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Yamaha R-V905 Won't power up
"ICESoft" wrote in message .. . Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. .............. Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- Open up, check your power transistor/mosfet temperature after it power off, if hot then it proofs your thermo cutoff is working. Next figure what causes it to overheat. |
Yamaha R-V905 Won't power up
Been working on this unit off and on for a while. It will power on for
about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. ............... Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- |
Yamaha R-V905 Won't power up
ICESoft wrote in message
.. . Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. .............. Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- As the display goes out , is it a switch mode power supply ? -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
Yamaha R-V905 Won't power up
"Jakthehammer" wrote in message ... "ICESoft" wrote in message .. . Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. .............. Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- Open up, check your power transistor/mosfet temperature after it power off, if hot then it proofs your thermo cutoff is working. Next figure what causes it to overheat. Useless generic advice - and contradicts what the OP already said about this unit. The R-V905 has no thermal cutoff. It's detecting a power supply problem, though it could be falsely triggered. Mark Z. |
Yamaha R-V905 Won't power up
"ICESoft" wrote in message .. . Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. .............. Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- Loop the main (polarized!) power cord back into one of the switched outlets at the rear. Run a double - ended polarized cord from the other switched outlet to your variac or switched power strip. In this way you can bring up all the internal voltages without regard to protection status. A few Yamaha models had problems with the backup cap leaking near the microprocessor and causing problems like this - but I'm thinking your model is NOT one of these. Worth keeping in mind, though. If it comes to troubleshooting the protection function of the micro I can probably help. Post back here or you can e-mail me direct at: and revers the domain name to read sbcglobal.net Mark Z. |
Yamaha R-V905 Won't power up
Mark D. Zacharias wrote in message
... "ICESoft" wrote in message .. . Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings .................................................. .............. Posted via TITANnews - Uncensored Newsgroups Access at http://www.TitanNews.com -=Every Newsgroup - Anonymous, UNCENSORED, BROADBAND Downloads=- Loop the main (polarized!) power cord back into one of the switched outlets at the rear. Run a double - ended polarized cord from the other switched outlet to your variac or switched power strip. In this way you can bring up all the internal voltages without regard to protection status. A few Yamaha models had problems with the backup cap leaking near the microprocessor and causing problems like this - but I'm thinking your model is NOT one of these. Worth keeping in mind, though. If it comes to troubleshooting the protection function of the micro I can probably help. Post back here or you can e-mail me direct at: and revers the domain name to read sbcglobal.net Mark Z. Important safety note: A mains cable with an unshrouded plug on either end is very dangerous practise, especially in the UK. If you must have such a cable lying around , add some sort of springloaded shroud on one end. eg cable tie around the cable, to take one end of a spring and a small plastic bottle , cap end touching the other end of the spring. The bottle large enough to take the plug but deep enough when retracted to be reasonably enclosed. ps could anyone explain to me why my newsreader has failed to pick up the jackhammer posting, no cross-posting AFAICS, checking on Google grouips, which does have that posting. About once a week it occurs in a thread I'm following. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
Yamaha R-V905 Won't power up
ICESoft wrote:
Been working on this unit off and on for a while. It will power on for about 1/2 second then power right back off. History on this unit is that for a while it started to power off on its own with no rhyme or reason, it progressively got worse to the point that it wouldn't power up. Display just barely appears before the unit turns back off. I've checked the output transistors, they tested ok, also checked supply voltages, they appear good as well. I also resoldered any suspect solder joints I could find, still no dice. I don't have a full manual to work by, just some schematics for it. Looking for a kick in the right direction... Thanks, Benjamin Jennings Check the caps in the power supply.. You most likely have a bad one in the safety circuit and is shutting down due to a ripple in the voltage there. At least that is what I have found in a few amps I just recently serviced for a local business. http://webpages.charter.net/jamie_5" |
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