[Build] CAPI LC25-LC40, 500 Series Rotary Graphic EQ's, Official Support Thread

[jchudyk]

Hey Jeff!

Any known issue of compatibility with older API consoles of lunchboxes?

My LC25 works great in newer API boxes but in some older boxes, like the custom API console I have (the one I sent you a picture of) the LC25 does not pass audio when active. It bypasses audio just fine.

Any thoughts? Might have to do with the relay?

The build is done as it should be, just wondering if there is something I can do to have it work in that console. Bypass the bypass?

 

[jsteiger]

Hey Jeff!

Any known issue of compatibility with older API consoles of lunchboxes?

My LC25 works great in newer API boxes but in some older boxes, like the custom API console I have (the one I sent you a picture of) the LC25 does not pass audio when active. It bypasses audio just fine.

Any thoughts? Might have to do with the relay?

The build is done as it should be, just wondering if there is something I can do to have it work in that console. Bypass the bypass?

Hey Joe, sounds to me like that console is not 500 series compatible. All of my VPR style modules will work properly in any true VPR style rack. I would further investigate the pinouts on that thing.

 

[jchudyk]

Thanks Jeff,

All my other modules work great in it, including the BT50s and FC526s. The LC25 also seems to have an issue in the old 10 slot API rack, the one with the optional 48v.

Audio comes in to the edge connector on pins 8+10 then pins 2+4 go to the API fader and those return to the bus cards.

Pins 12,13 ,14 get power correctly.

 

[jsteiger]

Thanks Jeff,

All my other modules work great in it, including the BT50s and FC526s. The LC25 also seems to have an issue in the old 10 slot API rack, the one with the optional 48v.

Audio comes in to the edge connector on pins 8+10 then pins 2+4 go to the API fader and those return to the bus cards.

Pins 12,13 ,14 get power correctly.

Make sure the DC-link shunt jumper is set to "N". There is no gold finger for the 48V pin on the card edge. There is really nothing different about this card compared to the others you have.

 

[mdmitch2]

I built one of the LC25s and  tried it on a horribly recorded kick, which I had previously sample replaced. Within 20 seconds, I had a great sounding track... pretty unbelievable.

Also I thought the 25hz band might only be useful for cutting, but was surprised to find that it's  very useful for boosting, and adding some major heft.

 

[Potato Cakes]

Does anyone know what the signal level is needed to activate the peak light? I tried pounding it with signal till my converters clipped and it still doesn't light up. I jumped the - side of the LED to ground and it lights up, so I know it's working. I know it probably has more headroom than my converters, I was just trying to find a way to check to see if it was working properly.

Everything else works properly right out of the gate.


Thanks!

Paul

 

[jsteiger]

Does anyone know what the signal level is needed to activate the peak light? I tried pounding it with signal till my converters clipped and it still doesn't light up. I jumped the - side of the LED to ground and it lights up, so I know it's working. I know it probably has more headroom than my converters, I was just trying to find a way to check to see if it was working properly.

Everything else works properly right out of the gate.


Thanks!

Paul

It should fire off at around +28dBu. Try sending it a high level and cranking a few EQ bands.

 

[Potato Cakes]

I did try cranking some of the bands. I think +28 is quite a bit more than what I can output. I'm not going to worry about it. If I ever need it that hot I'm doing something wrong.

As always,  excellent work!

Thanks!


Paul

 

[AndyKolp]

First time poster, 3rd piece of CAPI gear (2-vVP28's - awesome) I just finished my first LC40 EQ. As far as the Grayhill switches go, if I happen to install 5 of them backwards (which I did) such that the stop pin is at the 6 o'clock position, would that cause the eq not to function properly?  When I turn switch from bypass to on, and all rotary switches at 0 position, the db level drops slightly and bottom 4 knobs only change the sound when turned one click counter-clockwise. The 11 o'clock position causes an INCREASE in db for those bands. I think I really hosed this up. My plan is to use the desoldering vacuum at work and try to salvage the switches so I can install them correctly.  I was just wondering if the lack of function is due to incorrect installation of the rotary switches, or if I need to look at other things as well.

Also, I may have exposed Q3 and Q5 on the DTO5 to too much heat as I swapped them accidentally and needed to solder wick them out. Not sure if this could also be the problem. Good times..

Thanks for any help

 

[jsteiger]

Yeah those switches need to be seated correctly or their 0 position will be somewhere other than 0 on the panel. If you have the knob pointing to 0 then you will have some boost or cut happening at those positions.

 

[duantro]

Finished an lc25 and it sounds great. The switches don’t turn smoothly though. I used a spacer to get the knobs off of the nuts, but some positions don’t have a clean “click” feel. Almost feels like the knob is spinning, but it’s not. Any thoughts?

