Hi In the previous mailbag video David Voss kindly sent in. this Sony fixes Ips 360 Gps from 1991. it's an absolute, uh, classic. And what I didn't mention in that video is that, um, there is a fault with it.

Um, so I thought we'd actually take a look at it. Not really because I want to use this thing because it's like huge and oh, it's not obsolete. It could still give you a Gps. uh uh, you know, reading and things like that.

But yeah, it's compared to today's modern Gps is what you get in your phone, or just a regular E-track scam and Etrex or something like that from 15 years ago. It doesn't even compare, but I thought it'd be interesting to do some troubleshooting of this thing and see if we can get it working. Now the fault is, I've got four double A batteries in there. I've got it all hooked up.

Here's the power switch on the side and it should. Yep, there we go. It goes. Beep comes on.

that's it in the position mode so you can see the corresponding keys there and we can put it in Nav mode and stuff like that. But of course the fault is is that we're getting absolutely nothing on the Lcd there and having a look at different angles like it. There's just not a thing there. So um, it seems to work.

Apart from that. Uh, because you know we're getting like a response. Uh, the leads are changing. It's beeping.

It means the process is working. Everything's doing just fine. It uses a Hitachi H8 process as we saw in the teardown in the mailbag. It's got a Xylinx Z80 series processor up in the main receiver up here, but all that stuff's running on the H8, but nothing on the screen.

and usually these Lcd modules don't die. so we've got a senior chipset on the back. The first thing I did, of course is reset the flat flex cable. look inspect for you know, any broken Uh wires inside there and things like that and I couldn't see anything.

I haven't buzzed out every single connection over there for the flat flex, but um, yeah, I don't look. It doesn't look like there's any issue there. so there's something else going on, possibly in terms of the bias voltage for the Lcd. Perhaps that could have failed could be one of the Lcd drivers failed? I hope not, because I won't have replacements for it.

But anyway, let's go through troubleshooting step by step. Now, the first thing I've done is just disconnect this receiver. Put that out of the way because that's not what we're focused on, just the processor and the Lcd here. So I've re-powered it up and it, uh, basically.

as you'd expect without the receiver there, it'll give you some sort of sort of error, but multiple beeps error position mode. but it still goes between the various modes and but it won't go back to position mode because well, it knows that there's no receiver there. So anyway, it's still working so still expect to see something on the Lcd with that disconnected. Anyway, with that disconnected, we can take this top board off here that's got the super cap on it for the battery.

Our replacement looks like there's some power supply stuff here. Dead giveaway is of course the large tracers coming in and out cap either side. So they're going to have an input to bypass cap output bypass cap, so that's probably a regulator. It might be another regulator package up there as well because we've got a big output surface mount electrolytic cap there.

So yeah, that looks like some power supply stuff. And of course, the first rule of troubleshooting thou shall test voltages and it looks like there's a lot more power supply stuff here. I took this uh top board off and there's nothing on the bottom there. So but here's our.

um, it looks like we've got a Dc input jack down here and we've got a little transformer, so that's going to be some sort of switcher. And sure enough, that Rf5rd part there. I wasn't able to get a data sheet, but I think it's a ricoh and it appears to be a step up Dc to Dc converter with that regulator. So yeah, that's what you'd expect under the transformer there.

now. nothing on there is immediately familiar. So yeah, I'm not going to attack that first. I'm going to do the easy stuff that I know.

But what we are going to look for is the easy stuff are the voltage test points first if we can find them. So let's have a look. Hello, it looks like we've got minus five volts there. Is that? Yeah, that's plus five is it? And nothing else? Buzzer? Um, that's not going to help us.

Oh, and by the way, you'll notice that minus 5 volts comes from this connector here, which was used to connect through to this board and you might see something familiar. Or I certainly do a 760 voltage inverter there, or a a a capacitor voltage inverter slash doubler. So it's either doubling that or usually it's generating a negative. um, output.

