the Pimeta-V2 thread - Page 11

Maybe so, the more I think about it, the more I think it will be easier to use an unbalanced input into a balanced amp rather than the contrary.

Thanks,

Greg

I've been working the last couple of days on a Pimeta v2. I've gotten it mostly put together, successfully tested the power supply, and gone on to the buffers. I soldered pin 1 of the first buffer to its pad, and then gently nudged one of the other pins with my iron. The chip simply fell off the board, pad and all.

I think the work that I have put into the amp has instantly been trashed. These are the only components that absolutely have to be surface mounted, and with no pad, there is no way to attach it. Correct?

I am going to get a drink.

check the schematic... that pin is probably not used if it fell off that easily...  (Something similar happened to me on a Mini^3.)

Yes, thanks, I figured out what to do after I stopped freaking out about it and looked at the schematic. Pin 1 goes to V-, I will jerry rig that pin and hopefully it will work fine.

If I want 3 milliamps from biasing by using the stock values and don't want adjustability, do I solder RBLIM so that it "spans the switchable bias jumper pads" as shown in the step by step assembly guide, or do I solder it so that it spans all the way into the RBIAS slot too?

Your question is answered at the bottom of the parts selection guide section on RBLIM: http://tangentsoft.net/audio/pimeta2/pguide.html#RBLIM  There's even a picture.

Well I mean, that's what confuses me. So the assembly guide assumes that you'll be wanting to use an adjustable trim pot and the selection guide doesn't. I was just making sure is all.

Oh also, the schematic values for C3 says that it should be 470 uF but the part selection guide/list says and gives parts for .1uF. This also confuses me and I'm kind of wary of soldering any on since the values are so different.

I didn't want to bump the thread so edit: Thanks for fixing things! I appreciate the clarifications.

All fixed now.

Aw nuts!!  Just checked my DC offset. OG about 1mV; OR about 25mV; OL about..... 233mV!?*#%

Solder joints look good, nothing gets hot, everything else checks out. Using AD8066/8065. Battery

power (1 - 8.4V NiMH). Any ideas?

Oops! Just realized I don't have anything in C6G 'cuz I only ordered two cap's instead of three.

Maybe that' the problem with the ground channel.

Yes, C6 is most definitely not optional.

     Well, um, er, it appears that all I did wrong was install the L channel buffer BACKWARDS!!!!

     Jeez! Now I know why my name and the word 'smart' never appear in the same paragraph.

All is well. I replaced the L channel buffer, installed a 33pF C6G that I had and it's up and it's sounding great. Now I need to

order some 25V C2's as I'm measuring a little over 17V to the (16V) C2's I've got in there now when I connect

the 18V PS to charge the battery. The 25V cap's are 16mm tall, so I hope they'll fit.

Good to hear it.

A cheaper way to fix the C2 problem would be to put another diode or two inline with the power supply's V+ line.

Also, be sure you're measuring at the caps, not at the power inlet pads on the board.  The existing on-board diode OR bridge will buy you a half a volt or so already.

Yep, measured at the cap's; 17.1V. I'll try new C2's since I have to put in an order anyway. I'll report back if the 16mm tall cap's fit in the Serpac. Or should

I say, how I got them to fit. :)