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Old 18th June 2006, 08:48 PM   #401
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Above I should have said the second half is not sinking anything at all.... No LED!
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Old 18th June 2006, 09:29 PM   #402
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Quote:
Originally posted by Mark A. Gulbrandsen
Above I should have said the second half is not sinking anything at all.... No LED!

replace IRF 820 from shunt part in CCS part-just to check its burned or not;

you can use even TL07x (08x) as substitute,for testing ;I dunno for stability versus LF.... but for test it will be OK

hehe- orientation of pins for irf-same as in your's Aleph's output stage,biasing too........

did you checked what you get on inputs of OP?
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Old 18th June 2006, 10:05 PM   #403
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Well, I changed the LF351 and the output of it varies from .68 to .230 volts now. I even fed voltage directly from my bench supply bypassing the CSS part into the shunt section alone and its still dead... Will change the 820 and report back in a while...

Mark
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Old 18th June 2006, 10:26 PM   #404
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Changed IRF820 out and still nothing.
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Old 18th June 2006, 10:58 PM   #405
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you didn't swapped plus and minus OP input?

plus goes on voltage ref (pin 2)
minus on voltage sens divider (pin 3)


what voltage you have on pin2?
what voltage you can set on pin3?

somewhere there is catch22

at least to my knowledge,max voltage you need to achieve at output of OP is ....hehe....full throttle .....Uled + voltage for open mosfet....~ 3 +4 V.....coincidently-almost same as voltage reference.......
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Old 18th June 2006, 11:19 PM   #406
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Here are the voltages...

Pin 1 n/c
2 7.09
3. 6.38 to 7.58 depending on pot setting
4. Gnd
5. .68 to .210 Seems too low to me...
6. N/C
7.15.00
8. N/C
Pin 2 is obviously seeing the 7 volts + refrence. Seems like the comparator is not functioning correctly. I even disconnected the drive out(pin 5) to see if it would climb at all. I've changed the IC once already! Also it is definately wired correctly.. been over it a dozen times .

Mark
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Old 18th June 2006, 11:31 PM   #407
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I think I just found the problem. I have the output tied to pin 5 as per the Cook Book diagram but the IC spec sheet says pin 6 is the output. Will try it and be right back.........

Mark
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Old 18th June 2006, 11:33 PM   #408
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Quote:
Originally posted by Mark A. Gulbrandsen
Here are the voltages...

Pin 1 n/c
2 7.09
3. 6.38 to 7.58 depending on pot setting
4. Gnd
5. .68 to .210 Seems too low to me...
6. N/C
7.15.00
8. N/C
Pin 2 is obviously seeing the 7 volts + refrence. Seems like the comparator is not functioning correctly. I even disconnected the drive out(pin 5) to see if it would climb at all. I've changed the IC once already! Also it is definately wired correctly.. been over it a dozen times .

Mark
is it the same if you use 30V on pin 7,instead 15 V ?

if you can't use higher voltage than 15V, try to decrease these 10K resistors to 5K ;
start with resistor in series with zenner



EDIT: just saw your post about pinout mess,while I typed -you posted that.........

Mark : http://www.diyaudio.com/forums/showt...311#post941311

moral of the story:
always triple check pinouts..........you repair things,,for living-amongst other activities ?......I learned that -in a hard way..........you can imagine mess with pinouts ,when you live in area with parts from all over the world....including West and East.......
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Old 19th June 2006, 12:26 AM   #409
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Hey Geek......I wonder if I just found your problem too??? Mr Wright has some Wrong things in his Cookbook on the Wregulator diagram thats for sure! He DID have the output pin listed as pin 5 but it is indeed pin 6 on the chip. He also has the pass devices drawn wrong. I believe the arrow on the MOSFETs is supposed to go the other direction! I had to change the IC and shunt device and LED again as I believe hooking the drive output up to pin 5 cdamaged the 351. When I moved it to pin 6 it powered up for a flash of the LED and then quit, the shunt device had shorted.

As you can see the LED is now lit up and all things are happy!
For 50 ma draw I think the drive voltage on pin 6 was about 11.5 volts or there abouts. The sink got a bit warmish at 50 ma. When I actually hook it all up I will post all of the correct votage readngs.

The finished unit below...... Won't have time for a couple of weeks to hook it up though as I'm off on a trip to Montana tommrrow for a while.

Thanks Choky for all your help with this! It just goes to show that even Mr. Wright can also be Mr. Wrong.....

Mark
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Old 19th June 2006, 12:44 AM   #410
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Quote:
Originally posted by choky

use two 5s in series,then use good ole 317 as CCS , adjust for needed current in range of 6V3 (~600mA).........
and ,yes,use one 317 per tube
Hi Choky, I tried using the CCS on heaters for my 5687WB headphone amp. It has 14V winding which is bridge-rectified. I had set the 317CCS to ~0.45A using a 2.8R. I do see the slow rise in voltage at turn on, but it rises to over 13V too... so I quickly shut off the mains... did I do something wrong here?
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