I have an NES that freezes after sometime of use. I have a new 72pin connector, disabled lockout chip and squeaky clean games. Does anybody know which chips I can replace on the board to fix this? I have already replaced the electrolytic capacitors. I'm trying to keep my original board since I've had it since 1985.
Take apart your games and clean them with some Weiman's Glass Stovetop Cleaner [$5 at walmart for a near lifetime supply] and then clean them with that, put a little bit on a rag and then rub against the connector as hard as it needs to clean it. Do it for both sides and then wipe the connector with some alcohol and it'll be good to go.
It's fun, I also have a NES that have the exact same problem, it freezes after some time, but now it eats dust in my garage.
The connector was certainly not the problem, I didn't try to replace all electolytic capcitors but if you say this didn't change a thing then this is probably not the problem in my NES either.
I guess this has something to do with some heat problem, as once the NES freezes, it won't restart even if you reset or power cycle. Maybe changing the power supply completely by a modern switching regulator that doesn't dissipate heat would fix the problem ?
I cleaned all my games with a pencil eraser and some Q-tips with rubbing alcohol, I was able to remove most all oxidation on some pretty dirty games. I suspected some kind of overheating, though I wouldn't even know where to start by installing a switching regulator. I was thinking of buying a new proven mobo and swapping out the PPU and CPU to see if that takes care of it.
It sounds like heat especially if it won't work after cycling the power like Bregalad's does.
I would remove pull everything apart removing the screws and then just loosely put it back together without the screws. Then play it till it freezes. Pop it apart quick and feel all the ICs. Nothing should be WARM except the power regulator. The heat sink on the regulator should be warm but not HOT.
If it is a problem with the power supply you should be able to just replace the bad components instead of a full switching PS replacement.
If other IC's are not unusual hot, it's better to replace 7805 and caps around, include ceramic ones
80sFREAK wrote:
If other IC's are not unusual hot, it's better to replace 7805 and caps around, include ceramic ones
What's 7805 that ur referring to 80sFREAK?
A linear voltage regulator. The 7805 regulates its output to 5V, provided it has suffisent voltage at its input. It should be near the place where you plug the AC adapter in the NES.
(If you're curious, check this
datasheet)
Ok I might have found it. Its right outside of the power sup with 3 prongs part# is HA 17805. When the games freeze up the heat sink around it is hot ass hell.
Oh and the IC's are only slightly warm when the games freeze. So I'm guessing their ok.
Well it sounds like you're hot on the trail. You could try to do some further verification if you wanted by trying to better cool that component itself. Perhaps shield off everything except that heat sink and blow a fan on it. See if it keeps it cool enough to play longer or stay on.
Either way it's a fairly likely component to fail and wouldn't hurt to replace especially if it gets to hot to keep you fingers on. My sink gets warm but never too hot to hold with your fingers.
http://search.digikey.com/us/en/products/BA17805T/BA17805T-ND/658262
That looks to be you're direct replacement. But I'm guessing any standard +5V 1A regulator you can get your hands on will work.
EDIT: one good thing to check though, it's possible some other part has failed and is then drawing a lot of current so the voltage regulator can't keep up and over heats. It would be a good idea to do a resistance check between Vcc and GND somewhere should be pretty high atleast a couple Kohms or more I don't know a more exact number.
martinpal80 wrote:
Ok I might have found it. Its right outside of the power sup with 3 prongs part# is HA 17805. When the games freeze up the heat sink around it is hot ass hell.
HA17805=7805
check voltage on the pin 1(left pin, when you can see "face", some IC's have opposite). if there is more than 9V, you have to choose proper power supply. let me guess, yours is cheap noname "universal adaptor"
I guess they now make switching power supplies which does not dissipate heat that can replace 77xx regulators in most applications.
The way the power suply of the NES has been engineered is plain stupid, if the NES uses 1W of power, it will dissipate ~2W in heat. A switching regulator is the only way to solve this problem.
Bregalad wrote:
I guess they now make switching power supplies which does not dissipate heat that can replace 77xx regulators in most applications.
