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The Objective2 (O2) Headphone Amp DIY Project
The Objective2 (O2) Headphone Amp DIY Project
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Old 20th August 2012, 08:24 PM   #2721
Rullknufs is offline Rullknufs  Sweden
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The Objective2 (O2) Headphone Amp DIY Project
Okay, just powered up my board and followed the instructions here
NwAvGuy: O2 Details
"Briefly Check The Supply Voltages" was all right. But after installing U2 I got stuck. The above mentioned test was still fine as before but measuring from negative of BT1 to pin 4 of empty U4 socket my DMM showed nothing. Well, it displayed a minus sign but not -11.8 as it should be it just said -0.00 but if I switch the probes (red on minus battery and black in the socket) i get 25V as on the battery tests above. And measuring between BT1 minus and pin 8 of U4 shows 25V and not 11.8.
My battery tests also showed 25V. I have a really cheapish DMM so I was thinking maybe it can't measure lower than 25V and no minus voltages?

And by the way, I've cut the ground traces at J2 to prepare for installing the ODAC. Maybe this is why? I don't know...
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Old 21st August 2012, 10:45 AM   #2722
everlong is offline everlong
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When charging the batteries. I don't need to push the power switch on?
And fow how long should the take to fully charge the batteries? (Tenergy 250mAh)
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Old 21st August 2012, 11:03 AM   #2723
sofaspud is offline sofaspud  United States
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No, the batteries charge any time the AC adapter is plugged in. Figure a good 10-12 hours to fully recharge.
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Old 21st August 2012, 06:41 PM   #2724
VJK is offline VJK
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@Rullknufs - It is unlikely that the fault is due to DMM or you cutting the ground traces. The 7812 and 7912 are normally robust enough to take some beating unless you have switched their positions (a mistake I did on my first build). My current theory is that the MOSFETs might be the issue. These creatures are very delicate and need to be handled very very carefully.
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Old 21st August 2012, 07:24 PM   #2725
Rullknufs is offline Rullknufs  Sweden
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The Objective2 (O2) Headphone Amp DIY Project
The problem was that I had my DMM on AC instead of DC. But I also borrowed a high-end DMM from a friend and measured everything and everything was as it should be. Thank god!

So, now I've mounted it in my case (no pins touching the case, triple-checked that!) but I haven't mounted that ground wire I've seen some people do. And since I've cut the ground traces, is it ok to use it even though I haven't installed my ODAC yet?

Can I run it as O2 only until I mount the ODAC?
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Old 21st August 2012, 08:24 PM   #2726
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RullKnufs : You should connect the ground wire to the chassis, but not connecting the ODAC and the Amp should be ok
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Old 21st August 2012, 08:44 PM   #2727
Rullknufs is offline Rullknufs  Sweden
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Quote:
Originally Posted by VJK View Post
RullKnufs : You should connect the ground wire to the chassis, but not connecting the ODAC and the Amp should be ok
Should I solder it to the chassis, does that work? I am pretty new to this.
In that case I'll try it tomorrow, using some old Steelseries Siberia headphones and not my Denon AH-D2000 for the first try
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Old 21st August 2012, 08:52 PM   #2728
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I have not soldered it, I just scratched the inside of the chassis a bit and made sure that the wire is squeezed between the back panel and the chassis thus making sure that it actually is electrically connected.
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Old 21st August 2012, 08:58 PM   #2729
Rullknufs is offline Rullknufs  Sweden
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The Objective2 (O2) Headphone Amp DIY Project
Quote:
Originally Posted by VJK View Post
I have not soldered it, I just scratched the inside of the chassis a bit and made sure that the wire is squeezed between the back panel and the chassis thus making sure that it actually is electrically connected.
Okay, so I can just take a piece of wire, solder it to the ground pin on the board and then drag it under the whole PCB to the back of the board. Then scrape some paint of the back plate (is it ok to use the back plate or does it have to be the chassis?) and then squeeze it tight? Or how do you mean? I have maybe a millimeter clearance at either the front or the back of the board in the chassis so I could put a piece of cable there I think.
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Old 21st August 2012, 09:08 PM   #2730
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@Rullknufs : Here is what I did - Soldered a wire to the ground ran it under the board. On the other end of the wire I removed the insulation for about 6 mm divided the copper conductors into 2 like 2 braids and put it in-between the back plate and the chassis in such a way that one of the screws runs in-between them. I also made sure that the strands are spread so that the back plate doesn't show a bulge.
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