Need CAP Replacement Help on Technics SA-300

[BILL IN NC]

My Technics SA-300 receiver is great to play my old LP's on. Nothing like cranking up some Dire Straits! I have read that replacing capacitors can improve sound quality....

I am interested in replacing some of the caps and would like recommendations on which ones to replace. I have a copy of the original instruction manual that lists every cap in the receiver (big list). I'm counting 42 electrolytic caps plus an additional 87 random ceramic, polyester, and polystyrene caps. I hope every cap won't need to be replaced... I have a .PDF copy of the original instruction manual if that might help. It contains the list of caps and a diagrams of the circuit boards. Any help will greatly be appreciated! Thanks.

[BILL IN NC]

Maybe I posted this in the wrong forum topic? Anyone?

[sakis]

ok ... though what is your question?
how old is the machine ?
did you remove any caps to see if and how bad are they ?
is your tuner losing the frequency ?
do you have the skills and instruments to do both repair and upgrade
do you also know that this is a job worth doing but will consume time

given the opportunity you may upgrade many of the electrolytic to something bigger regarding the capacity /voltage /temperature that will give you better filtering/linearity/durability

then again same apply to ceramics there are a lot of places that these can be removed and be replaced with better types such is film types mica styroflex and/or others

this your margin to do things ....

[ingenieus]

It is a fine looking piece of kit. They really don't make them like this anymore.



Replacing the big capacitors in the power supply and elsewhere is a good idea and usually straightforward. Replacing every capacitor in sight is not a good idea, even if you are handy with a soldering iron.

If you think about it, why stop with caps? How about replacing every resistor with a brand spanking new state of the art metal film thingy? And then there are those transistors from the previous century...

Don't fix something that is not broken. You may improve the receiver a little, but then again you could ruin it.

[sakis]

ingenious .... you are very very wrong and seems that you haven't got a clue on what are you talking about

fact !!!!
all vintage amplifiers need recaping after this age ....check specs and life expectancy of capacitors and you will find that caps of the time was rated for 2000 hours under stress and in no condition 30 years ....

fact !!!

one amplifier with leaky filter caps will only need them when the power increases ....if only the 10% of life exist inside the capacitors this is enough to start the amp and listen music from in low power ....

ONE AMPLIFIER WITH ONLY ONE LEAKY CAP IN THE FEEDBACK CHAIN WILL NOT PLAY AT ALL OR PLAY WITH NO FREQUENCY RESPONSE ..... ONE AMPLIFIER WITH LEAKY BIAS STABILIZER COULD POSSIBLY BLOW OR WORK WITH THE WRONG BIAS AND EVENTUALLY BLOW .

at east electronics we repair an average of 300 amplifiers per year where the greatest percent is vintage and the rest is modern or professional .... the above comments is a direct feedback of our work ...

finally the approach ''dO NOT TOUCH ANYTHING THAT WORKS " is worst and very childish and to put in other words will mean that one may have in his garage a 1978Ford pinto washing every day and driving kids to 5KM school every day and of course the car is still working after so light duty ....and then you take this car and hit the highway ..... you will eventually end up dead ....

i am very sorry to see such an approach in the forum ....

[sakis]

by the way .....
often we had replace also resistors in amplifiers ...some lines of resistors if exposed to excessive heat or moisture ...roll and go open a value is drifted.

Most of the times the Japanese carbon resistors proved reliable enough and precise enough ...

As about transistors the Japanese made transistors of the time proved to be exactly what they where made for ... no need to change any of them if not broken

[ingenieus]

I stand corrected, but the work is not trivial and lots of things can go wrong. That's the point I tried to make. I've seen at least two threads on this forum where somebody poked around inside a working amp, caused a short circuit and is now looking at doing a repair.

If the receiver still works it might be best to let sleeping dogs lie if one is not confident of one's abilities to do the work. But that is only a short term answer. With the aid of the service manual, there are tests that can be done to make sure that it still works within spec. This would tell you what is needed before you start replacing things en masse.

[BILL IN NC]

Sounds like there are mixed opinions on replacing caps in old amplifiers.... I would not do the soldering - an electrical engineer in my office would.

My question: Which caps are best to replace?
1) Caps in Power Supply
2) Caps in Amplifier Signal Path
3) Both 1 & 2

I have a .PDF of the original manual with a full list of caps and circuit diagrams. Would someone be kind enough to let me know specifically which ones I should have replaced? I ordered a brand new Pink Floyd LP and need my amp sounding as best as possible. Thanks a bunch!

[BILL IN NC]

Anyone? Thanks....

[a95sonoma]

As long as your sure your friend is a competent with a solder iron and a solder sucker , just start the electrolytic's in the preamp and amplifier section. Soldering skills for this job are more important then any degree. If he does a good job, then maybe you go deeper, but when you start messing around with the tuner, you might throw it out adjustment. FM long ago became a chip function with digital control, and these old tuners are pure analog. Schools don't get into analog FM tuner function and design these days, so his degree might not mean a thing when it comes to adjusting a old tuner.