Hi all
First off I've never opened a home theatre amplifier before, and what an appalling sight! Taking this thing apart I can see is going to be an absolute nightmare but I'm hoping to get help in diagnosing the fault nonetheless!
So I've had my Denon AVR-1910 for about 4 years, hooked up to my PC via toslink cable and connected to two large front speakers, and two surround speakers. No problems up until now when a few nights ago I switched it on and after about 10 seconds started hearing buzzing / interference from the speakers. Then a few seconds later the amp switched itself off and went into a red power led blinking every 0.5 second mode. On looking through the user manual it states either a speaker / speaker cable problem, or the amp has gone into circuit protect mode and must contact Denon.
I checked all cables and connections and they were fine. So I disconnected everything from the unit completely apart from the power lead and tried turning it on. The main relay clicks as it always does / has done within about 5 seconds, get a solid green power led, but then within another 1-10 seconds the unit will power off and resume the blinking red power led every 0.5 seconds.
Any subsequent attempts with the speakers plugged back in is the same - buzzing \ static noises from them after 5-10 seconds and then a automatic power off within another 5 seconds.
So I've watched three Youtube videos of people checking other model Denons, whose insides look completely different to my AVR-1910 to my untrained eye
, and a lot seem to end up being a voltage regulator issue.
I think I've found where these are on this amp but I'm not sure. I know I need to probe with my multimeter and check what voltage is being output on the middle legs for each regulator when the amp is powered on - but I don't know what voltage readout I should be expecting, or what would confirm the problem even. The video I watched showed how to expect about 50-60 volts positive on one regulator, same but negative on the other regulator.
I've attached pictures of the location of the circuit board I've found these and close ups of the regulators in question. They are 7812A JRC transistors. Allegedly I could get them from here in the UK: https://cpc.farnell.com/stmicroelect...0-3/dp/SC08364
Although note one of the three is a 7912A.
So I guess my question is am I on the right track, and can anybody help me with what values would show on the multimeter that prove these transistors are at fault?
Thanks in advance for any help :-)
First off I've never opened a home theatre amplifier before, and what an appalling sight! Taking this thing apart I can see is going to be an absolute nightmare but I'm hoping to get help in diagnosing the fault nonetheless!
So I've had my Denon AVR-1910 for about 4 years, hooked up to my PC via toslink cable and connected to two large front speakers, and two surround speakers. No problems up until now when a few nights ago I switched it on and after about 10 seconds started hearing buzzing / interference from the speakers. Then a few seconds later the amp switched itself off and went into a red power led blinking every 0.5 second mode. On looking through the user manual it states either a speaker / speaker cable problem, or the amp has gone into circuit protect mode and must contact Denon.
I checked all cables and connections and they were fine. So I disconnected everything from the unit completely apart from the power lead and tried turning it on. The main relay clicks as it always does / has done within about 5 seconds, get a solid green power led, but then within another 1-10 seconds the unit will power off and resume the blinking red power led every 0.5 seconds.
Any subsequent attempts with the speakers plugged back in is the same - buzzing \ static noises from them after 5-10 seconds and then a automatic power off within another 5 seconds.
So I've watched three Youtube videos of people checking other model Denons, whose insides look completely different to my AVR-1910 to my untrained eye
, and a lot seem to end up being a voltage regulator issue.I think I've found where these are on this amp but I'm not sure. I know I need to probe with my multimeter and check what voltage is being output on the middle legs for each regulator when the amp is powered on - but I don't know what voltage readout I should be expecting, or what would confirm the problem even. The video I watched showed how to expect about 50-60 volts positive on one regulator, same but negative on the other regulator.
I've attached pictures of the location of the circuit board I've found these and close ups of the regulators in question. They are 7812A JRC transistors. Allegedly I could get them from here in the UK: https://cpc.farnell.com/stmicroelect...0-3/dp/SC08364
Although note one of the three is a 7912A.
So I guess my question is am I on the right track, and can anybody help me with what values would show on the multimeter that prove these transistors are at fault?
Thanks in advance for any help :-)
Attached Files
), I can see that on the INPUT pin on the 7912, it gets negative 20 volts but only for a second or two after powering up the amp. Then my meter just reads "-1", and this is before it has powered down itself.
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