LG 50PQ6000 unstable 5v standby

[tom66]

Re: LG 50PQ6000 unstable 5v standby

I think modding one in would lead to poorer performance.

A diode's current rating is determined by both the size of the die (high current density destroys the device) but MAINLY decided by the amount of heat it can remove (0.6V at 3A ~ 1.8W, must be able to get rid of this without overheating.)

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Use the 5v and add a mini pc fan directed at the diode? Maybe.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Might help, but a mini fan will screeeeeeam in standby mode.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Ok back at home now, I was using the smart phone while working away its some what challenging.

So is there a way to test the control board to see if some component is faulty and pulling too mutch current through that diode and making it go O/C? OR am I totally wrong with that theory do you think?

[tom66]

Re: LG 50PQ6000 unstable 5v standby

No, I doubt that's the issue. The diode is simply running too hot.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

ok then maybe the replacement I found had a slightly different spec to the original. I will have a proper look later online.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Yeah, it was 150V rated instead of 200V. The new one is 200V.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby



So I wounder what would happen if I put one of these in instead?

Manufacturer's Part Number: SF47G R0

4A 500V 35ns Super Fast Rectifier Glass Passivated

[tom66]

Re: LG 50PQ6000 unstable 5v standby

It's not a schottky diode (low loss type), but it may work.

[ben7]

Re: LG 50PQ6000 unstable 5v standby

If the original shottky diode got hot and fried, then that diode will certainly fry faster!

tom66, why you think it would lead to poorer performance? A heatsink could be added to the TO-220 device also, to keep it cooler. I don't understand how that would lead to poorer performance :S

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Because a TO220 device with a crappy heatsink is going to be just as limited as that package. Maybe it would run a little cooler, but the correct solution is to find the right diode.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

I thought I found the right diode when I fitted the VSB3200 and it fried :0/

[ben7]

Re: LG 50PQ6000 unstable 5v standby

Because a TO220 device with a crappy heatsink is going to be just as limited as that package. Maybe it would run a little cooler, but the correct solution is to find the right diode.

Ah, so you mean like a fast enough recovery time, reverse current, and capacitance?

The original diode, a VSB3200 claims that it is a high-efficiency diode (VF=0.63V) - the SMPS is designed terribly because of that 'high-efficiency' diode overheating!

Really should get a new test diode, and then scope the diode, to see if it really needs to be a 200v diode.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Really should get a new test diode, and then scope the diode, to see if it really needs to be a 200v diode.

Shame I have one more VSB3200 test diode but no scope. Guess it cant be done on a DVM?

[tom66]

Re: LG 50PQ6000 unstable 5v standby

It's definitely a VSB3200? Not incorrect part? CHS have done that to me before!!!

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Well if I look at the original its markings are:

VSB3200
M944A

and the replacement was:

SB3200
1142

(eventhough the CHS label says: VSB3200 DIODE GENERAL) You could be right here Tom.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

It looks to be similar.


Odd that it failed quicker than the 150V diode!

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

It looks to be similar.


Odd that it failed quicker than the 150V diode!

Im still not sure where the 150v diode came in (confused.com)? I never used a 150v diode just went straight to the (what I thought was a VSB3200) SB3200 as a replacement thinking it would be a better option?

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

I wounder if I should have a moan at CHS.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

I thought I linked you to the 150V part on Farnell?

I would think that if the original diode lasted -X- years then their replacement can also be expected to last -X- years.

So I would think the diode isn't a directly substitutable part, you need to find a VSB3200 not an SB3200.