Yamaha RX-A2020 delayed audio at power on

5

59ctd

Audiophyte
I've had this Yamaha RX-A2020 for a few years now - purchased new from BB. I have not used it myself much for the past 2 years since my teenage son has taken over the basement as his appt. He has used it every day and night for quite a while now. Lately when powering it on it takes a long time for the audio to kick in. Does not seem to matter which audio/video source is selected and the time seems somewhat random from a few minutes sometimes to several hours other times. Any ideas? Is it worth getting repaired or trying to tackle myself? I am fairly versed with electronics and repair but am unsure where to even start with a diagnosis.
 
TLS Guy

TLS Guy

Audioholic Slumlord
I've had this Yamaha RX-A2020 for a few years now - purchased new from BB. I have not used it myself much for the past 2 years since my teenage son has taken over the basement as his appt. He has used it every day and night for quite a while now. Lately when powering it on it takes a long time for the audio to kick in. Does not seem to matter which audio/video source is selected and the time seems somewhat random from a few minutes sometimes to several hours other times. Any ideas? Is it worth getting repaired or trying to tackle myself? I am fairly versed with electronics and repair but am unsure where to even start with a diagnosis.
The problem is going to be with the timer circuit to the speaker relays. A lot of amps, if not mos, send out a thump to the speakers on turn on. This can be damaging to the speakers. So the output from the power amps goes to a relay that has a timed delay, to close the speaker relays after the turn on thump.

This relay is usually controlled by the ubiquitous LM 55 timer circuit. The LM 555 is an common IC for this purpose from Texas instruments.

For this purpose the timer is usually set up in monostable mode.

This is a typical circuit.



Now the time is set by the ration of C1 and RV 1. The timing of the circuit is usually set by calculating the correct value of RV1 and using a fixed resistor. Now C1 also affects the timing, and the most common reason for the problems you are encountering is failure of C1. The IC itself could also be at fault.

Now your problem is going to be finding this little IC circuit in a cluttered unit like a receiver. What makes it really difficult is that manufacturers rarely publish circuits and or service manuals. You might be able to trace the circuit back from the relays. It will be in the circuit that sends the power to activate the relays in the speaker output circuits.

First check that the value of the cap is correct. If so check resistor values. If these values are correct them the LM timer chip needs replacing. They cost 80 cents each. Good luck. Odds are heavily on the cap being the problem.
 
5

59ctd

Audiophyte
Ah the old LM555 timer IC. I remember working with those back in high school in the early 80s. I too was thinking about the issue likely being a capacitor that is bad. My wife's Samsung TV has a bad cap that prevents power-on sometimes. Is this capacitor likely to be exactly 1000uF or just around that value? One thought was to open it up and see if there are any caps that look swollen at the top end. I found another post with a similar issue with an RX-A2000 and someone recommended looking for bad caps in the power supply. Unfortunately there was no response or resolution there.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Ah the old LM555 timer IC. I remember working with those back in high school in the early 80s. I too was thinking about the issue likely being a capacitor that is bad. My wife's Samsung TV has a bad cap that prevents power-on sometimes. Is this capacitor likely to be exactly 1000uF or just around that value? One thought was to open it up and see if there are any caps that look swollen at the top end. I found another post with a similar issue with an RX-A2000 and someone recommended looking for bad caps in the power supply. Unfortunately there was no response or resolution there.
I don't know what the value of the cap will be. The time out is set by the RC ratio. The circuit could well be on the power supp;y board. The cap is low voltage and will be small. It is highly improbable that the cap will have any physical evidence of failure.

If you can not locate the timer circuit then you are out of luck. You have to find that chip circuit or you will be SOL. I have not done a search for a circuit or service manual of that unit, but you should. You sometimes get lucky with older receivers.

It is very hard to service anything that complex without a circuit and preferably also a service manual, then you can see where the parts you are looking for are located.
 
S

snakeeyes

Audioholic Ninja
What conditions cause this type of failure? Too much dust? Bursts of power?
 
M Code

M Code

Audioholic General
Firstly...
I would check the contacts on the subject power relay..
After so many years of ON/OFF use the contacts can/will create pits making poor, intermittent contact...

Just my $0.02... ;)
 
5

59ctd

Audiophyte
Firstly...
I would check the contacts on the subject power relay..
After so many years of ON/OFF use the contacts can/will create pits making poor, intermittent contact...

Just my $0.02... ;)
That should be easy enough to locate and verify good power passing through there. The unit appears to power up normally but the speaker relay is what is delayed.
 
5

59ctd

Audiophyte
Trying to locate the service manual with schematics is proving to be difficult for the RX-A2020. I found the service manual for the RX-A3020 but I am unsure if that might be even close to the same internals. I've located a few non-Yamaha sites that claim to have the service manual for a $10 or $16.99 fee but I am leery of doing business with an unknown entity when I have no idea what their product consists of. I also found a usa.yamaha.com page telling me what item# format to use for a service manual for this unit (S M RXA2020) but have not figured out how to order the item from them yet.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Firstly...
I would check the contacts on the subject power relay..
After so many years of ON/OFF use the contacts can/will create pits making poor, intermittent contact...

