Hi all,
A friend of mine asked me to repair his Japanese (100V AC) Roland RE-3 Space Echo which wasn't powering up. He was using an external 220V AC to 100V AC transformer (cheap one).
Inside the unit I found the internal transformer dead (primary open) and the fuse on the primary blown (F400mA), the external 220 to 100v transformer is OK. I asked Roland for a 230v replacement of the internal transformer and of course they're discontinued. I ordered a custom toroid from a local company following the specs of the original but changing the primary input from 100v to 230v, I gave them the original transformer as sample, and the circuit schematics. The secondaries outputs are 0-9.5v and 22-0-22v. I received the custom toroid and testing before mounting it I noticed the outputs where a bit higher: 0-10v and 24-0-24v, I went ahead and used it as the unit has LM7805, LM7815, LM7915 regulators and I checked maximum input voltage of them are around 45v so I guessed it is ok.
I asked the company that built the toroid for the value of the fuse they recommend me to use on the primary and they said 260mA/250V, a value hard to find. I tried with 250mA, fuse blows, tried with 250mA slow blow and it worked fine just because I replace it immediately after blowing the previous, so I guess the capacitors were charged. If I wait for a while, the slow blow also blows when powering on. I've contacted Roland and they recommend 160mA/250v slow blow for 230v and 400mA/250v fast blow for 100v version.
The unit works fine if I use t he 400mA fuse with the 230V transformer, but I want to use the proper value and not just to go higher without asking.
Could dried capacitors cause a higher demand of amps on the powering up?
What would be your advice on this situation?
Thanks in advance.
View attachment SE-3_schematic.png
A friend of mine asked me to repair his Japanese (100V AC) Roland RE-3 Space Echo which wasn't powering up. He was using an external 220V AC to 100V AC transformer (cheap one).
Inside the unit I found the internal transformer dead (primary open) and the fuse on the primary blown (F400mA), the external 220 to 100v transformer is OK. I asked Roland for a 230v replacement of the internal transformer and of course they're discontinued. I ordered a custom toroid from a local company following the specs of the original but changing the primary input from 100v to 230v, I gave them the original transformer as sample, and the circuit schematics. The secondaries outputs are 0-9.5v and 22-0-22v. I received the custom toroid and testing before mounting it I noticed the outputs where a bit higher: 0-10v and 24-0-24v, I went ahead and used it as the unit has LM7805, LM7815, LM7915 regulators and I checked maximum input voltage of them are around 45v so I guessed it is ok.
I asked the company that built the toroid for the value of the fuse they recommend me to use on the primary and they said 260mA/250V, a value hard to find. I tried with 250mA, fuse blows, tried with 250mA slow blow and it worked fine just because I replace it immediately after blowing the previous, so I guess the capacitors were charged. If I wait for a while, the slow blow also blows when powering on. I've contacted Roland and they recommend 160mA/250v slow blow for 230v and 400mA/250v fast blow for 100v version.
The unit works fine if I use t he 400mA fuse with the 230V transformer, but I want to use the proper value and not just to go higher without asking.
Could dried capacitors cause a higher demand of amps on the powering up?
What would be your advice on this situation?
Thanks in advance.
View attachment SE-3_schematic.png
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