The way the power suply of the NES has been engineered is plain stupid, if the NES uses 1W of power, it will dissipate ~2W in heat. A switching regulator is the only way to solve this problem.
back in early 80'? I don't think so. Also if you dissipating more than 30% of load, your transformer is not suitable - voltage is too high. Good switching regulator is quite expensive device, otherwise it's very good source of EMI
Then the NES should have been powered in 6V AC instead of 9.
Also NES was released in mid 80's, not early 80s.
I can tell I definitely came to the right place to get help with this problem. It makes sense that the regulator could be the culprit. When I replaced the elec caps I used the same mF , but had to use ones with a higher voltage tolerance since that was all I could find. After that it would actually last a lot longer before freezing.
Bregalad wrote:
Then the NES should have been powered in 6V AC instead of 9.
Also NES was released in mid 80's, not early 80s.
I guess, you should go to library to read some books about basics electronics. Also, do you think, if NES been released in
80', design took one night? You are kidding or you definately need to read smth apart from manga
martinpal80, good to hear that. Voltage doesen't really matter, except three things - 1)not less than 16V 2)than higher voltage, than higher price 3)than higher voltage, than bigger size, so they might not fit. By the way, did you checked voltage on pin 1, when your console "on and running"?[/url]
Bregalad wrote:
Also NES was released in mid 80's, not early 80s.
The NES might have been, but the Famicom is from '83, and if you consider the time needed to design the console, it's definitely early 80's technology.
EDIT: Oops, 80sFREAK already mentioned the date thing.
infiniteneslives wrote:
You could try to do some further verification if you wanted by trying to better cool that component itself. Perhaps shield off everything except that heat sink and blow a fan on it.
Or turn over a can of compressed air and blow the cold liquid on it. I used to repair monitors and would sometimes identify failing components by doing this.
James wrote:
infiniteneslives wrote:
You could try to do some further verification if you wanted by trying to better cool that component itself. Perhaps shield off everything except that heat sink and blow a fan on it.
Or turn over a can of compressed air and blow the cold liquid on it. I used to repair monitors and would sometimes identify failing components by doing this.
Good trick!
Tx for the great ideas everybody! Hopefully I can tinker around with this tonight after work. I'll check voltage on the IC's and try to keep that regulator cool. I'll post back soon.
Quote:
I guess, you should go to library to read some books about basics electronics.
You know I've been studying EE in my country's highest school for now 4 years. Of course I have yet a lot of things to learn about EE, I won't deny it, and yes I hate reading exept manga/comics but I know the concept of linear voltage regulator and power supplies, as opposed to what you're suggesting.
A voltage regulator needs 1.5V to 2V more than the output voltage to function correctly, in the case of a 7705, it needs 6.5 to 7V as input, if the input will be any higher it will work but this will be a total waste of energy. Therefore, to get a ~7V DC input, you need a 7/sqrt(2) = 4.9 V AC -> 5V AC would work perfectly fine.
The reason a higher voltage is a waste of power is the following : All the current that the NES uses passes through the regulator and is consummed at the input of the regulator, but at a higher voltage, and Power = Voltage * Current.
For example, if the NES uses 1A of current, the power used by the NES is 5V * 1A = 5W, but the regulator will draw 9*sqrt(2) V * 1A = 12.7W, therefore 12.7-5 = 7.7W will be dissiped as heat, which is plain stupid as I've already said.
If instead they used a 5V AC -> 7V DC supply, the power consumption would be 7V * 1A = 7W, and only 2W would be dissiped as heat, greatly improving the power ratio of the system from 39% to 71%. A switching supply would improve it further to about 90%.
Sorry for offtopic, but your calculations have some mistakes. You definately need to read "Horovitz and Hill. The art of electronics".
80sFREAK wrote:
Sorry for offtopic, but your calculations have some mistakes. You definately need to read "Horovitz and Hill. The art of electronics".
I find it amusing how quickly you'll say there are mistakes but not point out what they are...
infiniteneslives wrote:
80sFREAK wrote:
Sorry for offtopic, but your calculations have some mistakes. You definately need to read "Horovitz and Hill. The art of electronics".
