Home » VintageKustom.com » Comment Board » Vibe Controls SC-150

Show: Today's Messages :: Polls :: Message Navigator

Vibe Controls SC-150 [message #8279] Sun, 18 February 2007 15:47   oldnavycdr Messages: 38 Registered: July 2006 Location: Sanford, NC Member When I owned Kustom equipment in the 60's I was strictly a bass player although I did play guitar on occasion -- through a Fender Super Reverb. Having gotten back into the Kustom mode -- thanks to this site -- and now owning a SC-150-7, I find I don't understand how to differentiate the operation of the tremolo vs. the vibrato. The front panel controls are speed, intensity (on/off) and trem-vib. Then, there is the footswitch (which is original) with a button for for reverb and one for the vibrato. Depressing the vibrato button seems to turn both the reverb and the trem/vibe on. The reverb button doesn't seem to activate anything suggesting a problem with the footswitch. What I can't figure out is how to switch between tremolo and vib. Moving the trem-vib pot from left to right doesn't give me much of a change in sound. Shouldn't the vib produce a tone change and the tremolo a volume change? I don't get much, if any tone change but the solid volume change which varies with the intensity and the speed control. If the optical vib is not functioning why do I still get the trem sound? Foot switch? Old Navy Report message to a moderator

Re: Vibe Controls SC-150 [message #8280 is a reply to message #8279] Sun, 18 February 2007 16:40 rodak Messages: 511 Registered: October 2001 Location: Georgia Senior Member The Vibrato should be a pitch change, and the Tremelo a volume change. There is no optical circuit in the SC-150 (unlike, say, a Twin reverb). It does sound like your footswitch is messed up, though. I also have an SC-150, and while the Tremelo works well, the Vibrato doesn't do much in the way of pitch change - it's more like a Tremelo with an irregular waveform. I've not yet bothered to try to figure it out, but when I do, I'll probably come here for help, too (so I'm hoping one of the other tech guys here will offer some direction!) www.combo-organ.com Report message to a moderator

Re: Vibe Controls SC-150 [message #8281 is a reply to message #8279] Sun, 18 February 2007 17:12   oldnavycdr Messages: 38 Registered: July 2006 Location: Sanford, NC Member You described my issue exactly. Perhaps the SC-150 just doesn't have a very strong vibe? So, I'm correct in thinking that moving the trem-vib pot should control the change from trem to vib? Thanks for the reply. I'll check out the foot switch and see what is up with that and wait for other posts on the vibe vs. trem. Old Navy Report message to a moderator

Re: Vibe Controls SC-150 [message #8283 is a reply to message #8281] Sun, 18 February 2007 21:59 rodak Messages: 511 Registered: October 2001 Location: Georgia Senior Member Yes,I'm pretty sure that's how it's supposed to work. I just wish mine did. www.combo-organ.com Report message to a moderator

Re: Vibe Controls SC-150 [message #8285 is a reply to message #8279] Mon, 19 February 2007 07:05   stevem Messages: 4739 Registered: June 2004 Location: NY Senior Member Yea, it sounds like somethings up with that foot switch. I have never had a sc150 to check out the trem/vib function, but I can tell you in my combo 100 that the vib function is a noticable difference from the tremolo. so I can not say if your vibrato function is normal or if you have some drifting cap values that may not let the circuit oscillate fully. Report message to a moderator

Re: Vibe Controls SC-150 [message #8286 is a reply to message #8285] Mon, 19 February 2007 12:48 chicagobill Messages: 2005 Registered: April 2003 Senior Member Rodak is correct, the vib-trem control is supposed to change the effect from pitch change to volume change. The metal front amps do this very well, but in my opinion the plex front circuit is not as effective. The circuit is basically the same as the 200B vibrato, but the 200B is designed as Vibrato only. The vibrato works by mixing the straight in-phase signal with a frequency modified out-of-phase signal. The balance of the signals mixed together is what determines the depth of the vibrato effect. If the tremelo is working strong and can be varied with the speed and depth controls, then I would check the balanced modulator circuit centered around transistor Q10003. The transistor, the Trem-Vib pot, and the 0.0047 capacitor (C1011), should all be checked. Bill Report message to a moderator

Re: Vibe Controls SC-150 [message #8288 is a reply to message #8286] Mon, 19 February 2007 20:37   oldnavycdr Messages: 38 Registered: July 2006 Location: Sanford, NC Member It just keeps getting weirder. While checking the amp out today I discovered that the reverb was being controlled by the Intensity pot which should control the trem-vib. Turn Intensity off, reverb goes off. Turn Intensity on, reverb comes back on. This was with the footswitch plugged in. I disconnected the footswitch and got the same result. I then used a guitar plug to "short" the footswith and things returned to normal. I think it is time to get this baby in for a check up. Anyone know a quality Kustom tech in the Northern VA/Washington DC area? The rest of the amp is just fine with Killer Kustom sound...but there seem to be some issues here with the effects and I don't think this baby has had a thing done to it since it came out of Chanute in '72. Old Navy Report message to a moderator

Previous Topic:	new push button switch replacement
Next Topic:	empty bass cabinet -Krossroad AR200 210H

Goto Forum:

- VintageKustom.com  Comment Board  Replacement Part Suggestions  Repairing Kustom Amps- Classified Ads  For Sale  Wanted- FUDforum Questions & Problems  Questions & Problems about FUDforum