I have the subject receiver. It's 2nd hand to me and only cost me $25. I bought it for its' height - it is 5" tall and fits the available cabinet space for it just right. I like it very much, and wish to save it from the scrap heap. Recently, the tuner has started behaving weirdly. It only displays a frequency range from 76.0 to 90.0 for FM. I feel this might be some kind of a regional configuration issue? There is nothing in the Owner's Manual about how to set this, and a note to the Yamaha tech support team yielded nothing helpful. Oddly, there is a strong signal at 89.7 from a local station that the tuner is not pulling in, but then that is true of any signals at all. Everything else on the receiver works fine. Whenever I play a CD, it does a good job without any issues.
Has anyone ever encountered something similar, and if so, have any advice? Many thanks for all responses ...
Has anyone ever encountered something similar, and if so, have any advice? Many thanks for all responses ...
Problems like this can be down to numerous causes but if you suspect a software/configuration issue then check if the unit uses a backup battery or "super cap" to retain uprocessor settings. These can give weird faults when faulty. If it has one then it can be worth removing it and seeing if the fault clears although it won't remember any configuration settings etc.
A word of caution... altering software settings is done at your own risk and you have to be sure you know how to reconfigure any settings that might be lost.
A word of caution... altering software settings is done at your own risk and you have to be sure you know how to reconfigure any settings that might be lost.
Thank you for your recommendation. I was thinking along similar lines, as I found in the Owners Manual that if the unit was unplugged for one week or longer, the station presets would be lost. This made me think the config could be 'reset' as it were, by draining the cap that was backing up the settings. So ... I unplugged the unit yesterday. I will try it again after the New Year. Wish me luck!
In rare cases (and again you need to be aware of the implications) you can place a piece of tinfoil over the uP and "press" it hard onto the pins to fully discharge everything.
You MUST be sure there are no higher voltages around that could cause damage though.
This is something that has got me out of trouble many times as a repair tech. In rare cases even leaving something unplugged for a week doesn't reset things.
Of course we are assuming this is the problem... it may not be
You MUST be sure there are no higher voltages around that could cause damage though.
This is something that has got me out of trouble many times as a repair tech. In rare cases even leaving something unplugged for a week doesn't reset things.
Of course we are assuming this is the problem... it may not be
Service Manual
Try to get the Yamaha Service Manual for your Receiver. Yamaha Receivers have for many years, had a built in trouble shooting problem. I found this out recently when I was given a RX-V540 Receiver. The Service Manual will tell you how to enter the troubleshooting program.
MLStrand56
Try to get the Yamaha Service Manual for your Receiver. Yamaha Receivers have for many years, had a built in trouble shooting problem. I found this out recently when I was given a RX-V540 Receiver. The Service Manual will tell you how to enter the troubleshooting program.
MLStrand56
Could not find the exact manual, but found one for an RX-V440. Thinking it may be close in some respects, and out of curiosity, I dl'ed it. It was interesting to find a section on how to read the MP settings. Even more interesting to learn that there are tuner settings for the bands based on regions, which confirmed my intuition. What was missing was any detail on how to configure the MP. I think there must be some kind of bench diagnostic tool to do this. I also think that unless leaving it unplugged for an extended period does the trick, I am going to be out of luck. All advice is still welcome, and at least I am getting closer to a final determination. Much thanks all around!
Attachments
Today I plugged the unit in after a week off. Regrettably, it had no affect on the settings of the tuner. I tried resetting it to default factory settings per the instructions I just received from Yamaha tech support, with similar lack of results.
So ... I removed the top and peeked inside. The unit was amazingly clean, practically spotless with almost no dust at all. All the fuses were fine, no signs of anything, anywhere having smoked. I found what COULD have been the Mp and used the foil tip from Mooly. Again, no dice.
I am going back to Yamaha and ask them to contact the factory for me on how the settings were originally applied, as I am convinced it has to be some sort of regional configuration. Likely as not, it is done by some form of combining buttons that are pressed, and then reading the LCD panel, in a similar vein to the reset procedure.
So ... I removed the top and peeked inside. The unit was amazingly clean, practically spotless with almost no dust at all. All the fuses were fine, no signs of anything, anywhere having smoked. I found what COULD have been the Mp and used the foil tip from Mooly. Again, no dice.
I am going back to Yamaha and ask them to contact the factory for me on how the settings were originally applied, as I am convinced it has to be some sort of regional configuration. Likely as not, it is done by some form of combining buttons that are pressed, and then reading the LCD panel, in a similar vein to the reset procedure.
It was worth trying...
I see you tried the foil. Its worth physically looking for a backup cap to be sure and discharging it. They often look like this,
backup capacitor - Bing Images
As you say, it may well be a software setting that is corrupted.
I see you tried the foil. Its worth physically looking for a backup cap to be sure and discharging it. They often look like this,
backup capacitor - Bing Images
As you say, it may well be a software setting that is corrupted.
After I posted this today, I found a service manual online. It had information on what the default settings are supposed to be, and how to reset them, which I did. My unit is not lining up with what they should be according to the manual. I guess it is toast - disappointing! For the life of me, I don't know how this occurred, and why it cannot be resolved. As I thought about it, I seriously doubt that Yamaha is going to tell a user how to muck around with a unit beyond what they have provided me already. So, I either find another, or else I use this one for it's remaining capabilities. Thank you for your suggestions, I truly appreciate them.
