Can the export model of the Blues Jr. III be wired for 120V or does the PT need to be swapped out for the US version?
Thanks Jon. Sorry, should have included the following:
The service manual shows the same transformer part numbers for all Blues Jr amps. The 049968 export part number description shows "100v-115v-230v-240v". Unfortunately the schematic only has wire colour labeling and the layout diagram doesn't show the traces. Not sure if some of the primary taps are just "parked" on the board with no actual connection, allowing re-wiring to make for different primary voltages.
Also, the domestic model shows a 120V primary, so if it is even possible to re-wire the export model for 115V, the secondary voltages will be higher. Around here line voltage is between 120-124V. Not sure if this will cause the amp to run too hot.
The service manual shows the same transformer part numbers for all Blues Jr amps. The 049968 export part number description shows "100v-115v-230v-240v". Unfortunately the schematic only has wire colour labeling and the layout diagram doesn't show the traces. Not sure if some of the primary taps are just "parked" on the board with no actual connection, allowing re-wiring to make for different primary voltages.
Also, the domestic model shows a 120V primary, so if it is even possible to re-wire the export model for 115V, the secondary voltages will be higher. Around here line voltage is between 120-124V. Not sure if this will cause the amp to run too hot.
115 and 120 are both ways to refer to the nominal 120v US power grid. DOn't make a distinction. Used to be we called it 117v.
What a horror-show!! Have these things ever been voltage-changed without blow-up??
http://www.thetubestore.com/lib/thetubestore/schematics/Fender/Fender-Blues-Junior-Schematic.pdf
Here's my work-up. There is NO 120V connection for the transformer on the first page of the schematic linked above. There is however a 130V connection which may be close-enough for higher wall voltages. It only uses half the total wire, which is usually a poor idea. However it *appears* the 100V connection also only uses half the wire, even though there is a clear way to use most of the wire. Unless I have misinterpreted all those CP numbers. It also flows double-current through the 30V winding, which won't add much total heat, but could cause local heat.
So you could "solve" it by burning-up the export iron and being forced to buy the North American iron.
http://www.thetubestore.com/lib/thetubestore/schematics/Fender/Fender-Blues-Junior-Schematic.pdf
Here's my work-up. There is NO 120V connection for the transformer on the first page of the schematic linked above. There is however a 130V connection which may be close-enough for higher wall voltages. It only uses half the total wire, which is usually a poor idea. However it *appears* the 100V connection also only uses half the wire, even though there is a clear way to use most of the wire. Unless I have misinterpreted all those CP numbers. It also flows double-current through the 30V winding, which won't add much total heat, but could cause local heat.
So you could "solve" it by burning-up the export iron and being forced to buy the North American iron.
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