Help needed, someone knowledgeable to building a power supply for my Mares Connoisseur phono preamp. My rebuilt 20 yr old power supply built by Ric Schulz went kaput, flamed out. Hoping to find someone here who might be able to build one or direct me to someone. After consulting with Ric, says he doesn’t do anymore such work. Thx.
Paul Wong
Located in the Monterey Bay area
559 240-1841 cell
Paul Wong
Located in the Monterey Bay area
559 240-1841 cell
If you can provide some details of the supply someone will be able to advise where you can obtain a suitable replacement or how to make one.
Power supplies provide an output voltage at the required current.
If this information is unavailable then some internal pics of the original supply may provide sufficient clues.
Power supplies provide an output voltage at the required current.
If this information is unavailable then some internal pics of the original supply may provide sufficient clues.
It might be a good idea to mention how this arrangement may benefit the other party, the person who is deciding whether or not to build a power supply for you. Perhaps reveal a few details about what it is that you are proposing?
This is essentially a dual (for separate stereo channels) ac supply with transformers
115V ac primary and 18-0-18V secondary with the dedicated cable and plug in a
primitive case. Mains switch and mains fuse are missing, this is a design error.
I doubt the transformers are broken, it does not look like this. One of them has
suffered from heat, probably still working. Maybe there is a short in the amp itself.
Transformer replacement should be easy, but the preamp must be checked. Every
competent technician can do this. Jonathan Carr in this forum knows more.
115V ac primary and 18-0-18V secondary with the dedicated cable and plug in a
primitive case. Mains switch and mains fuse are missing, this is a design error.
I doubt the transformers are broken, it does not look like this. One of them has
suffered from heat, probably still working. Maybe there is a short in the amp itself.
Transformer replacement should be easy, but the preamp must be checked. Every
competent technician can do this. Jonathan Carr in this forum knows more.
I would like a much clearer idea as to what has actually gone on here. Why do you think there is a short? What actually happened? Have you lost one channel? Is there any evidence of overheating inside the preamp? Did you connect it to 120V AC?
Which clearly shows, why you should not put your power electrics in a wooden (or plastic, if it's not flame-retardent) box.
At least use a metal base plate (grounded) if you want to keep the original design.
No shielding, wooden box (really?), no fuse (!!!), no power switch, no PE but PE IEC inlet, overheating, maybe underpowered, too thin and even burnt wiring. Way below amateur level build so probably highly valued and appraised in the connaisseur (correct spelling) audio world. It is a bit of a small miracle that it lasted 20 years really.
If I am not mistaking the PSU needs to deliver 2 x 36V AC but at what current? The transformers have no labels. The Mares Connoisseur has a 4 pin Lemo connector so I take one needs to measure and wire 2 x 36V xA (unknown factor) to the right pins. I think it would be a good thing to test/check the transformers as at least one of them seems to have overheated maybe because of overload by the preamp or a short in the wiring and since there is no fuse whatsoever it just kept overheating. When they test OK reconnect them temporarily with thicker wires to measure currents (verification if all is OK and to check if the transformers are not overloaded) and then to rebuild the thing as it should be. So metal casing, filtered IEC inlet with built in fuse holder and PE connected, adequate wire gauge, power on/off switch.
If the preamp is OK then rebuilding with 2 new transformers 2 x 18V won't break the bank either. Making this looking good and safe plus functioning correctly would be a nice job but I am at the other side of the ocean.
If I am not mistaking the PSU needs to deliver 2 x 36V AC but at what current? The transformers have no labels. The Mares Connoisseur has a 4 pin Lemo connector so I take one needs to measure and wire 2 x 36V xA (unknown factor) to the right pins. I think it would be a good thing to test/check the transformers as at least one of them seems to have overheated maybe because of overload by the preamp or a short in the wiring and since there is no fuse whatsoever it just kept overheating. When they test OK reconnect them temporarily with thicker wires to measure currents (verification if all is OK and to check if the transformers are not overloaded) and then to rebuild the thing as it should be. So metal casing, filtered IEC inlet with built in fuse holder and PE connected, adequate wire gauge, power on/off switch.
If the preamp is OK then rebuilding with 2 new transformers 2 x 18V won't break the bank either. Making this looking good and safe plus functioning correctly would be a nice job but I am at the other side of the ocean.
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Oh yes, the secondary cables are also burnt, this confirms my suspicion of a secondary short.
It can as well be in the cable plug. I do not think that two transformers of 50VA label each are
underrated for a preamp. This rating hints at core size M65, set up with simple "Ready Core"
laminations here. Comparing with the size of the IEC inlet it can as well be a M74 transformer.
It can as well be in the cable plug. I do not think that two transformers of 50VA label each are
underrated for a preamp. This rating hints at core size M65, set up with simple "Ready Core"
laminations here. Comparing with the size of the IEC inlet it can as well be a M74 transformer.
I stock those exact Lemo connectors (non audio and Swiss so about the best one can use) and it is tricky to use thicker wires than these are designed for. Shorting IN either one of the connectors is very well a possibility. As you can see both male and female versions are meant to have wires soldered in the pins. This is not always understood right 🙂
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