No Phantom Power, weird Trim?

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No Phantom Power, weird Trim?

Postby masterpony » Sun Nov 16, 2014 6:29 pm

Unit is running fine with dynamic mics, just not getting phantom power. Jumpers installed correctly. Getting 45v at D4, R45, R50, R48 and pin 2 & 3 of SW2 when switched on. With neg lead on pin 2 @ J1 i get; 45v at Q7 E, B and C. At Q8 I get 45v at just E and B. I get 45v at R46 and 47. No voltage at CONN 1 at leads or sockets. I've reflowed many times, transistors are in right and place/way. I'm getting resistance of (3.3) on R46 and R47 while installed. With diode test on my meter I get a reading both ways for Q7 BE (.6 and 1.2), both ways BC, both ways CE. And for Q8, readings both ways for BE, one way for BC (.6), and one way for CE (.8)

Also, is the Trim pot suppose to act like a master volume regardless of where the gain is? No matter what step my gain is at, the Trim can reduce the volume completely. Does this have to do with the 4 blue filter caps i installed? Thanks, Sounds great!
masterpony
 
Posts: 2
Joined: Sun Nov 16, 2014 6:08 pm

Re: No Phantom Power, weird Trim?

Postby masterpony » Fri Nov 21, 2014 5:36 pm

Ok got this solved. I was reading all good voltages up to CONN1 pin, so I was starting to think CONN1 was faulty. Not so. I installed a Jumper on pin 2 and 3 of CONN3 on the new board accidentally. I guess I just got previous instructions mixed up with the new board. Step 51, I read it wrong. It just doesn't apply to the new board. J3 and J4 don't exist, so no need for a jumper. Its clearly labelled CONN3 I just assumed it was a jumper connection, and I should jumper pins 2 and 3. My bad. Removed my faulty jumper connection and it worked.
Also, if you don't install the 4 blue caps that come with the new version, your unit will not pass signal. I thought it was an option, it's not. Only by digging through the forums did I find this info out!! That kinda bums me out. I spent big dollars on this stuff and I understand that I'm expected to be able to read a schematic (to know these are needed to complete the circuit) but I don't like installing "extras" when they are not in the instructions, and I know I'm not alone in my thinking. Please update the photos or at least specify if there are new parts in the instructions. I quote from the first paragraph of Assembly Instructions; "The patience to follow instructions precisely ..."....well I can't follow what's not there.

The trim is normal operation, obviously different from other units like the A12, but again, without digging through the forums, I wasn't informed of this, leading me to believe I may have done something wrong. Worth every penny, and I'm pleased with the product.
masterpony
 
Posts: 2
Joined: Sun Nov 16, 2014 6:08 pm


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