Scammed on eBay. Fake chip. IBM 5155 Portable and PCjr repair

IBM 5155 Garbled screen & PCjr two beeps and black screen. + Overclocking.
PCB Prototype the Easy Way. Full feature custom PCB prototype service. www.pcbway.com/
Gerbers for Skinny Sprint here: github.com/epi...
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Support me on patreon.com/Epictronics
Join me on Twitter: / epictronics1
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Tools I regularly use
DeoxIT D5 Contact Cleaner
Hanstar 861DW Rework Station
Pro'sKit SS-331 Desoldering Station
UNI-T UT61E Auto Ranging Multimeter
UNI-T UT890D Manual Ranging Multimeter
MESR-100 mk2 ESR meeter
PINECIL Soldering Iron
PinePowerPSU
TS-100 Soldering Iron
AMTECH NC-559-ASM Flux
Kester 951 Flux pen
MaAnt Grinding Pen
Multicore 60/40. 0.38mm and 0.5mm solder
TL866 II Plus Programmer
RIGOL DHO800 70MHz four-channel digital scope
Tektronix 2246A 100 MHz four-channel analog scope
FNIRSI DPOX180H 180MHz Handheld Digital Oscilloscope
InfiRay P2 Pro Thermal Camera
PCBs from PCBWay.com
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patreon.com/Epictronics
Join me on Twitter: / epictronics1
Music by Karl Casey @ White Bat Audio

[@Epictronics1]

Gerbers for Skinny Sprint here: github.com/epictronics/Skinny... Support me on patreon.com/Epictronics

[@Darxide23]

The reason scammers keep getting away with things on eBay is because eBay doesn't care. You write in the description that you're selling something as "untested" and you're immediately immune to any claims filed against you. You can knowingly sell fake stuff all day long.

[@Skracken]

Of course they're not trying too hard, or at all, because they're still getting money from the scam sales. And since the scammers write "untested" or similar about the item, eBay has plausible deniability.

[@Roobotics]

Not entirely true, I've gone after people selling fake things as-is on ebay(even something as mundane as flash-drives). If they listed it as a genuine branded thing, it damn well better be that genuine thing, untested or not, broken or working. Fakes are not what you purchased, so prove it's a scam/fake and you usually win on those grounds.

[@Roobotics]

19:20 Never let them get away with it, always gather sustainable and explainable evidence, and open a case to pursue them ASAP. Never accept halfway consolations from these sellers either where you drop the case from the record. For me it's not even about getting the money back, but more not standing for the con and lack of integrity.

[@maxtornogood]

That moment when Epictronics has to bring out the censor beep cos of a faked chip!

[@Epictronics1]

I'm glad no one was around to hear me when I wiped that chip! lol

[@SimonZerafa]

Name and shame the arsehole eBay seller! Hopefully you can file a dispute and get a refund at least 🫤🤷‍♂️

[@doomednetwork]

You also want to resolder the first bank of RAM. They usually have 200ns chips installed on 16-64k motherboards. While they can tolerate a 15-20% overclock, it is best to install the fastest available 120ns chips.

[@Epictronics1]

Yes, I have a set of faster RAM chips set aside for the project

[@UpLateGeek]

Almost forgot, [insert "it's a fake" clip from Star Trek: DS9 S06E19 here].

[@Thelemorf]

Paypal claim is up to 180 days after purchase

[@RudysRetroIntel]

Sad about the fake chip, but it's a great video! Thanks for sharing

[@Epictronics1]

Thanks Rudy!

[@chaoticsystem2211]

I bough a fake USB hub on ebay once. The seller claimed it to be USB3, the id was that of a USB2 device, while the chip was USB1. When i tried to get the cash back, the seller blamed it on my system. Eventually, he sent the money and wanted the device back. He got it back in pieces. Never heard from him again...

[@JohnJones-oy3md]

Tantrum-throwing buyers like you don't help either.

[@SidneyCritic]

If the part is expensive, there is a big chance of fakes. Needed expensive automotive rated ST MOSFETS, and they sent fakes that looked the same. Latter on they didn't even bother making them look the same, they re-numbered cheap IR MOSFET that looked totally different.

[@tony359]

that nasty IC, they didn't even bother to print it better LOL! I love the PSU on card of the IBM JR :)

[@Epictronics1]

yeah, the PCjr is so quirky and interesting!

[@rarbiart]

from my experience overclocking AT03 systems: the DMA (used for floppies, on the controller(!)) was one the first one giving up, limiting most times. So in case you can swap the controller, just try a different one.

[@Epictronics1]

Thanks. I'll try that!

