Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tylerpenn on April 21, 2023, 06:26:16 am
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Anyone have any experience with this amp? There seems to be no information out there, managed to find a relatively basic manual but no service manual or schematics anywhere.
I purchased it from a European seller and it’s set for 230v operation. The main power transformer is the same on others I’ve seen that have sold in the US and set for 120v operation, so looks like the transformer is multi tapped.
Inside there looks to be a jumper soldered between two black leads that is wired differently between the 120v versions and the 230v version I have. I’ve thought of just changing the jumper to match what the 120v versions look like but I’m afraid there may be some other components that may need to be swapped out in the power circuit and don’t want to risk frying anything unnecessarily.
Hopefully someone out there has some info. Thank you!
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Here's a typical dual primary that can be jumpered for 120V or 240V operation.
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Here's a typical dual primary that can be jumpered for 120V or 240V operation.
Excellent, thank you. Here are example photos clearly showing the different jumpering between a 120v and 240v wired Dual 75 amp.
I would love to think it's as simple as changing the jumpering, but is there any concern about any other downstream components that could be damaged if not swapped for different values? Or is it generally normal in the amp world that if an amp has the jumpering/switchable power supply cabling all of the components are able to handle both power inputs?
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The jumpers are the only thing that should be changed (well, maybe the power cord). Everything downstream remains the same.
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Ok great. Luckily the amp uses a standard IEC power jack.