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A turntable using a moving magnet or moving coil cartridge needs a step up amplifier referred to as a phono stage or phono preamp. I have two, one using valves for my 'main' turntable and a 'solid state' unit for my secondary deck.
Recently the solid state Pro-Ject phono stage failed. The fault was both channels had developed a very nasty hum, one channel had a louder hum than the other.
I took a swift look inside and noted that the greater majority of components were surface mount which are almost impossible to remove and replace so put it down to bad luck and put the unit aside and accepted I'd have to replace it. I purchased it a little over 4 years ago for £119.00, it's now £139.00, this one Here.
I got to thinking though and thought it would be worth checking the external PSU as faulty adapters are often the cause of hums developing. I was surprised to find the adapter/PSU was in fact just a transformer giving 17V AC. This meant smoothing (components changing AC to DC) had to be onboard in the unit itself so I took another look. There I saw a pair of easily replaceable capacitors directly next to the AC input, each 470uF 25V.
A quick rummage in my junk/really useful parts and I found a pair of 470uF 35V capacitors which fitted. So I fitted them (grammatical note, I know some folk just say 'fit' but I like to use the old term 'fitted'. 'Fit' is what young girlies call desirable young men/partners, after all).
And it worked
So that's a few quid saved eh? Me one happy bunny 
One of the old caps was dead short.
However, this temporary breakdown prompted me to gather the parts for a VSPS (Very Simple Phono Stage using an NE5532 IC) and also order a pre-assembled phono stage PCB from China This one. Both use a 12-0-12 PSU which I've already made and cased, next step will be the making of the VSPS on veroboard. This is a hobby after all
Here's a couple of pix of the unit after the new capacitors were fitted:
Recently the solid state Pro-Ject phono stage failed. The fault was both channels had developed a very nasty hum, one channel had a louder hum than the other.
I took a swift look inside and noted that the greater majority of components were surface mount which are almost impossible to remove and replace so put it down to bad luck and put the unit aside and accepted I'd have to replace it. I purchased it a little over 4 years ago for £119.00, it's now £139.00, this one Here.
I got to thinking though and thought it would be worth checking the external PSU as faulty adapters are often the cause of hums developing. I was surprised to find the adapter/PSU was in fact just a transformer giving 17V AC. This meant smoothing (components changing AC to DC) had to be onboard in the unit itself so I took another look. There I saw a pair of easily replaceable capacitors directly next to the AC input, each 470uF 25V.
A quick rummage in my junk/really useful parts and I found a pair of 470uF 35V capacitors which fitted. So I fitted them (grammatical note, I know some folk just say 'fit' but I like to use the old term 'fitted'. 'Fit' is what young girlies call desirable young men/partners, after all).
And it worked
So that's a few quid saved eh? Me one happy bunny One of the old caps was dead short.However, this temporary breakdown prompted me to gather the parts for a VSPS (Very Simple Phono Stage using an NE5532 IC) and also order a pre-assembled phono stage PCB from China This one. Both use a 12-0-12 PSU which I've already made and cased, next step will be the making of the VSPS on veroboard. This is a hobby after all
Here's a couple of pix of the unit after the new capacitors were fitted:
.
Aint that always the way, I think you farmers usually repair things with a big hammer and a blow torch 
