Yamaha RX-V440 turns off after 1/2s after power on

[AndyMacSteve]

I found a Yamaha RX-V440 amplifier at a dump and I powered it on and I saw the screen light up for 1-2 seconds and then turn back off  after that time

How can I either bypass it  and / or fix this? I did some research and I think it is the protection circuit, and it still shuts off even with no connection to any speakers. What could it be? Could it be a capacitor? Could it be a short?

[mzacharias]

http://elektrotanya.com/?q=showresult&what=yamaha%20rx-v440&kategoria=&kat2=schematics

Here is a link for the service manual.

Diagnostics described starting on page 21

Protection cancel mode on page 23

Could be a blown amplifier channel, a power supply problem, or something else.

Post back with what you find. Voltage readings are critically important.

[AndyMacSteve]

I saw the values somewhere and it says:

"DC: 92% PS: 23%"
The normal value for DC is 17-29% and for PS the normal value is 8-26%

It must be a PSU problem but I don't know what could be the problem though.
I ASSUME it must be some capacitors resistors or a multitude of them. I hope that it's just one of those sorts of problems

[mzacharias]

Turn it on normally and let it fail.

Have a pen and paper ready to write down an initial display which will only show for 2 or 3 seconds.

Turn on in Diagnostic mode and write down the initial display error message.

Post back here.

[AndyMacSteve]

I turned it on normally and allow it to fail. It lasted for 1.25 seconds. The initial display error message reads

"PS PRT : 23% D"

Hopefully the problem is just the power supply end and something like a capacitor or something

[xavier60]

I turned it on normally and allow it to fail. It lasted for 1.25 seconds. The initial display error message reads

"PS PRT : 23% D"

Hopefully the problem is just the power supply end and something like a capacitor or something

If you have a Variac transformer, try it with reduced voltage to see if anything changes. I occasionally find faulty 3 pin regulators that work when the mains voltage is reduced.

[mzacharias]

I turned it on normally and allow it to fail. It lasted for 1.25 seconds. The initial display error message reads

"PS PRT : 23% D"

Hopefully the problem is just the power supply end and something like a capacitor or something

This appears to refer to the the microprocessor receiving about 1.15 volts at a PS input where 5 volts is the norm. This would indicate a positive voltage regulator IC is probably bad. Could even be bad solder at an IC leg.

In any case, you need to start up in Protection Cancel mode, at which point the unit will stay on so you can troubleshoot at your leisure.

Check the output of each of the IC voltage regulators, one voltage will be low or missing.

Most of this stuff is conveniently located on the "Main 3" board, shown in the upper right of page 86 of the PDF manual. This board is mounted along the top of the amplifier heat sink, and includes a rear center channel amplifier channel.

I find a long thin multimeter probe handy in these situations. If you cannot quite get to an IC output lead, get your probe on the capacitor associated with it's output.

[AndyMacSteve]

I turned it on normally and allow it to fail. It lasted for 1.25 seconds. The initial display error message reads

"PS PRT : 23% D"

Hopefully the problem is just the power supply end and something like a capacitor or something

This appears to refer to the the microprocessor receiving about 1.15 volts at a PS input where 5 volts is the norm. This would indicate a positive voltage regulator IC is probably bad. Could even be bad solder at an IC leg.

In any case, you need to start up in Protection Cancel mode, at which point the unit will stay on so you can troubleshoot at your leisure.

Check the output of each of the IC voltage regulators, one voltage will be low or missing.

Most of this stuff is conveniently located on the "Main 3" board, shown in the upper right of page 86 of the PDF manual. This board is mounted along the top of the amplifier heat sink, and includes a rear center channel amplifier channel.

I find a long thin multimeter probe handy in these situations. If you cannot quite get to an IC output lead, get your probe on the capacitor associated with it's output.

I probably can't do either. I feel like just removing the board and testing the parts against their ratings. For example, if there is a capacitor rated at a substantially lower/higher number than what it is rated for I can probably assume that the part in question is dead

Now I have to remove that board I think. I personally think it's easier for me to test it like that. It probably won't be as effective but I feel that I'm better able to check for bad caps/resistors this way

[mzacharias]

I can't understand why you would not at least take a voltage reading or two to guide you before you tear it apart. Cold checks of individual components is laborious and probably unnecessary. If for example there is 18 volts into a +12 volt regulator, and small voltage out, that regulator is bad, or maybe the cap at the output is shorted. In any case, you've reduced your troubleshooting time with only a couple or a few voltage readings. Troubleshooting is fun and satisfying. Give it a try.

