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sweatyk
Copper Member
USA
21 Posts |
 Posted - 04/28/2009 : 05:39:24
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Well there is good news for my CH-1. It has been repaired!!!!!!
I had sent it to a friend and this was his comments:
"You know the voltage divider that biases the LFO - R42 and R47?
Well, the schem says that they are both 10k resistors, right? Turns out the schem wasn't revised, because R42 is now supposed to be an 8.2k resistor (centres up the LFO evenly from 2 volts up to 7, instead of with 2 x 10k which gives you 1.5 to 6.5).
When you took it apart to check all the parts, you solved the initial problem (bad caps) and introduced another, because you swapped those 2 resistors around, so it refused to oscillate. I constructed the LFO from the schem in the simulator, then spent ages "breaking connections" to see what I could make happen to get the pin voltages to read what I was observing, then I started taking components off the pedal, one by one and checking them for value and I got to the resistor in the R47 slot and found it was 8.2k, not 10k, plugged that value into the sim and Presto! The sim stopped oscillating and all the pin voltages were what I was seeing on the PCB.
Swapped them round and the sim worked again, so I swapped them on the board and now she's good again (tested it and everything works tickety-boo)."
Just wanted to let you guys know the outcome. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 04/28/2009 : 06:32:54
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| Holy cow! What an ordeal! Congratulations the fix! (and for having such a good friend!) |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/28/2009 : 14:53:35
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Hi sweatyk
Thanks for the log awaited reply-fix.
Such a simple problem in the end.
Two accidentally swapped resistors.
But most importantly, another working Boss Pedal.
Regards Dr. Bob  |
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sweatyk
Copper Member
USA
21 Posts |
Posted - 04/29/2009 : 01:03:54
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| To clear up on one of his comments, I never swapped any resistors. I lifted one leg out of the PCB to eliminate such mistakes. That was how it came from the factory. They were factory solder connections on those......go figure. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/29/2009 : 13:21:36
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quote:
Originally posted by sweatyk
To clear up on one of his comments, I never swapped any resistors. I lifted one leg out of the PCB to eliminate such mistakes. That was how it came from the factory. They were factory solder connections on those......go figure.
Hi sweatyk
Understood.
What a bummer, another faulty Boss pedal from the factory.
I guess a forum like this brings out both the best & the worst of the product.
I'm glad that it is working now, send my well done,
to your Tech friend, for being do diligent.
You might want to suggest he joins our forum, we always need more Techs.
Regards Dr. Bob
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Edited by - Dr. Bob on 04/29/2009 13:22:53 |
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sweatyk
Copper Member
USA
21 Posts |
Posted - 04/29/2009 : 14:59:08
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Thanks Dr. Bob. My techie friend happens to be a member of the guitarist.net forum. That is where I hooked up with him. I live in the US and he lives in the UK. If you have never heard of Guitarist.net it is a great place with good people just like this forum is. I actually posted this problem there originally and was referred to this forum by one of their members being it was BOSS specific. As with this site it has a lot of good info and everyone is very friendly and helpful. I have personally gained great knowledge from both sites. The user name of the genteman that assisted my is known as R O Tiree on guitarist.net.
Thanks again to all. |
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sweatyk
Copper Member
USA
21 Posts |
Posted - 05/05/2009 : 02:45:24
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| Just received my CH-1 today via snail mail. It works great!!!!!! I'm a very happy camper. And for those who might be curious if you did not already know of such. My techie friend troubleshot the circuit with a simulator called LT Spice. It's a pretty cool program for a freebie. There are better ones but you would have to purchase them. You can change the circuit to see how it will react. Good stuff to know...... |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/05/2009 : 11:57:12
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Hi sweatyk
That's great news.
I bet you're glad to have it back & working properly.
Regards Dr. Bob
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Topic |
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Need help with a ch-1
