The regulator should be short-circuit protected, so not burn out very easily. Have you bought the regulators from a reliable source, there are lots of counterfeit LM323's around and maybe also LM317K?

Powering up the MPU on the bench will enable you to measure current consumption, should be about 0.3 - 0.5 amps from the 5V line.

Check that your CPU board or connector does not have a short between +5 and +12V, the regulator is usually quite robust but does not tolerate external higher voltages at output.

Yeah, i would not be surprised of counterfeits.

This is the best replacement for the WPC driver board. https://www.ezsbc.com/product/psu5-nonoise

Unfortunately, I don't see a LM317k replacement for the WPC95 driver board on this website.

Your LM317K's are fake.

Buy a switching regulator like the EZSBC as it is guaranteed to be short circuit protected and won't blow up if you have some board fault.

There are just too many FAKE LM317K around to trust ANY of them these days. Don't waste any more time of money trying them.

Another tip - don't shotgun parts for a repair, it rarely ends well and often introduces additional faults. Troubleshoot LOGICALLY and replace ONLY what is actually causing the fault. After fixing the fault, it is sometimes prudent to replace known troublesome caps etc but please don't do this as if it is normal repair procedure - IT ISN'T!

I would ditch that LM317 altogether and replace it with the fixed 5V switching regulator EZSBC.

Only mods I can see you would need to do are ground the pin that currently goes to the resistor dividing network (R1 & R2) and rip out those two resistors.

I can't see any reason NOT to make this small mod?

pasted_imagev (resized).png

It seems a little more involved then that. The data sheet for the LM317K that is used on the WPC-95 power driver board shows that pin 1 is the adjustment, pin 2 is Vin, and the case is Vout. The data sheet for the LM323K that is used on the WPC power driver board shows that pin 1 is Vin, pin 2 is Vout, and the case is ground. If we assume that the PSU5 has an identical pinout to the LM323K, then mods need to be done to isolate all pins and the case and then jumpers need to be run to make all of the appropriate connections.

(started documenting required mods, but deleted it)

Doing a bit more research shows that somebody has already documented how to make the PSU5 work in a WPC-95 machine. Please have a look at:
https://pinside.com/pinball/forum/topic/installing-an-ezsbc-psu5-into-a-wpc-95-power-driver-board

I would personally make all of the cuts as close to Q1 as possible, rather than far away as shown in the above link. This should allow for much shorter and cleaner jumpers to be used. At the end of the day, though, as long as Q1 is fully isolated and connected appropriately using decently thick jumpers, it will not matter.

Not a switching regulator like the EZSBC but ... NTE970 is a valid replacement.

Not cheap but I believe NTE still actually manufacture the part. Fakes are not re-labeled as NTE. Available from various merchants and from NTE via the Digikey marketplace.

May I ask which eBay user you bought these from?

Are you going to contact Marco and Amazon to let them know they are selling fakes and get a refund? I doubt Amazon will do anything more than refund you, but hopefully Marco will remove these bogus parts from their inventory and source genuine parts of the NTE equivalent that you used. It would be a shame to see another owner jump through the same hoops that you did!

Post a picture of them please -- would love to see the manufacturer and dates on them.

52nd week of 2004 date code - the production date is proper for National Semiconductor.
Part marking is correct for that time frame (note "-MIL" does NOT mean Military). Military parts either have the military part number or have a "/883" suffix signifying they have been screened to Mil-Std-883. Usually the Military grade of these would be "LM117K/883" where the LM117K is the extended temperature version of the LM317K.
Part marking on your part looks like shit but I have seen genuine National parts look like shit. Can you remove the lettering using acetone (fingernail polish remover)? If it comes off easily, it's fake.

Noted bad thing for your LM317K, that date code of 0452 is on every National Semi LM317K part listed on Amazon (and many on ebay). And the marking orientation is also all over the place - some vertical and some horizontal. That is not a good sign. A semiconductor manufacturer always picks either vertical marking (as shown by yours) or horizontal marking. They do not switch back and forth in the same batch.

NTEs are pretty much the way to go for these. Note that NTE does NOT make parts but are packagers. They buy residual die's from manufacturers and package the parts themselves. Even NTE parts are counterfeited from time to time so be careful who you buy them from as well. If the NTE parts ever do dry up and you're desperate for a new regulator -- Texas Instruments still makes these National Semiconductor parts. Only downside is they're about $60 each. ouch!

Maybe removing the case top with a hacksaw from the original part and one of the suspect counterfeits could reveal difference in die size.

Just checked my latest batch of spare LM323K's from eBay. All have date code 0452, and all the markings could be wiped off with some contact spray. Bummer!

I wouldn't be surprised if you find a weenie 15 cent TO92 of some cheap brand of LM317 inside the metal can.

https://lcsc.com/product-detail/Linear-Voltage-Regulators-LDO_UMW-Youtai-Semiconductor-Co-Ltd-LM317G_C347367.html

Some of the fake LM323K seem to go into shutdown mode around right around 1a. People have used them in a bally game successfully until they add LED displays or something. Probably jam the jelly bean dirt cheap TO220 die version inside those and its not well thermally bonded...