I find it amusing how quickly you'll say there are mistakes but not point out what they are...
There is two ways in this world - to give fish or to give fishing rod and teach, how to catch fish.
1)DO NOT mix up AC and DC
2)keep in mind, how filter working and how to choose capacitance proper
3)RTFM and study what is voltage drop
4)keep in mind pulsation and current density in the coils
and all this things just for simple "aincient" linear power supply. Do you think that design of switching power supply is more simple? Oh, boy, i have bad news for you
He's right I made an error and forgot to add 1.4V because of the diode bridge, so the minimum "ideal" DC voltage that should be (7+1.4) / sqrt(2) ~= 6 V AC.
So the true optimal power ratio is not 71% as I stated but more 5 / (7+1.4) = 59%.
So in our example of the NES using 1A, 5W would be actually used, 6.3W dissipated as heat in the regulator and 1.4W in the diode rectifier : It's arguably pretty bad.
Also, I considered the reservoir capacitor after the diode bridge was sufficiently high to neglect the voltage drop between two maximas - if this is not the case you just need to increase the capacitor's value.
I never stated a switching power supply would be simpler - I said it would greatly improve the power ratio and therefore dissipate less heat, solving martinalpal80's problem.
Even if you limit yourself to a classical linear power supply, 70% power ratio is possible but Nintendo went for 39% instead, which is a bad design choice, unless you can proof me otherwise with arguments instead of misplaced arrogance.
You're right to point this probably didn't exit yet back in the 80s, but today they make regulators that fits in those TO package and that use switching technology so that they doesn't dissipate heat - and I'd consider replacing the 7705 by such a chip in the NES.
80sFREAK wrote:
There is two ways in this world - to give fish or to give fishing rod and teach, how to catch fish.
Except in this world, it's not give a fishing rod as much as sell a fishing rod.
Price: 9378 Bells
Bregalad wrote:
He's right I made an error and forgot to add 1.4V because of the diode bridge, so the minimum "ideal" DC voltage that should be (7+1.4) / sqrt(2) ~= 6 V AC.
So the true optimal power ratio is not 71% as I stated but more 5 / (7+1.4) = 59%.
So in our example of the NES using 1A, 5W would be actually used, [b]6.3W[/b] dissipated as heat in the regulator and 1.4W in the diode rectifier : It's arguably pretty bad.
Also, I considered the reservoir capacitor after the diode bridge was sufficiently high to neglect the voltage drop between two maximas - if this is not the case you just need to increase the capacitor's value.
OMG
a bit better now, but still way to go.
two more things - shottky diodes exist and you can not increase capacitor's value in the filter, because....
Ok, checked all IC's and have 5v VCC to ground on all. Def overheating though as I could not get it to freeze up when running the NES dissassembled in my freezing cold basement. Only with the cover on, and in my entertainment stand does it seem to freeze. I'm about to order that new IC regulator... That heat sink get real hot. Can't keep my finger on it.
http://search.digikey.com/us/en/product ... -ND/658262
Hey I noticed there is two different regulator item numbers at this site. Any ideas why?
martinpal80 wrote:
http://search.digikey.com/us/en/products/BA17805T/BA17805T-ND/658262
Hey I noticed there is two different regulator item numbers at this site. Any ideas why?
What two are you specifically referring too? If I search 17805 I only get one viable choice. The other two choices are the wrong package and require quantities in the of 500 or more.
I'm sure there are dozens of 5V regulators to pick from but as far as a direct part number match you've linked to the one I'd buy.
martinpal80 wrote:
Ok, checked all IC's and have 5v VCC to ground on all. Def overheating though as I could not get it to freeze up when running the NES dissassembled in my freezing cold basement. Only with the cover on, and in my entertainment stand does it seem to freeze. I'm about to order that new IC regulator... That heat sink get real hot. Can't keep my finger on it.
