SMD Fuse Identification

[Darky8]

Ugh, tiny little surface mounted fuse things... anyone got ideas on the values of these...? they have SD(?O)C 5000, and 3150 marked on them but marked as Resistors on the PCB.

0.5 Amp and 0.315 Amp perhaps?

Need to order some

Thanks!

[jetadm123]

Re: SMD Fuse Identification

Since they are marked R101 and R12? on the circuit board, that would indicate they are resistors. 5000=500 ohms and 3150=315 ohms.

[budm]

Re: SMD Fuse Identification



I would say 5A and 3.15A, look through the catalog and see, or contact SOC.

[Darky8]

Re: SMD Fuse Identification

There may be marked as resistors (for some reason) but they are open. Working ones elsewhere on the board not show any resistance either, so I'm pretty sure that's a red herring.

Budm, I looked everywhere on the net to find them Thank you!

Wow 5 amp, that's a fair bit. Hope it doesn't blow the things again.

Cheers

[budm]

Re: SMD Fuse Identification

5A is my guess, that is why you should check the current draw with your DCA meter, for the fuse to blow it may be due to shorted circuit some where. You can check the resistance between each end of the fuse against GND to see what they show up as first before checking the current draw or before replacing the fuse..

[Darky8]

Re: SMD Fuse Identification

Well I checked everything out and it seemed to be fine. I replaced the fuses but now all I can hear is the power supply flicking off and on The sound is from the Primary side and it's flicking off every second or so.

PSU is fine without the DC/DC converter board, but as soon as it's connected it starts. It sounds like some sort of protection kicking in.

It wasn't doing this before the fuses were replaced.

Any pointers? I have included pics of the board and PSU.

BTW it's a Panasonic WJ-HD316 Digital Recorder.

[Darky8]

Re: SMD Fuse Identification

UPDATE : I took the fuses back off and the problem went away. I replaced only one of them and it was ok.

So not enough to make the machine work, but it's the left hand bank of three looking at the top of the DC/DC board that is the problem.

I can#t find anything obvious, any likely suspects..? Or could I bypass something to get the thing running?

Cheers

[budm]

Re: SMD Fuse Identification

You do have problem some where in those switching power supplies (BUCK CONVERTERS) or the loads. You need to use Ohm meter to check the resistance of all the diodes, the SCR, the caps, the buck converter ICs (MD1222N) to see if any of them show low resistance in both directions.

[Darky8]

Re: SMD Fuse Identification

Budm, Thank you for your helpful images.

Everything checks out the same, except the SCR's (NEC 3P4J) with the non-functioning channel exhibiting less resistance (Anode to Cathode), but they both behave in the same way when polarity is reversed.