Author Topic: VFE Standout IC Voltage question  (Read 78 times)

rfdvrcasey

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VFE Standout IC Voltage question
« on: November 21, 2021, 09:17:29 AM »
Hi, I'm trying to troubleshoot this Standout and I could use some advice. When I engage the pedal it sounds heavily distorted so I checked the voltages on the ics (JRC4580DD) and I'm hoping some can steer me in the right direction.  There is one value that is very off:
Upper IC reads:        Correct voltage:
3.96   0.0                 3.67    0.0             
4.72   3.72               4.43    3.77
4.73   4.55               4.43    4.21
8.67   4.55               8.18    4.44

Lower IC reads:      Correct Voltage
4.54    0.00             4.21       0.00
4.54    3.89             4.21       3.67
7.96*  4.73             4.21       4.44  *this is likely the issue?
8.18    4.73             8.67       4.55

Can someone please point me in the right direction? 

madbean

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Re: VFE Standout IC Voltage question
« Reply #1 on: November 21, 2021, 09:27:11 AM »
That's definitely a problem. That's the output of the effect (goes to the 22uF cap before OUT). There are a few possible areas - the .1uF cap right next to pins7 and 8 could have a problem (maybe reflow those solder pads), the LVL pot or the 1k43 resistors.

If you have the IC socketed, remove it and take a voltage reading on pin7 of the socket. You should have about 0v. If not, some DC is getting to it when it should not.

rfdvrcasey

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Re: VFE Standout IC Voltage question
« Reply #2 on: November 21, 2021, 11:05:43 AM »
I do have it socketed and showed 0v on pin7. I relflowed all of the suggested parts and now the ic reading is just under 3v but there is no change to the output sound.  I'm going to try again and see if there is another change.  I've checked all the resistor values and they're correct.