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MervsMods
Bronze Member
USA
133 Posts |
 Posted - 11/08/2009 : 00:20:54
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Hi guys,
I have a couple of Boss pedals that have the same issue. Both work FINE on battery power, but when I plug in my PSA adapter, the led dimly flashes, and then NOTHING (together or individually). Signal passes, but no effect when engaged. Any ideas? Pedals in question are MT-2 and SD-1
Thanks!
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 11/08/2009 : 00:51:38
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Hi MervsMods and welcome!
That is very strange... When you say "dimly flashes", can you explain that? Does the LED sit there actually flashing?
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MervsMods
Bronze Member
USA
133 Posts |
Posted - 11/08/2009 : 01:58:23
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| Nope it flashes once. then nothing |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 11/08/2009 : 05:01:51
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Hi MervsMods
Welcome to the forum from Australia.
Have the pedals been modified in any way?
I noticed you call yourself MervsMods, is that just a screen name,
of do you do some mods for friends now & then?
Regards Dr. Bob  |
Edited by - Dr. Bob on 11/08/2009 05:07:06 |
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MervsMods
Bronze Member
USA
133 Posts |
Posted - 11/08/2009 : 05:06:01
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Hello Doctor!
Yes on all accounts.... These pedals have been modded by me. That's what I do. I'm the mod guy for Monte Allums here in the US. What's so strange is that I've done these mods before on other pedals without issue. These pedals were pawn shop specials that I picked up to mod for myself, because when I tested my customers, they sounded SO GOOD... It's possible they were like this before my screwdriver touched them. I tested them in the store (un-modded) using a battery only. I just assumed....
Merv |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 11/08/2009 : 05:16:55
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Hi MervsMods
Any chance you might upload some pics?
Check that the switch inside the DC input socket is working.
I guess it might be as you said they work on batteries.
We are assuming you meant that they work 100% correctly & with effect,
when you run them off batteries.
Also check your DC supply - it might not be working correctly - or supplying enough current.
Have you tried a different & known good supply?
I guess being Monte Allums mod guy, you have the schematics for both pedals.
What else have you been able to deduce while tying to analyze these faults.
Regards Dr. Bob
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Edited by - Dr. Bob on 11/08/2009 05:17:58 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 11/08/2009 : 05:38:26
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There really isn't anything different about the circuit for the external power - it just breaks the battery connection with the power jack switch and feeds external power straight in where the battery +9V used to feed. If it works on battery, it almost has to work on external power - there is actually one less component in the circuit! (the DC jack switch)
The only things it can be are dirty contacts in the jack - squirt the jack with contact cleaner to fix that (or replace it), or as Dr.Bob said, the power adapter itself is dead. Does the adapter work on other Boss pedals?
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MervsMods
Bronze Member
USA
133 Posts |
Posted - 11/08/2009 : 06:26:18
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Hi Guys and thanks for your posts!
What I've done...
1. I have a good power external power supply.
2. Replaced the DC in jacks on with known good ones.
3. Made sure the pedal(s) work on battery supply.
4. Checked all components in the PSU circuit.
5. Haven't checked the traces yet. (that's all that's left) Didn't think about it until just a minute ago.. Will let you know.
If you have any more great ideas, please let me know!
Thanks for your HELP so far!
Merv
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 11/08/2009 : 09:09:37
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Just had a thought... is the battery getting hot? Better still, break one of the battery connections and measure the current. If there is something in the pedal putting a huge load on the power supply, the effect you would see is a quick flash then dimming of the LED as the supply current rating of the adapter is exceeded. The battery might be able to keep up (at least for a few minutes).
Another thought... if your adapter is switched mode, some switched mode supplies will not regulate unless there is a minimum load on the supply. The MT-2 and SD-1 are both pretty low current pedals... If you have been using the adapter on something else that draws a lot more current you might not have seen this behaviour before. One way to test this is to daisy-chain the pedal you know the adapter works on with the MT-2 and try it?
Just thinking out loud...
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Edited by - Laurie on 11/08/2009 09:10:06 |
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MervsMods
Bronze Member
USA
133 Posts |
Posted - 11/11/2009 : 22:14:34
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Found the issue in the SD-1. Would you believe that a bad resistor (going to short) caused it not to function under adapter power? It was the resistor going to the LED. It's strange though that it worked FINE under battery power. Will check the MT-2 later today..
THANKS GUYS! While you didn't know off the top of your head, you pointed me in the right direction. |
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Topic |
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Power Issues
