Came in "dead", but only had really really bad tape monitor/source switch c ontacts. Cleaned all controls and switches and runs fine, except the FM se ems to have weak sensitivity. AM seems OK. Might be normal but I'd like t o eyeball the FM section anyway.
One net article suggests that the 7951 is a cosmetic (black) variation of the 795.
HiFiEngine.com doesn't have pages for the AH795/AH7951, but has a page for the AH794, and the service-manual for that model implies that it might apply to the 90, 92, 95, and 99 models as well. Philips seems to have produced families of receivers which varied cosmetically and in their audio power outputs, but it seems plausible that the basic schematic may be the same (or at least quite similar) across the family.
So, go register at HiFiEngine.com (it's free, and I've not gotten any spam or other nonsense from them after registering years ago) and download the AH794 service manual. I'd guess it'll be close enough to let you debug the FM section.
If it is, I don't think you should expect miracles. If I'm reading the schematic for U1001 (the FM tuner board) rightly... well, it appears to have _one_ varactor-tuned RF amplifier transistor (a BF324 run common-base) and the varactor-tuned local oscillator, feeding a one-transistor BF494 mixer/amp, which then feeds a 10.7 MHz crystal filter, a BF494 IF amplifier, and another crystal filter. There's more IF gain in the TBA570A AM/FM chip. There's a double-tuned transformer in front of all of this, which probably gives it some selectivity against out-of-band signals, but that's it.
So, its selectivity isn't going to be wonderful. Sensitivity might be something you can address, perhaps... RF and IF alignment, maybe changing out those BF324/BF494 transistors with something a bit less Neolithic :-)
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