Krell KSA300S Power Conversion

If power transformer of your Krell have additional power leads, than using variac, you can ID these by measuring an output voltages to be same as with 110V. In other words, all you have to do is record measurements between lead and chassis, compare and swap one with corresponding other. If you don't have variac(a-must for most of electronic work indeed) than simply, figure out each output of secondary winding of transformer leads for 220V conversion will have approximately half the voltage as ones originally in the circuit. Most companies usually mark down the voltage values on PCB, but if that's not the case, you should measure each output voltage with disconnected lead(unsoldered if necessary)

If power transformer has only one set of leads, than you will need to replace it with 220V version which is less likely the case. 

Also, if you find service manual, or able to convince dealer or manufacturer to provide you one, than you'll be in great shape knowing color code of each corresponding lead to make it much faster. Lately I found most of manufacturers believe you're dumb and not savvy to fix equipment therefore would not share with you any information about any DIY on their stuff. It brings them more money selling new units. You may also search service manuals on vinylengine.com, but this site mostly have vintage units that used to provide them together with unit in good old 60's,70's, 80's. Most of these manuals would simply state "if you're not sure to troubleshoot yourself, bring it to qualified tech". 

Good luck with your endeavor. 

Thank you for your help.

You are going to have to call Krell. There are other things associated with conversion (fuses are going to have to be changed to a lower value at a higher voltage, e.g.). 

Conversions are done either by switch, jumpers or a combination of both. Sometimes the jumpers are quick connected sometimes they are soldered. In any case, if you do not have a service manual or a schematic of the power supply you will be flying blind. Krell will probably want a few hundred dollars to do this but IMO it's money well spent.

" Krell will probably want a few hundred dollars to do this but IMO it's money well spent".
Hey don't forget about +another $hundred shipping turnaround. In some cases international shipping can apply as well.
" In any case, if you do not have a service manual or a schematic of the power supply you will be flying blind"
It's all about tracing power transformer to clear visibility. Not every time schematic needed.

Thank you very much for your help. I think i ned to open the unit to look inside of it. :)

I think you posted this question before and you were told you could not do it because it requires a computer chip / board change but I guess you did not believe it and want to go ahead and try anyway.

To save you the hassle, what the previous answer in that thread says is true. I owned the same amp about 20 or so years ago. All the KSA S series amps cannot be voltage changed the way you want to do it. I moved from a 220V country to a 240V country - a local technician did it that way and it would always trip the fuse after a few listens when being turned on. You are going from 110V to 240V an even bigger jump. You really need to have Krell or an agent change the board that controls the voltage as I eventually did . There is no way around it even if you don't like hearing this. I doubt they would still have the parts to do so.

By the way it's not worth the hassle for such an old amp - the entire batch of S series amps were made with faulty capacitors to begin with - mine would literally smoke and blow up even with the correct circuit board change. Ditto for same era KRC pre's. That's why they were superceded by the FPB's very quickly.

Good luck

Thank you.

I tried to change from 110 to 220. You cannot with this model