AMB Laboratories DIY Audio Forums

[BMF]

Admin note: Split from another thread because this is a new case.

No click on or off so I followed the recommendations in this thread. Q3 and Q4 seemed to be bad so I removed them and then turned on the power resulting in that "sweet clicking goodness." OK. So, I figure the problem is solved...all I need to do is solder in new Q3 and Q4 transistors, which I just did. I made sure the solder flowed all the way through on each lead. Turned on the power....and NO click. I'm stumped.

BTW, this e12 is connected to EHHA Rev A +30 and -30 rails. When Q3 and Q4 were Not installed And the relay clicked, it did so with e12 V+ to the EHHA Rev A +30 rail and the e12 V- to the EHHA Rev A -30 rail (~59.5 volts measured between e12 V+ and V-; it also clicked with e12 V- connected to the Star Ground (~29.5 volts between e12 V+ and V-).

If anyone has any ideas, I'm All Ears.

Thanks,

BMF

[amb]

Some information is missing. Did you do the steps outlined in the ε12 website "Initial setup" section? The trimpot needs to be calibrated to match the ε12's VG potential to the amps' ground.

[BMF]

AMB,

Thank you for the help.

e12 V+ connected to EHHA Rev A +30 V rail and e12 V- connected to -30 V rail:

I followed the initial setup. The relay did not click but I followed the rest of the setup and measurements are:
U1 pins 4 to 8 = 22.92 V
U1 Pin 8 to e12 VG = 11.49 V
U1 Pin 4 to e12 VG = 11.46 V

Still no click.

[amb]

If you can't get the relay to click "on" in the initial setup, then it's not likely to work when fully connected to the amp.

Were you able to adjust the trimpot so that the voltage across VG and the amp's ground is as close to zero as possible (step 8)? If so what's the voltage you achieved?

[BMF]

Yes, e12 VG to EHHA Rev A Ground is trimmed down to 0.0 V.

Maybe it's my hearing! Holding e12 right next to my ear I sometimes hear the click but other times not.

Thank you for taking the time to help me troubleshoot.

[amb]

You can measure the relay contacts to see if they are closing...

[BMF]

I'm using Omron G5V-2-H1 relay. The data sheet indicates 2.8k ohms between the coil terminals and that's what I get. If I'm interpreting The data sheet diagram correctly, it looks like pins 4 to 6 and 13 to 11 are NC and both measure 0 ohms with power off. Pins 6 to 8 and 11 to 9 are NO and read close to 1M ohm with power off. Turning on power does Not change these values.

A friend sent me an epsilon 12 that worked for him. I did not hear the relay click on this one, either. I got similar readings on its relay with power off and then with power on.

I rechecked e12 U1 pins 4 to 8 on both e12s = 22.7 v. Each of these to e12 VG reads 11.4v.

My EHHA Rev A powers up.

This is puzzling.

[amb]

Don't forget there is a time delay between power-up and relay activation.

[BMF]

I remembered and waited 30 seconds before measurements.

I also checked voltage between V+ and V- pins on molex connection and under the board on the solder joints and got 59.x volts.

[amb]

The EHHA may exhibit a high output DC offset when it's initially turned on, causing the relay not to activate. After it warms up the offset should settle down. If you measure the DC voltage across the relay coil contacts, it will show ~0V (or a very low voltage) when it's not activated. The voltage should rise to 20-something volts when it clicks in.