Lead acid and Li ion/polymer batteries in private homes are a pain in the neck indeed. Laymen underestimate the power batteries can deliver.
Dealt with high power AC/DC and high power battery installations for years and when stuff goes south things can be pretty frightening and damaging. They got the green stamp though (a laisez-passer) and are installed in private homes. We’ll see.
Dealt with high power AC/DC and high power battery installations for years and when stuff goes south things can be pretty frightening and damaging. They got the green stamp though (a laisez-passer) and are installed in private homes. We’ll see.
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I think you would be OK to modify the Topping to 12 volts with respect to its power dissipation on this particular load. You would of course invalidate any warranty but it could continue being useful for much longer and be capable of future useful mods for use with other kit if needed.
The topping probably uses a minimum of 12 volt AC transformer. After full wave rectificiation and say a factor of 1.2 of transformer regulation and at low load the minimum voltage its regs would be seeing would be about 19 volts. This means there is about 4 volts minimum across its 15v regulator IC and as it is specced for 1 Amp it should be designed for that same reg to dissipate at least 4 watts.
Under the Fiio load which i measure at a steady 0.27 amps and after resetting the regs to 12volts (with maybe a parallel resistor and a switch on the case), the regulator would need to be able to dissipate 0.27 X (4+3) Amps i.e less than 2 Watts. There's plenty of margin for error, around 100% in fact. It would be best to label the switch "Fiio R2R Dac only" or "12v 0.5Amp max".
The mods are starightforward and cheap. You would need a small single throw switch (optional though), some twisted low current wire and a single 0.25W resistor soldered to the end of the appropriate existing voltage setting resistor on the correct regulator (tricky) with the return lead on its other end. You would need to measure the setting resistor to determine what value resistor to fit. You could then try it without the switch first by just putting the new set resistor in parallel. Suggest the set resistor is kept secure with a dab of hot melt glue. You could fit the switch later or remove all of these mods to return the supply to normal but without its warranty. You should not do any of the above if you don't have the necessary experience working on such mains connected kit please.
If you added an inline regulator after the Topping instead of the above it would be a more difficult job. You would then get additional line regulation but it would be a more costly and there would be much more DIY and potentially pride to be had!
John
The topping probably uses a minimum of 12 volt AC transformer. After full wave rectificiation and say a factor of 1.2 of transformer regulation and at low load the minimum voltage its regs would be seeing would be about 19 volts. This means there is about 4 volts minimum across its 15v regulator IC and as it is specced for 1 Amp it should be designed for that same reg to dissipate at least 4 watts.
Under the Fiio load which i measure at a steady 0.27 amps and after resetting the regs to 12volts (with maybe a parallel resistor and a switch on the case), the regulator would need to be able to dissipate 0.27 X (4+3) Amps i.e less than 2 Watts. There's plenty of margin for error, around 100% in fact. It would be best to label the switch "Fiio R2R Dac only" or "12v 0.5Amp max".
The mods are starightforward and cheap. You would need a small single throw switch (optional though), some twisted low current wire and a single 0.25W resistor soldered to the end of the appropriate existing voltage setting resistor on the correct regulator (tricky) with the return lead on its other end. You would need to measure the setting resistor to determine what value resistor to fit. You could then try it without the switch first by just putting the new set resistor in parallel. Suggest the set resistor is kept secure with a dab of hot melt glue. You could fit the switch later or remove all of these mods to return the supply to normal but without its warranty. You should not do any of the above if you don't have the necessary experience working on such mains connected kit please.
If you added an inline regulator after the Topping instead of the above it would be a more difficult job. You would then get additional line regulation but it would be a more costly and there would be much more DIY and potentially pride to be had!
John