[@richards7909]

If you went via PayPal, they seem to allow disputes up to 6 months after. If you used a credit card it may also be possible to recieve a refund.

[@jozsefizsak]

On the subject of IC sockets, back in the 80s it was routine to phone up a large company with a question and be connected to an engineer in the relevant department. Thus, when I called AMP wanting to know which socket was the best, which their big shiny catalog did not make clear, I was told that the double wipe beryllium copper was it, if memory serves. The fact I want to stress is that he told me the machined socket was made due a military spec demanding it explicitly, but it was not a good design, though it is admittedly rugged. It has an inadequate contact area since the hole is not at all the shape of an IC chip finger. He said it's expensive, not very good and don't use it. The spring contact material is what needs to be good so the contact pressure is maintained. There are budget sockets that are not easily recognized as compromised, along with single wipe ones, for saving pennies which you and I don't want to do at the expense of reliability.

[@Epictronics1]

I would agree. Machined sockets are best for machined pins. Dual-wipe sockets are more reliable for regular ICs

[@jozsefizsak]

@@Epictronics1 That's so funny; I didn't know about machined pins, although I may simply have forgotten!

[@moshly64]

@@Epictronics1 I'd say machined pin sockets are best only for new (un-soldered/cut pins) chips. Any extra dimension on the pins damages the socket, even stacking sockets damages them as the pins are slightly too thick for the copper slug inside the pin. If you look closely at pin headers intended for machine sockets, one sides pins are thicker than the other. The small side is intended to be plugged into the socket, the thick side soldered to the PCB.

[@Putersdcat]

At least put the sellers account name here and on X so others can avoid them. 22:26

[@50shadesofbeige88]

Yes!

[@Epictronics1]

I'm talking to they guy. I think he got scammed too. If he wipes those chips down with acetone and removes the bad chips from his stock, then he's ok

[@communalnoodle1356]

​@@Epictronics1hope he sends you a replacement too.

[@charlesdorval394]

​@@Epictronics1 I agree. Nobody is safe from being screwed, seller or not. Sure, some of them are crooks, but others are just being screwed as "we" are... I once got fake FETs from one of the major 3 electronics distributors, everything was handled professionally, saved other customers. If I didn't have an original part to compare with, I wouldn't have been so "lucky". One batch of our boards we're having a LOT of failures in the field. Edit: F... I hate CGA, can't stand the damn thing lol

[@retrotomat]

I’d be curious if you can achieve higher overclock on the 5150/5160 with the P8284A-1. The fastest I could go reliably with the PC-SPRINT was with a 22.11MHz crystal (so 7.37MHz CPU) and P8284 rated at max 24(osc)/8(CPU)MHz. It wasn’t stable above 22.11MHz oscillator speed. So the O/C bottleneck on these two IBM models might not be related to the clock generator max rating… But maybe you can go above 8.7MHz with a P8284A-1 on the PCjr 😊

[@AntonyTCurtis]

I had ordered a 80287XL and it turned out to be a fake... Acetone took off all the paint. Thr original markings had been sanded away so I couldn't tell what it was. When I got around to de-lidding it, it turned out it was actually an original 8087.

[@Epictronics1]

Maybe we should have a look inside this chip. How much magnification do you need to read the text on the die?

[@danielhumphrey5231]

When you speak of dividing the frequency from 4.7mhz to 7.5mhz, you are actually dividing the time period.

[@Popclone]

"Angry Beeps!" Angry Birds ? lol

[@ovalteen4404]

That demo mode comes up when you hold down a certain key combination (ctrl-alt-ins?). As for BASIC, I can't remember if there's cassette BASIC in ROM, but cartridge BASIC was always a better option. It also has hooks that PC DOS 2.1 looked for, to make the DOS BASIC.EXE command just run the cartridge instead of loading from disk. Later PC DOS doesn't support this (since the PCJr flopped) so you will find that BASIC.EXE and BASICA.EXE on later versions wouldn't run. You had to use GWBASIC or QBASIC.

[@Epictronics1]

Great. I'll see if there is a project out there to build a new Basic cartridge

[@ovalteen4404]

@@Epictronics1 If all else fails, the PCJr Technical Reference Manual has the specs for the cartridge size and its pinout.

[@Epictronics1]

@@ovalteen4404 Yes, I think we need to build a few cartridges for this PCjr

[@TheSimTetuChannel]

Hope you manage to push that 5155 to 8Mhz once you get a good chip!

