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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Yamaha HTR5790 schematic
Hello, first post on this group.
Doing research on-line I found that quite a few people had the same problem as my HTR5790 receiver. The receiver would shutdown right after power up. Reading the forums found suggestions by Mark Zacharias on checking C43 C44 C97 C98 which are the 47uF 50v. I gathered from other posts that there was a bad batch of those caps. Well in my receiver the C97 was bad. I checked around all other parts on that board to see if something else was dead, but didn’t find anything obvious. So I reassembled the receiver but it still has the same issue. Here is a little history, the receiver would shutoff as soon as output relays were clicked on; it did this for a while then sometime later the issue went away for several weeks, then it came back again, now the issue is gone but so are the main channels, receiver works normal otherwise. I assume something else has burned out. I checked the main driver transistors and they seem to be o.k. although without knowing what they are it is hard to say, but they are not shorted and measure similarly to other transistors which I know some of them are still good.. I am kind of lost without schematic and was wondering if someone could help me with that, or maybe can point me into right direction where I could get one. Thank you very mach for helping. |
#2
Posted to sci.electronics.repair
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Yamaha HTR5790 schematic
(Windoze Mail not quoting properly...)
"Sinij kot" wrote in message ... Hello, first post on this group. Doing research on-line I found that quite a few people had the same problem as my HTR5790 receiver. The receiver would shutdown right after power up. Reading the forums found suggestions by Mark Zacharias on checking C43 C44 C97 C98 which are the 47uF 50v. I gathered from other posts that there was a bad batch of those caps. Well in my receiver the C97 was bad. I checked around all other parts on that board to see if something else was dead, but didn’t find anything obvious. So I reassembled the receiver but it still has the same issue. Here is a little history, the receiver would shutoff as soon as output relays were clicked on; it did this for a while then sometime later the issue went away for several weeks, then it came back again, now the issue is gone but so are the main channels, receiver works normal otherwise. I assume something else has burned out. I checked the main driver transistors and they seem to be o.k. although without knowing what they are it is hard to say, but they are not shorted and measure similarly to other transistors which I know some of them are still good.. I am kind of lost without schematic and was wondering if someone could help me with that, or maybe can point me into right direction where I could get one. Thank you very mach for helping. ************************************************** ************************ Should have replaced all 4 of those caps. Probably would have solved your problem. I did have a similar model the other day which coincidentally had the cap problem AND a problem in the protection circuit; however this would be really rare and very unlikely yours would have the same scenario. Replace the caps. They are on 2 different boards. I can help you find them. You can e-mail me direct at: reverse the domain to read sbcglobal and notice there is an underscore _ between the first and last name. Mark Z. |
#3
Posted to sci.electronics.repair
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Yamaha HTR5790 schematic
Mark Zacharias wrote:
(Windoze Mail not quoting properly...) "Sinij kot" wrote in message ... Hello, first post on this group. Doing research on-line I found that quite a few people had the same problem as my HTR5790 receiver. The receiver would shutdown right after power up. Reading the forums found suggestions by Mark Zacharias on checking C43 C44 C97 C98 which are the 47uF 50v. I gathered from other posts that there was a bad batch of those caps. Well in my receiver the C97 was bad. I checked around all other parts on that board to see if something else was dead, but didn’t find anything obvious. So I reassembled the receiver but it still has the same issue. Here is a little history, the receiver would shutoff as soon as output relays were clicked on; it did this for a while then sometime later the issue went away for several weeks, then it came back again, now the issue is gone but so are the main channels, receiver works normal otherwise. I assume something else has burned out. I checked the main driver transistors and they seem to be o.k. although without knowing what they are it is hard to say, but they are not shorted and measure similarly to other transistors which I know some of them are still good.. I am kind of lost without schematic and was wondering if someone could help me with that, or maybe can point me into right direction where I could get one. Thank you very mach for helping. ************************************************** ************************ Should have replaced all 4 of those caps. Probably would have solved your problem. I did have a similar model the other day which coincidentally had the cap problem AND a problem in the protection circuit; however this would be really rare and very unlikely yours would have the same scenario. Replace the caps. They are on 2 different boards. I can help you find them. You can e-mail me direct at: reverse the domain to read sbcglobal and notice there is an underscore _ between the first and last name. Mark Z. I had one last month that i did a lot of net research on and came up with the large value backup memory super cap. I subbed one in and the issues went away. bob |
#4
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Yamaha HTR5790 schematic
"bob" wrote in message ...
Mark Zacharias wrote: (Windoze Mail not quoting properly...) "Sinij kot" wrote in message ... Hello, first post on this group. Doing research on-line I found that quite a few people had the same problem as my HTR5790 receiver. The receiver would shutdown right after power up. Reading the forums found suggestions by Mark Zacharias on checking C43 C44 C97 C98 which are the 47uF 50v. I gathered from other posts that there was a bad batch of those caps. Well in my receiver the C97 was bad. I checked around all other parts on that board to see if something else was dead, but didn’t find anything obvious. So I reassembled the receiver but it still has the same issue. Here is a little history, the receiver would shutoff as soon as output relays were clicked on; it did this for a while then sometime later the issue went away for several weeks, then it came back again, now the issue is gone but so are the main channels, receiver works normal otherwise. I assume something else has burned out. I checked the main driver transistors and they seem to be o.k. although without knowing what they are it is hard to say, but they are not shorted and measure similarly to other transistors which I know some of them are still good.. I am kind of lost without schematic and was wondering if someone could help me with that, or maybe can point me into right direction where I could get one. Thank you very mach for helping. ************************************************** ************************ Should have replaced all 4 of those caps. Probably would have solved your problem. I did have a similar model the other day which coincidentally had the cap problem AND a problem in the protection circuit; however this would be really rare and very unlikely yours would have the same scenario. Replace the caps. They are on 2 different boards. I can help you find them. You can e-mail me direct at: reverse the domain to read sbcglobal and notice there is an underscore _ between the first and last name. Mark Z. I had one last month that i did a lot of net research on and came up with the large value backup memory super cap. I subbed one in and the issues went away. bob The same model? Sounds more like an older one. Mark Z. |
#5
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Yamaha HTR5790 schematic
************************************************** ************************
Should have replaced all 4 of those caps. Probably would have solved your problem. I did have a similar model the other day which coincidentally had the cap problem AND a problem in the protection circuit; however this would be really rare and very unlikely yours would have the same scenario. Replace the caps. They are on 2 different boards. I can help you find them. You can e-mail me direct at: reverse the domain to read sbcglobal and notice there is an underscore _ between the first and last name. Mark Z. Mark, I will email you off line and post my finding on this board. |
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