Repairathon 2022: A hot 386 mainboard, sometimes size matters

[@TC_here]

Fair play to the wife for donating her nail varnish.. hopefully it wasnt her best bottle.. love these repair vids

[@Arivia1]

Clear topcoat is a commodity so she likely wasn't too worried.

[@BobHannent]

My wife sometimes doesn't like a particular nail varnish, she knows she can offer it to me. Although she never has offered me anything too pink and sparkly

[@AB0BA_69]

Necroware is the only guy I know who would call a MoBo from the 90s as "cute". Very wholesome :)

[@freeculture]

Actually that particular compact board is cute, and i had one around for quick testing parts from others back in the day.

[@pwissink1]

Great job. No bodge wires, that makes it very satisfying to watch.

[@atheatos]

Nice Video / Restoration. Thank you again for the mention.

[@ruxandy]

Excellent video, as always! Please don't ever stop doing what you're doing! 🙂

[@markissboi3583]

Nothing like getting the old dinosaur pc working again that'll justend up back in scrap heap

[@AngelaTheSephira]

Yikes. People like you are why they wind up in the scrap heap.

[@Shogunrainsonn]

НекроВаря ;) Всегда приятно смотреть и слушать

[@Quickened1]

Definitely the preferred trace repair method! I would have liked to have seen the benchmark with 8 megs of ram... Fantastic repair👍

[@quantumfoam42]

You have the hands of a surgeon when you solder! I love watching your repairs. I guess this is about as fast as a 386 can get?

[@gamefragments]

Very professional job rethreading vias with micro-wire, and using flux to align the leading trace. I have also used flux paste and like its spreadability.

[@Vermilicious]

That's an adorable little mobo.

[@BigBadBench]

Very nice work!

[@darthtripedacus1]

I miss CPU Galaxy. I hope he is well.

[@necro_ware]

Yeah, unfortunately he didn't make any videos for a while.

[@Roadkill7878]

Love seeing these old vintage boards brought back from the dead

[@BlueSkyYGO]

Nice one

[@MrEd-qg8td]

Excellent work as usual

[@erikmerchant567]

A terrific repair video. Thanks!

[@MarcoGPUtuber]

Yay! New repair video!

[@fynn1202]

I got some pinkish polishing tips, they are very soft, you can even use them on flexible PCBs without any problems

[@minombredepila1580]

Loved this video. Goes to my list of videos to look back on when repairing !!.

[@Stratotank3r]

I really love yours repair vids! Nice that you put the 486DLC into the board. Exactly such a system i had back in 1995. Played Dune2, Stunts, Cosmo, Civ1, Colonization, X-Wing, LHX and so on on it. Good memories. Would love to see more benchmarks between 386DX-40, Cx486DLC and 486DX-25,33,40.

[@freeculture]

And Stunts is the proper benchmark 🙂

[@--fishiiki-]

Great video! always love to watch these :)

[@FeArhsma21]

That's just awesome, thank you for sharing you experience. Much love and God Bless my friend.

[@kyoudaiken]

This is exactly how I would approach it!

[@rodhester2166]

great work.. thanks for all the time spent creating your videos.

[@osamely_varan]

that is one happy old motherboard.

[@catriona_drummond]

Worth mentioning that this kind of soldering tip is ideal for doing the tinning and the trace repair like that. Ask me how I found out... I still find it amazing how precise and steady your soldering is, I tried something similiar recently (on a much smaller scale) and did in the end succeed but I needed extra precautions as to use Kapton tape very close to the soldering area or I would just solder my wire to ALL parallel traces too.

[@chainq68k]

Thanks for installing the DLC in it en the end even if just for a test. I'm a big fan of these old Cyrix/TI chips (had one back in the days), and when you picked the 386dx first, I was like NOOOOO, pick the DLC, pick the DLC... :) Then I got my reward in the end. Cool video.

