Power Loss in Magnavox VCR/DVD Combo

[eric.mathison]

I have a Magnavox VCR/DVD Combo that one day it suddenly lost power. I opened it up and noticed that the power supply is located all onboard; no seperate box or enclosure. Fairly simple though. So the first thing I noticed was a powdery substance around one of the 150uF/200V Radial Capacitors. I desoldered it and tested it with a multimeter thinking that it was bad and nope. It tests fine. So I soldered it back on. Upon further investigation and testing, the power completes the circuit and the device powers on IF ONLY the VCR is connected. Upon connecting the power to the DVD player something on the main board (in the area of the power/capacitors/ and transformer) makes a tick noise then a faint hiss, then the device powers off. So, it seems as if some component is not yet dead but is dying and cannot supply all the power that it used too.

My question is how can I find out which part is bad so I can replace it? I'm pretty sure that the piece making the hissing noise is the part, but I can't tell which one it is.

Thanks for the help.

 

[alec_t]

The DVD has a fault causing it to take excess current. This causes the power-supply to trip out; hence the ticking sound, which is usual when power supplies repeatedly go into a shut-down state. The hissing sound is a puzzle but the part creating it is not necessarily the faulty component (which is in the DVD).

 

[Nigel Goodwin]

The DVD has a fault causing it to take excess current. This causes the power-supply to trip out; hence the ticking sound, which is usual when power supplies repeatedly go into a shut-down state. The hissing sound is a puzzle but the part creating it is not necessarily the faulty component (which is in the DVD).

I would agree, it sounds most likely that the DVD is drawing too much current.

However, another lesser option is that the PSU can't supply enough current - which could be capacitor failure?.

But in either case, the part making the noise is almost certainly not at fault (and is probably the transformer).

 

[alec_t]

another lesser option is that the PSU can't supply enough current - which could be capacitor failure?.

I agree with that. Try powering only the DVD. If you still get the noise/shut-down then that points to the supply being ok and the DVD being faulty.

 

[Nigel Goodwin]

I agree with that. Try powering only the DVD. If you still get the noise/shut-down then that points to the supply being ok and the DVD being faulty.

It's not usually something you can do - it's easy to unplug the DVD, but you can't unplug anything else.

 

[alec_t]

it's easy to unplug the DVD, but you can't unplug anything else

True. Time to get out the wire cutters!

 

[vedo35]

(First sorry for my bad eng)
I want to help u with my smps repearing expreience. When we repair of the sat- receivers. We had also smsp problems thats always ticking. Mostly seconder sides fast rectifiers(diods) broke down(short cut) or tl431 but i changed less. Jusat first control all fast diods at seconder side. Second primer side main filter cap ( like 47mf/400v) some kind of smsp producer making for extra hold stron on pcb borad using white gum glue or shose glues or slicon that white is white gum glue for extra strong hold on pcb. i hope helped some of my hints. good luck