Adcom GFP-565 IC Part Numbers???

[Zero Cool]

Anyone have a cross reference sheet for Adcom IC's???

I am repairing a GFP-565 pre-amp that has a bad Adcom 7A chip. it is the buffer chip for the record out jacks.



Zc

 

[Bill Fuss]

Look for the article about the 565 in an older AudioXpress. Quite a bit was discussed regarding the opamps. I have it but I recently moved, haven't shown up yet. I'll PM you if they show up soon.
Best, Bill

 

[jackinnj]

LT1057 -- according to Galo they were used in Class-A and were prone to an internal failure of the positive rail connection. In Galo's article he substituted an AD744KN and and AD811AN gain/buffer a la Jung.

 

[Zero Cool]

I dug out my copies of Audio Express and read through them. the Tape output buffers are out in my pre-amp. The main outs are still working (I see he used the AD744KN and and AD811AN combo for the main outs) In the article he replaced the tape buffer LT1057's with AD712's at first retaining the pull down resistor on the output for Class A, and later he replaced those with OPA2604AP's without the class a resistors.

I have some OP275's on hand and im wondering if they would be suitable and if so, should I use the pull down resistors with the 275's???

 

[jackinnj]

There was an update in 2004 -- I am thinking of using the LME49600 as part of the compound buffer.

 

[Zero Cool]

There was an update in 2004 -- I am thinking of using the LME49600 as part of the compound buffer.

Right, but the compound buffer was for for the main outputs, not the tape buffers.

I just need to repair the tape buffers so i can sell the pre-amp. Or are you talking about making a compound buffer setup for the tape outs too?

Zc

 

[jackinnj]

No, just replacing the existing Main Out.

I appreciate what Gary was trying to do, but a pre is still a pre and I like the ability to drive phones, tone controls. I don't think you need "contour", however.