Hello,
As title, I am looking for schematics for the Musical Fidelity The Preamp. Bought the amp with a couple of Typhoon power amps back in 1996. Everything has been working well until last week when the preamp no longer powered up, the switch LED stays off and nothing coming out of either channel via the Typhoons and a pair of sweet Mission floor-standers. I have taken a cursory look inside and there are no obvious signs of burn-out or component damage.
I have a couple of engineering degrees and feel OK probing around what is a well-laid out board with easy component access, but would feel happier with a set of schematics. Can you help? Please advise.
Thanks in advance.
Best, BritFi
As title, I am looking for schematics for the Musical Fidelity The Preamp. Bought the amp with a couple of Typhoon power amps back in 1996. Everything has been working well until last week when the preamp no longer powered up, the switch LED stays off and nothing coming out of either channel via the Typhoons and a pair of sweet Mission floor-standers. I have taken a cursory look inside and there are no obvious signs of burn-out or component damage.
I have a couple of engineering degrees and feel OK probing around what is a well-laid out board with easy component access, but would feel happier with a set of schematics. Can you help? Please advise.
Thanks in advance.
Best, BritFi
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This is a Preamp 11 with schematic -
HiFi: Musical Fidelity 'The Preamp II'
If you have two engineering degrees this should be easy for you --circuit is simple .
HiFi: Musical Fidelity 'The Preamp II'
If you have two engineering degrees this should be easy for you --circuit is simple .
Hi duncan2,
Thanks for the materials.
I believe that I have an earlier version with the PSU/Transformer inside the unit.
I have attached some photos of the main board.
Best, Elwyn
Thanks for the materials.
I believe that I have an earlier version with the PSU/Transformer inside the unit.
I have attached some photos of the main board.
Best, Elwyn
No photos added BritFi --no link.
I am looking at a MF B1 preamp circuit while not the same as your their design philosophy as regards this early design is a very simple full wave rectifier and simple smoothing .
Power supplies unless fully stabilized are very easy to test for faults and even more complicated preamp versions usually include voltage regulators which are usually 3 pin.
First check the output from the rectifier which will be either a square block of plastic or four diodes connected together--bridge rectifier .
If no voltage then the rectifier or the output AC from the secondary of the mains transformer is missing .
If no AC output then either a fuse has blown or the secondary winding's are blown .
Get back with the tests please.
I am looking at a MF B1 preamp circuit while not the same as your their design philosophy as regards this early design is a very simple full wave rectifier and simple smoothing .
Power supplies unless fully stabilized are very easy to test for faults and even more complicated preamp versions usually include voltage regulators which are usually 3 pin.
First check the output from the rectifier which will be either a square block of plastic or four diodes connected together--bridge rectifier .
If no voltage then the rectifier or the output AC from the secondary of the mains transformer is missing .
If no AC output then either a fuse has blown or the secondary winding's are blown .
Get back with the tests please.
check out my own created schematic of the Phono-RIAA MM stage from "The Pre-Amp" (first preamp model of Musical Fidelity) in post #5 (first PDF) under
https://www.diyaudio.com/community/threads/head-pre-for-denon-dl-103.155449/
In the attachment you will find two different - the schematic belongs to those from the first jpg
https://www.diyaudio.com/community/threads/head-pre-for-denon-dl-103.155449/
In the attachment you will find two different - the schematic belongs to those from the first jpg
Attachments
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