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June 27, 2022, 05:19:22 PM

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Samick SM-10 Amp

Started by Tassieviking, April 19, 2022, 12:28:03 PM

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Tassieviking

I was given a pair of small practice amps last week, one was a Samick SM-10.
I searched the Net for a schematic and some information,-----Nothing----.

I wanted to know what I had before I started re-assembling it, it was pulled apart.
This was the hardest circuit I have ever traced, and strangest for a budget amp.
I have traced it as well as I can for now, but I think I will do it again in the future just to see if I can find any faults in my tracing.

It has a strange setup with the Volume pot and Overdrive Pot.
I have no clue yet what the Overdrive Socket does, when I get it working I will try shorting it out to see if it kills the Overdrive I think.
Serial Number is 94060140, 1994 model ?

Here is the schematic I have traced at this moment:


 
There are no stupid questions.
There are only stupid mistakes.

Tassieviking

Quick question for someone, when you change capacitors in an old amp,
do you just change the Electrolytics ? (Preventative Maintenance)

I have only changed the electrolytics in most amp I have come across.
Should I change greencaps and ceramics as well ?

In the 45 years I have been an electrician I never replaced capacitors just because they were old, and I mainly worked in maintenance, Industrial electronics mainly.
Lots of huge DC drives for DC motors, PLC's, big stuff mainly. I also did instrumentation  calibration and testing as well.
Just never any Audio stuff, until now.
Thanks
There are no stupid questions.
There are only stupid mistakes.

joecool85

I'm sure someone will correct me if I'm wrong, but I've always only replaced electrolytics - and even then, only if they were causing an issue.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Tassieviking

#3
Thanks Joe.
I was given this amp and a Marshall G15R-CD for free, apparently the pots are noisy.
I am thinking of giving them to the local primary schools music department if they want them.
I think young kids will like them, as long as the school has some guitars.
I think I will change all the Electrolytic caps and all the pots in both amps before I ask. The amps are 23 and 28 years old I think

Caps and Pots will cost up to $13 total for both amps from Tayda, and I am putting in an order soon anyway. That's if I use the best Electros Tayda has.
I might also mount some speaker cloth across the backs to keep the little fingers out of the speaker. Or maybe a metal mesh would be better.
There are no stupid questions.
There are only stupid mistakes.

phatt

These are small practice amps and In My Experience a waste of time changing every cap that will likely not make any difference to the sound these cheap amps produce.
Re scratchy pots
I just spray the pot guts with RP7 or WD40 and unless the pots are totally stuffed they usually come back to life.
As example, I scored a home Hifi years ago that had a scratchy volume pot, a squirt of WD40 and still going fine, that was 10 years back.

Note; some tecks will frown on using RP7 or WD40 but Cricky it's a cheap guitar amp.

If you want the best pots then track down the conductive plastic units as they last much much longer.
Phil.

joecool85

Quote from: phatt on April 20, 2022, 11:16:12 PMThese are small practice amps and In My Experience a waste of time changing every cap that will likely not make any difference to the sound these cheap amps produce.
Re scratchy pots
I just spray the pot guts with RP7 or WD40 and unless the pots are totally stuffed they usually come back to life.
As example, I scored a home Hifi years ago that had a scratchy volume pot, a squirt of WD40 and still going fine, that was 10 years back.

Note; some tecks will frown on using RP7 or WD40 but Cricky it's a cheap guitar amp.

If you want the best pots then track down the conductive plastic units as they last much much longer.
Phil.


100% agree.  I use contact cleaner rather than WD-40 though lol.  And I like conductive plastic pots as well.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Enzo

And electrolytics do dry out with age, but the little film and ceramic caps should last forever.   REALLY OLD caps like the wax covered ones in really old tube stuff will need to be changed as well.

And I agree, on these little practice amps, it really is unlikely you need to change out the caps at all.

Tassieviking

Thanks for all those comments guys, I was only thinking of replacing the Electro-caps and the pots if the school wants them.
I just wanted to make them last as long as possible for the kids.
There are no stupid questions.
There are only stupid mistakes.