[Colindsv]

Just finished building.  

When I send signal through the EQ and twist the knobs.  Nothing is happening. 

There’s nothing shorted to the chassis plate.  No smoking or burning smell.  On visual inspection everything looks normal. 

I’d like to be able to run through some of the voltage tests, but I can’t connect to the test points with my DMM since it needs to be in the rack. 

How can I go about supplying power to it outside of the rack so I can test DC voltages at the various points noted in the troubleshooting guide above?

[JPK]

It looks like it stays in bypassed mode. Check the solders on the relays, R12, the switch SW2 and check the direction of the diodes D1 and D2.

How can I go about supplying power to it outside of the rack
You will need an XT500.

[Colindsv]

Relays look good, in the correct direction.  As are D1 and D2.  R12 also looks good and is the correct ohms.

The switch looks good…I didn’t think it needed to be installed a certain direction, so that could be an issue if it’s directional.  I do get continuity readings on my DMM with it.  

Any other suggestions?

[JPK]

To move forward, you will need to do some voltage measurements as shown here.

[Colindsv]

Ok all of the voltages without running signal were good.  All points A-N tested very close to the target measurement.

The next step was to send a sine wave and test.  Here is where I’ve run into issues.  I don’t know if it’s the way I’m testing though

I have a battery powered behringer cable tester that is also a tone generator.  It has a 1000hz sine wave at +4dbu.  I measured AC voltage at the pins of the XLR and got 1.4v

Plugged this into the unit and measured tp1 and 0v and I get a reading of 0.0 AC voltage on the meter.  

Is this because my sine wave is 1000hz and measuring 1.4VAC from the source?  Or should I be getting a reading?

[JPK]

You should get 0.68VAC on TP1.
Except if the EQ stays in bypassed mode.
Can you check the DC voltage across D1 which also is the coil of relay RLY1. It should be above 20V when the EQ is activated.

[Colindsv]

When I measure DC voltage across D1 putting a meter probe on either side of the diode, I get 32V when the EQ is is in XLR 

Both switched Off and PRE give me a DC voltage across D1 very low 0.02V

[JPK]

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.

[Colindsv]

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.

How do I measure coil resistance across the diode?

[JPK]

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

[Colindsv]

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

Ok power off measuring resistance with a meter probe on either side of D1 gives 0.0ohms
D2 gives 2.8kohms

 both relays and diodes were double checked for proper orientation and are ok. 

Also I did not have to desolder/resolder the relay

[JPK]

It looks like you need to replace RLY1.
Contact us here for a replacement.
Or get one more quickly, locally:
https://www.mouser.com/ProductDetail/Panasonic-Industrial-Devices/TQ2-24V?qs=HLLy2pIPwuvqeFYAg5JtGw%3D%3D
https://www.digikey.com/en/products/detail/panasonic-electric-works/tq2-24v/251775

[Colindsv]

Thanks, ordered.

I’ll update when I put it in