[rtate]

I have been troubleshooting a "hiss" problem with my VA model 3.

I realize that this particular model was made after Frank left the company but I'm hoping that some
similar parts might have been used in later model amplifiers.

I am looking for OP17GJ op amps and also a 14 pin chip SG4194CJ(I'm not sure what this is..)
These components are on a "bootstrap" board and I do not have any documentation.
I only have a schematic for the amplifer board.

[avahifi]

The OP17 is a fast uncompensated linear Op-Amp with a standard pin-out.  I think you can substitute a National LM357 or similar.  I have no idea what the other device is or what it is used for.

Sorry I can't help more, I never saw a Model Three.

Frank

If the devices are socketed, try swapping them from channel to channel to see if the noise follows one of them.  I certainly would line a schematic of the audio circuits if you can supply it.

[Brett Buck]

I have no idea what the other device is or what it is used for.

   Near as I can find in a short search, it's a voltage regulator, which makes sense. They appear to be obsolete (no surprise given the age) but widely available with a Google Search.  I couldn't find an English-language data sheet in my brief search.

    Brett

data sheet: http://www.ecadata.de/searchnew/such.php?ECA_KEY=SG4194CJ (have to pay for something to get it)
one of many places to buy:  http://www.ctg123.com/parts/letter/s-part-1/5988/

[rtate]

Thank you for the replys...

Frank, The Lm357 is also used on the amplifier board, I was wondering if there might be a better(more recent) sub for this unit, It is in a TO-99 package, or is this still the best choice for an application like this??

Brett, you are correct, it is a voltage regulator that supplies +/- 15V to the rails on the amplifier board.
I have tried a couple of sites from the google search and all so far have replied that they do not have any in stock.

Any suggestions on how to find a substitute??

[avahifi]

As I recall, the OP17 was a fast fet uncompensated op-amp.  You might try an AD845 or similar.  If the OP-17 is by-polar (don't remember without looking it up) then try an AD-847.  But then watch out for DC offset in the circuit!

Regards,

Frank

[rtate]

the ad845 is the recomended sub but i can't find it in a TO-99 package.
I know there are "browndog converters but I would prefer the metal can...
here is a link to the op17 datasheet:

http://www.datasheetcatalog.org/datasheet/analogdevices/400238910OP15_17_a.pdf

right now I think finding a sub for the regulator is going to be the hard part of this...

[Brett Buck]

Brett, you are correct, it is a voltage regulator that supplies +/- 15V to the rails on the amplifier board.
I have tried a couple of sites from the google search and all so far have replied that they do not have any in stock.

Any suggestions on how to find a substitute??

   I just dug through a few of the Google links and at least one place (which, I have no idea, sorry) had 85 of them in stock. Or claimed to. If worse comes to worst, since you know what it does, shouldn't be too hard to put together a power supply for regulated + and - 15V or find another 15v regulator with the same pinout.

    Brett

[rtate]

Thanks Brett, I tried to get quotes from several places from the google search.
All of the places that responded have a $200 minimum order.

Does anybody know of any good +/- 15 power supply diy kits??

Or a way around the Minimum order issue??