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Old 03-27-2018, 11:10 AM   #21
Coldstream
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Default Re: Yamaha RX-V673 power problems

Quote:
Originally Posted by R_J View Post
T3701 is the standby transformer, it is part of the switch mode power supply, D3704 does not get 90 volts, if it did you would blow up the 25 volt caps!!! It gets about 4.5 volts [at 67khz] not 50hz

You need to measure the voltage across C3706, it should be around 300 volts (220vac input) When measuring voltages in the primary of T3701 you MUST use C3706 (-) or HOT GROUND for ground. it is NOT the same as chassis ground.
when measuring the voltage on C3708, measure across the cap or use the HOT ground
If there is less than 15 volts DC across C3708 it is likely the ic is bad.
Like I said earlier, check the value of R3704, if it is open the the ic likely shorted.

NOTE: if you measure the ac voltage on the primary of T3701 using the chassis ground, it will likely show 90vac. this is NOT the way to check this voltage.
Also be carefull when working in the primary side, itis not isolated. and be carefull around C3706 as it can stay charged when the unitis unpluged. To discharge that cap use a 5K 10 watt resistor as noted in the manual

Thanks, yes the ~ on the schematic confused me there thats why i wasn't sure. Checking the IC list, and specifically the datasheet of D3704 was part of that.
I didn't understand that part properly but for sure they would blow if there would've been 90V going to them.
C3706 has 315V, that makes sense.
Can the R3704 be tested in the circuit?
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Old 03-27-2018, 12:14 PM   #22
R_J
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Default Re: Yamaha RX-V673 power problems

Yes, R3704 should check as a short. If the resistor does check ok, the ic could still be bad. What can happen is the internal startup circuit can fail, it should take the 300 volts and internaly supply the vcc for the ic to start working, once the ic starts, then the vcc gets supplied via D3702.
Like I said, check the voltage across C3708, if it is less than a 10 volts, the ic is bad
You could also check R3708 to make sure its not open but I suspect it is ok

Last edited by R_J; 03-27-2018 at 12:17 PM..
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Old 01-08-2019, 06:59 AM   #23
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Default Re: Yamaha RX-V673 power problems

hello everyone,

I have the exact same amp as stated above but with a different issue. So the symptoms with my amp are the next. The 5amp fuse on power board was blown out, after replacing and turning the unit on it has blown straight away. With the blown out fuse I can enter self-diag. mode with the error code ps2 prt 30l. Of course it's gonne be low because no power coming out of the transformer. Then disconnected the 90v lines(5 cables) from transformer so power amp would stay off while left the 5v and 12v lines on. When powering it on 3 out of 10 times is does come on otherwise it shut of before the last relay click. After this shut down if I go back to self-diag it says DC PRT 80H so measured all the speaker terminals where I get 0.10v on most of the channels and 0.45v on Center, Sur L, Sur R. while the unit is off i was measuring the same channels resistance and got 0ohm while the rest has about 0.10ohms..strange..Also mesaured the transistors in the power amp and all of it shows about 0.136ohms so I guess they're good. There is anyone here who had the same issue or can give some advice where to find the problem?

Thanks!!
Tom
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Old 01-08-2019, 10:00 AM   #24
R_J
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Default Re: Yamaha RX-V673 power problems

If you have disconnected the transformer for the power amp section, of course you will measure 0 volts at the speaker terminals, There will be no voltage anywhere to the power amp. Also there are protection relays on all speaker lines so if the relay contacts are open you will measure 0 volts, you need to have the transformer connected and then measure the voltage at the center of the 0.22 Ω emitter resistors.
If you are measuring 0Ω on the speaker terminals with the unit off you are doing something wrong, meter in too high a range maybe. (megΩ)

The PS2 monitored voltages are the -VP, +5T, +&-5V (check those voltages) a shorted hdmi chip can cause this error, see if they are getting hot. (ic1, ic2, ic3 etc) on digital board

Last edited by R_J; 01-08-2019 at 10:38 AM..
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Old 01-08-2019, 10:42 AM   #25
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Default Re: Yamaha RX-V673 power problems

Sorry I forgot to meantion that I put a new fuse in then disconnected the 90v line so the transformer was giving power out.Only disconnected the 90v from transformer, the 5v ac and 12v ac are still connected to the power amp board and the sp. terminal boards and when measuring the terminals I still get 0.45v on the C, SR, SL and the rest of the channels are having 0.10 volts only the zone 2 cennectors has 0v on it. Unfortunately can not measure the voltage on it with the transformer connected back because in that case the fuse burn out in 4 seconds..

