gar2520 build thread

[gar381]

fragletrollet...

Very Nice CLEAN Job!!

Congrats

GARY

 

[fragletrollet]

Thank you Gary, considering I`m just starting I feel a little proud 

I was most concerned about shorting the pads closest to the millmax pins to the millmax sockets. In retrospect, after looking more at the photos, it looks like it wouldn`t have mattered anyways, as they are traced anywways?

 

[smokinpcb]

So I recently built 6 gar2520's for a pair of fc526's, and 5 worked out great. After realizing I'd put the BD transistors in the wrong spots, I decided to replace all the caps/ transistors/diodes to be safe. I didnt replace the resistors as they all tested fine.
After A/Bing the new op amp to the others I've noticed the rebuilt op amp sounds like it has a HPF.
The compressors definitely aren't an issue as they work great with good opamps.
Any Ideas on what could be causing this?

 

[pidah]

Dear people,
I've built around 12 x 2520 and 6 x1731. They all work, verified in VP25,VP26,AnalogAllstars,and TB550a projects.

I also happen to have an Api2500 stereo compressor that lost one 2520 opamp. Well,you know..
I made sure I could fit the "short legged"  gar2520 in (bij moving/resoldering a cap that is in the way,under the opamp) So far so good,verified with the one still working APi2520 opamp.

I inserted a Gar2520,switched on and was greeted by massive noise. Not good.  Tried another one,same result. Tried a third,same noise. Note that all these opamps were tested,and working. Trying them in a vp25 again, which verified that they still  work properly.

I then put in a Gar2520 whilst the machine was on.Yes I should'nt have done that.. But it worked,and sounded fine. Weird..? I then switched off the compressor, switched it on again,and again the loud noise was there. It was even audible when I switched to bypass (2500 uses relais for that),so it must be quite spikey... Trying that opamp in a vp25 again verified that it is still in a good shape.

Has anyone encountered such a problem in the 2500 compressor? Is there a solution?

Thank you,
Pieter

 

[bugbrand]

Can anyone (Gary/Gar381) tell me what surface finish is used for the two DOA PCBs available from Jeff @ ClassicAPI, please?

As they're not gold plated, it is unclear whether they'll be leaded or lead-free HASL (or something else?).

Thanks!
Tom

 

[gar381]

Tom..

HASL -Hot Air Solder Leveling

GARY

 

[bugbrand]

OK - cheers - leaded solder it is then...
(slight sigh..)

[these days, it is as cheap to get RoHS boards as non-RoHS. Lead-free boards can be used fine with leaded solder, but not vice-versa, so I would suggest producers moving to RoHS - would not in anyway stop builders who like the lead still sticking with their old ways]

 

[gar381]

Kester 44      63/37 recommended. 

GARY

 

[Golgoth]

Hello everyone!

Is there a way to test 2520's & 1731's without pluging them in a module? With a DMM for exemple?

Thank you,
G

 

[gar381]

Hello everyone!

Is there a way to test 2520's & 1731's without pluging them in a module? With a DMM for exemple?

Thank you,
G

Without some sort of test jig,  plugging them into a working module is the best way.

GARY

 

[mikeb]

Hi, noob on building DOAs - have built a number of SCA pres, guitar amps, etc., and decided to try the gar2520.  When I power up, Q8 gets very hot quickly.  I've checked that Q7 and Q8 are in the proper locations and correctly positioned, and have been through looking for solder bridges / shorts between leads.  I know I did something wrong, would appreciate any advice on where to look.  thanks much!

BTW, have tried at +/- 16 and 15 volts, no higher.

 

[buckethead]

Hey guys!

I'm working on some gar2520s and I ordered quite a few BD139-6 instead of BD139-16 by mistake - too much work right now. Do you guys think using 139-6s is negligible in this circuit?

Thanks in advance and best regards,
Mathias

 

[gar381]

Hi Mathias

The only difference is hFE.  I have used BD139-10 in the early days
of this DOA and could not hear any difference.  hFE on these outputs
is not that critical.  I never tried the -6 version.  I would use -16 guys
if you can get them but try the -6 in one and See what it sounds like.
You might be OK.

Best

GARY

 

[buckethead]

Hi Gary!

Thanks for your help!

I tried one with a -6 version and this one seems to distort a little bit earlier when pushed harder than the ones with the -16s (tested in VP26s). I guess the question should have been more like "is it ok to mix BD140-16 with BD139-6, or will I face serious problems with asymmetry in the output stage?"

Best regards,
Mathias

 

[gar381]

Hi Mathias

Sounds like you might be happier  using the -16 guys.

Best

GARY

 

[buckethead]

Hi Gary!

Alright, I'll get some -16. Thanks for the quick help!

Best regards,
Mathias

 

[JessJackson]

Does anyone know if you can use 1n4149's in this instead of 4148's.

I've built 28 for a mixer and I soldered in the wrong ones already. Spec sheets seem to look more or less the same.

Cheers

 

[gar381]

Hi Jess

Never tried the 1n4149 but it looks like it should work.  Fire one up
and see how it sounds.

GARY

 

[JessJackson]

Hi Jess

Never tried the 1n4149 but it looks like it should work.  Fire one up
and see how it sounds.

GARY

ok cheers gary, its a while before the mixer is complete though.

i read on another forum that 1n4148 is 20pf and 1n4149 is 10pf if that sheds more light?

 

[Tommy T]

I built my first gar2520 and it did not work. So I built 2 more and these are not working either. I dont even know where to begin to try and trouble shoot . I have a magnifing Lamp and can see pretty well that there are no shorts/Bridges. all that I can think of is maybe I got a component to hot ? I have been soldering for years, not on things quite so small but it didn't seem like I got anything to hot. Anyway any suggestions on where to begin on trouble shooting would be helpful.

Thanks much,
Thomas Thew