Hello everybody
When they say "No good deed goes unpunished", they really mean it! My friend in Europe asked me to buy him a Classe DR-9 amp. I found one, in decent shape. Then he asked me if I could convert it to 220 volts. I asked Classe and they sent me a diagram, which, actually, comes as standard in the service manual, which I downloaded. It seemed as simple as one-two-three, so I told my friend I'll do it. It boils down to reconfiguring windings on the block-post. I did it according to the diagram, asked my super to give me a 220 on my fuse box, and plugged it in. There was a huge "bang" as the fuse went, and it began to smell pretty funny. I reconfigured it back to 120, put it on variac (should have done it in the beginning, but it looked so simple, and my variac is only 120), stated to raise the voltage, and around 60v saw the burned parts. They are all on the filter circuit-board all the way down at the bottom, and you need to disassemble the whole thing to get to them (very smart). On top of that, all the bolts are so frozen, that I can't even undo them. Eventually, I think I will get to the board.
I called Classe and asked them if they have a schematic for that board, answer is - no.
So my questions are:
1) what caused the damn thing to blow-up in the first place, if I followed their diagram?
2) were the 220 that my super wired for me responsible in some way? Is the amp very sensitive to where exactly hot and neutral do?
3) does anybody have a schematic for the filter/protection boards? Protection board has 3 red LEDs on it, and I don't know what they are for, service manual says nothing.
4) can anybody fix the amp for me?
Thanks in advance
Mark
When they say "No good deed goes unpunished", they really mean it! My friend in Europe asked me to buy him a Classe DR-9 amp. I found one, in decent shape. Then he asked me if I could convert it to 220 volts. I asked Classe and they sent me a diagram, which, actually, comes as standard in the service manual, which I downloaded. It seemed as simple as one-two-three, so I told my friend I'll do it. It boils down to reconfiguring windings on the block-post. I did it according to the diagram, asked my super to give me a 220 on my fuse box, and plugged it in. There was a huge "bang" as the fuse went, and it began to smell pretty funny. I reconfigured it back to 120, put it on variac (should have done it in the beginning, but it looked so simple, and my variac is only 120), stated to raise the voltage, and around 60v saw the burned parts. They are all on the filter circuit-board all the way down at the bottom, and you need to disassemble the whole thing to get to them (very smart). On top of that, all the bolts are so frozen, that I can't even undo them. Eventually, I think I will get to the board.
I called Classe and asked them if they have a schematic for that board, answer is - no.
So my questions are:
1) what caused the damn thing to blow-up in the first place, if I followed their diagram?
2) were the 220 that my super wired for me responsible in some way? Is the amp very sensitive to where exactly hot and neutral do?
3) does anybody have a schematic for the filter/protection boards? Protection board has 3 red LEDs on it, and I don't know what they are for, service manual says nothing.
4) can anybody fix the amp for me?
Thanks in advance
Mark
Its possible, when wiring two 110 volt windings in series, to get the 'phase' wrong. If this happens then the magnet field cancels and the primary impedance is very low - this will pull a huge current from the mains until something opens the circuit, hopefully a fuse. Reversing the connections on ONE of the windings will correct the situation.
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Hello DRC
I just found a very fine print in the service manual. In addition to rewiring the windings, you are supposed to "replace the varistor with correct value". Which value, they don't say. I found a DR-15 manual, which says that the varistor should be replaced from 221 to 441, it does not say however, where this mysterious varistor is located.
???
I think that this is exactly what burned.
I just found a very fine print in the service manual. In addition to rewiring the windings, you are supposed to "replace the varistor with correct value". Which value, they don't say. I found a DR-15 manual, which says that the varistor should be replaced from 221 to 441, it does not say however, where this mysterious varistor is located.
???
I think that this is exactly what burned.
As long as the part is rated for the voltage it doesn't make any difference, the difference will be in the current that passes through the device. I bet if you look up the specs you will find the 221 is rated for 2x the current of the 441. The amp will pull 1/2 the current at 220 that it does on 120.
