This has several resistors and an area about the size of a quarter that is looking a burnt brown on the pcb near the front of the unit. There are about 5 or 6 ringed resistors total in this area. I fluked the resistors in this burnt area and they are within range (still connected to board, page 24 of included schematic I believe?).
When using the tuner/radio portion all seems to be fine (uses the bypass mode for tuner) but recently this started to smell like something is cookin and now not using the unit until it's sorted out.
When using the bypass feature (which only utilizes the 2 rear channels I believe) for the video/theater audio, this works too. The video source does work but not all the time. Shame to toss this in the trash because this receiver is an oldy but goody. Seems like I could solder a few replacement components and all would be well?
My hope is someone smarter than I can read that schematic and show me the location of the components on the afftected circuit and help find the culprit behind these overheating resistors.
Hopefully the community here will be familiar with the issue. Thanks in advance!
I have located a service manual but lack the knowlege to read it. I also have pics of the overheated resistor location.
Could it be something shorted in an IC chip or diode on the same circuit providing to much power to these resistors? I'm guessing ...
I am NOT an electronics guy but understand a little. This would seem to be a far easier fix than the sanyo project I ditched months ago. I used those speakers elsewhere. I have more pics if needed.
Actual board part number (I think) is ncar-5121. These are numbers from the board anyway. I didn't find them on the schematic but that service manual is the same model as my receiver.
Resistors in the burnt area:
r923 (actually labeled r23 on pcb)
r925 (actually labeled r25 on pcb)
r926
r928
r929
r930
r935
Hi!
This is the power supply part. This is where 5.6 volts and + & - 12 volts are produced from + & - 22 Volts. Onkyo engineers like to “heat up” their amplifiers, so they use resistors to reduce voltage instead of using multiple branching transformers.
As a first step, check the values of the listed resistors, if they match the drawing, you should re-solder their legs because heat can cause a poor contact fault.
Next step, check the voltage at the outputs of Q921-922 - Q923 - Q924, and Q925
Sorry for the wait but still working on my bathroom remodel. Tub install is no longer a problem now . I have done what you asked and results I've found is included in the picture written at the bottom of the link / page. I've resoldered all of those resistor and transistor contact points plus re-soldered all contacts on about 1/3 of this board. I was able to get my magnifying headset on and locate a few bad/cracked solder points as well in other areas. Improvement has been noticed as not all of the resistors listed below are as hot as they were with the exception of the 3 listed below. https://www.dropbox.com/s/m66gysdhfqyojzm/Results1.png?dl=0
The resistors and their tested values are:
r930= 118.8 ohm HOT TO TOUCH!
r929= 118.5 ohm HOT TO TOUCH!
r928= 18.4 ohm HOT TO TOUCH!
r935= 22.1 ohm
r923= 1.5 ohm
r925= 11.4 ohm
r926= 11.5 ohm
These seem to be within range?
Values for outputs tested by touching the negative to the G (?) terminal and pos to to O terminal (is this the correct way to test?):
q921= +11.7v
q922= -11.6v
q923= +6.02v
q924= -5.8v then drops to 0 usually (this one drops voltage after heating up)
q925=+5.5v
If components need replaced could you provide suggestions on comparable replacements if needed? Where to get? Thanks. I've have been studying on how to test these transistors as well. Is it necessary to remove them first? I would not have gotten this far without your help. It took a bit of hard study to be able to read that schematic and still don't understand much but am able to limp thru so far :) I look forward to the next step :)
Hi and thanks hifi! I'm currently going back and forth between repairing a shower wall and this so bare with me. I'll locate, test and reply within a week. Sorry but water issues in the tub have me spread thin. Thanks again.
OK, continue to investigate.
This is a detective work, patience and perseverance.
You found a good trace, but it's just a fingerprint.
The behavior of Q924 is abnormal. This is a stabilizer IC and short circuit protected.
To decide whether Q924 is the defective component or elsewhere there is a short-circuit part, it would be possible to select the -6V portion of the JL701 connector. Drastic solution, but it should cut the wire (so that it can be re-soldered later), then measured -6V remains constant at the Q924 output. If stable -6v can be measured, either the Q802 IC (AK5339) or 3 NJM4558 IC are incorrect. This -6V is performing these with power supply.
Thanks so much hifi I'm trying hard with this but it's not my cup of tea. I remain persistent but patience leaves me often. It's an inner battle to be constantly fought for sure. I'll try to paraphrase but not sure I'm following the idea? Are you wanting me to temporarily cut a wire to resolder later? If so, cut -6v wire at the JL701 connector? If I understand correctly, I am to then measure -6v at the q924 voltage regulator output? Will this help me determine whether the Q802 IC (AK5339) or the 3 NJM4558 IC's are faulty? Just want to understand your instructions first before acting.