OMG
It's obvious 5V on Vcc otherwise you could get fried chips. It's dissipating much more than suppose to be. You have to check voltage
BEFORE voltage regulator. Pin 1 of IC to GND 8-9V is ok, if much more, there is smth wrong with your power adaptor, or you just using noname "universal" one. Sometimes, when input voltage for 7805 regulator about 15V, IC starts working unstable and could cause "freezing"
infiniteneslives wrote:
martinpal80 wrote:
http://search.digikey.com/us/en/products/BA17805T/BA17805T-ND/658262
Hey I noticed there is two different regulator item numbers at this site. Any ideas why?
What two are you specifically referring too? If I search 17805 I only get one viable choice. The other two choices are the wrong package and require quantities in the of 500 or more.
I'm sure there are dozens of 5V regulators to pick from but as far as a direct part number match you've linked to the one I'd buy.
BA17805T and BA17805T-ND
That's the same thing.
The manufacture's part number is BA17805T
and the supplier's (digikey's) part number is BA17805T-ND
they are just two different ID numbers for the same item. Digikey basically slaps a ND on the end of all the part numbers to let you know that's their part number for the item.
Ok great! Tx for clearing that up infiniteneslives! I'm ordering some right now, along with a few spares.
80sFREAK wrote:
martinpal80 wrote:
Ok, checked all IC's and have 5v VCC to ground on all. Def overheating though as I could not get it to freeze up when running the NES dissassembled in my freezing cold basement. Only with the cover on, and in my entertainment stand does it seem to freeze. I'm about to order that new IC regulator... That heat sink get real hot. Can't keep my finger on it.
OMG
It's obvious 5V on Vcc otherwise you could get fried chips. It's dissipating much more than suppose to be. You have to check voltage
BEFORE voltage regulator. Pin 1 of IC to GND 8-9V is ok, if much more, there is smth wrong with your power adaptor, or you just using noname "universal" one. Sometimes, when input voltage for 7805 regulator about 15V, IC starts working unstable and could cause "freezing"
9.5 VDC to ground. Sometimes 10. Official original NES power supply.
Ok installed my new regulator last night on both motherboards, and left one of the NES's on all night... It didn't freeze!! Finally! That heat sink is still quite hot though, too hot to keep a finger on after just 20mins. Why didn't Nintendo use a 7V pwr sup? Were 9V supplies cheaper, and more readily available. I might just install a case fan to keep things cool.
What is the voltage in your power socket? And why did you said "9.5V sometimes 10"?
120V. Cause there is some fluctuation there.
He asked what your power adaptor ouputs, not what comes in your power adaptor. He expects an answer like, "9 VAC" or "12 VDC", for example.
9.5V - 10VDC to ground from the power adapter connector
Spoke to soon. Left the system on overnight this morning it worked. Left it on all day and when I came back from work it was frozen. Then refroze thereafter every time I cycled power.
martinpal80 wrote:
9.5V - 10VDC to ground from the power adapter connector
Sorry 9.5-10VAC to ground
~J-@D!~ wrote:
He asked what your power adaptor ouputs, not what comes in your power adaptor. He expects an answer like, "9 VAC" or "12 VDC", for example.
You were worng, he gave exactly the answer -
120V. Looks like adaptor have transformer for 100V grid, so you have 10V instead of 8V. Best way to sort this problem is... use noname universal adaptor and setup 7.5-8V
before regulator, when NES is
on. 10V is too much. Or another way is install bigger heatsink.
Just to be clear, since I haven't seen it mentioned, that with an unregulated linear power supply (like the original Nintendo AC adapter), the voltage will vary by the current used.
This page has some measurements from various ones. The voltage/current rating of 9V/500mA means it's supposed to output at least 9V when 500mA are drawn. If it's unregulated, it may be 13V or something if it's passing less current.
And also, the front-loading NES connects the unregulated power to it's expansion port, so it made sense for the NES to have some extra power available. You wouldn't need an extra AC adapter for the Famicom Disk Drive (nor a battery compartment like the FDS had).
I've been designing a board (haven't worked on it lately) that includes a switching power supply powered by the NES expansion port, and I've expected the input voltage to be in the range of 7V-20V. When using a 12V power supply I think it may be as high 20V.
