struggling with opamps
« Reply #320 on: February 11, 2020, 01:42:20 PM »
Hi,

I assembled some of the 2520s for the CAPI VP28 kit, and I seem to have run into a snag.  I powered up the unit and fried the 10R resistors.  I don’t see any bridges and everything appears to have proper orientation.  Can poor pin connections cause this sort of reaction?


jsteiger

Re: struggling with opamps
« Reply #321 on: February 11, 2020, 01:48:29 PM »
Hi,

I assembled some of the 2520s for the CAPI VP28 kit, and I seem to have run into a snag.  I powered up the unit and fried the 10R resistors.  I don’t see any bridges and everything appears to have proper orientation.  Can poor pin connections cause this sort of reaction?
Yeah if they weren't fully seated.
https://capi-gear.com/catalog/DOA_Install.php
Visit the CAPI store at http://www.capi-gear.com

CAPI is not affiliated with, endorsed by, or sponsored by API.

Potato Cakes

Re: gar2520 build thread
« Reply #322 on: March 26, 2020, 01:22:46 AM »
Hello, Gary,

I'm building more of your 2520's and I was wondering how exact the value of R10 needed to be and I don't seem to have 806R resistors on hand. Would up to 2% be too much? Would it better to be to be higher or lower? I'd like to avoid making another order as I don't have a need for any other parts.

Thanks!

Paul

gar381

Re: gar2520 build thread
« Reply #323 on: March 26, 2020, 01:44:02 AM »
Hi Paul

As CLOSE  as you can come on the high side.

GARY
RETIRED.....  from 51yrs in Show Biz

gar2520, gar1731,garAM10,gar918 DOAs at  http://capi-gear.com/catalog/index.php?cPath=71_72
NEW Sphere section  http://gar381interests.com/gar381interests.html

Potato Cakes

Re: gar2520 build thread
« Reply #324 on: March 26, 2020, 03:33:37 AM »
Hi Paul

As CLOSE  as you can come on the high side.

GARY

Gotcha.

Well, it turns out I also don't have any 1000pF caps and I'm short some 5R6 1/2W, so an order will need be made anyway. Oh well.

On a completely random note you should know that for the 550 553 style EQ I installed for the bus channels of my TAC Scorpion I wound up liking the 2520's over the 1731s. They were both close to each other, but when boosting the HF there was a slight euphoric sensation that I was physically feeling in my ears, which sounds corny, goofy, and a myriad of other subjective, unhelpful adjectives, but that is the best way I can describe it. I don't know if it was attributed to a distortion characteristic, but I A/B'ed in real time and that minor physical interaction was definitely happening. The 1731 also sounded real nice, but since I mostly use these EQs to boost HF and MF, the characteristics the 2520 for this particular band won the decision. Just thought you might be interested to know. I am pretty much using the original schematic for this particular equalizer and inductors are from Jeff, which are fantastic.

Thanks!

Paul
« Last Edit: March 27, 2020, 06:54:21 PM by Potato Cakes »

Fuzz Face

Re: gar2520 build thread
« Reply #325 on: March 27, 2020, 08:48:14 AM »
I assume you mean 553 since that’s the one with inductors. Did you make a new PCB for those?

Potato Cakes

Re: gar2520 build thread
« Reply #326 on: March 27, 2020, 06:53:47 PM »
I assume you mean 553 since that’s the one with inductors. Did you make a new PCB for those?

Yes. Sorry. 553. Yes, I did. It is this:

https://groupdiy.com/index.php?topic=71753.msg911236#msg911236

Thanks!

Paul

Fuzz Face

Re: gar2520 build thread
« Reply #327 on: March 27, 2020, 08:04:25 PM »
That’s a really cool project, nice work! Sorry for the little sidetrack there

gar381

Re: gar2520 build thread
« Reply #328 on: March 28, 2020, 03:53:55 AM »
RETIRED.....  from 51yrs in Show Biz

gar2520, gar1731,garAM10,gar918 DOAs at  http://capi-gear.com/catalog/index.php?cPath=71_72
NEW Sphere section  http://gar381interests.com/gar381interests.html

 

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