Yamaha HT-R4065 won't start

[tibimakai]

I have picked up this receiver in very good condition with all the accessories.
All it does when it is turned on, is the power button LED it blinks a couple of times.
I have downloaded from elektrotanya the SM for the HT-R4063, which seems pretty close to this one.
I have managed to turn it on in service mode, without protection turned on.
Not sure what to do next. Anybody has any input? Not sure what is causing to get into protection mode.

[newbiesat]

Re: Yamaha HT-R4065 won't start

Do you check the output transistors to see any short out ?

[tibimakai]

Re: Yamaha HT-R4065 won't start

After I have posted that I have took it apart and I didn't have time to check all of them but I have found a pair shorted after the first measurements. After cutting there legs it was still in protection mode, most likely some other components are shot too.
I'm having difficulty removing the wire ribbons from there connectors. The ones from the HDMI board.
It seems like the plastic tab slides out, but the ribbon doesn't want to come out.
Any pointers?
On the Onkyo receivers, the tab has to be pushed in to release the ribbon.

[tibimakai]

Re: Yamaha HT-R4065 won't start

I have found a couple bad parts, I will post the list when I will be home.
I'm having difficulty with a SMD diode. The marking is A2, found at another channel, because the surface is to rough to be able to read the marking off of that one.
When I'm looking for this diode, under that marking are a couple of other diodes show up, which one should I look for? A basic 1N4148 in that package should be fine?
http://www.marsport.org.uk/smd/mainframe.htm

[tibimakai]

Re: Yamaha HT-R4065 won't start

Nobody can help with the A2 diode?

[tibimakai]

Re: Yamaha HT-R4065 won't start

It was a 5.1V zener diode.
Replaced all the bad components, that I have found, and after clearing th error, the receiver turned on and worked fine with the front speakers, when I connected the two rear channels(SL had the issue), then the same channel. Luckily, I have another set of parts.
What should I check next time, before I turn it on?
It blew up only with load, without speaker it was fine.

[tibimakai]

Re: Yamaha HT-R4065 won't start

Found the amplifier schematic in another Yamaha receiver. The one that I have found earlier, did not match my receiver.
I have replaced the two finals, the two pre finals, the zener diode, the .22 ohm resistor(one side it was open), a 120 ohm resistor(need to check which one).
What do you guys think, which component did I have missed.
Now I will have to check which ones blew up.

[tibimakai]

Re: Yamaha HT-R4065 won't start

If the DC bias is the same as the rest of the channels, then that channel it should be fine? I can connect the speaker?

[tibimakai]

Re: Yamaha HT-R4065 won't start

I have managed to blow it again. It had even caught fire.
I would really need some help here.
I have tested each component at this amp. All were OK.
At first didn't want to turn on, then I have reset it with Tone control+Info+Powr on and then blew up.

[rievax_60]

Re: Yamaha HT-R4065 won't start

At what point did it fail?

[tibimakai]

Re: Yamaha HT-R4065 won't start

First time I have managed to clear the error and the unit turned on. Only when I connected that speaker(SL channel) blew up.
Now, when I cleared the error, blew up right away.
I have measured the finals against the heatsink, they were all fine, no short there.
R2123 cut fire. It's the resistor at the emitter of the PNP pre amp transistor.
The schematic that I have it's not exactly the same as mine.
The first part of the amp: Q2005, Q2012 and Q2019 section, it's not there.
The whole amp section, is so simple and I have managed to blow it up two times. I can't believe it that it happened.

[rievax_60]

Re: Yamaha HT-R4065 won't start

If the 5.1v zenner was shorted before, it implies that Q2028 is intermittently disconnecting or has been blown open circuit.

[rievax_60]

Re: Yamaha HT-R4065 won't start

The circuit you posted shows that the feedback loop remains closed even when the output transistors are removed. You can take advantage of this to do some relatively safe testing.

[tibimakai]

Re: Yamaha HT-R4065 won't start

The zener blew each time. Q2025, it's the SL channel. That transistor is under the heatsink.
To me it seemed OK when I have removed it and tested it.
I will order a new one, it's not cheap and hard to find.
I have ran out of parts, I need to order new ones.
0.22 Ohm resistor is open, the finals, pre finals are all bad, the 120 Ohm resistor is burned.
You are saying that I should start it up next time without the finals?

[rievax_60]

Re: Yamaha HT-R4065 won't start

The zener blew each time. Q2025, it's the SL channel. That transistor is under the heatsink.
To me it seemed OK when I have removed it and tested it.
I will order a new one, it's not cheap and hard to find.
I have ran out of parts, I need to order new ones.
0.22 Ohm resistor is open, the finals, pre finals are all bad, the 120 Ohm resistor is burned.
You are saying that I should start it up next time without the finals?

Yes, that is an option. You need to check that the feedback loop really closed like in the yamaha amp.pdf
Do you understand the function of that small transistor under the heatsink and what happens if it goes open circuit because of a cracked solder joint?

[tibimakai]

Re: Yamaha HT-R4065 won't start

No, I don't understand and that may be the case. At one of the pins the copper ring has lifted.

[rievax_60]

Re: Yamaha HT-R4065 won't start

No, I don't understand and that may be the case. At one of the pins the copper ring has lifted.

Its not a good idea trying to fix amplifiers without leaning something about how they work. I think we have been over this ground before.
If any pin on that transistor has really become disconnected from the circuit, all output transistors turn on hard drawing over current from the rails.
I can see why 2SD2705S is expensive. Its primary function is as "mute transistor" which are becoming scarce for some reason.
If it has failed this time, try to find something else that is used in the same location in another brand/model.

[tibimakai]

Re: Yamaha HT-R4065 won't start

I know that I should learn about amplifiers, but I don't want to be an expert in these.
I'm repairing LCD TVs as a hobby to make some side money. Receivers are just to fill in, when I don't have TVs to repair.
I had a bad feeling about that transistor, but it seemed like it was OK.

[tibimakai]

Re: Yamaha HT-R4065 won't start

That transistor is 2SD1915F, not as in that schematic.

[rievax_60]

Re: Yamaha HT-R4065 won't start

I know that I should learn about amplifiers, but I don't want to be an expert in these.
I'm repairing LCD TVs as a hobby to make some side money. Receivers are just to fill in, when I don't have TVs to repair.
I had a bad feeling about that transistor, but it seemed like it was OK.

The transistor may still be ok. I would rather blame the lifted pad you mentioned.
Does it look like the track is really broken. If it wasnt actually broken, then this is not the reason for the output transistors failing.