XR600B IC4741cp

[corkyperez]

good day, i have a peavey xr600b, looking for replacement for ic on master diagram. any help would be appreciate it. Unit keeps clipping.

[52 Bill]

I believe that IC4741cp is a standard single op-amp, generically known as a 741. Where in the amp is this part located?

[corkyperez]

xr600b

Bill thanks for the reply, this ic is located at the master board with 4 more and a 4558

[52 Bill]

Are you sure the distortion is being generated in the master board?

[corkyperez]

xr600b

as of this moment im no longer sure. i have injected a signal through pa input I know power amp is good. im trying to trace the signal from preamp or mixer to determine the cause. I do not have a service manual, but im using a schematic. As soon as main is above four compression light stays lit.

[52 Bill]

I can't remember if you can bypass around the compressor on that model. Is there an fx or monitor output, that you can patch into the power amp in? At least that way you can see if the problem is in the compressor circuit.

[corkyperez]

xr600b

Bill, there is a mon out that can be patched thru pa in. I did performed this test with the main out through pa in, no compression problems found.I did find on the master board 3 chips 4741cp and 1 ecg859 repacing the onther 4741. If im not mistaking i think is 70404741, not sure if this 859 is equivalent or would substitude for this condition if in deed it has something to do with compression.

[52 Bill]

I'm not sure what the chip should be. Somewhere I have the Peavey cross-reference book that will list what it should be. I'll see if I can find it for you. Or later on today, when Enzo signs in, he can tell you exactly what to replace it with.

[corkyperez]

xr600b

Thanks Bill. I will continue troubleshooting the amp, checking for updates...Thanks again

[Twist]

The 70404741 can be replaced with a TL074 quad op amp. This is a 14 pin IC.

[Enzo]

Yep. Plain old vanilla TL074.

And from that era, it is probably in a socket already making the job even easier.

if it sounds OK plugging into the PA in jack, then the entire PA is OK. If all the channels come out the master sounding the same bad way, then chances are the channels are OK and the master is bad.

Geez, why would anyone waste their money buying ECG or NTE ICs for this? Mouser sells TL074 for 35 cents and the NTE version costs over $4.

[corkyperez]

xr600b

Thanks for the reply, I have connected thru pa and still clipping occurs. i have replaced ics on main output board and still same problem of compressor. Do you suggest starting from speaker output all the way in until hopefully I would come across a bad stage.? any help would be aprreciated...Thanks again.
as far as mouser and others, it just takes longer to get parts shipped to PR specially with PO Box adresses...

[Enzo]

Of plugging a signal into the POWER AMP IN jack still clips, then the power amp has the problem. What power amp module is the rear panel, I forget? 400B/G? 400BH? something else?

[corkyperez]

xr600b

Enzo, the power amp is 400b.

[Enzo]

So there are NO ICs on the power amp board?

Does the output clip symmetrically or just one polarity?