I know I keep banging on over this
Have you located the backup 5 volts supply (I know we're assuming it has one rather than non-volatile RAM) and done some checks ? Is the supply correct ? Is the supply maintained on power off ? Is the backup cap leaky and so pulling the supply down ? Remove the backup cap, discharge everything and try again without it fitted.
The uP is always always always the last suspect. I 've been here countless times and seen other technicians fall repeatedly into the same trap. 99.9% of the time its something simple. Is the keyscan OK to the uP ? No shorted tact switches or data lines being pulled down.
Have you located the backup 5 volts supply (I know we're assuming it has one rather than non-volatile RAM) and done some checks ? Is the supply correct ? Is the supply maintained on power off ? Is the backup cap leaky and so pulling the supply down ? Remove the backup cap, discharge everything and try again without it fitted.
The uP is always always always the last suspect. I 've been here countless times and seen other technicians fall repeatedly into the same trap. 99.9% of the time its something simple. Is the keyscan OK to the uP ? No shorted tact switches or data lines being pulled down.
I know I keep banging on over this
Have you located the backup 5 volts supply (I know we're assuming it has one rather than non-volatile RAM) and done some checks ? Is the supply correct ? Is the supply maintained on power off ? Is the backup cap leaky and so pulling the supply down ? Remove the backup cap, discharge everything and try again without it fitted.
The uP is always always always the last suspect. I 've been here countless times and seen other technicians fall repeatedly into the same trap. 99.9% of the time its something simple. Is the keyscan OK to the uP ? No shorted tact switches or data lines being pulled down.
Sorry to show my lack of knowledge here, but I don't even know how to check the things you have suggested, although I am more than capable of giving it a go with a little TLC ;=}. I have a schematic from the service manual, if I shared that could you point out what to check and how? I have a V-O-M meter, but not a silly-scope. Anything is worth a try in my book. Thanks much!
Its no problem
Here's the backup 5 volt supply. With the power TOTALLY OFF check what the voltage is on this cap and pin of the system control processor. It should be 5 volts.
Assuming it is, then what you then need to do is to discharge the cap with a resistor (anything from 100 ohm to 10K ohm).
You then have the option of trying it all again. If its still the same then repeat the discharge procedure and then totally remove the cap I ringed. Try it again and see if it will set up.
Here's the backup 5 volt supply. With the power TOTALLY OFF check what the voltage is on this cap and pin of the system control processor. It should be 5 volts.
Assuming it is, then what you then need to do is to discharge the cap with a resistor (anything from 100 ohm to 10K ohm).
You then have the option of trying it all again. If its still the same then repeat the discharge procedure and then totally remove the cap I ringed. Try it again and see if it will set up.
Attachments
Okay, I will try this in the morning. I don't have any resistors, but my neighbor might. I assume that I put the resistor across both leads from the cap? It seems to me that in a long ago and far away place I once learned that a cap could be drained by shorting it - is that not the case? Or (more likely) is it just a bad idea? What is proper procedure to use?
And, if the cap is drained and I still have no luck finding the correct frequency ranges, then I suppose I have gone as far as I can go - correct?
And, if the cap is drained and I still have no luck finding the correct frequency ranges, then I suppose I have gone as far as I can go - correct?
Generally its not good practice to short caps, and particularly not large ones.
Backup caps are a bit different and have relatively high internal resistance and so you could just short it (but the mains MUST BE OFF).
If its still doesn't work or allow you to set it up after discharging the cap then REMOVE the cap completely and try again. If thats a no go then yes, you've gone as far as you can.
Final results - found and drained the cap, no better outcome. Looks like it's headed for the scrap heap. Still, it was worth the effort. Luckily for me, I found another on Clist one town over for $50 just listed two days ago. This one cost $25 and was three years newer. Sigh ...
Post mortem: I learned a lot along the way, both about myself, and about the value of Internet 'friends' :=}. I am still 100% convinced that this could be salvaged, if only I knew how to program the Mp. The service manual was somewhat useful, but strangely silent on this aspect. Hope that my next experience has a better outcome, but I could not have had better help along the way. Many thanks for all assistance!
Post mortem: I learned a lot along the way, both about myself, and about the value of Internet 'friends' :=}. I am still 100% convinced that this could be salvaged, if only I knew how to program the Mp. The service manual was somewhat useful, but strangely silent on this aspect. Hope that my next experience has a better outcome, but I could not have had better help along the way. Many thanks for all assistance!
Thanks for the kind words... a pity it wasn't a better outcome.
I'd go along with your suspicions too, it doesn't sound like a genuine fault (as in a component fault).
The very final suggestion is to remove that cap and then put the whole thing on one side for a week or so and then power it up again (with the cap still out).
Better luck with the next one
I'd go along with your suspicions too, it doesn't sound like a genuine fault (as in a component fault).
The very final suggestion is to remove that cap and then put the whole thing on one side for a week or so and then power it up again (with the cap still out).
Better luck with the next one
I stumbled on this thread (and forum) Googling specs for the RX-V480 because there's one for sale near me. There's probably nothing wrong with it; 76-90 is the FM broadcast range in Japan. That said, there may or may not be a setting to actually change it, so no big deal if you already tossed it. But if you haven't it might be worth playing around with or at least reselling.
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