MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

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Joe Malone
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MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Joe Malone » Tue Mar 03, 2015 9:14 am

MAC RACK KIT Build Thread before slow attack led on front panel

MAC rack kit uses 2 x dINgO kits
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Blank dINgO PCB with full overlay shown (All parts numbers in () or [] brackets are not used with JLM99v opamps)
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dINgO kit with all small parts shown. There will also be PCB XLR's in MAC rack kit.
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If you are not 100% with resistor colour codes use a multimeter to check values as you place the resistors
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Fit all resistors at once bending the legs sightly outwards to hold them in place. This helps to make sure no resistors are put in the wrong position.

Start with fitting of the 10k resistors into the PCB and bend the legs slightly outwards so they do not fall out when PCB is turned over.
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Fitting of the 33R resistors
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Fitting of the 5k1 resistors
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Fitting of the 10R resistors
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Fitting of the 470R resistor
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Turn over PCB on flat surface and solder and trim all resistors legs
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Fit the two 24v zener diodes with stripes lined up with stripe on PCB and solder and trim legs
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Fit the 4 x 47pF ceramic caps folded flat to the PCB and solder and trim legs
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Fit the 3 x 100nF mono caps with one folded flat to the PCB and solder and trim legs
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Fit the 2 x gold pin sets to the PCB and solder. Best to solder one pin on each and check if they are sitting straight before soldering all pins.
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Fit the 2 x 10uF & 2 x 100uF electro caps the check way around to the PCB and solder and trim legs. (+leg is the long leg of the cap)
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Fit 2 x 10pin IDC headers to the PCB and solder and trim legs.
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Fit 24v relay to the PCB and solder and trim legs. Make sure stripe on relay matches stripe on PCB
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Fit 4 x 470uF 16v Non Polar electro caps to the PCB and solder and trim legs. These are Non Polar so can be fitted either way around.
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Fit 2 x 3way terminal block to the PCB and solder and trim legs.
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Fit 12 pins for the 2 x JLM99v opamps to the PCB and solder and trim legs.
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Fit Male and Female XLR to the PCB and solder and trim legs. There maybe left over 3 way terminal blocks in the kit.
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Trim side of Female XLR with sidecutters as shown
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Fit input polarity jumpers as shown for correct phase.
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Fit 2 x JLM99v opamps to the 12 sockets on the PCB
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Fit ground link jumper beside XLR. Thid dINgO is built and ready. Build second dINgO and then move on to MAC PCB kits.
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MAC PCB Schematic with MAC alignment
http://www.jlmaudio.com/MAC/MACSCH.pdf

MAC PCB parts kit
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Fit all 8 x BAT85 diodes with there Cathode POLARIZED black stripe matching the white stripe on the MAC PCB overlay
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If you are not 100% with resistor colour codes use a multimeter to check values as you place the resistors
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Fit all resistors at once bending the legs sightly outwards to hold them in place. This helps to make sure no resistors are put in the wrong position.

Fit 4 x 47k resistors
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Joe :-)
JLM Audio
Capturing Audio without Injury

Musepro
Posts: 5
Joined: Fri Jan 16, 2015 1:59 am

Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Musepro » Thu Sep 10, 2015 6:46 am

Hello!

Just built my latest pair of Mac-Racks. Both builds went perfect, as usual.

However, on ONE of the Mac-Racks, channel 1 has about 2.8dB less output than channel 2 when the comp in ON (3:1, VU or GR, SCF Flat). This 2.8dB deviation occurs throughout the range of the make-up knobs, watching both channels go up and down. When the MACs are in bypass, both channels are at equal level, so I assume all is well with the Dingos.

For trouble shooting, I tried the following:

1. Swapped OPA2604s on the Mac cards.
2. Swapped ribbon cables on the channels.
3. Swapped make-up knobs.

After trying and testing each of these, I still have 2.8dB less output on Ch1 than Ch2. I confirmed all components are in their proper place and match between the two Mac cards. The NSL-32 optos were put in the proper place (I'm excessively careful about this). In fact, the comp calibrates and matches perfectly between the two channels as far as gain reduction goes as well as VU and balance. The only issue is that Ch1's Mac card has 2.8dB more insertion loss than Ch2 with all controls set to default. A slight bump of Ch1's make-up to compensate for this and the compressor works as it should.

Any thoughts as to what is going on? Thanks!

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Joe Malone
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Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Joe Malone » Thu Sep 10, 2015 8:11 am

Musepro wrote:Hello!

Just built my latest pair of Mac-Racks. Both builds went perfect, as usual.

However, on ONE of the Mac-Racks, channel 1 has about 2.8dB less output than channel 2 when the comp in ON (3:1, VU or GR, SCF Flat). This 2.8dB deviation occurs throughout the range of the make-up knobs, watching both channels go up and down. When the MACs are in bypass, both channels are at equal level, so I assume all is well with the Dingos.

For trouble shooting, I tried the following:

1. Swapped OPA2604s on the Mac cards.
2. Swapped ribbon cables on the channels.
3. Swapped make-up knobs.

After trying and testing each of these, I still have 2.8dB less output on Ch1 than Ch2. I confirmed all components are in their proper place and match between the two Mac cards. The NSL-32 optos were put in the proper place (I'm excessively careful about this). In fact, the comp calibrates and matches perfectly between the two channels as far as gain reduction goes as well as VU and balance. The only issue is that Ch1's Mac card has 2.8dB more insertion loss than Ch2 with all controls set to default. A slight bump of Ch1's make-up to compensate for this and the compressor works as it should.

