fortuyn79

Hi,

I don't know a lot about electronics but I can replace parts on PCB's without messing it up (too much). Lately I had some problems with amps which were all solved pretty easily by resoldering some bad (lose) connections.

I've bought a ltd edition VS100 from 97 and started tweaking at it a little. I replaced the ancient tube with a Shuguang 12ax7b which I really like. I've replaced the Goldback with a Vintage 30, soldered new monster cable speaker wires directly on the PCB and speaker and I closed up the back of the combo (huge effect). It's sounds a lot better from the original setup. The thing is, the amp hums just a little, it's not really that bad and I don't hear it anymore after turning the volume up just a little but it still anoys me. I've started reading about caps and how they go bad over the years and cause amps to hum and potentially wreck the tubes or possibly the OT. I read tons of different stuff, maybe someone can clear up the truth about all this.

I also have a TSL100 thats from 99, I never had any issues with it but it also hums a little, maybe this is just normal. Since it's from 99 I figured that maybe the caps need replacing along with the VS100's caps. If I do this :

- Will I have to replace ALL the caps on the board or just the really big ones?
- The TSL has one mainboard, are the caps that relate to the possible humming only on this board?
- How do I drain the caps?
- If I let an amp sit for 24 hours without being plugged in, will it automatically drain itself? Someone told me my TSL100 does this but Im not sure about the VS100
- Is the VS100 less dangerous than the TSL 100 of terms of shocking myself? :/

I know many of you will probably advise me to let an amp tech do it, but I'd like to learn to do this myself. I feel most techs around here (Holland) overcharge a lot for the simplest maintenance jobs and I like being able to fix my own amps. Like everything is easy when you know what do I think this will be no different.

I know, lot of questions but I'd appreciate some feedback..

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Sander
http://www.myspace.com/underdog_79

Apostle Tone

In the short time I've been here I know there are others who know whole lot more than I do, but since they've not answered yet let me provide a wee bit of help.

It seems you know the dangers so don't forget them - you know keep one hand in your pocket when poking around.

Draining the caps: According to Dave Funk's "Tube Amp Workbook" you can leave the amp in "Standby" if you have a standby switch and that will drain the caps. I've never actually measured this to verify that it completly drains the caps, but I do let it sit in standby for a few minutes before powering down.

Then I always take a wire that has alligator clips at both ends and inbetween them is a 470 ohm 5watt resistor in line (series). I connect one end to the chassis and the other end to the biggest caps positive side (+) with the indent to let the cap drain. I actually do it with all the caps since I've never measured if it takes it from all of the caps by connecting to one. It doesn't take long and I feel safer doing it this way. Some one else here can verify the need to do that with all of them or not. I'll probably still do it with all of them though.

I don't know about your specific amps as I am hear to learn about building Marshall type amps - I've only built two amps so far and neither are based on Marshall's design. However, all DC voltages are dangerous - Deadly dangerous. DC is more deadly than AC because it does not alternate the current ~ when it grabs it may not let go...

I'm just sayin'

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Ignorance+Ego+Insecurity+Technology=funny