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Post by Deleted on Sept 23, 2010 21:12:45 GMT
Claus..
This is the relay that switches off after DC has been detected on the output.
measure the voltage on pin 2 and pin 7 when it has switched off.
These should be near 0V but expect 1 or both channels to be higher.
Sorry I don't have time to trouble shoot 'live' via chat but could do this around sunday.
I could guide you to where what voltages should be and what could be causing this.
Don't worry it'll work for sure.
It's a pretty straightforward (almost classic) design.
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Post by PinkFloyd on Sept 23, 2010 21:44:22 GMT
Claus, Been there, done that  "CRAP! Put her all together, tested the DC offset etc. all was fine.... switched her on, shoved a CD in the tray, hit play and I was almost deafened Volume control at ZERO and sound comes out of the left channel at FULL volume... friggin' great I got a very quiet track and hit play again.... FULL volume from left channel but pot is working correctly on right channel. Obviously, the first place I am going to look is the pot itself.... it's too late tonight so I'll do it tomorrow. All I can think is that when I was desoldering it out of those god awful through hole plated pads I have, inadvertently, damaged it in some way.... whatever it is, the left channel is coming through at full blast. Great! Now I'm going to have to strip the blasted thing down again" Turned out to be a resistor I had forgotten to solder  |
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Post by clausdk on Sept 23, 2010 21:44:38 GMT
Claus.. This is the relay that switches off after DC has been detected on the output. measure the voltage on pin 2 and pin 7 when it has switched off. These should be near 0V but expect 1 or both channels to be higher. Sorry I don't have time to trouble shoot 'live' via chat but could do this around sunday. I could guide you to where what voltages should be and what could be causing this. Don't worry it'll work for sure. It's a pretty straightforward (almost classic) design. Where do I find pin 2 and 7 ?  is it the pins on the black box ? The click is like the one when the amp is switched on.. |
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Post by clausdk on Sept 23, 2010 21:47:13 GMT
It sounded quite good and the pot worked fine, just a click and then nothing..
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Post by PinkFloyd on Sept 23, 2010 21:49:38 GMT
Capistance for me is a town in Russia and to be honest I do not care, I know a cap is a small battery (almost), but my knowledge does not go very deep on that subject.. I am in for the challenge and I like soldering, it is like a zen thing to me.. I do not need to know those things to enjoy them, I am also uncapable of building a engine for my car, but I still drive.. I am not offended, but to me it is the same as if I told you that you should not eat icecreme, if you do not know about emulgators and stabilisators and what they do and why, you should not make sauce if you do not know what happens chemically when you add the thickening ingredient.. we all do a lot of things, without knowing what we are really doing and if we do not do those things our lifes would be less.. (crossing fingers that mine will work ) I very much doubt you are presently of the same opinion and would desperately like a fix to your problem? See what i meant? |
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Post by PinkFloyd on Sept 23, 2010 21:55:27 GMT
Go to bed tonight Claus, don't think about it.... be assured that it will all be fine Mike. |
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Post by clausdk on Sept 23, 2010 22:05:18 GMT
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Post by meliphicent on Sept 24, 2010 2:24:51 GMT
I used the $50 back paypal promo to score one of these, based solely on this thread. I'm very excited to be making it  |
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Post by Deleted on Sept 24, 2010 9:41:26 GMT
hi Claus don't worry things like this do happen to us all. usually if it has not blown up it's going to be a small thing  just a thought but did you set up and re check the DC offset voltages with the trim pots. dc on the output could mean that the DC offset voltage is set to high. a strange question maybe but does it only switch off with music playing? with HP plugged in and out? is the fault both channels is a good question from mike as it helps to fault find. maybe no help but just a thought.  most of all don't worry and keep us posted I'll take a quick look at the circuit diagram to see how many ways it can pass dc onto the OP.  it all helps us to learn  take care Shaun |
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Post by Deleted on Sept 24, 2010 18:06:59 GMT
I used the $50 back paypal promo to score one of these, based solely on this thread. I'm very excited to be making it These things catch don't they. It sounds really good value from what Mike's said. |
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Post by clausdk on Sept 24, 2010 18:33:58 GMT
I have adjusted all 4 trimpot to 1,2 volts.
offset is about 0,2 V
Both channels dissapeer..
I messured between those that could posseble could be 2 and 7 one was zero the other was 0,7 volts, I start counting at the square marking and then up and the row two..
the thing that is strange is that it just shuts off..