[@Epictronics1]

That would be great :)

[@BeniD82]

Instead of the Intel part I bought a set of M82C84A-2 Oki chips off eBay which is a functional equivalent (set of 5 came in at a little over $7 + shipping). Obviously a somewhat more modern part but works well and seems to run a bit cooler. The spec sheet for this part shows operation of up to 25 MHz and a temperature range of -55°C +125°C. Might be worth the consideration?

[@Epictronics1]

I wasn't aware of this chip. I went ahead and ordered a few to test. Thanks for sharing!

[@BeniD82]

@@Epictronics1 no worries. I had good success with mine so hope you will as well!

[@Epictronics1]

@@BeniD82 We'll try them out in a few weeks. I'll make a video :)

[@retrotomat]

Beware, the 25MHz max rating is that of the crystal oscillator, not the CPU. You have to divide by 3, so that gives about 8MHz. Same as the original Intel P8284.

[@Epictronics1]

@@retrotomat Oh no. So, these are no better than the slow 8284A :(

[@jaredwright5917]

Fake chips on eBay suck. I've had better luck scavenging chips from bulk lots of scrap ICs over the past several years. Sure there may be some (or many, depending on the source) dead parts, but I've managed to find entire functioning XT motherboard chipsets this way.

[@johnmay4803]

fantastic vid as always pal

[@Epictronics1]

Thanks!

[@davidmckendry4491]

Don't copy that chip....

[@GianmarioScotti]

"How are they getting away with it" - bad things happen when good peole do nothing.

[@ReinMixTape]

People who buy those fake chips probably write them off as faulty and because the malicious seller said they were 'untested', the buyer has next to no come back for a refund. And for those who do acetone off the fake print... the malicious seller will have more than enough spare money to make it right with the one-in-a-billion savy buyer who spots the fake.

[@djdoo]

When Repairing computers or building computers 2 things are the most difficult to manage... Cables and Anger, but it is also the most satisfying thing when you got them managed and the system 99% of the times is alive! Great video very interesting as always, cheers from Greece, Jim. P.S Also surface mount soldering requires absolute lack of caffeine in your blood to be done properly...

[@Epictronics1]

Thanks Jim. I always make sure to never drink more than 5 cups of coffee before I solder SMD ;)

[@rogiervanlierop]

Sadly enough there are people with rotten souls who want to benefit from honest, good people. The time will come for them, karma is still a b/&@......

[@BigBadBench]

I was working on a C64 where they had folded all of the chip legs into hooks. It’s so awful! But I was thinking that it probably makes assembly of the board easier b/c you can insert all the chips and flip the board over and solder without any of them falling out.

[@Epictronics1]

Wow, that must have been a pain to work on! I guess they didn't expect us to repair these boards :)

[@ErrorMessageNotFound]

Often times the ebay seller isn't the one who faked the chips. Most likely they bought them in good faith.

[@SianaGearz]

Good faith? Perhaps not quite. I mean yes it's never the sellers that you buy from that personally repainted the chips, they buy them like that. But they either have no idea what they're reselling and/or they suspect their product is all sorts of dodgy and they just don't care. Perhaps they prefer not to look into it. Perhaps they set the margin high enough to refund the occasional grumpy buyers.

[@SireSquish]

These old computers keep trying to die, but the limitless patience and expert necromancy revives them over and over.

[@Epictronics1]

The PCjr is an exception actually. Most of the machines I have restored and repaired are still working :)

[@tarstarkusz]

No, this will be the death of these machines. Overclocking is not good for them. But more importantly, they are WORTHLESS overclocked. They are only good for one thing today and that is gaming. 5150 and XT class games are notorious for going too fast on faster computers.

[@bikkiikun]

Why are they getting away with it? Because the victims usually don't bother to file a claim or go though any hassle for a couple of dollars. Ultimately, while individual victims' damages are generally too low to bother, the volume combined with low risk makes it worthwhile for these fraudsters. And it makes it worthwhile for... let's call them: "negligent sellers" as well, as they can claim the chips to be "untested".

[@UpLateGeek]

Thanks for the reminder, I forgot I hadn't got around to checking the Philips SAA1099 chips I bought from Aliexpress a while back to upgrade my Sound Blaster cards with CMS. I still haven't got around to shoving them into the cards and programming the PAL chips, but at least now I know they're probably not fakes, since the printing didn't come off with acetone.

[@GianmarioScotti]

Did the eBayer sell you those ICs as "untested"?

[@Epictronics1]

No, no mention of tested or untested

[@vitorluis_freerider]

I think the Hercules cards is actually made by Hercules, it says in the silkscreen in the back and as the black connectors.

[@MatthewCenance]

They're selling fake chips now? This must be a really important chip if they decided it was a good idea to start counterfeiting it.

