Aaah...the learning experience.

[thearnicasync]

Hey everybody,

So, this is the funny part: My card wasn't connecting properly, so in the process of testing I torched it. How? By being an idiot, not finishing the new harness beyond covering the splice points with tape (to test) and then crossing two lines on the PS02. Fantastic. So, I sent it back to you Tim, and you found nothing wrong with it. Why? Because there WASN'T anything wrong with it. <b>Pin 1 on the connector (on the card) was very slightly bent, so it wasn't connecting. Literally, three seconds with the needlenose pliers and voila!</b>

So, I decided to rebuild the wiring harness, only I wasn't bright enough to notice that the voltages (as measured on the card) are in REVERSE to the connector on the power supply, when you measuring, so I did just a straight pin-to-pin harness and something blew on the A12. Not the N72, strangely enough.

In any case, I'm hoping to ask a couple of quick questions.

Basically, I'm getting normal voltages on the N72 (27.2,-27.2,48.5) and normal, fantastic N72 tone!

When putting the A12 into the mix (and disconnecting the n72), I get a strange positive voltage of like 2v and the others stay normal.

So, my crappy intuition says it's a problem somewhere in the diode cap - LM317 - diodes/resistors network that feeds the opamp. For the record, I'm also getting -18v on the op amp socket.

So, I've replace all the diodes in that network, the lm317 (actually easy to excavate from the board), and still weird votage. The other thing is that the lamp on the power supply dims when the a12 is connected, and I'm getting that weird voltage there, too.

Ultimately, if someone has ANY idea great, but I'm chalking this card up to learning, and I want to start over. I've learned bunches about these since I started, and I want a perfect card alongside my perfect n72. I'm just wondering, before I start a new kit, if this condition suggests any problems with the power supply. Again, I'm assuming it doesn't because all works perfectly with only the N72.

I've made so many mistakes, but I'm learning too: checking continuity, voltage measurements on the card's positive voltage regulation. I'm not getting any voltage on the 1500uf cap, but the diodes show continuity to it and seem to test out ok using the diode test funtion of the multimeter - that is if I understand the said test function. I am getting v in/out/adj on the negative regulator, and all components leading to it.

Really, from what I can figure, it should be the diode maybe?

I can't wait for another shot to do this right. And, even if this card is shot, I can still salvage the transfos and whatnot to build my own from scratch maybe...

Anyway, thanks if anyone can answer this: Does this sound like it could in anyway be a ps02 issue? I just want to make sure that if I build another card, it more than likely won't do the same thing.


Kellyb

[tele_player]

If my memory serves me correctly, the wiring harness on the PS02 is straight pin-to-pin. It's been a while since I built mine, but it works correctly with a mix of N72, A12 and J99.

[thearnicasync]

Interesting. Basically, I wired it backwards. Fixing it (fun) produced the proper voltages for the N72. This could have been the dumbest mistake yet!

kb

[tele_player]

I think you should revisit the wiring of your harness. You can wire it wrong, and still get an N72 to work correctly. For instance, you can run the N72 using the ground and -27 outputs from the power supply, but it's definitely not correct. (to do this, you'd connect -27 on the PS02 to GROUND on the N72, and GROUND on the PS02 to the +27 pin on the N72)

I'm about 99% certain (from memory) that the correct wiring of the harness with a PS02 involves no crossed wires. In other words, all pin 1's are connected, all pin 2's, etc...

Tim: is my memory correct on this?

[thearnicasync]

Wow. Here's my question: Do the pins (specifically the "windows" on the molex connector that allow for measurement) correspond, left to right, with the connector off of the power supply? If so, they'd have to be reversed because the connector (mobile, from the ps) turns 180 degrees before plugging into the card.

I think I'm making it way to complicated...I'll check my wiring again.

kelly

I think you should revisit the wiring of your harness. You can wire it wrong, and still get an N72 to work correctly. For instance, you can run the N72 using the ground and -27 outputs from the power supply, but it's definitely not correct. (to do this, you'd connect -27 on the PS02 to GROUND on the N72, and GROUND on the PS02 to the +27 pin on the N72)

I'm about 99% certain (from memory) that the correct wiring of the harness with a PS02 involves no crossed wires. In other words, all pin 1's are connected, all pin 2's, etc...

Tim: is my memory correct on this?

[thearnicasync]

Thanks, Tele...

Yes, it's wired one-to-one, correctly...now. The issue that I originally was not thinking to turn the connector upside down first, if that makes any sense. I still can't imagine why that voltage is weird, and if anyone wants to take a stab, great. If not, I'm gonna put in on hold 'til I learn more or until I salvage it for stuff. I must have the A12, though...man it sounded so good on electric guitar!

Thanks, and thanks to Tim for being so patient all along. And Tim, don't worry...if I get another kit, I will not haunt you or the board. I've been practicing a lot! I build my own little bipolar supply for a Craig Anderton project...the "clarifier".

Kelly

[tele_player]

Was the cable correctly wired? Did fixing it change any of the voltages you're measuring? If you didn't destroy too many pads on that board, it should be fixable.

[thearnicasync]

I'm all ears about what the problem could be, but I think it's a tough one. No matter what I replace in the positive volatage regulation circuit, it's still not getting voltage past the diode. And yes, the board is getting pretty thrashed. I'm a baby...I'd really like to have a beautiful, trustworhty card next to my n72. Then, I can salvage and maybe build my own sigle channel with the unused transformers, etc.

It's probably a silly plan, but I think it'll be fun and educational.

Thanks!

kelly

[tpryan]

The harness is wired 1:1 all the way. All the connectors should be oriented in the same direction, no reversing or swapping leads. It's not supposed to be hard.

If you're still having troubles with the A12, get it out of the chassis where you can get your DMM probes on it and make some measurements. Troubleshooting isn't about intuition, it's about clear, logical thinking. Get out your schematic and write down the voltages you measure at each of the power connector pins, protections diodes, filter capacitors, regulator terminals, and op-amp pins. Make your measurements without the op-amp connected, BTW. Let us know what you find.