Hello all,
I have been hearing all the bad news about the YAMAHA CR -1040 not having replacement parts for the pre drivers.I picked up one cheap and thought I would give it a try.Can anyone explain to me how these pre drivers can prevent a relay from clicking when power is applied even though the protection light does not come on.I have a schematic of the unit.If anyone can shoot me some tips I would be very happy.
I have been hearing all the bad news about the YAMAHA CR -1040 not having replacement parts for the pre drivers.I picked up one cheap and thought I would give it a try.Can anyone explain to me how these pre drivers can prevent a relay from clicking when power is applied even though the protection light does not come on.I have a schematic of the unit.If anyone can shoot me some tips I would be very happy.
Yamaha
Good morning,
I havent tried to run a signal through it at all.When i first turn it on, no relay click at all.No protection light comes on either.Then about 5 mins after being powered up,the 250 v/ 2a fuse just burns out.I flipped over the unit and saw that on both amplifier chips that are mounted on the massive heatsink it looks like someone desoldered all the connections on both chips.I am going to resolder them here real soon.Since I cant get the unit to stay on long enough to check
any voltage I am kinda lost on how I can get some readings.
Dennis
Good morning,
I havent tried to run a signal through it at all.When i first turn it on, no relay click at all.No protection light comes on either.Then about 5 mins after being powered up,the 250 v/ 2a fuse just burns out.I flipped over the unit and saw that on both amplifier chips that are mounted on the massive heatsink it looks like someone desoldered all the connections on both chips.I am going to resolder them here real soon.Since I cant get the unit to stay on long enough to check
any voltage I am kinda lost on how I can get some readings.
Dennis
Yamaha update
Hello all,
Well..here is the update on the Yamaha cr 1040.Get sound while using headphones.When using speakers, only left channel works.No meter deflection on my VU Meters.When power switch is pushed relay clicks pretty fast.Doesnt give it time to slowly click in.Thinking its a timing issue with a cap on the main board.The schematic I have , is pretty bad.Got it from HI FI Engine.Cant really tell what voltages are where.Any ideas?
Dennis
Hello all,
Well..here is the update on the Yamaha cr 1040.Get sound while using headphones.When using speakers, only left channel works.No meter deflection on my VU Meters.When power switch is pushed relay clicks pretty fast.Doesnt give it time to slowly click in.Thinking its a timing issue with a cap on the main board.The schematic I have , is pretty bad.Got it from HI FI Engine.Cant really tell what voltages are where.Any ideas?
Dennis
You should recap the whole units electrolytics...it's cheap and typically is the source of major issues. All main and sub boards plus the main psu caps.
Take pics, document, desolder, order from Mouser or digikey.
Deoxit all switches and pots. I would also at least check that the major transistors are not shorted but they are pretty hardy unless abused.
Take pics, document, desolder, order from Mouser or digikey.
Deoxit all switches and pots. I would also at least check that the major transistors are not shorted but they are pretty hardy unless abused.
If you have headphone level output but not enough current for speakers, a common cause in transistor amps is the failure of the output stage in the relevant channel. Many will pass enough voltage from earlier stages to drive 'phones with normal clarity even if the caps are old and tired.
Usually, if amplifier caps are failing, hum increases audibly and can even dominate the output. Caps in the relay and protection circuit may be quite separate and should be routinely replaced if the relay events are abnormal, as others have said.
The protection relay may also malfunction if the normal current and voltage inputs it's expecting aren't there, as when an amplifier module has failed. Check the DC voltage across the output terminals of both channels when the relay is connected. It should measure <50mV DC with no inputs or speakers connected to the amplifier and volume right down. If not, and it's >50mV, you do have a module issue. Zero voltage is likely a connection issue which you can work around by measuring before the relay and headphone socket. Take care with meter probes slipping and shorting close spaced parts - it's so easy to ruin it all with just a split-second mistake.
BTW, I tried reading the hacked-up manual at Hi-fi Manuals website and that was near unreadable too. It probably needs printing out and pasting together to read it.
Usually, if amplifier caps are failing, hum increases audibly and can even dominate the output. Caps in the relay and protection circuit may be quite separate and should be routinely replaced if the relay events are abnormal, as others have said.
The protection relay may also malfunction if the normal current and voltage inputs it's expecting aren't there, as when an amplifier module has failed. Check the DC voltage across the output terminals of both channels when the relay is connected. It should measure <50mV DC with no inputs or speakers connected to the amplifier and volume right down. If not, and it's >50mV, you do have a module issue. Zero voltage is likely a connection issue which you can work around by measuring before the relay and headphone socket. Take care with meter probes slipping and shorting close spaced parts - it's so easy to ruin it all with just a split-second mistake.
BTW, I tried reading the hacked-up manual at Hi-fi Manuals website and that was near unreadable too. It probably needs printing out and pasting together to read it.
Update on Yahama receiver,
In my lastest reply, I mentioned that I had audio from receiver.Relay was engaging to quickly as soon as power switch was pushed.Replaced a timing cap that was reading bad.New cap was installed.Now when power button is pushed, no audio and no relay click at all.Looking like relay is the culprit.It has me scratching my head due to old cap made relay work with audio,but relay was engaging way to quickly.
In my lastest reply, I mentioned that I had audio from receiver.Relay was engaging to quickly as soon as power switch was pushed.Replaced a timing cap that was reading bad.New cap was installed.Now when power button is pushed, no audio and no relay click at all.Looking like relay is the culprit.It has me scratching my head due to old cap made relay work with audio,but relay was engaging way to quickly.
Or other faulty components are now making the relay work properly? Likely large amounts of DC on the outputs via bad caps or shorted transistors or both preventing relay from closing.
I would at least recap the main PSU caps and the amp board caps, there cant be but maybe $20 worth of caps there.
I would at least recap the main PSU caps and the amp board caps, there cant be but maybe $20 worth of caps there.
You are looking at a symptom, the cause is what enables the relay, which is what it's for; to shut the amp off when there is a fault like a burned amp module. 'Unlucky to start with a fault in that too, though.
How about checking the DC voltage where the amplifier outputs connect to the relay as requested? At least you can then identify the likely cause.
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