Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: glazcon on September 06, 2010, 11:30:43 PM

Title: KMD GS130SD / Need parts schematics
Post by: glazcon on September 06, 2010, 11:30:43 PM
I have a KMD GS130SD amp that has been stored in my garage for 18+ years. It powers up, but only the clean channel plays, but at no more than half the volume that it used to! There are two Phillips capacitors, 2200uf 100v 2222 050 59222, One runs out to infinity, but the other runs up to about 430 and stays there (When tested with a DMM). I can not find these capacitors online. Does anyone know where I can find these or can I cross reference with something else? Also I am not sure if this is the problem, but I figured it as a starting point!
Title: Re: KMD GS130SD / Need parts schematics
Post by: bry melvin on September 07, 2010, 12:49:11 AM
capacitors don't need to be replaced with the exact item.  just go to Mouser, Digikey or Newark electronics, Antique radio supply. ( or other) and use a capacitor with the same values. I assume from 2200 it's an electrolytic. I prefer Mouser. They have a search that let's you specify values and links to datasheets so you can check physical dimensions.

If one electrolytic in an amp is bad often it is a convenient time to change all electrolytics. The other types seldom go bad with age (except wax and paper covered ones and your amp is way too recent for them)
Title: Re: KMD GS130SD / Need parts schematics
Post by: J M Fahey on September 07, 2010, 01:16:01 AM
Did you measure them off board or in circuit?
In the second case some other component may cause that reading.
If you had a bad cap you would have strong hum, or instabilities, but not just "low power".
Those were very well made amps, the ones I remember were hybrid: SS preamp plus a couple output tubes.
Post a couple pictures.
Title: Re: KMD GS130SD / Need parts schematics
Post by: glazcon on September 07, 2010, 01:02:42 PM
Thanks for links. No hums. I tested in circuit. One problem I always had with this stack is that the effect loop has to have a cable plugged into it (one cable plugged in both jacks) to make it work. What I call capacitors might be the output tubes you referenced (JM Fahey) My pics are too large to post on this site, even when I zip the file! I could probably email.
Title: Re: KMD GS130SD / Need parts schematics
Post by: DJPhil on September 07, 2010, 02:35:02 PM
To easily make pictures from a digital camera forum friendly I use Irfanview (http://www.irfanview.com/). It's free and very useful. Download here (http://download.cnet.com/IrfanView/3000-2192_4-10021962.html?part=dl-IrfanView&subj=dl&tag=button).

Here's a short, somewhat half-assed tutorial that assumes some familiarity with computers:


Irfanview has all kinds of other options and abilities, and it's definitely worth the investment in time to learn the program if you work with digital images.

Hope that helps :)
Title: Re: KMD GS130SD / Need parts schematics
Post by: bry melvin on September 07, 2010, 03:06:05 PM
QuoteThanks for links. No hums. I tested in circuit. One problem I always had with this stack is that the effect loop has to have a cable plugged into it (one cable plugged in both jacks) to make it work. What I call capacitors might be the output tubes you referenced (JM Fahey) My pics are too large to post on this site, even when I zip the file! I could probably email.

It actually sounds like the first thing you should do with this amp is clean the jacks and pots etc with deoxit( or equivalent) and possibly change the jacks and go from there.