JRC A2053G amplifier used in Behringer CX2310

[David Gatti]

Does anyone have information on this device?
It's a 14 pin SMD used for the active filters in the Behringer CX2310.

[Groundloops]

Hi David ! Just yesterday evening I tweaked my cx2310 - changed any of the JRC (NJM4580 dual and NJM2060 quad) opamps for OPA2134 and OPA4134, swapped elytic caps for Sanyo Oscon and Rubycon ZL plus bridged 0,1 uF Wima MKS4. Now I´m wondering of what you found instead of the NJM2060. Searching the JRC website (http://www.njr.co.jp) gave no result for the something like a2053G. Strange ...

Do you intend to tweak your 2310 too ? Maybe you can post a detail photo of the A2053G surrounding to compare it with the pcb layout of my cx2310. So you could get an idea of compatibilty.

Btw.: Changing the opamps gives a great result ! In a separate thread I´ll tell more about it.

Cheers, Gerd

[David Gatti]

Thanks Smelly. Actually I've decided t's too hard to customise the CX231 for my requirements (12dB/octave) and have now gone for a Marchand XM-1 design.

[DEQ+TheEnd]

Originally posted by SmellOfPoo
Btw.: Changing the opamps gives a great result

My CX2310 will arrive tomorrow. SmellOfPoo, do you have some general tip on how to mod this unit?
Why you selected opamps as you did?
Schematic perhaps?
What changes you did made the bigest sonic impact you think?
Will it make sense, or are it possible to use different opamps for hi and low part?

regars
HansR

[Groundloops]

Moin (as we say here) Hans,

no schematic, sorry. I selected the OPA2134 / OPA 4134 because I like their sound - very clear and analytic. And they are a perfect drop-in replacement for the JRC stuff, no changes of circuit needed. As I found it impossible for me getting the schematic by looking on the pcbs, I simply changed any opamp. The easiest way to pimp your cx2310 would be to bridge the output caps by simple wire joints, that´s what I finally did. My CX2310 gives no DC on outputs, so I think you can omit them. Next would be to change the other crappy caps, thatfore I used Rubycon ZL plus bridged 0,1 uF Wima MKS4 for the 100 and 47µF caps, (Panasonic FC are good too) and Sanyo OSCON for the 10µF ones. The psu got a pair of Pansonic FC and Sanyo OSCON. I think there is no need to change the opamps in the low pass sections, but I wasn´t able (or willing) to locate them.

The hard thing is to get the front panel pcb out of the u-shaped aluminum profile. First pull off all the knobs, then pull out the white plastic stripes fixing the pcb with slender pliers. The stripes are fixed with nasty tough glue, so you´ll need some force to do it. After that there you´ll find remains of glue holding the pcb on the profile. Bend the profile´s open side a bit to loosen it, meanwhile put a blade between the profile and pcb and cut the glue carefully. After loosening the glue, push the pcb backwards on potentiometer shafts.

The pcbs are double-layer with through-plated fixing holes, so it is a serious thing not to destroy the hole plating as it´s impossible to solder something from the component side. Excessive heating will destroy the hole plating easily. To avoid that don´t try to desolder the caps. Carefully bend the caps forward and backward until the pins break, don´t care that they are getting useless because they all are just worst crap only good for environmental pollution. Then you melt the solder joints from the solder side of pcb and suck out the pins and solder from the component side. You need a soldersucker to succeed, don´t try this with desoldering braid.

The opams are also glued on the pcbs, so just desoldering them will not work. Cut the pins being shure not to hurt the copper traces. After that, grip the opamps with pliers and wind them off, don´t (DON´T !) try to rip them as you possibly would rip off some copper traces.

Next step would be to solder the new opamps, do that before soldering the new caps as there is more space for your soldering iron. Unsolder the remains of cutoff opamp pins and prepare the new opamps: Put a small amount of solder on the contact side of any pin. (I found it is much easier to use lead-containing solder, the stuff I use is Sn60 Pb38 Cu2 on 380 °C). Then fix the opams with super glue taking care not to put some of it on the solder points. When the glue is cured, solder the opamps by just touching the pins with your solder tip. Take a magnifying glass and check, check and re-check the soldering joints.

Hope this will be helpful ...

Regards,

Gerd

[DEQ+TheEnd]

Hope this will be helpful ...

Yes yes yes.... I have to say big thank you. I would most likely have ruin my own pcb if you havent give these important notes on how to successfully remove parts.

While you was working your way through this mod, did you notice if the CX2310 has a balanced design all the way through? Or is it only input and output stages that is balanced?

Originally posted by SmellOfPoo
The easiest way to pimp your cx2310 would be to bridge the output caps by simple wire joints, that´s what I finally did. My CX2310 gives no DC on outputs, so I think you can omit them.

...the lid came off even before the power cable was connected

I believe attached image shows the output caps you are refering to ?

regards
HansR

[Groundloops]

Moin Hans !

Sorry for late reply, been too busy the last days ...

The coupling caps are the 47 µF elytics close to the output opamps. Those I simply bridged by a piece of wire.

I have no idea of the cx´s topology, so I can´t say if it´s symmetric all the way or not.

Have you found out something worth telling ?


Cheers, Gerd