Wow it sounds like another possible usage for this infamous expansion bord I've never through of !
Of course the NES can both power something else via this port or be powered completely from this port.
Memblers wrote:
Just to be clear, since I haven't seen it mentioned, that with an unregulated linear power supply (like the original Nintendo AC adapter), the voltage will vary by the current used.
This page has some measurements from various ones. The voltage/current rating of 9V/500mA means it's supposed to output at least 9V when 500mA are drawn. If it's unregulated, it may be 13V or something if it's passing less current.
And also, the front-loading NES connects the unregulated power to it's expansion port, so it made sense for the NES to have some extra power available. You wouldn't need an extra AC adapter for the Famicom Disk Drive (nor a battery compartment like the FDS had).
I've been designing a board (haven't worked on it lately) that includes a switching power supply powered by the NES expansion port, and I've expected the input voltage to be in the range of 7V-20V. When using a 12V power supply I think it may be as high 20V.
Thanks, Captain
80sFREAK wrote:
~J-@D!~ wrote:
He asked what your power adaptor ouputs, not what comes in your power adaptor. He expects an answer like, "9 VAC" or "12 VDC", for example.
You were worng, he gave exactly the answer -
120V. Looks like adaptor have transformer for 100V grid, so you have 10V instead of 8V. Best way to sort this problem is... use noname universal adaptor and setup 7.5-8V
before regulator, when NES is
on. 10V is too much. Or another way is install bigger heatsink.
Be cautious if you do something like this. You'll be hard pressed to find universal adaptors providing AC power the NES requires. I really don't think your 9.5-10volts is a problem. I don't understand why there is still so much fixation on it. Nintendo didn't make different 100 or 120 volt supply versions of AC adapters. I'm pretty sure your not the only one with 120vac main power. Its also safe to say nothing broke with your adapter Since it would have had to sprout a few more windings to give you increased voltage.
Nor is a bigger heat sink a real solution. It would be more like a bad band aid.
So is the new regulator still overheating like the old one?
DC from universal adapter will pass the bridge and you don't need to worry about polarity of connector. 20% in AC will give you roughly double dissipated heat(guess why)
OK, I used another power adapter that is outputting 8.5VAC steady, and I still had the overheating issue. That's with the new regulator installed. I'm eying that big cap on the power supply. Thinking about replacing it, but I'll have to unsolder the whole power supply from the board to remove the cover and get to it. Either that or cut the cover.
80sFREAK wrote:
DC from universal adapter will pass the bridge and you don't need to worry about polarity of connector. 20% in AC will give you roughly double dissipated heat(guess why)
Why does everything have to be a quiz? I don't think anyone really cares to play along, or is impressed by your wealth of electrical knowledge. But whatever floats your boat I guess.
martinpal80 wrote:
OK, I used another power adapter that is outputting 8.5VAC steady, and I still had the overheating issue. That's with the new regulator installed. I'm eying that big cap on the power supply. Thinking about replacing it, but I'll have to unsolder the whole power supply from the board to remove the cover and get to it. Either that or cut the cover.
Yeah there is no real fault that could occur with the adapter to cause this issue or your indications which is what I was trying to say earlier. But at least you've proven that now.
It is possible that if your capacitor is leaking (shorted out) to the point it's drawing so much current that the regulator is then becoming overloaded. I'm not sure how likely that is to occur though. Usually failed caps have visible damage either bulged or leaking fluid though.
Why do you have to unsolder the whole power supply to remove the cover??? Unless something is different with your NES, I'm able to just remove the BOTTOM cover of the power supply with my fingers. Then I have easy access to the two solder pads for the large cap. It would be super easy to desolder and remove it, check it, and replace if needed without having to desolder anything besides the cap's two connectons. Just make SURE you keep the negative terminal of the cap pointed towards the regulator, or atleast that's how it's aligned in my NES.
Your right I could just unsolder it from the bottom, it physically looks OK, but at this point I'll try anything. There must be a common component of failure in these power supplies, since I have the same problem on two NES circuit boards. They both have the new regulator installed. One is my original from the 80's that only I owned and took good care of, the other is one off of eBay sold as broken that my friend used the case to make an NES pc.
