[BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread

[woolie]

I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.

 

[Potato Cakes]

Hello,

I got home, swapped resistors, cut the leads down again. Both units working great. Love your work, Jeff.

Thanks!

Paul

 

[Potato Cakes]

I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.

Did you see the previous post with the edge connector pinout? Just connect the proper voltages to the correct pin then wire in a male and female XLR (in/out) also to the correct pins and then you should be great. Make sure you adjust your Powerstation to the correct voltages beforehand.

Thanks!

Paul

 

[drummingninja]

I have a pair of these working for the past year, but one has just started making a crackling sound. Unit still passes audio, EQ functions well, everything seems as normal but theres a crackling. Occasionally there will be a rather large peak, which looking at the waveform, they come in twos, one positive, one negative then just crackling for a minute then another pair of large peaks.

Ive taken the board apart, crackling is still present without the freq selection board, still present without op amps, I've reflowed most of the joints, still crackling no matter what. Any ideas?

 

[Potato Cakes]

Does it still do it when unsoldered from the CB board (JP3-1)?

Thanks!

Paul

 

[drummingninja]

Does it still do it when unsoldered from the CB board (JP3-1)?

I just unsoldered the CB board from the trafo/doa board and recorded the output of just the trafo/doa board for a while, no crackling, no random spikes. Very interesting, must be something in the CB board. Thank you so much for the suggestion, nice to narrow it down to a single board at least.

 

[drummingninja]

Connected the CB board only of the crackling unit to the doa/trafo board of my other fully functional unit and there is crackling. I can now completely confirm it is just the CB board causing the crackling.

Any ideas beyond solder joints that can cause crackling and random spikes? Still trying to learn the deep nature of troubleshooting audio circuits.

 

[Potato Cakes]

No worries. It's a little more of a pain to remove A1-4 on the CB PCB on the Rev A since they are not socketed, but my bets on one of those guys. If you could find out which order they are in from output to input and work that way you should be able to find it. Also, have you seen the voltage test points for that board?

http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/Rev_B/9_CAPI-LC53A-Rev-B-Test-Points.pdf

Thanks!

Paul

 

[woolie]

I was wondering if you have any guidance for building your little test rig with the JLM Powerstation? Seems very prudent/handy to have a rig to test devices.

Did you see the previous post with the edge connector pinout? Just connect the proper voltages to the correct pin then wire in a male and female XLR (in/out) also to the correct pins and then you should be great. Make sure you adjust your Powerstation to the correct voltages beforehand.

Thanks!

Paul

I found the pinouts you were referring to. TY. As to the 'correct voltage', any ideas where I could find those? Sorry for the n00b questions.

 

[Potato Cakes]

http://www.capi-gear.com/catalog/images/gallery/LC53A/Build-docs/Rev_B/9_CAPI-LC53A-Rev-B-Test-Points.pdf

All the information for all of Jeff's modules are listed at the bottom of the CAPI website under support docs.

Thanks!

Paul

 

[choolder]

Hi guys,

I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?

Thanks!

Peter

 

[jsteiger]

I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?

Peter, the following points are involved for the 1.5k freq. All are on the LC-EP PCB.
1. Grayhill SW3, the 3rd pin in from the end where the wiper pin is located, this is connected to:
2. Caps C16 and C17 in parallel, which then go to:
3. The .25H pin on inductor L3.

I would first look for a bad solder joint on one of these.

 

[choolder]

thanks!

Peter

 

[Blackdawg]

Is this Kit gone? Not on the site anymore  :'(

 

[jsteiger]

Is this Kit gone? Not on the site anymore  :'(

I am out of the metalwork and have not reordered. Not sure I will since the release of the BT50. They overlap as far as responsibilities and I think the BT50 is an better overall designed module, cleaner/easier build and sonically a tad more aggressive than the LC53A.

 

[Blackdawg]

I am out of the metalwork and have not reordered. Not sure I will since the release of the BT50. They overlap as far as responsibilities and I think the BT50 is an better overall designed module, cleaner/easier build and sonically a tad more aggressive than the LC53A.

