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UNLEADED
Copper Member
Canada
10 Posts |
 Posted - 09/08/2009 : 07:43:23
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Just bought a non-working Boss PH-1 Phaser.The check light works.It does come on and off when I hit the lever but there is no effect sound when I tweak the control knobs.
Help needed please. |
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Plastic Stan
Copper Member
United Kingdom
14 Posts |
Posted - 09/08/2009 : 14:21:11
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| When you say no effect sound, do you mean it just passes the guitar signal straight through with no phase effect. If so i've just fixed a PH-1r with the same problem. Turns out it the JFETs that act as variable resistors in the 4 phase stages weren't biased right. So all I needed to do was set the bias with the trim-pot. There is only a very small range where it works, if you go too far one way or the other the phase effect doesn't work. It was easy to see on an oscilloscope where the right setting was, but if yours has the same problem because someone else has messed with the pot it should be possible to set by ear as long as you just go in small steps when adjusting. |
Edited by - Plastic Stan on 09/08/2009 14:22:37 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/08/2009 : 16:16:56
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Hi UNLEADED
Welcome to the forum from Australia.
Have you done a close internal visual inspection?
Perhaps you may have to upload a few pics.
Have you tried with a KNOW GOOD 9V battery?
What power supply are you using; As the PH-1, if I recall, is typically an ACA 12V unregulated pedal.
Regards Dr. Bob  |
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UNLEADED
Copper Member
Canada
10 Posts |
Posted - 09/08/2009 : 19:09:27
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Oh yes!Thank you so much Plastic Stan! .I just moved the trim pot a bit and BINGO! .My only concern now is how to trim the pot to the ideal position.I do not have an oscilloscope.I did it by ears.quote:
Originally posted by Plastic Stan
When you say no effect sound, do you mean it just passes the guitar signal straight through with no phase effect. If so i've just fixed a PH-1r with the same problem. Turns out it the JFETs that act as variable resistors in the 4 phase stages weren't biased right. So all I needed to do was set the bias with the trim-pot. There is only a very small range where it works, if you go too far one way or the other the phase effect doesn't work. It was easy to see on an oscilloscope where the right setting was, but if yours has the same problem because someone else has messed with the pot it should be possible to set by ear as long as you just go in small steps when adjusting.
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UNLEADED
Copper Member
Canada
10 Posts |
Posted - 09/09/2009 : 00:04:17
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Thank you Dr Bob.
I sure did an internal inspection before buying the pedal as I always do.
I also used the approppriate period correct Boss ACA 120 adapter/and or new 9 Volt battery.
I am not an expert so I was not aware of the trimming pot adjustment inside the pedal.
I guess some previous owner did mess with the trimming pot inside and that would explain why there was no effect sound.
Plastic Stan guided me to this.
He said; it may be just a question of trimming the internal pot and he was dam right.
So nothing was broken from the start.
I did adjust the pot inside until the effect sounded like it should(?!)to my ears.
Now,I would like to know if there is a way to fine tune this internal pot without the help of an oscilloscope.
Thank you so much for your timequote:
Originally posted by Dr. Bob
Hi UNLEADED
Welcome to the forum from Australia.
Have you done a close internal visual inspection?
Perhaps you may have to upload a few pics.
Have you tried with a KNOW GOOD 9V battery?
What power supply are you using; As the PH-1, if I recall, is typically an ACA 12V unregulated pedal.
Regards Dr. Bob
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Edited by - UNLEADED on 09/09/2009 00:06:45 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 09/09/2009 : 00:32:25
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G'day unleaded!
It really does need a scope to set it properly. Without a scope, let your ears be the judge - when it sounds best, then that's the right setting, almost by definition  |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/09/2009 : 14:36:11
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Hi UNLEADED & guys
Here is one non-scope method I have used, which works surprisingly well.
first read the Notes at the end of this article-post.
You will need a White Noise or Pink Noise source.
(Where do I get that from you ask?)
The hiss that you hear between FM radio channels works extremely well.
- and is somewhere between White & Pink noise.
(Note you my have to switch off the mute noise switch on your FM tuner)
Record a bit of this noise onto an iPoz, CD or tape.
Adjust the output level of your iPoz-CD-Tape player.
Then run this White Noise signal from the player & into the input of your Phaser.
Connect the output of the Phaser pedal to an amp, adjusted to a reasonable (not too loud) undistorted volume.
Then carefully adjust the trim pot to get the:
"Smoothest" swooshing sound.
Retest the Phaser with a signal from your guitar to confirm your setting.
Repeat the white noise then guitar signal setup if necessary.
Of course this is a quick & easy method for setting the trimmer.
It does not substitute for a signal generator & a Scope,
unless you don't have any other means of setting it up.
NOTES:
1 - Always mark the starting position of the trim pot before doing any adjustments.
2 - Use a KNOWN GOOD battery, or a fully regulated power supply when doing this procedure.
3 - For the quarenteed best results; Always try to take it to a Tech friend, or service guy/shop to have it setup correctly with a Scope & Signal generator.
4- If it ain't busted don't mess with it, it's surprising the false stories I read on the web, about adjusting these trimmer/s to get "Better Sound".
Regards Dr. Bob
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Edited by - Dr. Bob on 09/09/2009 14:42:13 |
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Plastic Stan
Copper Member
United Kingdom
14 Posts |
Posted - 09/09/2009 : 16:28:14
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Glad you got it sorted so easily. I also bought mine as a project nowing it was faulty but because it was so cheap compared to a working PH-1r I couldn't lose on it. I couldn't believe it was something so simple that was wrong with it. Took me a while to find out as I went through every part of the circuit before realising everything worked it was just the JFETs bias wasn't set.
I wonder how many of these pedals get discarded or sold as faulty but in reality just need the JFETs biased? Quite a few I imagine.
Do you think it's possible that as the components age the bias changes and needs reset? It was such a small range on the trimmer that actually gets the JFETs biased in the right place it must be a possibilty. |
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Boss PH-1 not working help needed