At this point, measuring current drawn by the NES might be some useful info, if you can do it.
I guess it is possible that one of the IC's on the main board are pulling for too much current creating the overheating. Not quite sure where I could test for current in series though, and still have the NES be operational. At least until the point where it freezes.
If you had some component drawing enough current to cause the regulator to overheat to the point you can't touch it, then that component itself should be hot to the touch especially compared to other components.
It's practically impossible to troubleshoot effectively by measuring currents in series on a circuit like the NES. Voltage measurements are your only viable option for in circuit trouble shooting.
Have you gone through and thoroughly checked everything visually? Looking for any corrosion, dirt, discoloration etc. That's one of your best tell tales, the other being heat sensing as you've worked with a bit already but wouldn't hurt to do a few more times looking for things you missed the first time.
If it's something that's a fairly common issue like you're saying I would have to suspect the giant power cap you've been considering. It's really the most likely component on the whole board to go bad. I think it's also possible that if it were to fail, the regualtor would be over worked and cause it to overheat. Without actually causing the cap to overheat itself contrary to what I suggested above. This is all just speculation though as I don't have a schematic to reference.
Well the hottest things on the board besides the heatsink and regulator is the CPU. I am able to keep my finger on it though.
Such a mysterious NES
CPU should be warm, it's normal. Do you have an old fridge at home?
Yeah my CPU was pretty warm compared to the other chips after a few hours. The regulator heat sink was also quite a bit hotter than I remember last time I checked it after a long duration. I could keep my hands on it but it was almost too hot for me to be able to.
IDK, still sounds like heat issue due to the time delay and everything. It's hard to really say anything else...
I ordered that big cap, so I'll replace that first. If that doesn't work I think I'll remove the power supply so I can get it open, and see whats going on inside. I think there is also some smaller caps in there. Def no leakage showing on the bottom.
infiniteneslives wrote:
IDK, still sounds like heat issue due to the time delay and everything. It's hard to really say anything else...
And, remember, he told, that voltage in his power net not very stable. I guess there might be some spikes from... whatever - old fridge, electric heater with regulator, hot water cylinder etc
80sFREAK wrote:
infiniteneslives wrote:
IDK, still sounds like heat issue due to the time delay and everything. It's hard to really say anything else...
And, remember, he told, that voltage in his power net not very stable. I guess there might be some spikes from... whatever - old fridge, electric heater with regulator, hot water cylinder etc
Unstable because it was 120VAC? Or are you referring to 9.5-10 volts from his adapter? Hardly "unstable" IMO
You're certainly entitled to your opinion 80sFREAK, but for what it's worth martinpal80 I for one can't imagine the above sources of "instability" could reasonably cause the issues you're having. And I would ignore his implied recommendation to replace all your electric appliances with gas ones
Things like: only that NES, it takes several hours to fail, fails sooner if covered, fails later if case removed, fact it won't restart until it sits and cools down...
Not a single one of those symptoms could reasonably be caused by what little instability there is in the supply power of your wall outlet. They all point to an issue with heat...
Why it's overheating???
What's the story about cartriges?
P.S. gas stove is much better then electric one - cooking in wok sometimes
found this in the unreplied threads today.
http://www.retrorealities.com/retroreality/classicvhs/nintrepair.html
If you really do have an issue with power supply and the regulator and cap didn't fix it the only thing left I see is the diode bridge. Go to half way through the second video to see where they're at and everything.
Have you checked to see what the regulator's input and output were AFTER it had failed? That might tell you whether or not you're wasting your time fixing a P/S that isn't failing.
Replaced that big cap. Will leave it on overnight, and see what I get in the morning.
infiniteneslives wrote:
found this in the unreplied threads today.
http://www.retrorealities.com/retroreality/classicvhs/nintrepair.html If you really do have an issue with power supply and the regulator and cap didn't fix it the only thing left I see is the diode bridge. Go to half way through the second video to see where they're at and everything.
