I have a Sony STR-DE505 that powers up normally, but then displays Protection on the LED display. What do you think the problem might be. I have read in other forums that it might be an audio outputage problem or a Power supply issue, but im not sure which way to go. Can you help me? Thanks for your time!
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If the speaker wires shorted together, it will trigger the protection circuit. If the output transistors/IC shorted out in the power amplifier section, it will also go into protection mode also.
Try disconnecting all the speaker wires to see if it will come on normal.
to have it fixed by the shop may not be worth it.
You cooked it. Maybe you lucked out and just blew a speaker.
Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.
Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.
You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.
If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.
If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.
Check for loose speaker connections at the speaker as a root cause for intermittent shutdown.
Check the input fuse first. If it is blown, there will be some short inside the power regulator circuit. Usually Sony sets uses STR regulated power supply. You can see this STR, and Ic, screwed onto a heatsink. Replace it with a same type and number. Before replacing the STR, check the diodes used in that section for damage, mainlu zener diodes. They might get shorted along the blowing of the STR. Check that section throughly before resoldering the new STR.
If any further assistance you needs, get me through Fixya. Ok.
The reason this happens is because it takes about 3 to 5 sec. for the output circuit relay to kick in after power up, im sure at this point is when your receiver shuts off and flashes red. You have a bad output Transister its shorted to ground and the sony's protection circuit kicks in and shuts it down. Unless you are a electronic Tech. you will have to take it in to be repaired its going to be about 120 dollars to repair. Now im assuming your speakers are ok, if you have them hooked up when you do this try disconnecting them and try to power up if it does you have a shorted speaker, but normally Sony just displays overload protection on the display. Im sure you have a shorted Trans. sorry for the bad news good luck.
Do you hear any clicks? If not, the standby transformer or related circuitry is bad. If you hear 1 relay click...the audio output section is most likely the problem. The first click you hear is the main power relay...and should see display.. the second relay click is the protection circuit relay engaging to let audio to your speakers...if the second click is not heard (it should occur in 3 to 5 seconds) there are shorted output transistors or a shorted output IC trying to blow your speakers with 50 to 75 volts dc. The protection circuit monitors the speaker lines for voltage. They should always read milli-volts only...not even 1 volt.Anyway, good luck
I have a problem with vintage reciever Sony STR-11L. Power transistors were replaced and I dont know what were original ones. Sound is no good and radiator is hot-I think problem is in replacement. Can anybody help me with?
I suspect intermittent 31V supply, filament supply or bad connections on fluorescent display. Check Q801 31V reg , R802, zener on base of Q801 located on DC board. Inspect all boards for bad solder joints, reflow and tighten pcb grounding screws.