Hi
I have taken the varistor out of the board via long wires, and mounted it on a rear panel, so its easy to replace. I have full service manual for this amp, so the schematic might be there. If you need it, I can look. I have it in PDF format on my drive.
Rgds
Marknoir.
Yes please.
I have a 12 page 'service manual' for the dr9, but it doesnt give more than a basic block flow chart of the overall unit.
If you have any sort of info or schematic for the mains side, that would be awesome.
I'll send you my email via pm if you wish to use that.
many thanks.....
My issue is one of these monsters (us 120v) has been dumped on me for a 240v conversion.
After doing the wiring as per their instructions, I also missed the damn varistor, so yes, sparks and smoke for me too. (blown varistor).
I've replaced the varistor with a 240v 5amp thermistor (very similar to a cl60)
Subsequent attempt to power up on my variac blew the variacs 3amp fuse at 5vac.
Even though I triple checked it, Im suspecting an incorrect primary.
I've just pulled the transformer so I can properly bench check/set the 4 primary windings that i thought I had right.
So i'd like to check test what I can before attempting power up again.
Yes please.
I have a 12 page 'service manual' for the dr9, but it doesnt give more than a basic block flow chart of the overall unit.
If you have any sort of info or schematic for the mains side, that would be awesome.
I'll send you my email via pm if you wish to use that.
many thanks.....
My issue is one of these monsters (us 120v) has been dumped on me for a 240v conversion.
After doing the wiring as per their instructions, I also missed the damn varistor, so yes, sparks and smoke for me too. (blown varistor).
I've replaced the varistor with a 240v 5amp thermistor (very similar to a cl60)
Subsequent attempt to power up on my variac blew the variacs 3amp fuse at 5vac.
Even though I triple checked it, Im suspecting an incorrect primary.
I've just pulled the transformer so I can properly bench check/set the 4 primary windings that i thought I had right.
So i'd like to check test what I can before attempting power up again.
This is just a helpful post for anyone that has to do a voltage conversion on one of these.
In the service manual they talk about changing the varistor with no other info.
The said varistor is on the soft start board, this is located under the speaker protector board, that is under the left channel amp board.
After gaining access to the board, just pull the varistor out and be done with it.
Next have a look inside the back of the amp, do you see another small transformer under the speaker posts ?
If you do then you have to rewire that to suit the new mains voltage.
That transformer is fed from the input mains on the underside of the soft start board.
There is no info on this so you will have to work out the two primary windings yourself.
Then you have the fun of identifying, labeling, and reconfiguring the four primary windings on the main transformer up front...
So, in short - DR-9 voltage conversion.
remove varistor on back board.
rewire small transformer primary up back.
rewire toroidal transformer up front.
I'm not certain, but I believe later DR-9's may have had another secondary winding on the main toroidal transformer.
That takes the place of the small transformer up the back.
Still have the varistor to remove and main transformer primaries to reconfigure.
Hopefully this info helps some one else out there..............
In the service manual they talk about changing the varistor with no other info.
The said varistor is on the soft start board, this is located under the speaker protector board, that is under the left channel amp board.
After gaining access to the board, just pull the varistor out and be done with it.
Next have a look inside the back of the amp, do you see another small transformer under the speaker posts ?
If you do then you have to rewire that to suit the new mains voltage.
That transformer is fed from the input mains on the underside of the soft start board.
There is no info on this so you will have to work out the two primary windings yourself.
Then you have the fun of identifying, labeling, and reconfiguring the four primary windings on the main transformer up front...
So, in short - DR-9 voltage conversion.
remove varistor on back board.
rewire small transformer primary up back.
rewire toroidal transformer up front.
I'm not certain, but I believe later DR-9's may have had another secondary winding on the main toroidal transformer.
That takes the place of the small transformer up the back.
Still have the varistor to remove and main transformer primaries to reconfigure.
Hopefully this info helps some one else out there..............
Hi Mark,
When you say full service manual do you mean with schematics for all boards or just what B&W had on their site, 12 pages.
Thanks,
Bruce
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