Last edited by tompar; 01-08-2019 at 10:48 AM..
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Old 01-08-2019, 11:08 AM   #26
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Default Re: Yamaha RX-V673 power problems

If the fuse blows with the AC_BL, AC_BH, lines connected you have a possible shorted D1040 bridge rectifier (not likely) or there is a short on either the plus or minus lines that supply the output section. there could also be an imballance in one of the amp sections causing the amp to load either the plus or minus (28/61v) lines.
Check the resistance of all the 0.22 Ω emitter resistors.
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Old 01-08-2019, 01:21 PM   #27
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Default Re: Yamaha RX-V673 power problems

Just checked the emitter resistors without taking them out and got 1.7ohm on the two side legs and 1.5ohm on middle and side legs. also checked the manual where is the d1040 rectifier and I did here i quite sparkling noise from that area when connected W104B and W102B. Didn't take the amp apart yet to check if there is anything blown and can't really see those parts there so will give it a try
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Old 01-08-2019, 04:46 PM   #28
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Default Re: Yamaha RX-V673 power problems

The resistors should check almost shorted 0.22Ω, check the resistance of your meter leads, when shorted together the resistance should be close to 0Ω Check the main board for poor solder connections on and around Wxxx pins, main caps etc.
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Old 01-09-2019, 05:56 AM   #29
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Default Re: Yamaha RX-V673 power problems

Thanks for the advice! You were right about my meter leads, they measure as 0.7ohm and get now 0.9 or 1ohm on the emitter resistors what I believe is good. In continuity the resistors should check as short? By the way I think you were right about the shorted D1040 bridge rectifier, last night I took apart the amp, checked it and only shows between 5-8 ohms while the D1041 shows around 5-600 ohms which is perfect for a diode?! So ordered a replacement RS603M and I'll see if it fix the issue.
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Old 01-09-2019, 10:01 AM   #30
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Default Re: Yamaha RX-V673 power problems

Quote:
I think you were right about the shorted D1040 bridge rectifier, last night I took apart the amp, checked it and only shows between 5-8 ohms while the D1041 shows around 5-600 ohms
What checks 5-8 Ω and what checks 5-600Ω?

Does your meter have "diode test" use that to check the 4 diodes in the bridge, Did you check the bridge out of circuit? You say you checked the bridge and get 5-8 Ω ... between which pins? and was the transformer connected at the time?
If you measured between the two center pins of d1040, with the transformer connected 5-8Ω would be normal.

Last edited by R_J; 01-09-2019 at 10:08 AM..
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Old 01-10-2019, 09:31 AM   #31
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Default Re: Yamaha RX-V673 power problems

Yes I was measuring it in "diode test" and no the bridge was in the circuit with the transformer connected. Checked the bridge in continuity mode as well and pin 1-2 was short, pin 1-3 was short and 2-3 was short too. Thats because of the transformer?!

Last edited by tompar; 01-10-2019 at 09:39 AM..
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Old 01-10-2019, 10:12 AM   #32
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Default Re: Yamaha RX-V673 power problems

If the transformer is connected you will be measuring the transformer winding, so unplug the transformer going to the board to check D1040
Another thing to check is the resistance across c1084 & c1085 (large caps) With no power applied, check if there is any voltage on the caps, if there is they need to be discharged, then measure the resistance across them, it will usually start low then slowly climb up. If there is a short across either of them, that needs to be located.
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Old 01-14-2019, 01:42 PM   #33
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Default Re: Yamaha RX-V673 power problems

So finally tonight I had some time. Disconnected the transformer measured the bridge and on pin 1-2 I have short the rest of the pins measure around 196ohm. When I measure the capacitors you mentioned C1084 is behave like short for about 3 seconds then the resistance slowly starts to climb up. whats the reason of this strange thing. Also on D1040 when I measured pin 3-4 it did the same thing, act as short for ~3sec then the resistance slowly climbed up to 196ohm. Strange..
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Old 01-14-2019, 02:14 PM   #34
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Default Re: Yamaha RX-V673 power problems

I suspect the bridge has a shorted diode (1-2) When the meter checks resistance it uses a small voltage, this small voltage across a capacitor will first show as a short, and as the capacitor slowly charges that resistance will increase. This is normal so I don't see any real shorts on the capaciotrs that would cause a problem.
The resistance on C1084 is likely caused by the shorted bridge rectifier diode.
To be 100% remove the bridge rectifier and check it out of circuit.

