schematic P4500
http://schnake99.sc.funpic.de/schematics/yamaha/yamaha P3200 P4500/yamaha P3200 P4500.pdf
schnake99
http://schnake99.sc.funpic.de/schematics/yamaha/yamaha P3200 P4500/yamaha P3200 P4500.pdf
schnake99
can you post the schematic diagram of xp7000.....or send to my email chinoks_capsighter@yahoo.com tnx...... 
Hi Tarzan.
Yes agreed the caps are 160V, but given that manufacture provides for 100 or 160V then that's what they need to be.
I've taken a further look at the unit and have since decided that 140V is probably correct, the 24V olt rails are about right.
The problem is the PNP output devices keep failing and I suspect it's due to exceeding the Vce max of the devices. The ramp up waveform from the EEEngine looks correct when compared to the other channel.
If run at reduced mains Volts then all is well. if the supply is taken to full mains then all still Ok. But if the input signal is taken up to max with the output swinging rail to rail then another PNP device shorts out (due as far as I can see to excess Vce).
I have 56R resistors in the rails to limit current so don't get catastrophic failure and running into a 100R load.
Any ideas?
Yes agreed the caps are 160V, but given that manufacture provides for 100 or 160V then that's what they need to be.
I've taken a further look at the unit and have since decided that 140V is probably correct, the 24V olt rails are about right.
The problem is the PNP output devices keep failing and I suspect it's due to exceeding the Vce max of the devices. The ramp up waveform from the EEEngine looks correct when compared to the other channel.
If run at reduced mains Volts then all is well. if the supply is taken to full mains then all still Ok. But if the input signal is taken up to max with the output swinging rail to rail then another PNP device shorts out (due as far as I can see to excess Vce).
I have 56R resistors in the rails to limit current so don't get catastrophic failure and running into a 100R load.
Any ideas?
Looking at the specs, it only claims 460 Watts into 8 Ohms. I'm assuming that's RMS, though it doesn't actually say so.
Doing the maths the peak output volts is 86 volts. lets say we lose 10 Volts across the devices (it should be less then that) so thats 96 volt rails.
The transformer is very big so regulation should be in the 5% regeion but even if we allow 10%, then our unloaded rail doesn't need to be above 110 Volts. Ok be generous and a high mains voltage and we're looking at a max of 120 Volts. Hence my suspition of the measured 140 Volts.
Doing the maths the peak output volts is 86 volts. lets say we lose 10 Volts across the devices (it should be less then that) so thats 96 volt rails.
The transformer is very big so regulation should be in the 5% regeion but even if we allow 10%, then our unloaded rail doesn't need to be above 110 Volts. Ok be generous and a high mains voltage and we're looking at a max of 120 Volts. Hence my suspition of the measured 140 Volts.
are you in need of the service manual?
There is not much in it but it can help with the biasing.
If the pnp's are failing all the time; then there must be another problem with the drivers probably?
I doubt very much that Yamaha will deliver an amp with a problematic final stage.
And the other channel is working fine?
Must be someting else...
There is not much in it but it can help with the biasing.
If the pnp's are failing all the time; then there must be another problem with the drivers probably?
I doubt very much that Yamaha will deliver an amp with a problematic final stage.
And the other channel is working fine?
Must be someting else...
A service manual would help possibly, I only have a copy of the circuit.
Agreed these amps have a very good reputaion for reliability and there's no way Yamaha could have got away with selling so many of them if there was any question there.
No there's definitly a fault but it's hiding itself well.
The other channel is fine, and the owner has had this unit from new.
It just died on one channel and he continued to use the other channel with no problems.
Agreed these amps have a very good reputaion for reliability and there's no way Yamaha could have got away with selling so many of them if there was any question there.
No there's definitly a fault but it's hiding itself well.
The other channel is fine, and the owner has had this unit from new.
It just died on one channel and he continued to use the other channel with no problems.
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