Tuner on Sony GX9ES stuck in Japan FM 76-90 mode?

One of the Sony tuner manuals says; If the appropriate display does not appear, the microcomputer in the tuner is not working properly. Turn the power off. Press and hold 0 and 9 while you turn the power on by pressing POWER. This erases stored memory and returns the tuner returns to its initial factory settings.

Might also try holding 0 and 9 while on and pressing power if that doesn't work.
Just tried this, but sadly didn't work. Thank you though.
 
it still only shows in whole numbers in increments of 10. It doesn't change to 530, 539, 548, 557, 566... Is that what I should be seeing?

No. The controller is clearly not changing stepping correctly. We have 9KHz spacing here in Australia. All our stations are divisible by 9KHz and the steps are 9KHz jumps. Stations are 612,972,1008,1134 etc.
 
No. The controller is clearly not changing stepping correctly. We have 9KHz spacing here in Australia. All our stations are divisible by 9KHz and the steps are 9KHz jumps. Stations are 612,972,1008,1134 etc.

Ok, thank you for clarifying. That at least gives me a better idea of where to look in the schematics. I do know that it has no problem tuning with those same two -/+ buttons though in both AM and FM. I've just pulled off the cover and faceplate to see if I could see anything unusual on that controller board, but no, everything looks normal - no burn/scorch marks, no odd smell, nothing. Even took the extra step to lightly prod at different components on it with a plastic tool while powered up to see if maybe there was some type of poor solder connection, but there again, nothing was resolved or even did anything funny for that matter.

Only just now put it all back together and am content (read:frustrated) to just leave it before something else stops working. At least the rest of it works properly. Only other thing I can think of is to leave it unplugged for about a month and see if the memory of everything just clears itself out like it says in the manual. (But that would mean leaving my new toy unplugged for a whole month :( )
 
Well, just got off the phone with united radio. They were not pleasant. A blunt, "None of our technicians work with anything that old. Can't help you. Try the internet."

Needless to say, nothing resolved there either.
 
I don't have time right now to look at the manual, but look at the schematic of the processor. Look for a pin that says "Reset." or MCLR. Short it to ground momentarily.with the power on.
 
I don't have time right now to look at the manual, but look at the schematic of the processor. Look for a pin that says "Reset." or MCLR. Short it to ground momentarily.with the power on.

Thank you for your suggestion. Let me just check with you before I do anything. Enclosed are both the schematic from the service manual, and the datasheet info for the UPD75108CW chip.

The datasheet says that pin 45 is the reset pin.

DatasheetControl.jpg


In the schematic, it is unlabeled, but it does lead off to a transistor there at the bottom right corner of the pic.



control.jpg



Just to fully clarify before I attempt anything, this is the pin I should short to ground momentarily?
 
I think it may have returned to Japanese intitial factory settings! :)

Yeah, that occurred to me too.:(

However, even if so, there must have been some provision for changing it from that to US settings, some sort of menu to select the country, like Sony's SW radios have.
 
Here's the datasheet:

Thank you for providing that permanent link.

So there on pdf-page 6, the drawing I have above. Pin 45 is the reset. Grounding that is just going to put it back to factory settings (not erase the chip itself)?

I’m totally cool to pull the cover on this again and try it out. I just wanted confirmation first that this is indeed the correct spot, so I don’t end up irreversibly damaging that chip.
 
Yeah, that occurred to me too.:(

However, even if so, there must have been some provision for changing it from that to US settings, some sort of menu to select the country, like Sony's SW radios have.

What you say makes sense, and I though so too, but there is nothing in either service/owners manual that refers to the FM side of the dial, only the AM. And as I’ve mentioned above, neither Sony Consumer Support nor Sony Pro/ES support have any idea how to switch it back.
 
It looks to me like pin 45 of the microcontroller is pulled low at every power up by IC904. Your manually pulling it low isn't likely to do anything additional. On the other hand, the Vdd power pin (pin 32) is held at positive voltage after power off by a combination of capacitors and that is likely how memory state is maintained. C903, C927, and C910 may all be contributing to that. C910 is of the "supercapacitor" type and is probably responsible for long term memory retention. Pulling pin 32 low (maybe through a resistor) with power off might accomplish something equivalent to leaving the unit unplugged for a month.

There was definitely some wisdom to what you said earlier about quitting when you were ahead, though. Get some other opinions before trying this.
 
Just pull the Supercap (C910 .1F/5.5v). Leave it out. Power up after 20 mins and see what happens. See whether the 9/10KHz AM step set works too after that.
 
It looks to me like pin 45 of the microcontroller is pulled low at every power up by IC904. Your manually pulling it low isn't likely to do anything additional. On the other hand, the Vdd power pin (pin 32) is held at positive voltage after power off by a combination of capacitors and that is likely how memory state is maintained. C903, C927, and C910 may all be contributing to that. C910 is of the "supercapacitor" type and is probably responsible for long term memory retention. Pulling pin 32 low (maybe through a resistor) with power off might accomplish something equivalent to leaving the unit unplugged for a month.

There was definitely some wisdom to what you said earlier about quitting when you were ahead, though. Get some other opinions before trying this.