Could you help with page locations on the service manual? Thanks. I was able to locate the JL701 connector on page 36 and Q802 IC (AK5339) on page 25 but not the 3 NJM4558 IC. As always, thanks. JL701 trace to output
Since the original problem is that there is a DSP error, the absence of -6 Volt on the Q802 DSP IC can cause this to appear on the display.
Therefore, it should be determined whether the Q 924 power supply IC is faulty or if there is a short in the -6 Volt branch coming from there.
These power supply ICs are overload and short circuit protected, so the voltage at the output goes down because the output current reaches the maximum allowed and is down-regulated, thus protecting itself.
Therefore, I suggested that the wire on which the -6 Volt goes from the power supply to the ICs Q802 and Q801-Q808-Q809 should be cut around the J701 connector.
This would take the load off the Q924 stabilizer IC and find out if the Q924 is faulty or need to look for a short circuit further.
If, after cutting the -6 Volt wire, a stable -6 Volt can be measured at the output of the Q924, then the fault is probably in the good and the part fed by it. In this case, with the device switched off, it would be possible to measure whether there is a short circuit on the side of GND and J701 facing the Q801-802 ICs.
This could be done by connecting The multimeter switch the beeping position, this could be done by between the GND (body of the device) and the end of the cable
. If the short circuit is over there, it will be harder to find the fault, but not impossible.
In the attached drawings, I marked in red the most probable parts that could cause a short circuit.
First I would measure the capacitor of Q802 (AK) C 812, ceramic capacitors sometimes become short-circuited.
Possibly the other C 810 capacitor, but it is less likely. Finally, one of the 3 NJM4558L Q801-Q808-Q809 ICs. The most important thing would be to find out if the power supply IC is faulty or there is a short circuit in the part it is feeding.
This can be decided by cutting the described wire. I hope my way of thinking is understandable, unfortunately my English is poor, so I have to use a translation program, but the structure of the Hungarian language is very different from English, so the machines do not translate really correctly.
Hmm...I can't upload the pictures, but I'm still trying.
Sorry for the long pause but life has its priorities elsewhere sometimes. Still fixing my home. How I am able to link to pictures I use dropbox and share a link to the uploaded pictures in dropbox. I'm sure there are other free sites that allow this feature as well. It has been a lifesaver at times. Thanks and I look forward to seeing those pictures. Thank you so much :)
This has several resistors and an area about the size of a quarter that is looking a burnt brown on the pcb near the front of the unit. There are about 5 or 6 ringed resistors total in this area. I fluked the resistors in this burnt area and they are within range (still connected to board, page 24 of included schematic I believe?).
When using the tuner/radio portion all seems to be fine (uses the bypass mode for tuner) but recently this started to smell like something is cookin and now not using the unit until it's sorted out.
When using the bypass feature (which only utilizes the 2 rear channels I believe) for the video/theater audio, this works too. The video source does work but not all the time. Shame to toss this in the trash because this receiver is an oldy but goody. Seems like I could solder a few replacement components and all would be well?
My hope is someone smarter than I can read that schematic and show me the location of the components on the afftected circuit and help find the culprit behind these overheating resistors.
Hopefully the community here will be familiar with the issue. Thanks in advance!
I have located a service manual but lack the knowlege to read it. I also have pics of the overheated resistor location.
Could it be something shorted in an IC chip or diode on the same circuit providing to much power to these resistors? I'm guessing ...
I am NOT an electronics guy but understand a little. This would seem to be a far easier fix than the sanyo project I ditched months ago. I used those speakers elsewhere. I have more pics if needed.
Actual board part number (I think) is ncar-5121. These are numbers from the board anyway. I didn't find them on the schematic but that service manual is the same model as my receiver.
Resistors in the burnt area:
r923 (actually labeled r23 on pcb)
r925 (actually labeled r25 on pcb)
r926
r928
r929
r930
r935
0
Hi!
This is the power supply part. This is where 5.6 volts and + & - 12 volts are produced from + & - 22 Volts. Onkyo engineers like to “heat up” their amplifiers, so they use resistors to reduce voltage instead of using multiple branching transformers.
As a first step, check the values of the listed resistors, if they match the drawing, you should re-solder their legs because heat can cause a poor contact fault.
Next step, check the voltage at the outputs of Q921-922 - Q923 - Q924, and Q925
0
Sorry for the wait but still working on my bathroom remodel. Tub install is no longer a problem now
. I have done what you asked and results I've found is included in the picture written at the bottom of the link / page. I've resoldered all of those resistor and transistor contact points plus re-soldered all contacts on about 1/3 of this board. I was able to get my magnifying headset on and locate a few bad/cracked solder points as well in other areas. Improvement has been noticed as not all of the resistors listed below are as hot as they were with the exception of the 3 listed below.
https://www.dropbox.com/s/m66gysdhfqyojzm/Results1.png?dl=0
The resistors and their tested values are:
r930= 118.8 ohm HOT TO TOUCH!
r929= 118.5 ohm HOT TO TOUCH!
r928= 18.4 ohm HOT TO TOUCH!
r935= 22.1 ohm
r923= 1.5 ohm
r925= 11.4 ohm
r926= 11.5 ohm
These seem to be within range?
