Looking for some info on this. Internet searches come up with very little. Normally a tuner I would just ditch the bitch (you know a divorce lawyer us ed that phrase in his advertising ? lol) but I see one went on eBay for lik e $79. That is alot for a tuner on eBay. I notice it has selectable IF band width as well. I've only had one or possibly two tuners in my life that had that. I know what it does and that it takes a little doing to put it in as a feature. So maybe this thing is worth fixing.
It does not use any of the usual front ends I recognize. The front end is n ot integrated PLL from what I see. It is bigger than the usual and it has t erminals marked "Vt" and I think "Fosc" or something like that. That indica tes the PLL is not in there.
There is very little out there on this thing, one sold on eBay, and there i s a monitor or something with the same or similar model number that polluts the web results. So I decided to attack the chipset. What I can see is an LA1247 AM IC, LA1235 FM IF/detector IC, LA3450 stereo decoder IC, two M5218 L OP AMP ICs near the audio output jacks and two "c1163" right near the fro nt end. (obviously upc1163)
I can get nothing on these for some reason. Web searches indicate it is equ ivalent to a Sony 8-759-111-72. They're only a seven or ewight pin SIP thro ugh hole. I believe they are probably just OP AMPs but it wod be nice to at least know their pinouts with them being right next to the front end.
Symptom is it pretty much tunes nothing. One time as I am hitting the up bu tton and the display is incrementing though the stations it got something w eak but it was at more than one station. Bottom line is that it is not tuni ng what it is supposed to be tuning.
None of these chips I see are a microprocessor. It might be a surface mount on the bottom of the board or it is might be on the front panel. Thing is I don't see any shielded cable running up there to feed it the local oscill ator sample.
That leads me to believe it could be a surface mount on the bottom of the m ain board.
Why are those obviously unsophisticated ICs right by the front end ? Are th ey the active filters for the digitally generated tuning voltage ? Perhaps one for AM and one for FM ? Anyone know WTF a upc1163 is ? Or the pinout ? I doubt they are for AGC, but then we are talking NEC. Sometimes they did t hings a little different. If this tuner is of the vintage I think, they did a little different in it.
The fact that it got a station on multiple station settings, when supposedl y being a PLL, means the L in PLL ain't there and it is therefore not Led. Any idea about what I should expect on a scope fron the "Fosc" or whatever that terminal is ? (don't have the unit in front of me right now)I popped t he lid and I don't see any ICs in there so I really doubt there is a presca ler of any kind. It is probably a direct sample. Hell, we are talking less than 20 mHz here. It must, however be somehow unloaded from the local oscil lator so it can run. That is especially true if they pipe it all the way to the front panel.
I do not even know what year the thing is. Information is that scarce, at l east to my searches. The year is not marked on it, rather a date code. Of c ourse that is not the holy grail either, it could have surface mounts on th e other side or even be those hybrid boards where they cover the IC with a blob of epoxy type stuff.
I can't say this is a labor of love, but it is something I will do in spare time. It would be nice to have a high end tuner. My one Pioneer tunes real ly well and I have a Technics that pulls in IHF 0.95 uV. Not that I use it. This, or that or whatever will probably go to my sister because I accident ally cut the dial string in her vintage Marantz. I mean really vintage, not the junk ones. A 2225. I have to order all the lamps for it and figure I'l l put it back together so she can at least use the amp for now. So it would be nice to have a tuner. (hmm, there is an Onkyo T-4055 around here she co uld use that we can't sell because of cosmetic issues, but I still want to fix this thing)
Either way, I am not as concerned that the resale value isn't all that high , I think it might be one hell of a good tuner. If it rivals the tuner in m y SX-850 which has been teaked and can pick up a stick in the mud from Chin a, and it has this IF bandwidth doohickey on it, I want it. Why not ? I got three turntables in the house and about five records. No, four, one is on loan from someome else lol.
But this might turn into REAL troubleshooting, and I might find a one meg r esistor open or some shit. Like the old days.
Any info you got is appreciated. Even comments unless they are, well you kn ow.
Thanx in advance.