So that would explain Plus five Minus five going into that connector. So our negative is most likely going to be the negative of our battery over here. That one looks like a big fat ground down there. You bet your bottom dollar it is.

so we can either probe it from there or from that point there. but it's not convenient. It doesn't have a Via so you can't get your probe off there and it could slip. Just be careful.

trap for young players don't want to short something out. All right. So here we go. Let's power this thing up and we're going to measure.

Oh, that's quite loud and uh, disturbing. And let's measure our plus five. Yeah, L Plus five is good. No worries.

Minus five One one. So if we follow the money on that minus five volt rail there, it's no surprise it's coming out there. There we go. It's coming out of our Um 760 inverter.

But hang on before we go off half cot. We've got another couple of test points in here. This one's actually I believe that's V Dig, so that would be V Digital. so that could be 3.3 or something like that.

And this one in here has got the Vrf voltage reference. so that's pointing to that one in there. so I'm going to just have a quick measure of those two. We know our minus 5 volts isn't there, but our plus sorry, our plus 5 is still there.

So let's measure our voltage reference: 1.43 I don't know what it's supposed to be, but that's all right. there's something there. And V Didge. Well, there's nothing on V Didge either.

Hmm. and you'll notice that V Didge is also coming from this. Oh, is it coming from the top board? No, Here's the connectors. It's going to that.

Oh, okay, yes, sorry. Yes, it's going. No, that's going over to the uh, Gps? um. Gps receiver connector.

So yeah, that could actually be on the Gps receiver. so we might plug that in and try it again. And let's measure that again. with the Gps receiver plugged in.

Aha, V-digi is now 5.1 volts. No worries. So yes, my hunch was correct. It needed this receiver board plugged in before it would feedback.

so that regulation's over on here, even though the test point is over here. So now, the only thing we've got to trace is the one thing one known fault we've got is the negative five volt rail. So back to that top board. Now the pin out of this seven 760 voltage inverter here seems to be a bit strange because normally Pin 8 is the power here.

And look, we've got this big trace coming in to this. uh, pin 7 and it. And then we've got the well, our output here. that goes off to our cap.

Okay, so that's no worries. it's going off to the negative of that cap. so that's normal. If the output was a negative supply, that's exactly what you'd expect to find.

So that's okay. But then this comes back to Pin six here. What's going on? And usually then there's a cap. Uh, between the switching cap, it's got seven double six o on it.

It's doing voltage inversion. It's got to be a seven double six O. But it's not. Don't doesn't look like the standard pin out.

It's weird. Anyway, you could go crazy trying to reverse engineer that, and well, you don't have to. You're just chasing a red herring down a rabbit hole. probably.

so we know that we're not getting our negative 5 volts. Well, what's the problem? Well, here's one. Here's our output cap. Could be our output cap.

Could be our switching cap. Perhaps I would suspect the caps over the 760. uh, inverter there? whatever the hell? pin out it is. So yeah, I would.

um. first port a call is I would, uh, suck those off and measure the value. Let's do the minus five volt output cap. What? what? Why 600 Nano farads? It's supposed to be 22 mic fail.

So we'll replace that one there with the 22 mic cap. And uh, we can measure the voltage across that. Wow. Still failed.

So that cap was definitely dead. So we've replaced it and we're still not getting our negative. uh. 5 volt rail out and I'll just show you that.

5 volts in and we're getting exactly the same as before. So we found a dead cap. but uh, that is not it. Hmm, keep going.

suspect the other cap now. So I sucked out the other one there, which I'm guessing is the switching cap and it's supposed to be 10 mike and 1.1 mike. So yep, that one's dead too. I have to replace that.

All right. let's try that one. I've replaced. Uh, the 22 mic cap and the 10 mic cap there around that.

uh, weird. R760 and winner winner chicken dinner. Look at that. There you go.

It was the 760. inverter, no antenna unit. Oh, we can fix that. All right.

Let's try the whole thing now. Sony Gps receiver weighting acquisition. Well, we'll be waiting for a while for the acquisition there because I'm in the middle of a concrete building here. Don't even have any windows to look out from, but there you go.

that is. Uh, that is fixed. And of course we can flip that over and measure that good measure. Just make sure that's fixed.

