| ManUtd |
Hi There,
Got an old version of AW-100DM from 1986.
One channel is defective and the other one has been repaired
with new transistors,diodes,electrolyts.
I now need to know the bias adjustment of this amp.
On working channel i can measure approx. 2mV DC across emittor
resistor in Outputstage.
Supply voltage for AW100 is +-42VDC for outputstage.
Picture shown is for AW65,but is almost same AW100 has more
outputtransistors.
Is 2mV a normal Bias voltage for this circuit?
Thanks for any helps.
ManUtd |
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| ManUtd |
| To bad picture,sorry. |
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| Rambi |
| quote: | Originally posted by ManUtd
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Is 2mV a normal Bias voltage for this circuit?
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If the emitter resistors are 0.2 ohm (I can barely determine that from the picture) then 2mV is about 10mA. In this kind of circuit I would expect something like 100mA (20mV).
I don't know/have this amplifier, so maybe someone else (who does) can confirm this?
Remco |
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| ManUtd |
Thanks for your reply.
Yes,unfortunately picture is of bad quality.
Resistors are 0,2R and 3watt +-5%
When it is cold i measure 0,5mV and when it gets
hot i measure about 2mV.
This is measured on the one that is working and gets "normal hot" after
some 1/2 - 1 hour usage.
ManUtd. |
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| Nelson Pass |
| quote: | Originally posted by Rambi
If the emitter resistors are 0.2 ohm (I can barely determine that from the picture) then 2mV is about 10mA. In this kind of circuit I would expect something like 100mA (20mV).
I don't know/have this amplifier, so maybe someone else (who does) can confirm this?
Remco |
I too would expect the 100 mA / device number after
warmup, which is about 20 mV across .2 ohm. |
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| Beachmountain |
Thank You, ManUtd!
I have an amp just like that where the left channel is frying bacon at me. It works fine for a few minutes, then it starts to misbehave.
This will definitely make it easier to find the fault.
Anyone with suggestions as to what might be wrong?
I have just recapped the whole thing, and the rying remains, so I suspect one or more of tge active components.
On the other hand am I no electronics wiz :-).
Regards/Beachmountain |
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| homemodder |
| What amp do you have??? Im not so sure the amp in the first post is a electrocompaniet, never seen a schematic of that company that even resembles that one. |
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| ManUtd |
| I got the copy directly from E.C so it is deftinately a original. |
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| jacco vermeulen |
And identical to the schematic of the Audiowire 65 that Mr Pairo used to have on his homepage.
The Norwegians seemed to have a thing for fast NEC output devices. |
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| homemodder |
It seems so, 80Mhz ft, I wasnt aware that one could find output trannies that fast.
Now for some questions, This model is AW100 DM ? I have schematics for AW100 but its a much more complicated amp, where did this one fit into the range??
There are slight diffrences with the schematic Jacco placed.
Manutd do you have any better version of schematics, difficult to read the one you placed. |
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| jacco vermeulen |
| How many would you like to see ? |
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| Zen Mod |
| quote: | Originally posted by jacco vermeulen
How many would you like to see ? |
Photoshop does wonders ........
:clown: |
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| homemodder |
Seeing is no good at all, Ill rather buy them for experimenting. Selling??? Price???
I would also like to buy some of those fets you had a picture of in another thread, 2SJ49 or 50 plus their complements it seemed to me , excellent parts. |
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| homemodder |
| Photoshop is wonderous indeed, but just maby Jaco has got piles of these devices he places pics of, maybe he would like to get rid of them.........:rolleyes: :rolleyes: |
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| Zen Mod |
| quote: | Originally posted by homemodder
Photoshop is wonderous indeed, but just maby Jaco has got piles of these devices he places pics of, maybe he would like to get rid of them.........:rolleyes: :rolleyes: |
nope ;
Jacco need them all , for retirement ....... then he'll use them to build something .....
:rofl: |
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| jacco vermeulen |
Merely a hint that these devices can still be found, somewhere.
Posting pics doesn't mean i sell stuff, just info.
The schematic i posted reads Jensen, not Electrocompaniet.
Abrahamsen learned his trade from Otala, who used plenty of NEC devices in the Citation XI and XX |
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| PaleRider |
| If you want that amp a lot more powerful and dynamic contact me. Mod blessed by Abe. |
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