Failing SPS705 power supply (68vdc Leadshine)

[cropwell]

You can still get the 100W Halogen filament strip lights they use in work lights at places like Toolstation. Would these be OK? It is only a resistive load you need. John - What do you think ?

[john swift]

I am not sure how the cold resistance of a Halogen bulb compares with that of a GLS bulb

As long as the cold resistance of the halogen lamp is not too low for the power supply to start
the Halogen lamp should be OK
cold the 240V 100W GLS bulb about 43 ohms


to setup the Forgstone TV Kit
the GLS bulb was used as a low cost alternative to a
600 ohm 100w resistor

since then I have use the bulbs to test other things like the speed controls used in a Clarke CL300M lathe

https://www.model-engineer.co.uk/for...s.asp?th=38809

John

[cropwell]

I am not sure how the cold resistance of a Halogen bulb compares with that of a GLS bulb
cold the 240V 100W GLS bulb about 43 ohms

The only halogen security light I have is 500W and that measures up at 8 ohms cold, so 40 for 100W seems a reasonable guess !

[dsc]

I'll get one from ebay if I can't find any locally.

Is there anything to pay attention to when hooking it up to the PSU? was thinking of using a lamp holder with two wires connected to the PSU to make sure all the connections are proper.

T.

[dsc]

Quick update to this thread, I've had another look at the way everything is wired and it turns out both this PSU and a servo controller is on the same AC supply, fired off the same main switch. There's an AC filter on the AC supply to stop anything flowing back into the AC line, but there isn't really anything protecting the PSU on the AC side. No idea whether any damage can happen this way when the servo controller is switched on / off, but I thought I'd check.

Also, just noticed that if I leave the entire rig powered for a long time (ie. over 10minutes), the PSU eventually produces around 40VDC which is fairly steady. Could this be related to a dead capacitor perhaps which is simply taking a very long time to charge? again, no idea if this even happens in a PSU, so just throwing an idea out there.

T.

[cropwell]

Could this be related to a dead capacitor perhaps which is simply taking a very long time to charge? again, no idea if this even happens in a PSU, so just throwing an idea out there.

I have not known a capacitor to fail in this way, normally they bulge and short circuit (BANG!) if bad enough.

[Clive S]

Also, just noticed that if I leave the entire rig powered for a long time (ie. over 10minutes), the PSU eventually produces around 40VDC which is fairly steady. Could this be related to a dead capacitor perhaps which is simply taking a very long time to charge? again,

Have you measured it with a load on. You could have a very high resistance (dry joint) to account for the long charge time.