Gottcha! Sorta figured they were the same(ish) but wasn't 100% sure.

BT50 it is 8)

 

[bleedingearaudio]

Tap tap tap...Is anyone still here?

I have an LC53A RevA that is not working.  audio is very low and distorted.  measuring +6V on inverting input of A1 (no DOA installed) and +15V on output of A3 only when A3 is installed.  when A3 is not installed, there is no voltage.  voltages measured with module in test jig and bench supply at+/-16.5V

I tried replacing A3 (DT05) but no change.  I can not see any other problems.  All caps are visually ok.  voltages measure correctly at all power pins. 

Thanks
Eric

 

[cryptokoan]

Hi guys,

I just build 2 LC53a's. One works perfect, the other has a problem with 1 frequency: 1,5k. If a boost/cut at that frequency nothing happens. Any starting points were to start looking?

Thanks!

Peter

I have the exact same issue, were you able to fix yours Peter? Re-soldered all the points Jeff mentioned, still not able to change the 1.5k range

 

[Mylithra]

Question about this Project.
A friend asked me to look at a LC53a that he bought off someone on Reverb that was having some issues.
Immediately, it wasnt passing any audio.
When I got the cover off this thing, the soldering was atrocious. Solder in little balls on the pad. Used way too much solder and didnt have good temp control. There was also residue all over all the boards.

1st step, pulled both DOAs, put it on a test jig and power it up.  Measure voltages at the DOA pads and voltages are where they should be.

Replaced both of the DOAs with known good DOAs and now it passes signal.

All the bands now work properly but neither of the HPF or LPF work.

2nd. redo all the horrid soldering. I used the Hakko 808 to desolder most of the pads and flow good solder into Them and I have it mostly cleaned up. While I was doing this, I was also making the leads a bit shorter coming off the back of the PCB.

There was this yellow fuzz looking stuff all around C14  and C12 was using a part that didnt look anything like C13. Further more. The pads on C12 are pretty shot. I'm guessing C12 exploded at some point. I can tell where the neg. pad went but I cant find the trace on the positive side pad. Does this pad indeed go to ground?

The 7.0H inductor is loose in the little plastic holder. None of the others seem loose. Should this be glued into its little holder with something like super glue? Is there a check I can do to make sure none of the leads between the inductor core and the pin got severed?

This one also seems to have more than unity gain. Im not sure how much yet but it was significant. I plan to revisit this once I had everything else addressed. Im still reading through the thread for everything to check but any quick wins would be appreciated.

Anything else I should look at on this thing while I got it apart looking for whats causing the HPF and LPFs to not function?

 

[Mylithra]

Just a quick follow up.

There was this yellow fuzz looking stuff all around C14  and C12 was using a part that didnt look anything like C13. Further more. The pads on C12 are pretty shot. I'm guessing C12 exploded at some point. I can tell where the neg. pad went but I cant find the trace on the positive side pad. Does this pad indeed go to ground?

C12 had indeed exploded and that was all the fuzzy stuff around. The part that was put in its place was a MUCH larger axial cap. I replaced it with an appropriate radial. The purpose of C12 and C13 is decoupling the power supply so the neg. lead of C12 goes to the -16, the positive lead goes to ground and Ive worked a very short re-route for the busted pad.

The 7.0H inductor is loose in the little plastic holder. None of the others seem loose. Should this be glued into its little holder with something like super glue? Is there a check I can do to make sure none of the leads between the inductor core and the pin got severed?

Using the silkscreening as a guide to what the taps on the inductor are, just tested resistance. All the resistance values varied on which tap I was measuring but they all measured something leading me to conclude the inductor is ok.

I had to replace one transistor that was crushed to crap by whoever built this thing.
I thought I had another J109 but I didnt and had to order from Mouser.

I think now that Ive cleaned up the assembly on this thing and redone most of the solder work, it will most likely work as it should, I just got to wait until I get the replacement transistor to verify.