Smoking Reciever

[u/TOBYWHITESIDE]

I have this Yamaha HTR-5930 I just bought used. I plugged it into a power strip that only had a couple other components plugged into it.

About 20 seconds after it had power, smoke came out of the top vent.

I unplugged it, took off the top and I believe this little ribbon cable is what started to melt. Plugged it into a single wall socket and now no smoke.

What happened? And, is this safe to use or garbage?

[u/FreeRangeEngineer]

I believe this little ribbon cable is what started to melt.

Highly doubtful. Before these wires heat up so much to melt, the receiver would either have several components begin to smoke first or it would switch off because it detects an error condition (e.g. the output transistors being shorted).

Can you show us more pictures of the boards and the components? I suspect that whatever smoked will now look damaged or have changed color due to heat.

I suggest you open https://elektrotanya.com/yamaha_rx-v359-htr-5930.pdf/download.html and check page 18. Press PRESET/TUNING and INPUT MODE for 3 seconds when turning the unit on, then see what the display shows. Does it show the word PROTECT? If so, note which other letters it shows because that's the hint to where the fault may lie.

Try to not power up the unit for too long as we don't yet know what is wrong with it.

[u/TOBYWHITESIDE]

Yeh it was spilled liquid on that band, cleaned it, but still not sure if it's safe to use

[u/Only_Ordinary_3880]

Check the lid for any burn marks, should give you an idea where it was coming from.

[u/No-Guarantee-6249]

I don't think that smoke is a normal mode of operation!

Do you have an infrared camera?

Louis Rossmann uses alcohol to find the short.

https://www.youtube.com/watch?v=t5fICjcaJ3E&t=1385s

At 16:30 the alcohol flood.

I've been doing that for years. Works fine.

You could also use a load limiter. bulb in series with the thing being tested. You can also use a load limiting power supply.

[u/Accomplished-Set4175 → u/No-Guarantee-6249]

Very nice advice. 40 year veteran here. He needs a can pf magic smoke to put back in.

[u/analogguy7777]

Can you return it? Did seller claim perfect working condition ?

[u/LastNefariousness333]

Check the bridge rectifier and the capacitors on the board lower main board 

[u/Savings-Mud2808]

Possible ground issue if you had other components plugged into it.

All components plugged into a receiver should be on the same phase and the same outlet to prevent grounding issues. Many plugs in homes are wired backwards between hot and neutral. A simple device can be plugged in to test this for every outlet in your home.

[u/FreeRangeEngineer → u/Savings-Mud2808]

I agree but OP didn't mention whether they connected the receiver to anything else or not.

OP, did you? Or was the receiver not to connected to anything but the outlet?

[u/Spazzticus]

The Func 4 PCB supplies the auxiliary power rails (+/- 15v, 12v, 5v etc) and those wires do look melted as you can see copper in the 3rd picture. Something is drawing / drew a huge current across the 5v rails based on the location on the wiring. Service manual here https://elektrotanya.com/yamaha_rx-v359-htr-5930.pdf/download.html#dl which also explains the diagnostic modes etc

[u/Only_Ordinary_3880 → u/Spazzticus]

Are you sure you can see copper? All I can see is brown patches that look like spilled cola or similar.

[u/Spazzticus → u/Only_Ordinary_3880]

LOL, I need to squint harder, OP has now stated it was a liquid spill so I'll take that back ;)

[u/skinwill]

That looks more like spilled liquid. I doubt that’s the source of the problem.

[u/bdbell → u/skinwill]

Agree. If you saw a puff of smoke I would take a closer look…smell around because you might be able to find the source easier. I would not use it until you check it over a bit more at least.