Any thoughts as to what is going on? Thanks!


So if you swap ribbon cables over between MAC pcb does the level change stays with the MAC pcb or the dingo PCB?
(you can unplug the link pcb and use the end idc cable plugs to reach across to opposite MAC pcbs)

If the MAC pcb make sure you 100k log threshold pots fitted and have NOT joined the front and back legs together to make 50k?

If the dingo pcb make sure the threshold pot is 10k rev log. If you disconnect the makeup pot wires check if the gain difference is gone or not?
Joe :-)

JLM Audio

Capturing Audio without Injury

Musepro
Posts: 5
Joined: Fri Jan 16, 2015 1:59 am

Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Musepro » Thu Sep 10, 2015 11:43 pm

Musepro wrote:So if you swap ribbon cables over between MAC pcb does the level change stays with the MAC pcb or the dingo PCB?
(you can unplug the link pcb and use the end idc cable plugs to reach across to opposite MAC pcbs)

If the MAC pcb make sure you 100k log threshold pots fitted and have NOT joined the front and back legs together to make 50k?

If the dingo pcb make sure the threshold pot is 10k rev log. If you disconnect the makeup pot wires check if the gain difference is gone or not?


I have the dual 200K threshold pots that came with the kit, and the legs have been joined for 100K. The make-up pots are the 10K rev logs sent with the kit and I swapped Ch1 and Ch2 make-up pots with no difference in outcome. Ch1 sounds a functions 100% as it should, save for the 2.8dB drop when IN. It wouldn't even necessarily be obvious if there wasn't a second channel to compare it to or I didn't know that a 2.8dB drop isn't normal when IN.

BUT, it looks like it IS in the Ch1 Dingo. When I swapped ribbon cables between the Mac PCBs, the level drop went to Ch2. I put the ribbons back to normal (Dingo1 to Mac1, Dingo2 to Mac2) then swapped the 99V opamps between the two channels, but it stayed on Ch1, so the opamps look good. I measured +/- 24V on all 4 sets of 99V pins and on the diodes. From these measurements and component values/polarities, everything looks good. Still has a 2.8dB drop with COMP IN.

Thoughts? Thanks!

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Joe Malone
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Posts: 1579
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Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Joe Malone » Fri Sep 11, 2015 8:19 am

OK sorry forgetting the new kits have 2 x 200k lof pots so yes soldering front to back to make 100k is correct.

Did you unsolder both makeup pot wires to see if both channels drop to the same level? Or if the mismatch is still there?

If you have a scope you can check levels at the dingo unbalanced in and out terminals to see if the drop is in the input amp or output amp?

Also worth swapping the output transformers or dingo pcb's over to see if the fault stays with the dingo or the output transformer?
Joe :-)

JLM Audio

Capturing Audio without Injury

Musepro
Posts: 5
Joined: Fri Jan 16, 2015 1:59 am

Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Musepro » Sun Sep 13, 2015 11:12 pm

Joe Malone wrote:OK sorry forgetting the new kits have 2 x 200k lof pots so yes soldering front to back to make 100k is correct.

Did you unsolder both makeup pot wires to see if both channels drop to the same level? Or if the mismatch is still there?

If you have a scope you can check levels at the dingo unbalanced in and out terminals to see if the drop is in the input amp or output amp?

Also worth swapping the output transformers or dingo pcb's over to see if the fault stays with the dingo or the output transformer?


I had already swapped the makeup pots with no change. I went ahead and disconnected them but there is still the 2.8dB difference. I don't own a scope, though I should probably get one.

I swapped the Dingos and the 2.8dB level drop followed the Dingo in question, which is now in Ch2, so it isn't the output tranny or ribbon cable. I reflowed the solder on all of the 99V sockets, but that didn't do anything either. I reconfirmed proper component values and polarities. And again, I tired different 99Vs with no change.

I will need to look further into this one Dingo and figure this out. Let me know if you have any other ideas. Thanks!

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Joe Malone
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Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Joe Malone » Mon Sep 14, 2015 7:49 am

Put in a 1k tone in at a high level that doesn't clip and check the AC volts using a voltmeter at the unbalanced out and in on both dingo pcb's to see if it is the input amp of output amp on the dingo that is having the problem. The out should 2 times (6dB) larger than the in. And both dingo in and out should match if the input amps are ok.

Let me know what you find and feel free to email me a large in focus well lit photo of the top and bottom of the dingo PCB with no opamps fitted so I can check it over as well.
Joe :-)

JLM Audio

Capturing Audio without Injury

bantam
Posts: 3
Joined: Tue Mar 06, 2007 1:17 am

Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby bantam » Tue Aug 23, 2016 11:28 am

joe

can i hook up a couple of unbal jacks to the jlm io port (assuming i get the pinout) or does the MAC require a Dingo?

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Joe Malone
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Re: MAC RACK KIT with RED MAC & DINGO PCBs Build Thread

Postby Joe Malone » Tue Aug 23, 2016 11:55 am

bantam wrote:joe

can i hook up a couple of unbal jacks to the jlm io port (assuming i get the pinout) or does the MAC require a Dingo?


You could if the output driving the MAC input is 100ohms or less and MAC output goes to a makeup amp with 100k input impedance.

You will not have a bypass as this is a relay on the dingo pcb. So the meter led will not light as well.

Otherwise a dingo is the easiest and best way.
Joe :-)

JLM Audio

Capturing Audio without Injury

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