Sharp NES freezing up

[Cornelius]

I'm thinking that's what it is, actually. It has "B P" prominently printed below the specs. Thanks for pointing me that way. Now, since I don't have that cap, can I replace it with a polarized one like it is on the front-loader? I'll do some reading.

Unless they drastically changed the board design(and it doesn't look like they did) then they should be the same. There is also such a thing as an non-polarized electrolytic called a bipolar capacitor...but I would lean more toward the first option.

[jb143]

It's weird that the regular front loader calls for a standard electrolytic and yours calls out a bipolar. But if it's on the board then they must have had a reason. Typically those caps are used if the design calls for an unpolaraized cap but the capacitance is too large for ceramic caps to be available/cheap enough
You can make an unpolaraized by tying 2 electrolytics in series (+ together I believe, you'll want to verify that). You'll use the series calculation to get your values(which is the same as the resistor parallel calculation). It's likely to be some value that's hard to find and may not fix your issue. At any rate, digikey and mouser should have an exact replacement.

That cap looks to be part of the lockout chip. Can lockout issues cause freezing like you're seeing or just the blinkies?

[Cornelius]

It's weird that the regular front loader calls for a standard electrolytic and yours calls out a bipolar. But if it's on the board then they must have had a reason. Typically those caps are used if the design calls for an unpolaraized cap but the capacitance is too large for ceramic caps to be available/cheap enough
You can make an unpolaraized by tying 2 electrolytics in series (+ together I believe, you'll want to verify that). You'll use the series calculation to get your values(which is the same as the resistor parallel calculation). It's likely to be some value that's hard to find and may not fix your issue. At any rate, digikey and mouser should have an exact replacement.

That cap looks to be part of the lockout chip. Can lockout issues cause freezing like you're seeing or just the blinkies?

I saw that trick with the two caps in series and may do that, you just get a component with half the capacitance. But I'm suspecting bad ram or other chip. I may try to hook it up so I can feel the chips during operation to see if on is getting hot. Bad idea?

[jb143]

How is power being fed into the board. I would assume a transformer replacing the AC adapter and everything else is more or less the same? Are you able to take measurements when it's running? To make sure it has a steady 5 volts before and during the freezing? Notice any smells when it's been running for a while? When you replaced the regulator did you add any thermal grease? I'd also search for tips on checking for a bad CPU.

Sorry I can't be of more help, I'm not familiar with the Sharp NES TV at all. If nothing else, I can give you ideas to try until someone who knows what they're talking about shows up

[Cornelius]

Yeah, that's about right, though I don't really know what's in the silver box where power comes into a regular NES. Picture of the power supply:



Running it while being able to test stuff is much easier said than done. I'll have to pull wires out of their routing completely and arrange things carefully. I'm sure it can be done, but a hurdle I haven't gotten around to yet. No smells. Used some Arctic Silver I had, then read not to use conductive compound, so I cleaned that off and used some other stuff.

Hah, yeah, I don't mind the help at all, I'm pretty much a novice at this stuff.

How is power being fed into the board. I would assume a transformer replacing the AC adapter and everything else is more or less the same? Are you able to take measurements when it's running? To make sure it has a steady 5 volts before and during the freezing? Notice any smells when it's been running for a while? When you replaced the regulator did you add any thermal grease? I'd also search for tips on checking for a bad CPU.

Sorry I can't be of more help, I'm not familiar with the Sharp NES TV at all. If nothing else, I can give you ideas to try until someone who knows what they're talking about shows up

[jb143]

What you could try to do is solder wires to points of interest on the board, such as the regulator and CPU power pins and run them outside the enclosure so you can take measurements while it's running. Just make sure you label everything and don't short anything out obviously. Overheating parts usually make a distinctive smell, that's why I asked about that.

I'm mostly going by what I remember being issues with a regular NES, and I'm pretty sure most freezing issues are either due to bad connections or power problems. It certainly wouldn't hurt to clean every connector again just to be sure. If it was a chip going bad, swapping one out from a working NES would be a pain but doable. You would just have to be careful not to pull up any pads or traces.

Are you talking about the RF modulator on the original? I think the power jack is inside of there. Yours shouldn't need one, at least I certainly hope not. Are they running composite to the TV? Like I said, I'm not too familiar with these...other than it's a cool collectors piece that would be a shame to have not work anymore.

[Cornelius]

Are you talking about the RF modulator on the original? I think the power jack is inside of there. Yours shouldn't need one, at least I certainly hope not. Are they running composite to the TV? Like I said, I'm not too familiar with these...other than it's a cool collectors piece that would be a shame to have not work anymore.

Yes, that's what I was referring to. You asked how power was being supplied, and I was just saying I didn't really know how it compares to what is in a regular NES. I think the rectifier(?) and other power stuff is all in the box with the RF modulator, but haven't looked in there to compare.