[AndyMacSteve]

I checked the connector with the wires coming from the transformer and i shorted the 2 connectors by accident and it shut off, but luckily I don't think it broke anything. It still turned on like normal.

Im just not sure what connectors to check for voltages. Theres a 4, 3, and 2 pin connector but theres also another weird connector that is attached to another PCB

[mzacharias]

You really need to check the output of the voltage regulators which are (fairly) conveniently located on that board. That's how this type of troubleshooting is done. If you can get on the DC output connector(s) that's fine and all (the AC inputs are OK at this point) but if you do identify a low or missing voltage, you'll still have to go back to the regulator involved. Your problem almost certainly involves this - a low or missing regulated power supply voltage. I know this isn't your day job - but this is easy stuff. When you do fix it you'll know what I mean.

[SoundTech-LG]

This is such a common failure. The regulators fail in most of these AVRs all the time. Check your regulated voltages! You are wasting a lot of valuable time as mzacharias has pointed out. If you are afraid of a probe slip, solder on wires while powered down. Worth that small effort.

[Diamant909]

Also, after turning on, the YAMAH RX-V440RDS receiver turned off after 1 second. When starting the diagnostics (press and hold the “6CH INPUT” + “STEREO” + “STANDBY/ON” buttons, if you press for more than 3 seconds it will turn on without protection) it gave the error: PS PRT: 23% D. As a result of the diagnostics, I replaced the 7805 stabilizer; did not produce 5 volts, it was 0 V, it was. Replaced it and everything worked. I tested a lot of things before, but everything was working. And so I replaced IC404, it is installed on the top board, on which the stabilizers are screwed to the amplifier cooling radiator. It comes with a 6-pin connector from the transformer (two orange and gray and two purple and white). According to the board diagram: MAIN (3) P. C. B.
Initially there were suspicions about the IC406 stabilizer, because... it heats up, and after measuring the voltage on it, I got 2 volts, this was not correct, since you can’t take the minus on the radiator! It will come from a 3-pin connector, which from this board is connected to the bottom board (gray-gray-red) next to it is a screw with a negative pad. I soldered the wires to these two stabilizers and made a break in the 5 volt output circuit, set everything up, ran it in diagnostic mode and measured the parameters of the incoming and outgoing voltage.

Так же после включения через 1 секунду выключался ресивер YAMAH RX-V440RDS. При запуске диагностики (зажимаете кнопки «6CH INPUT» + «STEREO» + «STANDBY/ON», если зажать больше 3-х секунд включится без защиты) выдавал ошибку: PS PRT: 23% D. В результате диагностики заменил стабилизатор 7805 он вообще не выдавал 5 вольт, на нем 0 В, было. Заменил и все заработало. Много что до этого тестировал, но все  было рабочее. И так заменил IC404, установлен он на верхней плате, на которой стабилизаторы прикручены к радиатору охлаждения усилителя. К ней подходит 6-ти пиновый разъем с трансформатора (два оранжевых с серым и два фиолетовых с белым). По схеме плата: MAIN (3) P. C. B.
Изначально были подозрения на стабилизатор IC406, т.к. он греется, и измерив на нем напряжение получил 2 вольта, это было не верно, так как минус на радиаторе не получится взять! Получится с 3-х пинового разъема, который с этой платы подключается к нижней плате (серый-серый -красный) рядом с ним винт с минусовой площадкой. Я припаивал провода к этим двум стабилизаторам и делал разрыв цепи выхода 5 вольт, все ставил, запускал в диагностическом режиме и промерял параметры входящего и выходящего напряжения.

[wasedadoc]

I had a Yamaha RX-V750.  Not the same but similar vintage.  PS protection fault.  Was the 5 Volt regulator.  Check that rail, especially if the regulator is made by JRC.

[FIXITNOW2003]

Seen a few off these RX-V range had a few where the 22nF 630v on the power board has failed different C location on each model V457 was C4 V757 was C405 ,V450 was C1