I think that this IC was only produced in one plugin, and for only a particular run of serial numbers.
I may have a problem with mine, I may not.? I'd be tempted to replace the whole board with an FPGA or a CPLD working at 500 Mhz, but I don't think I have enough incentive to do so.? If I ever found another 7D15, I'd be tempted to fix it, or mine, depending.
Best of luck, I think.
Harvey
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On 1/12/2022 7:57 PM, n4buq wrote:
Mark,
I'll try that. It could just be a "perfect storm" of several parts contributing to the failure.
Regarding one of these plugins, one of the custom ICs has one bad output (the 2^0 bit) which causes odd frequency values but most everything else works on it. I keep thinking I can retrofit something to take care of either the entire IC or, perhaps, just handle that one bit's output. I swapped that IC between the two and the problem follows the IC so I know that's the problem. I wish I could source one of those ICs but I think that's just about impossible now.
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Mark Vincent" <orangeglowaudio@...>
To: "tekscopes" <[email protected]>
Sent: Wednesday, January 12, 2022 5:46:13 PM
Subject: Re: [TekScopes] A Tale of Two 7D14s
Barry,
Change the resistors that are out of tolerance to see if that makes a difference
since you say they are almost double the rated tolerance. A "bad" transistor
can work in one area and not another. I have seen this with new in box active
devices before. The specs of the one transistor that will not work could be out
tolerance, e.g. voltage drop at saturation. This number plugin I would like to
get one day.
Mark
