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Old 2nd October 2010, 08:33 PM   #2081
Salas is online now Salas  Greece
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Where do you power the LS from? Separate rectification and filter?
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Old 2nd October 2010, 08:55 PM   #2082
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Quote:
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Where do you power the LS from? Separate rectification and filter?
Completely separate. Transformer+two stages of regulation. The DCB1 is just sitting on an antistatic bag with its dedicated transformer near by. The RCA ground tabs are soldered to a copper bar, all ground wires are connected to the centre of the bar, bar to SE point via a ground loop breaker.

LS 'out' goes to B1 'input', B1 'output' to amp.
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Last edited by Tripmaster; 2nd October 2010 at 09:17 PM.
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Old 2nd October 2010, 09:24 PM   #2083
Salas is online now Salas  Greece
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Its weird saying you can read any output voltage before the click, since before click there is no connection between the Jfets and output socket. I would expect that DC peak and slow DC die out if it was connected all the time. Check the continuity between 220R out to ouput socket when off, maybe its stuck. Can you also use 4 corner makeshift lifts instead of having it on the bag?
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Old 2nd October 2010, 09:26 PM   #2084
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Its weird saying you can read any output voltage before the click, since before click there is no connection between the Jfets and output socket. I would expect that DC peak and slow DC die out if it was connected all the time. Check the continuity between 220R out to ouput socket when off, maybe its stuck. Can you also use 4 corner makeshift lifts instead of having it on the bag?
Will do
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Old 2nd October 2010, 09:49 PM   #2085
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Its fine now, really strange.

There wasn't continuity between the 200R and output when switched off

Click the image to open in full size.

The layout is purely for testing. I plan relocate the 100K dual log pot towards the rear by using a shaft extension. I really need to shorten those power cables.
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Old 3rd October 2010, 04:41 PM   #2086
Atilla is offline Atilla  Norway
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I'm almost done as well. Got the last components yesterday, soldered everything but the 4x FETS in the audio path.

I've got ~1.9V LEDs, and I'm running 2x51Ohm resistors at R1.

The problem is, the 3 LED string doesn't light up. Around R1 I measure 6.9V. The 5 LED string has no problems and my output seems right - 10.3/-10.2 Volt.

I'm not sure what can be wrong yet, I'm sure the leds are in the correct orientation, etc.
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Old 3rd October 2010, 05:02 PM   #2087
AndrewT is offline AndrewT  Scotland
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6.9V across 51r//51r is ~270mA.

I think you will find the FETs running a bit more than warm.

Re-check the orientation of all the LEDs.
Measure the voltage across every LED. Any one that seems odd needs further investigation.
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Old 3rd October 2010, 10:19 PM   #2088
Atilla is offline Atilla  Norway
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Quote:
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6.9V across 51r//51r is ~270mA.

I think you will find the FETs running a bit more than warm.
That's totally intentional. I'll heatsink them and if it isn't enough, I'll mount them to the case, which is a gigantic aluminium heatsink. I planned to parallel a 3rd 51r with them when all is done if I can handle the heat.

Plus, I thought I'll sink some of that current in a headphone amp which should go in the same enclosure, that'll draw some current away from the shunt. I'll see how it goes.

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Re-check the orientation of all the LEDs.
Measure the voltage across every LED. Any one that seems odd needs further investigation.
The leds are all mounted right. They actually light up when I check for continuity with my DMM. The 2x2sk170 CSS transistors for them are also intact, since current flows if I check for continuity between the CSS and the last LED - it still lights up.

The voltage drops are off however, they're random values between 0.3 and 0.9V for all 6 leds there. Now that is weird. The leds in the 5-strings all drop 1.94V with their CCS (I'm guessing they're a little on the high side, but that's all good). I'm too sleepy to play with electricity right now, but I'll be on it tomorrow again.
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Old 3rd October 2010, 10:25 PM   #2089
Salas is online now Salas  Greece
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You can't be having 6.9V across the set resistor in an OK unit. 1.6-2.2V is what to expect. Those 3 Leds strings are not alight bcs either some or all are inserted in reverse. Else the CCS Mosfets are shot. When they will be alight the reference CCS voltage will come to normal too.
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Old 3rd October 2010, 10:38 PM   #2090
Atilla is offline Atilla  Norway
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I guess I'll trade Mosfet positions then and see what's up, since the LEDs are ok. Weird that I'd have 2 Mosfests dead and in the same position too, some luck I have. Tomorrow then, no need to fry something in the middle of the night.
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