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DIY Stompboxes => Building your own stompbox => Topic started by: powerplayj on November 11, 2005, 11:33:29 PM

Title: help with Ross Comp please (Tonepad layout)
Post by: powerplayj on November 11, 2005, 11:33:29 PM
Ross Comp using Tonepad layout: http://www.tonepad.com/getFileInfo.asp?id=9

2N5088 trannies, 9V well-regulated power supply (9.1V)

Symptoms:  No sound at all except increased hum/gaim when turning up volume pot.  Turning sustain pot has not affect sound (hum) ???

IC
2. 1.9V
3. 1.9V
4. 0V
5. 0.6V
6. 3.2V
7. 9.1V

Q1. 8.1, 0.1, 0.2

Q2. 6.4, 3.2, 2.6

Q3. 7.3, 0.0, 0.0

Q4. 7.3, 0.0, 0.0

Q5. 9.1, 7.6, 6.8

Ideal values from Fuzz Central are

IC
2. 4.9V
3. 4.9V
4. 0V
5. 0.6V
6. 2.8V
7. 9.5V

Q1. 8.0, 2.1, 1.7

Q2. 7.3, 2.9, 2.3

Q3. 9.5, 0.0, 0.0

Q4. 9.5, 0.0, 0.0

Q5. 9.5, 9.3, 9.0

Any help to narrow down the troublesome component would be much appreciated.  I'll work on the audio probe in the meantime.  Thanks,

Jason


Title: Re: help with Ross Comp please (Tonepad layout)
Post by: nelson on November 12, 2005, 09:00:31 AM
Just looks to me as if you VB is too low, check the voltage divider resistor values.
Title: Re: help with Ross Comp please (Tonepad layout)
Post by: Fp-www.Tonepad.com on November 13, 2005, 11:30:08 AM
Q1 is misbiased, check the resistors connecting to it.

Fp
Title: Re: help with Ross Comp please (Tonepad layout)
Post by: powerplayj on November 13, 2005, 01:57:26 PM
....touched up a few caps and resistors and now I am in business.  Wow!  this thing is nice and smooth and doesn't have the brittle tone that I noticed with the Dynacomp.

Thanks
Title: Re: help with Ross Comp please (Tonepad layout)
Post by: Fp-www.Tonepad.com on November 13, 2005, 05:59:00 PM
Congratulations!
Fp