Last edited by R_J; 01-14-2019 at 02:18 PM..
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Old 01-14-2019, 02:39 PM   #35
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Default Re: Yamaha RX-V673 power problems

yes, I was thinking the same about the capacitor just wanted to hear it from a smarter person just tried to take the bridge of from the board with the heat sink on.. obviously I can't so probably will wait till the other bridge gets here then take the whole amp apart and do it in one run because the lack of space. will get back to you
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Old 01-16-2019, 03:44 PM   #36
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Default Re: Yamaha RX-V673 power problems

Today finally the bridge rectifier has arrived, managed to change it after 15 minutes of soldering a couple of swear words.. It's up and running!! The only thing that concerns me is the PS1 value, it is change constantly between 77-80 in diagnostic mode. Hopefully it's not gonna be the cause of the next problem.. And a HUGE THANK YOU to R_J for all the help and the information he provided!
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Old 01-16-2019, 06:22 PM   #37
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Default Re: Yamaha RX-V673 power problems

Glad its working, I don't think that PS1 value is an issue, It could just be caused by the line voltage changing slightly. PS1 normal operating range is betweem 10 -100
going from 77-80 might translate to only be 0.1 volts or less?
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Old 02-06-2019, 12:18 PM   #38
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Default Re: Yamaha RX-V673 power problems

Quote:
Originally Posted by Coldstream View Post
Hello everyone,

I'm stuck finding the problems on this Yamaha receiver, i suspect a few things but after messing around the whole weekend it seems like i'm getting on a dead end. Must say, that i've not much experience with these newer devices and i'm a bit rusty.
First of all, i got this device from my friend.. The receiver's fuse went dead when he was just watching a movie.
So obviously, my first step was to get into the diagnostic mode (power sw+info+tone control from my head) and there it went fine with an error P2 (power supply 2, 34L 3.4 volt LOW?) i thought P2 should've been 3.3V so how did it went out that the power there is too low? anyways, before i even could analyze more, i simply removed a lot of dust and now the device won't turn on anymore either.
Previously, even the power led went on, now it's nothing. Obviously i checked all the cable connections.
So, my logic sense seems to be, previously we had the standby transformer/signal going properly, but even that is going crazy now.
For some reason, i can't get out of it properly with the schemes in the Service Manual for proper diagnostics, but if i am testing it right, the 5v and the 12v line both are way underpowered. But to be fair, i am not even sure if i am reading it from the proper points.
I will include the Service Manual as attachment of this post.
To me, the power relay doesn't switch and i think thats because it never gets it's 5v, just somewhere around 3,8v and that might be the problem.
Since i've been looking for problems the whole weekend, it might aswell be that i'm simply overlooking a simple thing as i'm looking way too far ahead.
The AC in is on the VIDEO 2 board, i suspect the problems lay on this PCB too.
If i'm thinking properly, the 5.5v DC comes from T3701 to D3704, end of D3704 gives me 3,8v where i'm sure this should be 5,6v?
Anyways, what also puzzles me is that the 12V line also is somewhere in the high 3v range?

Maybe a fresh pair of eyes, and someone with experience of newer audio equipment can help me out.
I can give measurement results as needed.

The service manual with all the schematics are here:
https://elektrotanya.com/yamaha_rx-v.../download.html

Thanks for any help


Hi, I have The same Problem with your unit. I got Yamaha RX-S600 and luckily I repaired it. I dont have 5dcv for stand by supply to triggerd the main power supply. there is no LED indicator also. Please Try to check this IC before the Transformer. Please check my Attachment.

Good Luck! Cheers!
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Old 02-12-2019, 03:09 AM   #39
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Default Re: Yamaha RX-V673 power problems

Good job.
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