Digimess HV30001 repair - 300V 1A bench DC power supply

[Behemot]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

I pulled the bulk mains caps which are rated at 1000uF 200V a piece while replacing the transistors on the heatsink. To little surprise they test considerably below rating at 850uF each, so they are probably 820uF caps.

That's still within +-20 %. Most even new large-can caps I've ever measured with ESR Micro or UNI-T UT210E always showed lower capacity. No reason to call them fake right away. Usually only Rubycon caps measure close to full.

[stj]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

those are shrouded and rated for 250v

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

insulated binding posts?

http://www.rapidonline.com/rvfm-4mm-30a-terminals-63907

You'll find those are typically not rated to 300VDC, more likely something around 60VDC. They'll handle it fine for most cases, but you don't want the exposed conductors anyway when you're dealing with anything around that kind of range. This comes down to insulation ratings in the plastic and the design with the exposed conductors which electronic loads don't generally have.

The other issue - is handling both extremes of high voltage and high current. You can get 400V rated MOSFETs cheap, but on resistance is pretty bad - like 0.1 ohms is the minimum for anything cheaper than "silly price". And if you want say 30A full load current, you're going to get a load of voltage drop across just one FET. So you need many in parallel. And this increases gate capacitance and control loop design complexity considerably.

[stj]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

insulated binding posts?

http://www.rapidonline.com/rvfm-4mm-30a-terminals-63907

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

It's pretty difficult to find ones that will allow wires to be mated to easily. Anyway, this is a project that will be done after 50 others on the list.

What I really want is something like this unit with these kinds of jacks on it:
http://www.ebay.co.uk/itm/Electronic...AAAOSwF1dURMd2

[stj]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

4mm shrouded jacks - like on meters?

some of those are rated 1000v and upto 32A
http://www.rapidonline.com/4mm-single-pole-connectors

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

JST-VL series connectors.
20A 600v

I'm talking about connectors you can easily screw in or use test leads with.

[stj]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

JST-VL series connectors.
20A 600v

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

Why would the connectors be a problem? At 1 Amp (actually, not even that with this bench PSU ), I imagine the drop should be small enough not to matter.

The problem is a high voltage high current design. If I were to design an electronic load I'd want it to have a high input voltage and high input current capability (obviously, not simultaneously, but connectors need be rated for both options.) And then connector choices are more tricky.

This is something I may end up developing soon, will depend on what turns up in the clearance section of my favourite store.

[momaka]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

I might end up building one, but 300V is quite a high voltage rating for such a design. Connectors and MOSFET choices get tricky.

Why would the connectors be a problem? At 1 Amp (actually, not even that with this bench PSU ), I imagine the drop should be small enough not to matter.

It's kind of strange to see one Lelon cap. That might be the best cap in the whole power supply.

That is sad. And would be even more sad if it's a fake Lelon.

atleast we know which bathroom to use!!

Good one!

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

I pulled the bulk mains caps which are rated at 1000uF 200V a piece while replacing the transistors on the heatsink. To little surprise they test considerably below rating at 850uF each, so they are probably 820uF caps.

I haven't had the guts to check ripple under load yet. I'm waiting for a faulty load unit to show up (rather than building a resistor array.) I might end up building one, but 300V is quite a high voltage rating for such a design. Connectors and MOSFET choices get tricky.

[japlytic]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

My Tenma 72-10495 (Korad 3005D-2S rebadge) had six fake Rubycon USP series units (rated at 105ºC, whereas genuine units of this series are actually rated at 85ºC), so I yanked them out and replaced them with better quality units.

[lti]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

The capacitors appear to be a mix of Chemicon, Rubycon and some odd Chinese brand with a Rubycon vent, though the Rubycon caps all look a little off, so they could be fakes.

From what I can see in the pictures, the "Rubycon" caps are branded Rukycon. I've seen them before. The Chemi-Con caps are almost certainly fake, although they're at least the right color. The fake ones I've seen were always black, no matter what series they claimed to be. It's kind of strange to see one Lelon cap. That might be the best cap in the whole power supply.

It looks about average for a cheap bench power supply. It definitely isn't worth £500.

[stj]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

atleast we know which bathroom to use!!

[momaka]

Re: Digimess HY30001 repair - 300V 1A bench DC power supply

we have many ways

That's what I mean! - Never conforming to a single common standard

[stj]

Re: Digimess HY30001 repair - 300V 1A bench DC power supply

Lol, you Brits always gotta have everything your own way

we have many ways

bayonet cap, 27mm ES, mini-bayonet, 14mm ES.

my lamp tester is one of these.

[momaka]

Re: Digimess HY30001 repair - 300V 1A bench DC power supply

Later determined it to be a second set of diodes bodged on top - MUR460 devices. They feed the large inductor, which is also connected to the transformer. The diodes are covered in thermal gloop in a vain attempt to thermally couple them to the heatsink.

Oh wait, I forgot it's a digiMESS... never mind what I was going to say.

It's different in Europe, in the UK we use Bayonet fittings.

Lol, you Brits always gotta have everything your own way .

Success!
...
Seems like the full 1 amp isn't available at 300V
...
Repair cost was about £15 all in...not bad really.

Nice, glad to hear you got it working!
Indeed not bad for the price you paid in parts.

[Per Hansson]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

Digimess Concept
What a mess that it ever left the concept stage!

[tom66]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

Hi Tom, what kind of lamp socket used in UK and EURO, Edison type like the US?

It's different in Europe, in the UK we use Bayonet fittings. But for the lamp test I just soldered wires to the bulb because the bulb holder I had was broken.

[budm]

Re: Digimess HV30001 repair - 300V 1A bench DC power supply

Hi Tom, what kind of lamp socket used in UK and EURO, Edison type like the US?