 

[jsteiger]

Finished an lc25 and it sounds great. The switches don’t turn smoothly though. I used a spacer to get the knobs off of the nuts, but some positions don’t have a clean “click” feel. Almost feels like the knob is spinning, but it’s not. Any thoughts?

Hmm, not sure I am familiar with this although I do recall someone early on who didn't have the switches properly seated when soldering. Once he tightened them down thru the bracket and faceplate it must have but a strain on the innards and some did not turn smooth. Not sure what else it could be.

 

[Studio Mollan]

Hi,
I've kust built a pair of LC25s and im having trouble with one of them. When engaged with all switches in "0" position im getting about 6db level boost.  Its flat, a +6db copy of the bypass signal. the bands work as they should however the 100Hz band is acting as a HI pass from -6 to -15 and something similar in the 6200hz band.
Ive tested different DOAs, all confirmed working in other gear. Ive confirmed that the slot in my 500 rack is wired, and working, properly. Ive reheated all solder joints on the entire pcb, including the Switch PCB. Cant find anything wrong by looking at the pcb. All components are seated and they match the working unit.
could it be a bad rotary switch?

 

[jsteiger]

Hi,
I've kust built a pair of LC25s and im having trouble with one of them. When engaged with all switches in "0" position im getting about 6db level boost.  Its flat, a +6db copy of the bypass signal. the bands work as they should however the 100Hz band is acting as a HI pass from -6 to -15 and something similar in the 6200hz band.
Ive tested different DOAs, all confirmed working in other gear. Ive confirmed that the slot in my 500 rack is wired, and working, properly. Ive reheated all solder joints on the entire pcb, including the Switch PCB. Cant find anything wrong by looking at the pcb. All components are seated and they match the working unit.
could it be a bad rotary switch?

I doubt its a bad switch. My guess is an error in the vertical resistor placement on the switch PCB. It would be a pain to test with all of the knobs but you could swap the switch PCB assembly between the units and see if the problem follows or stays. That will help narrow things down. Also, make 100% sure that no R's are too tall and making contact with the back of the L-bracket.

 

[Studio Mollan]

I doubt its a bad switch. My guess is an error in the vertical resistor placement on the switch PCB. It would be a pain to test with all of the knobs but you could swap the switch PCB assembly between the units and see if the problem follows or stays. That will help narrow things down. Also, make 100% sure that no R's are too tall and making contact with the back of the L-bracket.

Found the problem. A broken trace between R15-R16. Worksfine now. Thanks!

 

[myers1st]

Hi all-

I've just finished an LC25 and have the 'pass audio but no EQ' problem.  I do tidy builds and all solder joints are double-checked and  good.  I've also checked:

- 1731 op amp is good, works fine in my VP28.
- Transformers are good
- Chip placement and orientation is correct (I socketed them).
- Diode polarity is correct
- 90 degree pin headers and sockets to the switch PCB have clean joints and are seated well
- DC link shunt is in place "N"

Seems like it could be a relay?  I retouched all the pins to be safe but still nothing.  Ideas of where to look?

Thanks.

 

[jsteiger]

Hi all-

I've just finished an LC25 and have the 'pass audio but no EQ' problem.  I do tidy builds and all solder joints are double-checked and  good.  I've also checked:

- 1731 op amp is good, works fine in my VP28.
- Transformers are good
- Chip placement and orientation is correct (I socketed them).
- Diode polarity is correct
- 90 degree pin headers and sockets to the switch PCB have clean joints and are seated well
- DC link shunt is in place "N"

Seems like it could be a relay?  I retouched all the pins to be safe but still nothing.  Ideas of where to look?

Thanks.

You can check continuity between the rack's input and output XLRs. There should be basically a direct connection via the relays when the unit is bypassed and no DCR continuity when active. Check both pins 2 to 2 and 3 to 3. That should give an indication if the relay bypass is working properly.

 

[myers1st]

Indeed there is direct connectivity on pins 2 and 3, when bypass switch is in either position.  The green/red LEDs work by the way.  I tested the switch and it is working like it should.  Does this confirm that the problem is the relays?

Thanks Jeff!

You can check continuity between the rack's input and output XLRs. There should be basically a direct connection via the relays when the unit is bypassed and no DCR continuity when active. Check both pins 2 to 2 and 3 to 3. That should give an indication if the relay bypass is working properly.

 

[jsteiger]

Indeed there is direct connectivity on pins 2 and 3, when bypass switch is in either position.  The green/red LEDs work by the way.  I tested the switch and it is working like it should.  Does this confirm that the problem is the relays?

Thanks Jeff!

It confirms a problem with the relay circuit. Likely not the relays themselves. The LEDs are part of the control circuit but not exactly telling you if the relays have flipped their state or not.

 

[myers1st]

Ok, will try to trace through the relay circuit and see if I can find anything, thanks.

It confirms a problem with the relay circuit. Likely not the relays themselves. The LEDs are part of the control circuit but not exactly telling you if the relays have flipped their state or not.