OP
fitz
Ambassador of DIY
Isopropyl alcohol could be your friend.
Just looks nice, or do you think it's part of the problem?Say NO to flux poop…
NAD - 50w JMP clone
- Thread starter fitz
- Start date
syscokid
Ambassador of War & Peace
The poop is conductive too. So, only if it’s bridging to another solder pad. Maybe it’s best to be clean and safe.
It will look nicer and remove one source of a possible issue. I use a squirter bottle and a small 3/8” wide brush to brush the goop off.
OP
fitz
Ambassador of DIY
All good advice and much appreciated.
There would be no hesitation if it was something that I had assembled from a bag of parts like my Ceriatone buffered loop kit.
But if this flux issue is part of the problem, I'm going to leave it as-is until I hear back from Mojotone.
I sent a message through their website with a brief description of current events.
If they want it returned, I don't want to start trying to fix it.
No hurry.
IIRC, there's another amp or two laying around somewhere if I need one...
OP
fitz
Ambassador of DIY
Got a reply email from Mojotone and sent them the pics of the loop installed, along with close up of the discolored 10k resistor.
They had asked about where I was connecting the B+ for the power supply.
Waiting to hear what they say.
Brought the amp upstairs and tried it out on the Alnico cabs.
Definitely something wrong going on with the inputs.
Low input is too quiet, and the MV seems to do very little.
Signal comes through with the MV on zero, and doesn't get much louder as the MV is turned up.
High input goes from off to super loud at 1 on the MV.
It's going back down to the bench and I'm going to disconnect and rewire both inputs and the pre-amp vol pot.
I had visually verified the values on all the associated input resistors and caps, but If I disconnect everything, I can run the individual components through my little magic tester gizmo to check if they are actually what they should be.
Probably wouldn't hurt to do another once over on the rest of the amp while I'm at it.
They had asked about where I was connecting the B+ for the power supply.
Waiting to hear what they say.
Brought the amp upstairs and tried it out on the Alnico cabs.
Definitely something wrong going on with the inputs.
Low input is too quiet, and the MV seems to do very little.
Signal comes through with the MV on zero, and doesn't get much louder as the MV is turned up.
High input goes from off to super loud at 1 on the MV.
It's going back down to the bench and I'm going to disconnect and rewire both inputs and the pre-amp vol pot.
I had visually verified the values on all the associated input resistors and caps, but If I disconnect everything, I can run the individual components through my little magic tester gizmo to check if they are actually what they should be.
Probably wouldn't hurt to do another once over on the rest of the amp while I'm at it.
OP
fitz
Ambassador of DIY
Mojotone sent a $0.00 sales order confirmation, but they haven't shipped the new loop yet.
Took apart the input jacks last night to see if I could track down the odd volume difference.
I separated all the components so I could get good readings on them.
The 3 resistors readings were all in spec, but the 1000pF cap measured about 725, and the 500pF cap read about 260.
Going to be waiting on the replacement loop, so I ordered new caps and a pair of new jacks from Amplified Parts.
Took apart the input jacks last night to see if I could track down the odd volume difference.
I separated all the components so I could get good readings on them.
The 3 resistors readings were all in spec, but the 1000pF cap measured about 725, and the 500pF cap read about 260.
Going to be waiting on the replacement loop, so I ordered new caps and a pair of new jacks from Amplified Parts.
OP
fitz
Ambassador of DIY
Replacement loop installed the same way I originally did the 1st one.
Slight voltage drop at the B+ connection as described in the instructions.
Voltages across the rest of the board all within expectations.
Put a patch cable in the loop and the set the loop on & bypass volumes to equity.
Everything seemed to be working fine going straight in, so I hooked up the ME-90 in 4CM.
Atswhadimtahkinabaht!
Loop is working great - no clue what was wrong with the 1st one, but still got it for possible future diagnosis.
Now I just gotta find this little monster a place to live.
Slight voltage drop at the B+ connection as described in the instructions.
Voltages across the rest of the board all within expectations.
Put a patch cable in the loop and the set the loop on & bypass volumes to equity.
Everything seemed to be working fine going straight in, so I hooked up the ME-90 in 4CM.
Atswhadimtahkinabaht!
Loop is working great - no clue what was wrong with the 1st one, but still got it for possible future diagnosis.
Now I just gotta find this little monster a place to live.
syscokid
Ambassador of War & Peace
I’m assuming the most sensitive component on that loop board is the pair of LND-150 MOSFET’s. About $1 to $2 each. Replace that toasted 10K 2W resistor too, even though it tested at 10K. If it still doesn’t work after all that, then shoot it!