected from my work nr the Barbican in London)...don't really want to proceed until Irving works his magic though.

The seller will give a discount (though I've not asked/pushed him on this), & Parcel2Go will deliver upto 25Kg in weight door to door for about £7.50.

That aside, if you want to go your own way & can beast him down to a tenner each for 3, then with Parcel2Go as the courier, then that would only be £12.50 per PSU to your door!

[Kn8]

Hi I would be interested in joining in on a group buy and will be happy to purchase four supplies at the right price.
Ivan.

[HankMcSpank]

Hi I would be interested in joining in on a group buy and will be happy to purchase four supplies at the right price.
Ivan.

Once again...due to the weight of these, I reckon a 'group buy' will only work if people can collectin person, from North/Central London. In other words, the win here is mainly the £10 saving he's charging on the P&P ...by grouping these PSUs in blocks of 25kg, then some useful saving can be made on the P&P (plus whatever discount he offers on volume)

I've now emailed the seller for price break points. (but like I say, not worth pursuing unless the voltage output on these PSUs can be tamed to more usable levels)