Salas hotrodded blue DCB1 build - Page 253 - diyAudio
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Old 7th January 2013, 12:57 PM   #2521
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You can also check the polarity by seeing the circular led annotation on the pcb, showing for each group where the flat side (cathode) goes
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Old 7th January 2013, 01:11 PM   #2522
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Quote:
Originally Posted by dimkasta View Post
You can also check the polarity by seeing the circular led annotation on the pcb, showing for each group where the flat side (cathode) goes
I made a mistake there to. If you try to take a led out you will destroy them. They are not the best mechanical quality.
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Old 7th January 2013, 01:13 PM   #2523
Salas is offline Salas  Greece
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The small leds are usually soldering iron sensitive too. Need not be soldered for too long.
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Old 7th January 2013, 08:13 PM   #2524
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Not much happening but finished soldering. Have to hook it up somehow and test

Click the image to open in full size.

Has anyone experimented with bypassing the 100uf caps?
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Old 7th January 2013, 09:33 PM   #2525
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Don't bypass them. It will most likely oscillate.
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Old 7th January 2013, 09:46 PM   #2526
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Ok - thanks for the advice.

Had to "power up". Just for some seconds without heatsinks attached. One mosfet got very hot really fast btw.

Almost all leds glowed.. But not all. 3 of them did not.. Will look into this tomorrow I guess. Check orientation and so on ...

Did a couple of measurements between V+ , G and V- ... Got +9.95Vdc and -9.96Vdc
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Old 7th January 2013, 11:44 PM   #2527
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Sorry it this is like spam? Had a visual check on those leds and just as I expected. One was in wrong direction..
Unsoldered it and in again.. There is light - The relay clicks in after some seconds..

Had it on for a couple of minutes and measured V+,G,V-... Got +9.86 and -9.86 Vdc... Must recap this thread to see what other measurements that has to be done to make sure the buffer is ok.

My transformer for the test is a 15VA 2*12V transformer. (230Vac mains) - and I have another identical one also..
I measured it and it actually measures aprox 13.8Vac - because of somewhat higher voltage in my house. (approx 235Vac)



Sincerely
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Old 7th January 2013, 11:57 PM   #2528
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No need to go through the entire thread. It can be a real chore.
Check this out
http://www.diyaudio.com/forums/blogs...e-edition.html

The pdfs are really nice
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Old 8th January 2013, 02:02 AM   #2529
Salas is offline Salas  Greece
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Quote:
Originally Posted by bambadoo View Post
Sorry it this is like spam? Had a visual check on those leds and just as I expected. One was in wrong direction..
Unsoldered it and in again.. There is light - The relay clicks in after some seconds..

Had it on for a couple of minutes and measured V+,G,V-... Got +9.86 and -9.86 Vdc... Must recap this thread to see what other measurements that has to be done to make sure the buffer is ok.

My transformer for the test is a 15VA 2*12V transformer. (230Vac mains) - and I have another identical one also..
I measured it and it actually measures aprox 13.8Vac - because of somewhat higher voltage in my house. (approx 235Vac)



Sincerely
If the dc offset on both audio outputs is below 5mV, you are OK. Only sink it first. Secondary check left to do is to measure voltage across the 10 Ohm resistors, then divide by 10 each, so to verify you got 150-200mA running per side.
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Old 9th January 2013, 03:27 PM   #2530
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Thanks again..
Had an old cabinett. Sinked the dcb1 to the chassis and put it on.
Waited about 10 minutes and did some readings.

Vout: 9.86Vdc and -9.86Vdc
DCoffset : 3.1mV and 3.0mV
Over the power resistors: 1.66V (IRFB9240 side) and 1.55V (IRFB240 side..

These are good readings right?

Have ordered a "potted" 50VA 2*15V transformer.. Should be here tomorrow I guess.

My old lightspeed attenuators have been taken up again.
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