I have an old DVD player in my AV rack. Several times a year it locks up and I need to power cycle it. This requires me to pull the entire rack to get to the power connections. I was hoping to have a little reset button accessible from the front of the rack.

I opened the DVD player and the power supply is split voltage, 12V and 5V. I think the 12V is for all the motor stuff and all of the logic is 5V. If I open the 5V connection on the PS all of the lights and the display go off and I think it will reset the lock-up issue (although I cant get it to freeze on demand, and it will probably be a few months before it freezes on its own)

I wired a little normally closed switch to the +5V on the PS with about 30" of 24 AWG wire and have a nice little place I can hide it on the front of the rack. Closed up everything and tested it before putting back the rack. The DVD player is erratic. It starts up but before getting to the home screen of the player reboots and cycles through this loop.

I removed my PS hack and the DVD player works perfectly again. I confirmed that neither side of the switch wire was shorted to chassis ground and the switch works perfectly with a volt meter.

The only thing I can think of (and I am no expert) is that the 30" wire is picking up some sort of noise as there are a lot of caps and what appear to be filtering on the PS side before my splice.

Would using shielded wire fix this?

I don't want to switch 120V side as it would require much heavier duty wire and switch and make it hard to conceal on the face of the rack.

Any other ideas on the cause of the issue or how to switch the low voltage?

 

Try tightly twisting the two wires to the switch. It may solve your problem.

 

so instead of using 24AWG "speaker wire" which is side-by-side you are saying to split the wires appart and then twist them all the way from the PS to the switch?

If this works, is there a name for a single pair twisted wire in a jacket so I can order some?

 

If you remove the 5 V supply but leave the 12 V supply up and active, there is a strong chance that some unpowered 5 V parts will have voltages on input pins. Depending on the parts, this can cause erratic behavior and even component death. CMOS components are famous for this. If you are going to go this route, better to use a double-pole switch and control both DC sources at the same time.

ak

 

If you have room in the back of the rack for some "stuff" I would consider using a relay to switch the AC.

I would power the relay with a wall wart and bring a low voltage switch to the front of the rack, solving the size problem, and any noise issues etc.

Personally, that is the way I would do it rather than risk damage to the unit.

 

so instead of using 24AWG "speaker wire" which is side-by-side you are saying to split the wires appart and then twist them all the way from the PS to the switch?

If this works, is there a name for a single pair twisted wire in a jacket so I can order some?

It's called shielded twisted pair and usually comes with a braided sheath under the outer insulation. You probably don't need the sheath which is usually grounded. . If the problem is caused by the wires picking up stray radiated signals, just twisting the existing wires should do the job.

 

Thanks everyone.
I just went with the relay and 120V switching since not only does it not create my original problem with low voltage switching, but as AnalogKid pointed out I could potentially damage some of the CMOS components with the 12V still being live