ADA Depot - A Forum To Support Users of ADA Amplification Gear
Let's Get Technical => All PREAMP Tech Tips & Support => Topic started by: Rusty on October 09, 2015, 10:30:56 AM
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Hey MJMP, I seem to be clipping the LED light heavily with my ADA MP1/3TM that I recently installed.
It clips with the OD1 down at about 5.5 using my Strat that has the pickups DC resistance at about 6K ohms and it stays fully light nearly all the time with my guitar with passive humbuckers.
I have the newly installed trimmer pot on the main board turned fully anti clockwise. I think that it is a 50K pot that came with the kit, If I'm correct as my memory is going south. :P
Should I change it up to a 100k or more to get it within reason? what do you think maestro, sorry MJMP?
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No you need to go lower,but first check if the new trimpot is soldered correctly( makes good contact).Else try a 25k (or 22k).
Strange that this happends,did you have this before?Now this got nothing to do with the 3TM since the OD1 circuit is before the 3TM.
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No you need to go lower,but first check if the new trimpot is soldered correctly( makes good contact).Else try a 25k (or 22k).
Strange that this happends,did you have this before?Now this got nothing to do with the 3TM since the OD1 circuit is before the 3TM.
I see. OK I'll double check and re-do the soldering first. But I think it's ok, as when I turn it clockwise the LED never goes off and I cannot trim it at all with the OD1 tube set low on the front panel.
I really can't remember if it done it or not before as It was about a year ago that I used it. I knew it worked OK but I cannot remember if the OD1 led was coming on too early.
Thank you MJMP, much appreciated.
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Hey MJMP, Im thinking this OK, bear with me.
If I don't get any good results with the OD1 issue, can I send it over to you for a complete check up please?
The mains voltage here is very good at 240V and I have the MDRT installed too.
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Yeah sure but let's try to fix it here.I just saw all your gear so that must be possible.
Did you replace D16?
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Yip MJMP, I'll get it sorted here, I was out of action this past couple of weeks for other reasons.
Thank you.
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So did you check the thing i said?
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Yes MJMP, I checked the pot solder pads and re-flowed them and yes I changed D16 with the new one you supplied with the 3TM kit.
I am waiting on an order from Farnell element14 UK this week as I have ordered parts that includes the 25K and 22K trimmers for as you sugested for the 3TM. I have also ordered the components for the 3.666 mod that I will start when they arrive and other stuff for other projects and other unrelated repairs that I am doing at the moment on LCD screens.
Hopefully later in the week I will have the 3TM sorted then I'll start the 3.666 mod with the other MDRT and noise mod that I got from you.
Thanks MJMP, I'll keep you updated on the outcome's of both ADA's later on in the week.
Thank you.
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Go Rusty, the man with the hot soldering iron :thumb-up: , looking forward to hearing about the results my friend.
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Ok Rusty!!
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I'm just waiting on a new 500G roll of Multicore 60/40 solder as I have only about 2 feet left on my old 250G roll. I forgot about that one. :-[
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Hey Rusty, iron temp setting suggestions: IIRC MJMP uses/suggested (to me) 360C for soldering and 380C for desolder (but I'm sure it depends...))
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So did you check the thing i said?
OK MJMP here's what I did; I changed the OD1 trimmer pot to a 25K one and it improved the clipping very slightly but the LED was still clipping too much for me, so rather than de-soldering and messing around I parrelled R74 with another 20K resistor and effectively dropped that point another 10K ohms, that brought it into a better range for my guitars with humbuckers and single coils, for now, :)
Thanks MJMP, your help is so much appreciated and precious sir. :), :thumb-up: