Pioneer vsx-d307 no sound and protection issues, any help?

[The_I.M.P.P]

Good day guys i have a pioneer vsx-d307 receiver that comes on but doesn't play any sound, i do see a few obvious signs of problems like the power mosfet has scorching around them and theres a resistor (R459)that burnt completely off the board so i dnt know the value of it, i have downloaded the manual but couldn't find any information. Btw, when i press the power button it switches on then immediately goes into protection mode by displaying shut off and switches off, so i removed the front speaker assembly pcb and the unit switches on and stays on perfectly. Any help on the matter would be highly appreciated thanks

 

[Aud10file]

R459 is 100 ohms . R458 is same value and performs same duty for a different channel.

It is not in parts list in the manual but the value is noted in the schematic.

 

[The_I.M.P.P]

Thanx, that Makes sense even to a NOOB like me, just a quick 1, if you are familiar with mosfets I'd like to know if power mosfets (x2) are blown Would that cause the amp to go into protection? I figured it might be culprit for the no sound since its located next to the audio ic, but no clue so im just gonna relpace them to be safe. Thanx again

 

[Aud10file]

I took a quick look at the schematic. I can’t find mosfets in that area of the unit. If you are referring to to the powerpack, I would put that at the bottom of the list for now.
I’m not familiar with the unit, but if this were on my bench, I would check Q457, R461, R476, D458, and D457.

Note that R461 and R476 have a safety factor. Keep in mind to replace with same type, value, power rating resistor if these are bad.

 

[The_I.M.P.P]

Oh ok thanx i will most definitely pay more attention to those components after all thats why i bought this dmm lol. The safety factor of the resistors was something i hoped i wont encounter as this is an older system so parts will be hard to get.

 

[The_I.M.P.P]

But with enough research I'm sure i could get something with similar values n hope for the best. The mosfets i spoke of is located Q601,Q602 not sure why they used "Q" but I found that in the part description.

 

[The_I.M.P.P]

 

[Aud10file]

No need to replace any parts unless they are defective or out of spec. The resistors should be easy to find. The transistor and diodes may need to be a modern replacements if they are needed.

As per the parts list, the resistors values are listed below. Check the actual color code on the resistor that is in the unit. If it doesn’t match the parts list, then it’s best to put in the same value you take out.

As per parts list:
R461 - 82 ohm 1/4W 5% tolerance
R476 - 330 ohm 1/4W 5% tolerance

Last note: Something caused the resistor to get burned and the board to get scorched. Hopefully, it is just the burned out resistor. Once you fix the apparent problems, there may be other issues not seen. It would be best to use a dim bulb to protect from further damage once you are ready to power up again.

 

[Aud10file]

But with enough research I'm sure i could get something with similar values n hope for the best. The mosfets i spoke of is located Q601,Q602 not sure why they used "Q" but I found that in the part description.

In my experience, mosfet’s are pretty rugged once they are in circuit. I would take it a step at a time and troubleshoot methodically.

 

[The_I.M.P.P]

Yeah i suspect that there's more at fault than just a few resistors and transistors that are bad, but these first steps look like its in the right direction, i will make sure to follow those guidelines you have set out, Thanx you so much once again youve been a real help and a true champ.