Just pull the Supercap (C910 .1F/5.5v). Leave it out. Power up after 20 mins and see what happens. See whether the 9/10KHz AM step set works too after that.

Ok, so if I understand you guys correctly, this is the capacitor I'd want to pull from the board for a while to possibly reset the memory completely. Since I now see where it is, next time I've got the case open, I'll see if I can get to it.

C910.jpg


2k0666e15754.jpg


That bottom pic is from the OP over on that other site (2nd to last post on that page) that I linked to in the 'purchase thread', I now remember that he mentioned that his GX10ES wasn't retaining memory, and he replaced it with that capacitor in the photo (though he didn't explain his reasoning for changing its value). I didn't realise that this would also be possibly forcing mine to retain its current settings.

I've got a little basic knowledge of electronics at this detail, but certainly not enough to be able to just look at a schematic and a board like looking at a roadmap and be like 'oh yeah, that's what we're looking for...' LOL

Thank you very much! I do appreciate your patience and help. I'll let you know how it goes once I get that board out of there.
 
Shorting the supercap was going to be my next suggestion. Try shorting pin 45 to ground first, in case it isn't getting a good reset on power on. If that doesn't work, short the supercap. No reason to remove it and just removing it may not fully reset the memory. Usually that pin draws a very small current so it may maintain it's charge for a while unless it is grounded.
 
Shorting the supercap was going to be my next suggestion. Try shorting pin 45 to ground first, in case it isn't getting a good reset on power on. If that doesn't work, short the supercap. No reason to remove it and just removing it may not fully reset the memory. Usually that pin draws a very small current so it may maintain it's charge for a while unless it is grounded.

Ok, thank you. When I go to short it, which side gets shorted to ground?(The side electronically closest to pin45, or the opposite?) Or am I just supposed to short its terminals together with a wire or resistor?

You know, today pin 44 of that microcontroller is seeming kind of interesting to me, what with the way it is labeled in the schematic (like it has a function of some kind) but is just wired to ground through a resistor (like it has no real function). Kind of makes a person wonder what it might do... :D

Thank you for your suggestion, but please forgive that I don't completely understand - are you saying that pin 44's resistor may be bad? And beyond that, that resistor may be what tells the controller chip what country it's in? In other words, in Japan, Sony stereos using this same controller chip that resistor may be a different value?

Coincidentally, the Walkman from around that same era was able to switch on the fly using just an extended keypress and the hidden enter button. http://stereo2go.com/forums/threads...sony-wm-fx822-radio-tuning-to-us-region.2110/ The online service manual isn't clear enough to see the pin labeling on the controller chip to see if it's something even remotely similar to this one though.
 
FOUND IT!!! :D

Fellow member @andy had this same problem on his GX10ES waaaaayyyy back in 2004. LOL

I'm not sure if this is vintage enough for this forum, but I'm hoping someone here will be able to answer my question.

I have a Sony STR-GX10ES receiver works great apart from that the tuner seems to be in the wrong mode. It tunes from 79-90 MHz on FM and 522-1611
kHz on AM in 9kHz steps. I think this is the Japanese FM band.
There's no obvious switch for changing tuning modes and I'm sure this
receiver was made for the US market (120V with the manual in English).
It doesn't respond to the key combination that's supposed to switch
between 9kHz and 10kHz AM spacing. Is there a key combination for
changing it back to US tuning mode? I remember seeing such
combinations in the service manuals to other Sony receivers, but I
don't have the service manual to this one.

Which a member on a different site (which appears to be him too) managed to figure it out: http://www.edaboard.co.uk/sony-str-gx10es-tuner-in-japanese-mode-t19220.html

(Quoted from different forum)
It turned out to be caused by a bad memory backup cap. Removing the
old one was enough to reset it to US tuning mode. Installing a new
one has it working as it should. I guess the voltage was low enough
to corrupt the memory, but not low enough to reset it.

And even then, @dr*audio called that memory cap, too!

Think you may need the service manual for this one, but try a memory reset:
Locate the microprocessor, usually on the control panel pc board. There should be a large value capacitor or a battery on this board. sometimes it's on the main board. If it's a cap (4.7 Farad or something huge like that) with the power cord unplugged, short the cap for 1 minute, then plug the cord in and try it. If it's a battery (silver disc type) remove it by desoldering it, then reinstall it.
If this doesn't work, get the manual. You need to locate the reset line to the microprocessor. With the unit powered up, short the reset line to ground for 5 seconds, then check the tuning again. If this doesn't work it has to be a hard wired option. When you order the manual, make sure to ask for any technical bulletins on that model. They are available, you just have to know to ask for them. Get it from Sony DAPC
http://servicesales.sel.sony.com/web/index.jsp
You may want to call them to ask about the bulletins.

Guess the reason I wasn't finding the answer was that I was too specific about my model number, should've considered that the GX10ES was using the same controller/tuner.

I love the internet! It's the modern day Library of Alexandria.

Thank you to you all for helping me with this! Andy, you too, though you're probably only just now figuring out that you've helped me with mine! LOL

So, for the time being while I'm waiting for a replacement capacitor, would grounding this one at least get me back into US FM?
 
Back
Top Bottom