Is your opamp fully seated?adam.schw said:
http://capi-gear.com/catalog/DOA_Install.php
[Build] CAPI LC25-LC40, 500 Series Rotary Graphic EQ's, Official Support Thread
- Thread starter jsteiger
- Start date
Help Support GroupDIY Audio Forum:
http://capi-gear.com/catalog/DOA_Install.php
Well, if its not the opamp it could be a bad/cold solder joint somewhere. If things were working fine and then stopped, that's usually the case.
jsteiger said:
I mean I had it on and working for probably 20 or so hours so it wasn’t just a brief thing. I’ll order up an op amp today and see if that doesn’t sort it out if not I guess I’ll have to start searching the board for other issues
Hey Jeff,
Ordered a new 2520 and 1731 to see if the op amp helped. My unit is now working, but the 1731 has a very considerable amount less of headroom (something like 8db) before noticeable saturation. Is the normal or do you think I botched something on the 1731? Either way, I'm happy that the unit is working again!
Ordered a new 2520 and 1731 to see if the op amp helped. My unit is now working, but the 1731 has a very considerable amount less of headroom (something like 8db) before noticeable saturation. Is the normal or do you think I botched something on the 1731? Either way, I'm happy that the unit is working again!
This is way not normal. There should be zero difference in headroom between properly built discrete opamps.adam.schw said:
jsteiger said:
Hi Jeff,
I resoldered all of the resistors and caps listed above, as well as each point on the 5k knob, and the problem still exists... i might get a dB or two boost or cut at 5k with the knob FULLY cranked. I’m wondering if I should replace the two caps GC15 and GC16? Thoughts?
Thanks again for your time!
Chris
Post a pic of that section of the PCB. I wanna check and see that the R's are placed correctly.Thekahn said:
Looks like you have GR14 and GR22 mixed up.Thekahn said:
staylor200
Member
- Joined
- Apr 17, 2012
- Messages
- 5
Hi. Just completed an LC25. At first power up, PR6 started to smoke, then the green active LED stopped working. Thanks in advance for any help!
Potato Cakes
Well-known member
staylor200 said:
Read through this thread. You'll find things to check like op amp, solder joints, etc. Did you build the op amp? Did you power it up with no op amps installed? Are all of the ICs oriented correctly? Do you have an extension jig to test voltages?
Thanks!
Paul
I've built a LC25 and it works, but is distorted and the peak light is on. I'll check for bridges and placement of parts.
edit: I pulled 2520 out and powered up, to see if it was maybe an opamp issue. no clip light, but r17/ 10r went up in flames!
I inspected gar 2520 and it looks like I misread the "do not bridge/ bridge these pins for support" I must be going colorblind. maybe these circles should be yellow and red, instead of maroon and red! I had bridged the input + pin to c1 on the 2520. I've removed the bridge and will look for another 10r resistor and try it again tomorrow.
edit: I pulled 2520 out and powered up, to see if it was maybe an opamp issue. no clip light, but r17/ 10r went up in flames!
I inspected gar 2520 and it looks like I misread the "do not bridge/ bridge these pins for support" I must be going colorblind. maybe these circles should be yellow and red, instead of maroon and red! I had bridged the input + pin to c1 on the 2520. I've removed the bridge and will look for another 10r resistor and try it again tomorrow.
Blackdawg said:Hey Jeff,
I am eyeing a pair of LC25 and LC40 and am curious about a modification.
Which resistors effect the gain of the grayhills? Would it be possible to modify them for smaller steps?
As in possibly these gain steps:
-9
-6
-3
-2
-1
-0.5
0
+0.5
+1
+2
+3
+6
+9
Could make for a cool mastering eq I think.
Normally this would be simple but looking at how you have the switches on the PCB it looks like they are actually sharing resistors? Is that true?
And if this is possible....can some custom faceplates be ordered?
Thanks Jeff!
Hello there. How is the mod going?
I would be interested in the mod also. The large gain step is the only thing that prevents me from ordering a pair of LC25.
Thanks,
Leon
Just finished an LC 40 & a 25.
25 = perfect.
40: 40hz & 2.5k are inactive. I re-flowed those parts of the pot board and main pcb today & just retested; still no dice.
I’m assuming the chips are fine as 80 & 5 work fine.
I’ll swap the pot board with the LC25 tomorrow and see if that works (my a keys are at work! Numpty!).
It also looks (in Q Clone) that 5, 10 & 20 are shelving, not bell curving which is weird, right?
Ian
25 = perfect.
40: 40hz & 2.5k are inactive. I re-flowed those parts of the pot board and main pcb today & just retested; still no dice.
I’m assuming the chips are fine as 80 & 5 work fine.
I’ll swap the pot board with the LC25 tomorrow and see if that works (my a keys are at work! Numpty!).
It also looks (in Q Clone) that 5, 10 & 20 are shelving, not bell curving which is weird, right?
Ian
One or 2 things at a time...first like you said swap the switch sub assembly and see about 40Hz and 2k5. If that doesn't do it, post a pica of the gyrator caps and R's for those sections. Its super easy to mix up some R's that are 10x different.IanB said:
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