gar1731 build thread

[Rybow]

Hi Insomniaclown

Glad you got one to work for you !  congrats !!

The cinemags with the gar1731s do sound very nice.
I got 2 built up with the same Iron setup on some DIY 312 cards.

SMOOOOOOOOOTH !!

I really like them with Ed's Iron in Jeff's VP312 as well. Maybe even
a wee bit better.  Its all good !!
Lots of really great little audio crayons to play with.

GARY

Thanks Gary! For this build, I took my time, checked everything twice, and used just enough solder to properly hold the component in place. Don't know if I could do it right without that assembly manual!

Smooth is right! This is one crayon that I am so happy to have in my set up. It makes my apogee ensemble pre's sound, well, lame. The next few days are going to be a lot of fun. I have another channel that will feature your 2520 with Ed's iron for yet another colour. Just gotta get it working  . Edit: Got it working! Now time to compare. 2520 vs 1731, Cinemag vs Ed Anderson. Fight to the death!

Well, down to the workshop!

Ryan

 

[Stagefright13]

Just build them MikeClev. I turned my soldering station on before the UPS guy even started his truck back up! No lie. I'm getting some of these next to mix it up a bit.

John

 

[rob61]

I built some gar2520s and have some red dots. How do the gar1731s compare to these sound wise?

 

[3nity]

Hi Gary.
I ve built 2 of your 1731 and everything works fine!
I only would like to know if they coul work as in a Jensen twin configuration, of course running at +/-15V.
output would be a CMOQ-2s.
Thanks.

 

[gar381]

Hi Gary.
I ve built 2 of your 1731 and everything works fine!
I only would like to know if they coul work as in a Jensen twin configuration, of course running at +/-15V.
output would be a CMOQ-2s.
Thanks.

Should be fine.  Never tried that setup but I don't see a problem.  Give it a shot.

GARY

 

[jsteiger]

Yeah, for sure just try it. Let us know what you think.

 

[3nity]

Im all upset here! just found out that 1 of the 1731 i built dont work!
Really weird since i built them exactly at the same time and one works but not the other.
i compared all resistors, transistors, caps and diodes they all match..

I did measured on the - In pin -2.45V though!!

Any ideas??

 

[zmgwg]

so i had one of the diodes backwards and R15 and R14 burned. I fixed the diode orientation put new R14 and R15 resistors ... and same things happened. 15 and 14 started to smoke
any idea?

 

[Seditionary]

how do the sound of these differ from the gar2520?

thanks !

 

[zayance]

how do the sound of these differ from the gar2520?

thanks !

Buy one of each, and test it out, they are cheap and easy to build with the build manual...
You'll anyway use one or the other somewhere else if one doesn't fit your taste in a given circuit.

 

[mappyo]

so i had one of the diodes backwards and R15 and R14 burned. I fixed the diode orientation put new R14 and R15 resistors ... and same things happened. 15 and 14 started to smoke
any idea?

I had this same problem, except that R12 and R13 burned also. I double checked all the components and everything seemed to be in the right place.

It turned out that the diodes were not in correctly. The cathodes were all facing the circles on the PCB as was directed. But when I looked closer I noticed that the anodes of the diodes were in the wrong spots. I replaced all the burnt resistors and moved the diodes to the correct position and everything works fine now.

I'm not sure if this will help or not seeing as how you have checked the diodes on your board, but I thought all my diodes were in the correct position (even after double checking them ) until I examined them really really closely and noticed the anodes were in the wrong spots.

Hope this helps.   

 

[Meathands]

To clarify, where the instructions say to check for shorts between certain pins, are we checking for shorts or continuity?

I'm reading about 1k resistance between -IN and Pin 3 of Q2 on both my amps.

 

[gar381]

To clarify, where the instructions say to check for shorts between certain pins, are we checking for shorts or continuity?

I'm reading about 1k resistance between -IN and Pin 3 of Q2 on both my amps.

Shorts.. 0 ohms  you are looking for unintended solder bridges as these points are very tight.

GARY

 

[JimiB]

I just built up my first 1731 - didnt work at first - checked it - not hot. Then I found it. I was gain testing lots of 550C's and I accidentally put a 550C instead of a 560C in Q3. I pulled it and put a 560C in. Works great sounds killer. - I crank it all the way up - turn the output attenuator down and sing loud with a 58 sounds awesome - then I see the smoke. Q3 looks a little melty and maybe Q4 as well. Any ideas what I might have done putting the 550 in there first?
It in a VP26 rev 8.1 in an API lunchbox.

 

[gar381]

try replacing the BC560s (Q3,Q4) then get your magnifing light out
and check for solder bridges, parts wires touching on the componet side
and cold joints.

Best..
GARY

 

[JimiB]

Replaced Q3 and Q4 and checked all the resistors that feed them - tested the ones I pulled out and they tested ok. Cant find any shorts - hmmmm

 

[JimiB]

Got hot and made some smoke again - Now I can see that R15 and R14 are starting to burn up -

 

[JimiB]

Ok I put all 4 Diodes in wrong - that's what I get for using black and white printouts

 

[Indecline]

So after building, oh, about 15 of gary's opamps i finally made one smoke 

It seems that the BD140 transistor gets really hot and begins to smoke after a couple minutes. Diode placement is correct and it passes the shorts check. Any ideas on what to check?

 

[gar381]

Hi Indecline

Sorry you are having problems

Look thru the 2520 build thread. There are
some good tips that also apply to the gar1731.

http://www.groupdiy.com/index.php?topic=33970.0

Generally speaking, use a magnifier light to check
for problems and compare to a known working one. 

Look for:

Solder bridges top and bottom

Component leads touching on the top

Are a BC550 and a BC560 swapped?

Are the diodes in the correct position?
(This is a very easy mistake to make. I got to
check myself to this day every time I build one of these
and I have built 100s)

Are Q7 and Q8 in the right spot and facing the correct way?

This covers about 99% of problems folks are having.

Best of luck and I hope you can get this guy working.

Best regurds..

GARY