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TX-9500 II DOA AM section S.O.S.

Ricktptman

Ricktptman

High Fidelity Enthusiast
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Hey Audiokarma folks,
I'm down to the last few pieces that I put aside for a "someday" restoration and I thought this TX-9500 II would be an easy restoration if I could find the broken off level control pot. I found a source for NOS ACY-178's in Hong Kong, but I didn't think to test the A.M. band because the FM worked pretty well. There were some other small trauma issues from its previous life and I fixed those along with the level control pot. But...the AM section is flatlined. (I wish I'd thought to test that before I ordered that potentiometer.) So now, I only get voltages on one side of the HA1197 chip, so I suspect that it may be at least part of the problem. So, my question is this: Are the last three numbers on the HA1197 the individual run code? Are they all the same, apart from that identifier number? I've never done a lot with (replacing) IC chips, but I have (with 3 different last digits) an HA1197 0A1 (from a parts carcass SX-780) and the AM chip in the 9500 II is an HA1197 6E4. Will they sub for each other? Anything else I should look for before I haul that 6E4 out? Thanks in advance, Tuner gurus...
 
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I believe there is only one "flavor" of the HA1197, and what you are seeing is a lot/run/date code.

Verify the supply voltage up to the IC farther upstream in the circuits.

A 16-pin DIP socket may be a good idea, whether it ends up containing the original HA1197 or a replacement.
 
Thanks, Watthour. I just wanted to get a verification regarding what I was seeing. At this point, I guess I just need to swap 'em out and see what changes that yields. Thanks again...I'll post back what I find...
 
Thanks for the advice, Markthefixer! I deoxit-ed it before I installed it. It was an original and it works 100% great. I was just so dumb for not looking at what else was going to be needed. I like to try to save everything that I come across, and sometimes it's just not possible. I'm beginning to get a little discouraged. I've ordered a set of those 2SK55's, just because that whole section of the board is down. No voltage anywhere on that part of it. Again, all the fuses are replaced/good. Everything's been cleaned up although this was a nicotine fiend's tuner in its early days. But it's spic n' span (95%-ish percent, if I could find it I cleaned it) now. But it's final destiny might just be as an FM only tuner. I was able to successfully transplant that HA1127 and it changed nothing. Same symptoms as before...hmmm...
 
??HA1127?? HA1197....

There could be a depowered power trace, dying cap shorts out and pops an inline resistor?? Trace the power incoming to the board. as in RC filters for power..
 
Yep, I've been working through the night on this thing two days straight, and I was sleep-deprived. You know what my fingers meant to type, even if they didn't, lol. Thanks for the suggestions. I'm beginning to suspect the P.S., even though statistically I've only ever encountered ONE component (recently, though) where that was the actual problem. (I've owned a lot of gear, but it's still not at the volume level that you experienced as a full-time tech, I know that...) I can't keep everything, and at this point throwing serious parts money at it is becoming increasingly ill-advised. Somebody was in it before I got it, and I now think that the AM section was why it was "tossed" (and I found it out in the wild) in the first place. After these 2SK55's get here, I'll have to reevaluate. The voltages on the board seem okay, but I will recheck them after I get some shut-eye. Thanks!
 
Just trying to probe on these old devices, they are very tarnished, hard to make a good contact. Take a look at the HA1197 data sheet, it provides some info. Have to check if the LO is running, need a scope, inject a RF signal and trace.
 
That's a good suggestion. I haven't found any voltages on one entire side of either HA1197. (It wasn't the problem, evidently.) I'll do a little more digging. Thanks for the suggestion!
 
If you measure and post the HA-1197 pin voltages, that may help some of us. Measure carefully, with a shrouded meter probe tip to avoid any possibility of shorting anything.
 
Will do, Watthour. Thanks for the suggestions. Thanks again, Markthefixer, you've been a big help to me with some SX restorations in the past. I'm on it...got some shuteye last night...feeling a little better. Those 2sk55's are here, we'll see what they contribute... : - )
 
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