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Post by PinkFloyd on Sept 24, 2010 20:17:01 GMT
I have adjusted all 4 trimpot to 1,2 volts. NO NO NO! First off measure the voltage across each 1K5 resistor (at the points shown).... there is one per channel..... adjust each 500R trimpot VR4 / VR5 to get as close to 1.2V as you can.  OK.... now measure the DC offset at the headphone socket.... probe between tip and sleeve and ring and sleeve (sleeve being the ground) www.rock-grotto.co.uk/dcoffset.htmMake sure your meter (if it is not autoranging) is set to the millivolt setting "mV" NOT the Volts setting.... also make sure it's the DC setting. You say you measured 200mV DC (0.2V) , that is way too much...... Measure, as per www.rock-grotto.co.uk/dcoffset.htm and tweak the 200R trimpots VR2 / VR3 (one per channel) until you get the DC offset below 10mV per channel. Once you get the DC offset down I think she will work fine Mike. |
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Post by Koolind on Sept 24, 2010 20:37:09 GMT
Damn this thread ! Just ordered one. This will be my first serious DIY project, so the outcome will surely be interessting; Disaster or a slim chance of partial success ! I think that i will "just" do it right the first try |
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Post by PinkFloyd on Sept 24, 2010 20:43:17 GMT
Damn this thread ! Just ordered one. This will be my first serious DIY project, so the outcome will surely be interessting; Disaster or a slim chance of partial success ! I think that i will "just" do it right the first try Oh SHIT...... what monster have I created |
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Post by Deleted on Sept 24, 2010 20:49:56 GMT
All I can say is good luck!! |
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Post by PinkFloyd on Sept 24, 2010 20:50:48 GMT
An update.... the other three I have ordered are on their way so I'm looking forward to building up a few different versions over the stock amp..... should keep me busy during the long winter nights I still maintain this is the BEST (bar none) headphone amp "I" have ever had the privilege to listen to.... Hell, I even "bought" a new CD today.... that's a very good sign |
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Post by PinkFloyd on Sept 24, 2010 20:53:47 GMT
All I can say is good luck!! You don't have to rely on luck Ian, I will be sending a fully operational example of the Panda over to you shortly..... you know what my "address book" is like so I will need you to PM me your details again Mike. |
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Post by Deleted on Sept 24, 2010 20:53:50 GMT
Yeah ..... You were fiddling with that phone of yours Mike. I went on this afternoon and saw a little thing flashing by your name. The word ........ APPLE. You can't resist Santana eh? |
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Post by PinkFloyd on Sept 24, 2010 20:57:15 GMT
You can't resist Santana eh? Carlos is God when it comes to guitarists |
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Post by Deleted on Sept 24, 2010 21:00:17 GMT
You can't resist Santana eh? Carlos is God when it comes to guitarists Yes, he is rather good!! |
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Post by PinkFloyd on Sept 24, 2010 21:02:56 GMT
Carlos is God when it comes to guitarists Yes, he is rather good!! He knows his onions |
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Post by PinkFloyd on Sept 24, 2010 21:17:58 GMT
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Post by Koolind on Sept 24, 2010 21:36:08 GMT
Damn this thread ! Just ordered one. This will be my first serious DIY project, so the outcome will surely be interessting; Disaster or a slim chance of partial success ! I think that i will "just" do it right the first try Oh SHIT...... what monster have I created Hah, yea.. I think that the criteria for success in this case will be _not_ burning down the house The moment i pressed the "commit to buy" button the thought "how hard can it really be" crossed my mind. I suspect that i most likely will find out that it isnt easy at all. You have to start somewhere though; Learning by doing... (or catastrophy trying) |
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Post by PinkFloyd on Sept 24, 2010 21:45:09 GMT
Oh SHIT...... what monster have I created Hah, yea.. I think that the criteria for success in this case will be _not_ burning down the house The moment i pressed the "commit to buy" button the thought "how hard can it really be" crossed my mind. I suspect that i most likely will find out that it isnt easy at all. You have to start somewhere though; Learning by doing... (or catastrophy trying) You'll be fine, don't worry |
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Post by clausdk on Sept 24, 2010 21:57:21 GMT
I have adjusted all 4 trimpot to 1,2 volts. NO NO NO! First off measure the voltage across each 1K5 resistor (at the points shown).... there is one per channel..... adjust each 500R trimpot VR4 / VR5 to get as close to 1.2V as you can. OK.... now measure the DC offset at the headphone socket.... probe between tip and sleeve and ring and sleeve (sleeve being the ground) www.rock-grotto.co.uk/dcoffset.htmMake sure your meter (if it is not autoranging) is set to the millivolt setting "mV" NOT the Volts setting.... also make sure it's the DC setting. You say you measured 200mV DC (0.2V) , that is way too much...... Measure, as per www.rock-grotto.co.uk/dcoffset.htm and tweak the 200R trimpots VR2 / VR3 (one per channel) until you get the DC offset below 10mV per channel. Once you get the DC offset down I think she will work fine Mike. OK now the voltage over the 1500 is 1204 mV and 1205 mV, the offset is between 0 and -1 mV.. No sound, it also does not click when i turn it on anymore ?? The 200 trimpots does not seem to work the offset is the same when I turn the pot ?? The 200mV must have been a mistake because it showed zero as I messured it again.. |
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