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Lets get Technical > All Things Tube All about preamp and power amp Tubes.

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Author Topic: HELP! Clean/Distortion channels reversed!  (Read 2013 times)

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rnolan

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Re: HELP! Clean/Distortion channels reversed!
« Reply #15 on: Time Format »

Hey George, thanks for the links  :thumb-up:
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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s

shredbaron

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Re: HELP! Clean/Distortion channels reversed!
« Reply #16 on: Time Format »

C30 is not a 33µF cap, it's only 100nF (small yellow cap)

Q5 is a 2SK364 N-channel FET (don't use anything else)


MJMP, thanks! I haven't had a chance to get back to it, but was thinking to myself "How the heck am I going to figure out what type of FET it is without pulling it?" - you just saved my bacon. Now to start putting together a big Mouser parts order :)

Quick question - in my other MP-1 I replaced most of the op-amps with OPA2604s if I remember correctly.

In this one, on the main board,  U4 is an OPA 2604, U9 is a LF412. Both socketed, so I must have done them in 2010.

U11 and U15 are socketed TL072s.  From recent reading it seems TL072s are inferior - should I replace them with OPA2604 (I have a few lying around) or would NE5532 be better? Just leave the LF412?
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MarshallJMP

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Re: HELP! Clean/Distortion channels reversed!
« Reply #17 on: Time Format »

Those 2SK364 Fet's are obsolete now and there are a lot of counterfits on ebay so be careful what you buy.You can also use the 2SK363.
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shredbaron

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Re: HELP! Clean/Distortion channels reversed!
« Reply #18 on: Time Format »

The chassis is fine.So could be C30 or Q5, or both.

Hey MJMP, sorry to bug you - been solderin' up a storm last couple of days when I've had some spare time.

Stupid me...the one cap I forgot to order was C30. 100nF.  Also need to order a few oddball 50v caps (33uF and 4.7uF) - I mistakenly counted a bunch out as 0.47uF

Question: if I replace C30 with a cap that has a higher value than 100nF would it still work in this application? I know more capacitance is fine for filter caps, but not sure what the cap is doing here leading into the diode. I did manage to get my hands on a new 264 diode (and kept the old one, just in case).

desperate to fire this up, but don't want to take a chance that is IS the bad cap, and then I have to replace another diode :)

I have an extra 10uF (10,000 nF) non-polarized electrolytic - could it work in that application?

« Last Edit: Time Format by shredbaron »
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