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Author Topic: Any Love For The Digitech Valve FX?  (Read 30001 times)

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Sparker

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Re: Any Love For The Digitech Valve FX?
« Reply #30 on: Time Format »

Now you have the test tone, you will need an MP3/music player, etc, to play the sine track into the ValveFX.
You will also need a lead and maybe a jack adaptor to connect these together.

Set the ValveFX to bypass mode
Play sine track into ValveFX front input (set to repeat/loop)
GND meter lead should be on the front jack socket GND (sleeve) for all measurements

Set meter to 2V AC and connect to the signal on the front jack socket tip connection.
Measure the input signal, adjust the MP3 player volume (or whatever)
to give a reading of around 1V AC on the meter.

Measure the signal on TP4 on the PCB by the input jack socket
Measure the signal on U56 pin1 and pin7
Measure the signal on U32 pin1 and pin7
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MarshallJMP

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Re: Any Love For The Digitech Valve FX?
« Reply #31 on: Time Format »

You have to be careful with using a 1khz tone,not all multimeters can handle 1 khz,most of them are made for 50 or 60 hz.Not that it will get damaged but you can get crazy readings especialy with cheap types.Just a tip.
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DrDckhol3

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Re: Any Love For The Digitech Valve FX?
« Reply #32 on: Time Format »

Now you have the test tone, you will need an MP3/music player, etc, to play the sine track into the ValveFX.
You will also need a lead and maybe a jack adaptor to connect these together.

Set the ValveFX to bypass mode
Play sine track into ValveFX front input (set to repeat/loop)
GND meter lead should be on the front jack socket GND (sleeve) for all measurements

Set meter to 2V AC and connect to the signal on the front jack socket tip connection.
Measure the input signal, adjust the MP3 player volume (or whatever)
to give a reading of around 1V AC on the meter.

Measure the signal on TP4 on the PCB by the input jack socket
Measure the signal on U56 pin1 and pin7
Measure the signal on U32 pin1 and pin7


The closest I could get it to was .8 and that overloaded my Greenlee on 2V  so the measurment for TP4 is @ 20V
INPUT-.837
TP4-2.02

The U56 and U32, I was unable to find. The board has some listed beside them but others are beneath the opamps(I guess that is what those are?)

I have scoured the internet for a schematic but I guess I'm going to have to put this off until I get someone at Digitech to send me one, if that is possible.

 :poop:

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rnolan

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Re: Any Love For The Digitech Valve FX?
« Reply #33 on: Time Format »

Schematic
Didn't Sparker post the schematic here ?
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DrDckhol3

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Re: Any Love For The Digitech Valve FX?
« Reply #34 on: Time Format »

Schematic
Didn't Sparker post the schematic here ?

I downloaded it and it was just the manual
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rnolan

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Re: Any Love For The Digitech Valve FX?
« Reply #35 on: Time Format »

Sparker did 2 posts, the first was the manual, the next was the schematics (which I was looking at yesterday), here it is again (now there are 2 :metal: )

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DrDckhol3

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Re: Any Love For The Digitech Valve FX?
« Reply #36 on: Time Format »

I totally overlooked the second one thinking it was the same. Thanks :thumb-up:
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rnolan

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Re: Any Love For The Digitech Valve FX?
« Reply #37 on: Time Format »

No Worries  :)
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DrDckhol3

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Re: Any Love For The Digitech Valve FX?
« Reply #38 on: Time Format »

The U56 .860 and U32 .120 on AC 2V setting
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Sparker

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Re: Any Love For The Digitech Valve FX?
« Reply #39 on: Time Format »

Some whacky measurements there to start with (20V @ TP4), don't forget the meter should be AC. TP4 looks about right at 2V output with 0.8V input, U34 output looks low - can you check the ValveFX output level was turned to max when you measured U34 output?
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MarshallJMP

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Re: Any Love For The Digitech Valve FX?
« Reply #40 on: Time Format »

U56 pin 1 and pin 7 voltage should be around the same voltage as TP4 (in bypass mode).
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Sparker

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Re: Any Love For The Digitech Valve FX?
« Reply #41 on: Time Format »

.. and there is that as well. Could you put a little solder bridge, or short, across FET Q24, going from drain to source. Then, still in bypass mode, with the 2V AC signal at TP4, measure the AC signal at U56 pin 1. I'll try and get a pinout for Q24 in a bit.
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DrDckhol3

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Re: Any Love For The Digitech Valve FX?
« Reply #42 on: Time Format »

I'm going to have to put this project on the back burner. Thanks fro every ones help. Hopefully I'll have some time to get back on it soon.  :facepalm:
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Achben

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Re: Any Love For The Digitech Valve FX?
« Reply #43 on: Time Format »

I have a valve fx that had a similar problem.
 Turns out the Output potentiometer was broken. These pots were made by a company called ALPS who had some trouble with curing the ink in these pots and were forced to overcook them in order to make the ink in the conductors cure. This made the inside of the pots brittle. Mine was in three pieces. Easy fix. You can buy them from a German fellow on ebay called Nocrotec for about 20USD.
 Another issue, the input gain is a bit weak. I was wondering if I could adjust P1 to let raise the input gain.

 Thank you.
 
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Chip Roberts

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Re: Any Love For The Digitech Valve FX?
« Reply #44 on: Time Format »

Resurrecting a dead post, but I just picked one of these up for its onboard whammy and also some good reviews about the effects.  My question is, some people say you can bypass the preamp and others say it cannot be bypassed.  If the former is true, then any information on that would be greatly appreciated.  If the latter is true, then I'm a dummy for buying it since the preamp sounds are effectively useless.
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