Hi all, I have a S.M.S.L P1 Linear Power Supply that I bought and used in the US and is for 120v/60Hz. I have now moved to the UK with 230v/50Hz power and want to attempt a DIY conversion.
The Talema datasheet says (it may not be a Talema transformer but appears to be configured the same):
Now it appears that I have to break the two connections between 3-5 and 4-6. Then, connect 4-5. But my question is, what do I do with 3 and 6, and do I have to make any other adjustments?
(I also note that this has two LM317 regulators, which I wasn't able to find photos of anywhere else. I'd like to eventually replace those with drop in replacement LM3045 one day!)
The Talema datasheet says (it may not be a Talema transformer but appears to be configured the same):
- For 230 volt operation, connect primaries in series by connecting pins 5 & 4 together and apply 230 volts across pins 6 & 3 [It appears only pins 3 and 6 have 230v?]
- For 115 volt operation, connect primaries in parallel by connecting pins 6 & 4 together and pins 5 & 3 together, apply 115 volts across pins 6 & 5 [From these conenctions, it appears 3, 4, 5, and 6 all have 115?]
- To parallel the secondaries, connect pins 14 to 12 and 13 to 11 take the output across pins 14 & 13
- To place the secondaries in series, connect pins 13 to 12 and take the output across pins 14 & 11
Now it appears that I have to break the two connections between 3-5 and 4-6. Then, connect 4-5. But my question is, what do I do with 3 and 6, and do I have to make any other adjustments?
(I also note that this has two LM317 regulators, which I wasn't able to find photos of anywhere else. I'd like to eventually replace those with drop in replacement LM3045 one day!)
Remove jumper wires 3-5 and 4-6. Connect one of them now from 4 to 5. Solved.
Advice is to remove the screws of the regulators and put a very tiny dot heat paste between regulators metal part (in the middle) and the heatsinks. Remount the screws but with each a flat M3 washer.
I dealt with a few SMSL PSU's recently and there is a slight thinking error in these PSU's. Also in P1 PE is connected directly to Audio GND. This introduces a ground loop when your amplifier has Audio GND connected directly to PE too. You can connect a second (green/yellow) 0.75 or 1 mm2 wire from the IEC PE pin to the casing. Drill a small 3.5 mm hole between the IEC inlet and the DC connector (just above the CE marking) for this. Use a piece of adhesive tape and stick it to the area being drilled. Put the device on a cloth and work tidy to prevent scratches. Remove the tape after drilling and deburr the hole manually with a 6 mm drill at both sides. Remove all debris with a vacuum cleaner.
Crimp a connector with 3 mm hole to the green/yellow wire and mount it to the back with "toothed" and flat M3 washers. Solder the other side to the IEC PE pin where the blue wire already is. Then insert a 100 Ohm 2W resistor from the blue wire to the PCB. Make sure to put a heat shrink tube over it first. Only do this when you are experienced and know what you are doing.
Since I had SMSL products with fake electrolytic caps my habit is to replace them for known good quality electrolytic caps in higher value. Other types than the P1 sometimes become very hot which makes it necessary to drill 6 or 7 mm ventilation holes both at the bottom and near the heatsinks for longevity.
Advice is to remove the screws of the regulators and put a very tiny dot heat paste between regulators metal part (in the middle) and the heatsinks. Remount the screws but with each a flat M3 washer.
I dealt with a few SMSL PSU's recently and there is a slight thinking error in these PSU's. Also in P1 PE is connected directly to Audio GND. This introduces a ground loop when your amplifier has Audio GND connected directly to PE too. You can connect a second (green/yellow) 0.75 or 1 mm2 wire from the IEC PE pin to the casing. Drill a small 3.5 mm hole between the IEC inlet and the DC connector (just above the CE marking) for this. Use a piece of adhesive tape and stick it to the area being drilled. Put the device on a cloth and work tidy to prevent scratches. Remove the tape after drilling and deburr the hole manually with a 6 mm drill at both sides. Remove all debris with a vacuum cleaner.
Crimp a connector with 3 mm hole to the green/yellow wire and mount it to the back with "toothed" and flat M3 washers. Solder the other side to the IEC PE pin where the blue wire already is. Then insert a 100 Ohm 2W resistor from the blue wire to the PCB. Make sure to put a heat shrink tube over it first. Only do this when you are experienced and know what you are doing.
Since I had SMSL products with fake electrolytic caps my habit is to replace them for known good quality electrolytic caps in higher value. Other types than the P1 sometimes become very hot which makes it necessary to drill 6 or 7 mm ventilation holes both at the bottom and near the heatsinks for longevity.
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Addendum: the green/yellow wire must be stranded wire of course! Also ventilation holes (if necessary) should be far from points where mains voltage is.
So this is the complete story I think 🙂
So this is the complete story I think 🙂
A huge thank you for the detailed response. I'm so far only through at the "Remove jumper wires 3-5 and 4-6. Connect one of them now from 4 to 5. Solved." step, but it worked flawlessly with the complementing M2 and VA2.
Hi here is a change. The ground loop is a fact and the resistor can solve that. However, the GND of the PCB in other SMSL linear PSUs touches the casing sometimes thereby “shorting” the resistor. Still a ground loop when the casing touches the PCB. I can not see whether it is also the case in the P1.
Using only a 10 Ohm 2W from the IEC PE pin to the PCB (instead of the blue wire) solves that. Don’t use any wire so just the 10 Ohm to GND.
It is either this or the ground loop. Leaving GND floating is not a good idea.
Forget the remark about fake capacitors. It are sometimes simply old series/types of which datasheets can hardly be found. Probably a way to reduce costs.
Using only a 10 Ohm 2W from the IEC PE pin to the PCB (instead of the blue wire) solves that. Don’t use any wire so just the 10 Ohm to GND.
It is either this or the ground loop. Leaving GND floating is not a good idea.
Forget the remark about fake capacitors. It are sometimes simply old series/types of which datasheets can hardly be found. Probably a way to reduce costs.
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