[@Epictronics1]

It's a rare chip. I still haven't found a replacement :(

[@GianmarioScotti]

"How are these guys getting away with it?" - they are getting away with it because somehow nobody has the balls to tell us about bad eBay sellers. Name and shame could have been the immune system of our community.

[@tech34756]

I wonder if Aliexpress might be better for you? I'm not saying you wont be scammed, but at least you might save a few bucks since the only reason I'd go with ebay over AE is delivery time and/or returns, considering the latter tends to be cheaper for these thing from my experience.

[@Epictronics1]

I use both actually. Depending on where I can find the part I'm looking for

[@user-marco-S]

After removing the fake chip marking, did you try to see if the chip had remains of the original marking?

[@Epictronics1]

Yes, it was sanded down

[@thedopplereffect00]

Have you thought of designing your own RAM tester? A simple microcontroller could push different bit patterns and test reliability. Would be a fun project.

[@Epictronics1]

My skills are not quite there yet

[@drgusman]

Hey, do you know the Si5351? Is a programable clock generator and I'm wondering if it could be used to replace the crystal oscillator and then be able to change the frequency on the fly...

[@Epictronics1]

Yes, I actually have a chip. Coming soon on this channel :)

[@ouch1011]

"let that blob do the job" sounds like something I need on a t-shirt Places like eBay, Amazon, Wish, Temu, et al are basically lawless wastelands. There is no regulation about what is being sold. It doesn't have to be legitimate or even safe. Personally, I've had more bad experiences buying stuff on ebay than good, dating back all the way to the noughties.

[@Epictronics1]

That phrase seems popular :) Perhaps I should start printing T-shirts :)

[@LilMissMurder3409]

What I find remarkable is that expansion slot geometry - apart from the actual interface slot - has remained unchanged for nigh on 50 years.

[@eDoc2020]

I think you mean 40 years. The only thing that's changed is the board is now on the other side of the bracket.

[@AnthonyRBlacker]

What a rollercoaster this week!! Wow, great to see the final result on the PCjr!! Just because it may seem past the deadline to 'return' or 'claim' fraud, if the seller is BSing you, you can push eBay or PayPal, they'll make it right. I DOUBT the seller didn't know those chips were bunk, come on.. seriously?

[@Epictronics1]

Thanks! It's hard to tell. I sent him an email telling him to wipe them all down with acetone and scrap any fake chips. We'll see what happens

[@LetsPlayKeldeo]

How much more did the gold logo cost tho ?

[@Epictronics1]

I think for most people the plain PCB is good enough

[@lindoran]

I recently bought what I thought was a 1G dom from eBay for a project in my blog and it was 128MB reached out to the seller (obviously a no returns sale.) they offered a partial refund. I don't know if in my case it was intentional because the dom stickers are not so easy to read. At least they tired to make it right.

[@erik61801]

omg your audio. i thought my computer took a shit.

[@6LordMortus9]

Can you read the fake chip to see what's on it?

[@Epictronics1]

No, it has been sanded off the chip

[@joshhiner729]

Great video! Ok I have to ask. What is the title of Karl Casey’s tune which you use as your ending theme song? Man I love it. Id like to hear the whole composition. Thanks 😊

[@Epictronics1]

Thanks! The outro tune is Miami Sky

[@danielflakelar8193]

why not try solder paste and hot air,,,, Makes it so much easier to do smd work. they actually pull themselves into alignment and look neet. Give it a try and you will be surprised

[@Epictronics1]

Yeah, I really need to try solder paste.

[@billlewis9740]

Could you share the part nr. for that cool Wera "crowbar"?

[@Epictronics1]

Sure, I think it's WERA 05027456001 1429

[@billlewis9740]

@@Epictronics1 Cool, thanks. I just ordered one.

[@Epictronics1]

@@billlewis9740 Good choice. it's a great tool

[@billlewis9740]

@@Epictronics1 When I first saw you using it, I thought, "Did he actually bend (wreck) a nice Wera screwdriver?" But then I noticed the gentle curve and the little notch, and figured it was an actual product. I would imagine the tip would crack if you tried to bend one like that.

[@communalnoodle1356]

Love this video - not mamy are atill overclocking these old beaats these days.

[@Epictronics1]

Thanks!

[@communalnoodle1356]

@@Epictronics1 No worries!

[@jasmijndekkers]

Nice repair. greetings from Steven from the Netherlands.

[@Epictronics1]

Thanks

[@turntheblueiris4626]

Another great video. Cheers @epitronics

[@Epictronics1]

Thanks!