Got our five volts going in and Bingo! Minus 4.7 Good enough for Australia coming out. Beauty. So I was a bit curious as to exactly what was going on with this 760 and I traced it out. and this is what I got.

Pin 4 is the plus 5 volts that we measured on the other, uh, main board down here. at that test point, pin 8 is actually the ground that we measured on the other uh, test point, the negative of the battery and five and six is the switching cap. and and then, oh sorry, I forgot to have the minus. Oops.

Minus five volts there. Um, and then we've got a resistor between two and three here and one's not connected. So now because we found two faulty caps on there, looks like we've fixed the problem. Um, I would also suspect the third one, but if you're going to do that, then, well.

you got to start suspecting everything over on this Gps receiver as well. A lot of them might have come from the same batch. Are they the same value? 22s? Yeah, it could be. Um, they could have like even you know, come from the same real.

Um, so yeah. I wouldn't be trusting those. So yeah. Anyway, we fixed the problem, which is what we wanted to do.

We wanted to track that down, but just be aware that you could actually go further and test that and I'd have to take it outside and test the Gps. Which I might do actually and see if it works. Um, and yeah. well.

okay. I'll put it back together. All right. I'll go outside.

Need some Vitamin D? Anyway, Looks like it's a four channel receiver. We've got four satellites on there not getting anything in here, but look at this. It was, um, a lock could take 20 to 30 minutes for the initialization. You wouldn't want to be in a hurry.

Check it out. Looks like we have a lock on number seven. Lucky Seven and that's what L stands for so the others have yet to lock in. Oh, come on, you can do it all right.

What I'm gonna do is initialize the receiver because uh, it could have last been on the other side of the planet. In fact, it was. Um, so. uh, yes.

Clear recall. Uh, what do I do? Yes, clear, clear. Okay, it's certainly changed. uh, satellite numbers now so we'll see what happens.

No. tried another set and uh, doesn't seem to be picking up anything. I only managed to get that one so I'm not sure what's uh going on. Anyway, I think it's about start to rain here.

I might have to get back indoors. So there you have it. I was able to actually get lock onto one satellite, so I'm not actually sure what's going on here with this four channel system and how the initialization works and stuff like that. The manual does say can take up to 30 minutes, but I'm I'm gonna call that a relative win.

If we can lock onto one satellite then it's at least kinda doing the business. The receivers still kind of work in and it wouldn't show um, that if it wouldn't uh if it didn't actually get the data and was able to lock onto that one satellite anyway. So there you have it. I hope you enjoyed that little uh, troubleshooting thing.

Thank you very much uh, today for sending that one in. That was interesting. We at least fixed it. as far as the fault that we wanted to fix, which was the Lcd display that turned out to be the good old capacitor electrolytic capacitor again, as we've seen in previous videos.

Often, you're not that lucky though. It could have been an Lcd driver or something like that, but unlikely that it was from the get-go Was most likely to be something relatively simple like that. Could have been the Lcd itself. Old age.

Uh, it might have. You know something might have happened to it or something like that, But my initial guess, like the bias voltage and stuff like that driving the Lcd, so that negative rail that they were getting there that was doing some of that business. So there you go. Um, yeah, I could trace it further, as I suspect you might suspect other caps on the board, so as a matter of course, you might rip them off.

Test them things like that. But as I said, there are plenty in this receiver here. and well, this thing is uh, what? 25 years old? So yeah, it's not a real useful Gps anymore, but interesting. so I hope you enjoyed that little, uh, troubleshooting video.

If you did, please give it a big thumbs up. As always, links to the forum to discuss it down below or just leave it in the Youtube or blog comments. Catch you next time. Hi, check out what I saved from the dumpster.

A classic Hewlett-packard 1740. a hundred megahertz dual channel analog scope. haha. The centerfolds look at the center fold.

look at this. Wow. metal can socketed uh, flush with the board. Fantastic.

And here's another good example why it's not a bad idea to have a couple of multimeters lying around.