Don't buy active parts like this from Amazon and saddly it seems like Marco too. Authorized distributors only, if you are trying to save some money, check LCSC they have asian brands of some things that have a datasheet will at least not be a counterfeit of a western brand.

The metal can voltage regulators and power transistors are like 90% fake on amazon...

And yes, we have seen the 2N2222 or something like that in a TO-3 cased 2N3055. And also the 10000 uF electrolytics, with a Chinese brand 1000 uF inside the can.

I guess I will make a test bench for my LM323s, run them for an hour properly heat sinked at 2A and 10V input, making 10W power dissipation - about the worst case in WPC driver boards.

Fortunately I have not installed those eBay regulators in any of my friends boards yet.

lm323 (resized).jpg

Is it the picture, or is the lid on that part very off-centered? I don't see any kind of tolerance shown in the mechanical drawing in the data sheet for the LM323K for that, but I would expect a true National Semi device to be more centered than what is shown in that picture.

Yes, the lid is off centered in random direction in nearly all of the 10 pcs I have.

And what's even worse, the parts are either faulty, or are not LM323's. I will test them again as LM317's, because they look exactly like OP's fake LM317K. Maybe I will open one and try to look at the die with microscope, if there are any markings.

There won't be any markings on the die but its size will quickly give the game away.

Does not look like a 3 amp die or bonding wires to me.
lm323-3 (resized).jpg

The wires might struggle at 3A?

You would have to chop a known 'real' one to know for certain. The dies can be a lot smaller than you might think for some parts.

I might have one failed original part in my gameroom trash bin. Will open that when I get there.

So here. A Linear Technology dated 1992. The die size is not so much larger than the fake one, but there a two pairs of heavier bonding wires, going to different places on die, probably to minimize hotspots. Or there might be two output transistors in parallel.
lm323_92 (resized).jpglm323_92_1 (resized).jpg

Neat. Thanks for cutting open an original. Never would have guessed those wires would be so thin on a power part.

Nice job! Notice there is a LOT more metal that the die sits on than in the fake. Each of those connecting wires could easily handle 5+ amps so they are certainly adequate for this part.

Tuukka May I use those pics for the PinWiki?
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Sure!

Thank you sir.
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The first part shown cut open in this thread is an LM317, correct?

And the second part cut open is an LM323K, right?
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Chris Hibler - CARGPB #31
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The cut open parts and cases I posted are both LM323K's, first the fake then the original. The first picture by OP is his LM317 case.

As always @tuukka, thank you very much. Pic added here:
https://www.pinwiki.com/wiki/index.php/General#Counterfeit_Integrated_Circuits_.26_Blacktopped_Parts
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I've always wondered what the inside of that part looks like. Thanks for posting the photos.

My fake parts do not work as LM323, but not as LM317 either. I don't know what the die actually is.

Most likely something super common and cheap like a 2N3055?

If you have one of those cheapo component testers it might find it?

Now that's a good idea!
20220825_130257 (resized).jpg

Clearly, not a transistor either.

A working original LM323 connected to tester in same way resulted in "No, unknown or damaged part".

hefty hefty hefty, wimpy wimp wimpy.

The wires are short enough, but the real part has two bonding wires for each, and they look at least 2x as thick. The fake ones are probably hack job in China using the cheapest 7805 die possible. With a resistive load the fake one start to choke out right at 1a.

Hard to say what the totally fake stuff is. There is a couple chips on the SB300 that are quite obsolete i have to scrounge up. I saw one of them appear on AliE for pretty cheap so I took a chance on it. The chips are for sure a new produced item as the bottom side case imprints counted logically in the tubes A1, A2, A3 or whatever, all chips same perfect new plastic chip package. Funny looking logo to half imitate TI. There was active circuitry inside the chips and legs that where supposed to be connected to something are , power pins where at the right corners, but it did not work. I honestly think it was some screw up parts and they decided to try and sell them anyways. I have seen that dodgy looking TI logo before on functional jellybean stuff.

The fake switching regulators use on the cheap LM2596 modules seem to operate at slower frequency.

The component tester identified some of my 7805's as Darlington transistors with high Vf of about 3V. Some 7805 were identified exactly like the fake LM323, with normal diode between output and ground, and a high drop diode lookalike.

So it is very possible that the fake LM323's were made using 7805 die, but something went wrong, because they take almost 60 mA input current with output unconnected, and voltage at output is under a volt. I had 0.1 uF caps to ground at input and output so it was not oscillating. Just for fun, I might try testing all 10 pcs, but into trash they go even if some would imitate a 7805!

Edit: All tested. Two out of 10 were completely open (missing/broken bonding wires or forgot to install die?). The rest 8 were all alike. With 8V input, quiescent current was 60 mA and output 0,45V.

I tried swapping the input and output, just in case the faker had cross-connected bonding wires. Then I tried the negative voltage regulator pinout and connection. No luck.

Be careful what you buy, especially if it is an obsoleted component. With the LM323/LM317 regulators, especially watch out for the NS logo and 0452 manufacturing date.

"Sometimes you get more than you bargained for. Beware of unusual parts... in the Twilight Zone!"