Just my $0.02... ;)
That would be very unlikely, as you would have to postulate that all contacts to all the speakers failed at once and continue to lose and make contact at the same time. Honestly an impossible proposition as when the unit has no sound there is no sound from anywhere. So I stand by the proposition that this is most likely a failure in the timer/delay circuit.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Trying to locate the service manual with schematics is proving to be difficult for the RX-A2020. I found the service manual for the RX-A3020 but I am unsure if that might be even close to the same internals. I've located a few non-Yamaha sites that claim to have the service manual for a $10 or $16.99 fee but I am leery of doing business with an unknown entity when I have no idea what their product consists of. I also found a usa.yamaha.com page telling me what item# format to use for a service manual for this unit (S M RXA2020) but have not figured out how to order the item from them yet.
Give them a call and see if they will make a service manual available to you. Usually they only make them available to certified service centers. That also leaves the independent repair guys out in the cold. That is why they are on the endangered species list.

I have long been of the view that access to the circuit and a decent service manual should be available to all owners by law, and all qualified service techs. Firms use to do this. Back in the day Quad used to include all circuits in every user manual, but not now our Chinese masters have the whip hand.
 
5

59ctd

Audiophyte
I called Yamaha's toll free number and they were happy to send out a service manual on CD for me. Only $25 for the CD and shipping and it is on the way. They said they burn them to CD when there is an order instead of having tons of CDs stashed away in a warehouse.
 
TLS Guy

TLS Guy

Audioholic Slumlord
I called Yamaha's toll free number and they were happy to send out a service manual on CD for me. Only $25 for the CD and shipping and it is on the way. They said they burn them to CD when there is an order instead of having tons of CDs stashed away in a warehouse.
That will make life a lot easier for you.
 
rinjulian

rinjulian

Audiophyte
Hola, tengo el mismo problema con la Yamaha rx-a730, pensé que era el chip dts, cuando lo caliento con el secador de pelo, el audio sale en 2 o 3 minutos en lugar de 15 minutos, solo hice una Prueba y no volví a intentarlo, el cambio de esa placa es muy costoso. Al leer tu publicación, también es lógico que el sistema de retraso falle. Lo pudo solucionar?. saludos
 
M

mw2474

Audiophyte
i think i have the same issue with the exact same model, RX-A2020. The difference here is mine doesn't eventually come on, it arbitrarily works or doesn't work on power up. The relays on the mobo are audible on power up, but i still get no sound. In addition, when it does decide to work, only the main L/R speakers sound good, some of the other ports with the same speaker and wire sound weak and crackly. To me this sounds like a very similar problem and wondered if you guys would agree the culprit may be the same LM555 or maybe a similar speaker power issue? Do you guys think it would be worth it to have it fixed? probably not DIY possible?
Thanks for all the info provided thus far.
 
5

59ctd

Audiophyte
Based on your description I think that is a different issue than what I have. On my receiver when it does not startup the relay never would click to the closed position. Whenever I did hear the relay is when I kinda knew it had turned on properly.

FWIW, my RX-A2020 is still sitting here on my workbench waiting for me to have time to try and repair it. As a replacement, my son bought an RX-A780 (at least that is what I think it is from memory) so he is using that one in place of the 2020. Wow, they really reduced the number of input connectors on the newer models.
 
TLS Guy

TLS Guy

Audioholic Slumlord
i think i have the same issue with the exact same model, RX-A2020. The difference here is mine doesn't eventually come on, it arbitrarily works or doesn't work on power up. The relays on the mobo are audible on power up, but i still get no sound. In addition, when it does decide to work, only the main L/R speakers sound good, some of the other ports with the same speaker and wire sound weak and crackly. To me this sounds like a very similar problem and wondered if you guys would agree the culprit may be the same LM555 or maybe a similar speaker power issue? Do you guys think it would be worth it to have it fixed? probably not DIY possible?
Thanks for all the info provided thus far.
That is a different issue. Your issue is much more complex. It is likely a power supply issue but I could not guess what. Unless you are experienced in service and have a lot of test gear, you need to stay out of that unit.

As an aside it is not a good idea to use a unit with a significant unknown fault. That becomes not only a safety issue, but one of causing further damage to the unit.

Your choices are professional repair or recycle and replace.
 
G

GruntmaN

Audiophyte
Well another A2020 with delayed audio here. Just wanted to say thanks for the post. Mine is taking 5-10min almost like clockwork and I am getting the audible thump, that tells me sound is only a couple mins away. Guess it’s time to start looking at new receivers. Funny thing is I have 3 old Denon receivers dating back to the 2500 and finally switched to Yamaha from reviews. All 3 of my Denon still work flawlessly but just don’t have the features I need in my home theater.
 
mazersteven

mazersteven

Audioholic Warlord
Holy moly are you saying a Yamaha receiver is having issues and problems no way unbelievable don't let the Yamaha Fanboys read this. They will all have heart attacks
 

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