Can some one explain me this amp?

[Tarzan]

Hi, I stumbled acros this amp and I like to understand it.
I do not have it on the nbench any more so I can't give more details as given now.
It's a commercial design and I do not wish to disclose the manufacturer.

Here is a link:
http://docs.google.com/Present?docid...&invite=4dc5vw
But if you like mail me and I send you a good copy in pdf format.

1. If you look at the PSU, Where is the ground?
Are Q12 and Q15 setup to create a virtual ground?
2. Q14 and Q17 must be the power stage and Q5, Q18 the drivers.

At the moment I received the amp.
PSU part:
fuse F2 was gone.
R26, R73 of the -15V burned.
AMP part:
R16, 17 and Q5 gone.

After replacing this is what I noticed:
D16 is not lit (LED is OK)
+15V is present at R44. +1.8 over D16.
+20.9V at J1 with no load connected.
0V with load.

Why is D16 not ON?
Voltage to low but why?
I checked the parts around D16 and they are all OK.
All other power supp;y voltages measured normal.


What else can be said about this design.

[peranders]

The link you gave us is not particulary good.

[Jan Dupont]

To bad quality to see any details.......
Post the PDF here.....

[Tarzan]

I tried to make the file smaller in size but could not.
Every body who wants to have a look can write me and I'll send the pdfs.
Unless some one can tell me how to make a pdf file smaller and how to make them available?
I tried with importing it in Corel draw and exporting it to jpg. I could go to 250K. The limit is 102.4K.
Tarzan

[Tarzan]

Of course my address:

VMI at Advalvas dot be

Sorry, forgot...

[Jan Dupont]

You got email

[Tarzan]

Must be in your mailbox by now.
Tarzan

[Jan Dupont]

Got it...
Strange how these files can be so large ??????
I'm now trying to reduce the sizes, but have failed sofare

[Jan Dupont]

Here is the first file

[Jan Dupont]

And the second one