Have you looked inside? There might be a voltage selector for the power transformer. If not, then you need to go to Sim Lim Square and pick up the largest 120V/240V converter that you can get your hands on.
Let's take a look at the AC input board and switch.
The jumper switches are currently at 2-1-2. The power switch is rated for up to 250V. I didn't see any label on the transformer, which's permanently attached to the chassis. It appears that I can just swap out the cable and flip the jumpers to switch to 220V.
Advise?
The jumper switches are currently at 2-1-2. The power switch is rated for up to 250V. I didn't see any label on the transformer, which's permanently attached to the chassis. It appears that I can just swap out the cable and flip the jumpers to switch to 220V.
Advise?
Attachments
I also found some wiring diagrams for FPB 250mc.
It appears that the issue is not voltage conversion. The jumpers can achieve that. The real problem is converting the power line frequency to 50Hz. Looks like the FPB firmware chip is the one controlling it.
I guess I have answered my own question. I found a MCU chip with unlocked power line frequency on eBay.
Krell KAV-400xi Integrated Amplifier Replacement MCU Controller Chip 50/60Hz | eBay
It appears that the issue is not voltage conversion. The jumpers can achieve that. The real problem is converting the power line frequency to 50Hz. Looks like the FPB firmware chip is the one controlling it.
I guess I have answered my own question. I found a MCU chip with unlocked power line frequency on eBay.
Krell KAV-400xi Integrated Amplifier Replacement MCU Controller Chip 50/60Hz | eBay
I wouldn't expect any problems running 50Hz vs 60Hz mains. I have heard of turntables having problems running at the wrong speed, but any decent power amp should be fine IMO.
Chris
Chris
A decent PA should perform better at 60Hz than 50Hz. The main caps in the PSU will have less work to do. The transformer will also be under less duress. BT will be 20% lower.
In order to control grey market imports Krell inroduced this "feature" many years ago. It is not hard to bypass. Not sure if current models also contain this disgraceful reminder of dealers' greed.
So I just talk to somebody who has done this before. Krell wants $600 for that tiny little MCU chip. The guy who’s selling the mod chip for 400xi told me that the chip was device specific. He would need the actual amp to reverse engineer.
Why do you expect this chip to work in your amp? Are you certain your amp performs the frequency check?
The processor controls lots of specific functions and is definitely not interchangeable between models.
The little i remember about hacking the Krells is different: a very simple and cheap replacement chip generating 60Hz needs to be inserted along the AC sense line getting to the processor and that is all. An Arduino should suffice.
It's possible that the frequency must be very accurate, like the line voltage is.
Find where the AC line frequency is fed to the microcontroller... disconnect that from the AC input, and build a 555 timer to oscillate at 60Hz. Feed that in. Job done.
This sort of thing should be illegal.
This sort of thing should be illegal.
It's pure capitalism. Intentionally break things and charge you to make it work. Thanks for the advice.
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