Values for outputs tested by touching the negative to the G (?) terminal and pos to to O terminal (is this the correct way to test?):
q921= +11.7v
q922= -11.6v
q923= +6.02v
q924= -5.8v then drops to 0 usually (this one drops voltage after heating up)
q925=+5.5v
If components need replaced could you provide suggestions on comparable replacements if needed? Where to get? Thanks. I've have been studying on how to test these transistors as well. Is it necessary to remove them first? I would not have gotten this far without your help. It took a bit of hard study to be able to read that schematic and still don't understand much but am able to limp thru so far :) I look forward to the next step :)
0
Hi and thanks hifi! I'm currently going back and forth between repairing a shower wall and this so bare with me. I'll locate, test and reply within a week. Sorry but water issues in the tub have me spread thin. Thanks again.
0
Anyone? Please!
0
OK, continue to investigate.
This is a detective work, patience and perseverance.
You found a good trace, but it's just a fingerprint.
The behavior of Q924 is abnormal. This is a stabilizer IC and short circuit protected.
To decide whether Q924 is the defective component or elsewhere there is a short-circuit part, it would be possible to select the -6V portion of the JL701 connector. Drastic solution, but it should cut the wire (so that it can be re-soldered later), then measured -6V remains constant at the Q924 output. If stable -6v can be measured, either the Q802 IC (AK5339) or 3 NJM4558 IC are incorrect. This -6V is performing these with power supply.
0
Thanks so much hifi
I'm trying hard with this but it's not my cup of tea. I remain persistent but patience leaves me often. It's an inner battle to be constantly fought for sure. I'll try to paraphrase but not sure I'm following the idea? Are you wanting me to temporarily cut a wire to resolder later? If so, cut -6v wire at the JL701 connector? If I understand correctly, I am to then measure -6v at the q924 voltage regulator output? Will this help me determine whether the Q802 IC (AK5339) or the 3 NJM4558 IC's are faulty? Just want to understand your instructions first before acting.
Could you help with page locations on the service manual? Thanks. I was able to locate the JL701 connector on page 36 and Q802 IC (AK5339) on page 25 but not the 3 NJM4558 IC. As always, thanks.
JL701 trace to output
0
Since the original problem is that there is a DSP error, the absence of -6 Volt on the Q802 DSP IC can cause this to appear on the display.
Therefore, it should be determined whether the Q 924 power supply IC is faulty or if there is a short in the -6 Volt branch coming from there.
These power supply ICs are overload and short circuit protected, so the voltage at the output goes down because the output current reaches the maximum allowed and is down-regulated, thus protecting itself.
Therefore, I suggested that the wire on which the -6 Volt goes from the power supply to the ICs Q802 and Q801-Q808-Q809 should be cut around the J701 connector.
This would take the load off the Q924 stabilizer IC and find out if the Q924 is faulty or need to look for a short circuit further.
If, after cutting the -6 Volt wire, a stable -6 Volt can be measured at the output of the Q924, then the fault is probably in the good and the part fed by it. In this case, with the device switched off, it would be possible to measure whether there is a short circuit on the side of GND and J701 facing the Q801-802 ICs.
This could be done by connecting The multimeter switch the beeping position, this could be done by between the GND (body of the device) and the end of the cable
. If the short circuit is over there, it will be harder to find the fault, but not impossible.
In the attached drawings, I marked in red the most probable parts that could cause a short circuit.
First I would measure the capacitor of Q802 (AK) C 812, ceramic capacitors sometimes become short-circuited.
Possibly the other C 810 capacitor, but it is less likely. Finally, one of the 3 NJM4558L Q801-Q808-Q809 ICs. The most important thing would be to find out if the power supply IC is faulty or there is a short circuit in the part it is feeding.
This can be decided by cutting the described wire. I hope my way of thinking is understandable, unfortunately my English is poor, so I have to use a translation program, but the structure of the Hungarian language is very different from English, so the machines do not translate really correctly.
Hmm...I can't upload the pictures, but I'm still trying.
0
Sorry for the long pause but life has its priorities elsewhere sometimes. Still fixing my home. How I am able to link to pictures I use dropbox and share a link to the uploaded pictures in dropbox. I'm sure there are other free sites that allow this feature as well. It has been a lifesaver at times. Thanks and I look forward to seeing those pictures. Thank you so much :)
0
Any help would be appreciated?
0