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help to set dc offset to threshold s450
help to set dc offset to threshold s450
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Old 25th January 2016, 08:17 PM   #1
alfalf1 is offline alfalf1
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Default help to set dc offset to threshold s450

hi to all forum member i need our help to set the dc ofset of treshold s450.

i have purchased it used but in a right channel i read 1,2v dc and left channer i read -1,3 volts dc.

i nned also the schema or servece manual to teterminare the trimmer that regulate it.

i wait soon our help

thanks at all in advance and exluce me to my little english

i am italian

alfonso
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Old 26th January 2016, 07:04 AM   #2
Zen Mod is online now Zen Mod  Serbia
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help to set dc offset to threshold s450
well , put some Italian pictures here first ......

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Old 26th January 2016, 08:23 AM   #3
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Default same pcture

hi i see in the driver card only a blu trimmer

but i have tried to regulate it bat the cd remail aroundo 1.1 volts dc
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Old 26th January 2016, 08:29 AM   #4
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Default pictures

following pictures
Attached Images
File Type: jpg 20160125_131135_resized.jpg (147.1 KB, 127 views)
File Type: jpg 20160126_101010_resized.jpg (179.0 KB, 120 views)
File Type: jpg 20160126_100944_resized.jpg (186.4 KB, 117 views)
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Old 26th January 2016, 08:40 AM   #5
alfalf1 is offline alfalf1
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Default pictures

Quote:
Originally Posted by Zen Mod View Post
well , put some Italian pictures here first ......

help to set dc offset to threshold s450-20160125_131135_resized-jpg

help to set dc offset to threshold s450-20160126_101010_resized-jpg

help to set dc offset to threshold s450-20160126_100944_resized-jpg
Attached Images
File Type: jpg 20160125_131135_resized.jpg (147.1 KB, 153 views)
File Type: jpg 20160126_101010_resized.jpg (179.0 KB, 149 views)
File Type: jpg 20160126_100944_resized.jpg (186.4 KB, 148 views)
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Old 27th January 2016, 08:04 AM   #6
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help to set dc offset to threshold s450
to help me to determine which iteration of front end you have in that amp,read to me type of that 6-legged small metal transistor (on first pic)

then I can try to find schematic to point you in right direction

however , what you'll certainly need is to do some maintenance - for what you need to make front end pcb accesible

when you make that ,take few frontal pictures of pcbs and post them - so we can see is there need for changing small electrolytics and anything else

btw. pot you have on pcb is for setting Iq - standing current

you have appropriate info (pdf file) for that here : Treshold Treasure ?? while Papa was there : 400A | Zen Mod Blog

but , prior to that , you need to solve offset issues
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Old 27th January 2016, 11:06 AM   #7
alfalf1 is offline alfalf1
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Default the digit on transistor and foto

hi Zen the digit on metallic transistor si d8924

i dismount the left drive card following picture:


help to set dc offset to threshold s450-circuit_4-jpg

i wait your news
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File Type: jpg circuit_4.JPG (221.1 KB, 132 views)
File Type: jpg circuit_1.JPG (121.3 KB, 17 views)
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Old 27th January 2016, 11:42 AM   #8
alfalf1 is offline alfalf1
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Default right driver card

folloguing right driver card

help to set dc offset to threshold s450-circuit_dx-jpg
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File Type: jpg circuit_dx.JPG (205.6 KB, 122 views)
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Old 27th January 2016, 12:13 PM   #9
alfalf1 is offline alfalf1
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another information i dont know if is it possible to be usell about the problems

i have disconnect the power supplay 24 hors before, and when dismount the card on the 6 big power cap (33.000 UF) 5 was discharge and only one was still full chargeed.
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Old 27th January 2016, 01:02 PM   #10
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help to set dc offset to threshold s450
isn't that small transistor 2N5566 ?

however , while you're at it - replace those 2 electrolytics (1 per pcb)

take a gooooood look at solder side , re-flow any suspicious solder point

I'll dig adequate FE schematic later , maybe no before tonight
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Last edited by Zen Mod; 27th January 2016 at 01:04 PM.
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