Have you checked to see what the regulator's input and output were AFTER it had failed? That might tell you whether or not you're wasting your time fixing a P/S that isn't failing.
Wow this videos a great find!
Replaced the big cap, and it still froze. Gonna replaced that diode bridge. Any suggestions on where to order form? Also does anybody know how many board revisions they made? The video shows main boards NES-CPU-06 and 07. My oldest board is an 04.
martinpal80 wrote:
Replaced the big cap, and it still froze. Gonna replaced that diode bridge. Any suggestions on where to order form? Also does anybody know how many board revisions they made? The video shows main boards NES-CPU-06 and 07. My oldest board is an 04.
some prototypes maybe? like 2A03 rev E, but where A,B,C and D revisions?
i guess you have to resolder whole pcb first. don't forget to use liquid neutral flux
Can't just use plain old solder?
infiniteneslives wrote:
found this in the unreplied threads today.
http://www.retrorealities.com/retroreality/classicvhs/nintrepair.html If you really do have an issue with power supply and the regulator and cap didn't fix it the only thing left I see is the diode bridge. Go to half way through the second video to see where they're at and everything.
Have you checked to see what the regulator's input and output were AFTER it had failed? That might tell you whether or not you're wasting your time fixing a P/S that isn't failing.
10vdc going in, 5vdc going out even after it froze.
martinpal80 wrote:
Can't just use plain old solder?
yes, you can, but with flux results are much much better. Just do it
Any preferred brand or type? I see a lot of different types and brands out there.
martinpal80 wrote:
Replaced the big cap, and it still froze. Gonna replaced that diode bridge. Any suggestions on where to order form? Also does anybody know how many board revisions they made? The video shows main boards NES-CPU-06 and 07. My oldest board is an 04.
If it froze (and you still have video) it can't be the power supply. video would stop too.
Sounds like one of the chips are bad. Maybe the CPU (it gets the hottest). If you have freeze spray or canned air (that you turn the can upside down) you can cool each chip to see if it works again when you cool them one at a time.
i.e. reset, <nothing>. spray CPU. reset again. if it works, it was the CPU. try with the other likely suspects. (74139, RAM chip, PPU, 74368's in that order).
No guarantee it'd work but it's a decent way to go. The other is to use a scope and poke the data/address busses to see if they are working, and make sure the 21MHz clock is running (though, if that were bad, when it froze the screen would go grey or black or white. there would be NO colour at all since the burst would be missing).
martinpal80 wrote:
Any preferred brand or type? I see a lot of different types and brands out there.
Use rosin-core solder. Rosin is the flux. If it doesn't say rosin core, and "no clean", specifically, make sure it says "for electronics". There are solders for plumbing and other things that will ruin electronics. I like Kester solder better than the Radioshack stuff, but any brand of the appropriate type will work.
Oh than I should be alright then. The solder I've been using is Rosin Core.
Well that power supply was real tough to desolder. I'm starting to second guess that it might be the diode bridge. I used my multimeter and the diode check and found a forward voltage drop of 0.5 on all of them. They look ok.
Starting to think it just the cpu overheating...
Also, i think if the diode bridge were to be bad then I would have no power at all to the main board.
martinpal80 wrote:
Well that power supply was real tough to desolder. I'm starting to second guess that it might be the diode bridge. I used my multimeter and the diode check and found a forward voltage drop of 0.5 on all of them. They look ok.
Starting to think it just the cpu overheating...
Keep in mind when I checked my CPU it was significantly warm/hot compared to all the other ICs. Which makes sense, it's burning a lot more power than anything else on board. From what I remember I would almost have said the CPU was borderline "HOT" when all the other ICs were just "WARM". but it definitely wasn't hotter than the regulator's heat sink. Which sounds similar to what you've seen.
I would try the canned air trick like several people have suggested to confirm that it's the CPU or not.
And yes it sounds like your entire power supply is fine...
I noticed there is something that looks like a potentiometer inside the power supply. Does anybody know what that does?
martinpal80 wrote:
I noticed there is something that looks like a potentiometer inside the power supply. Does anybody know what that does?
photo would be good