[@freeculture]

Yeah, i remember those late AMI bios could enable the internal 1k DLC's cache. Without support in the bios you had to use some dos program to enable that at boot. Made a ton of difference in games like Simcity 2000. Oh yeah, i used to have a motherboard like this, with a VESA local bus and a 1mb "SVGA" VLB. That's right, i had a 386DX motherboard with a single VESA local bus. Actually i might still have it, and i did use it with both a 386DX40 and later a Cyrix DLC40 before i upgraded into 486DX realm with a different motherboard with TWO VESA local bus slots. That also allowed "true color" in windows 3.x and 95 at decent speed.

[@sinephase]

it's hilarious how packed full of things those old boards were but still need tons of addon cards for I/O

[@Arti9m]

GG on yet another resurrected board!

[@Lee_Adamson_OCF]

Ahhh, I used to have that very board. Back in the late 90s as a poor college student, I had a 3rd-hand 286 laptop, but it wouldn't run Linux. So I carried around that 386 board with a power supply and hard drive, in a shoe box, and used the 286 laptop for a serial terminal, lol.

[@freeculture]

I need to check but my brain says i still have a few of these, also the fuzzy memory in me remembers hating the NI-cd batteries and i would rip them out on sight, exactly because i experienced one of those leak and make the keyboard unusable (probably needed this same fix).

[@Xaltar_]

Lovely 386 board.

[@lmuacky3793]

keep up with this videos, i love them!

[@enilenis]

Glad I bought a set of those 20N ISSI cache chips years back. They find use on retro boards very frequently. I only have 128KB in 15N version, but I never notice any difference if I try them, or the slower ones that I have in abundance. On one 486 (M601A, I believe), to get a 133MHz DX-5 running I had to reduce 256KB cache down to 128KB, or the system wouldn't boot with anything higher than DX2-66. None of DX4 or overdrive support of any kind. I read about it being a thing with some 1st gen boards that could somehow handle DX-5. Speed is not the issue there. Only cache size. And it's strange to me that a faster CPU would need less cache and not other way around. I know this to be a thing, but I don't know what the reason is.

[@stevensexton5801]

Love your videos. Keep up the good work.

[@dieSpinnt]

Great video, good work and thanks for showing this off, Necroware:) Subscribed! Oh and excuse my nitpicky 2 cents, that are in no way a critique or do matter. Just some nerdy chemistry background, no one needs:P, hehe: 0:40 onward: "If the concentration is to high, it [acetic acid] will start to attack the copper traces ... if you let it there for too long". Yes and no. There is no "if - then" ... it is not a sequential action. The chemical processes of neutralizing/cleaning and etching start immediately and CONCURRENT!. Also every concentration will attack the copper traces, if they are not protected by soldering lacquer/protective coating. That's just how acids work (But that doesn't matter, see next part). "if you let it there for too long": A 5-10% acetic acid solution will take approx. 1-3 hours to etch away the standard copper layer thickness(if it is cleaned up like a newborns backside), where the alkalic battery fluid/electrolyte will take days to months damaging coating and traces. So you should pay attention to the order of magnitudes here(Cleaning takes seconds to minutes!). Just cleanup the battery mess ... then clean up the cleaning mess. There is no need to take any special precautions here[1] ... (if) harm was already done to the PCB, you won't make it worse by cleaning it. TLDR: NO PANIC! Hehe BTW: Oxidation is NOT Corrosion. They are different beasts (and some oxidized surfaces like Al2O3 are in fact a PROTECTION against corrosion). Also we have to distinct between electrolytic corrosion (by direct reaction with the pollutant) and galvanic corrosion (by current flows enabled by the pollutant). But that leads too far to treat that topic here. For further information see for example Altium's site, "PCB Trace Corrosion: Why It Happens and How to Prevent It" [1] Not talking about fumes, the delicate hands of the cleaner or the safety of his eyes and mucous membranes ... or the correct and environmentally friendly disposal of the waste. These are other topics and lie in the responsibility of the operator. P.S.: Just for the girls: Please check the nail polish for conductivity ... otherwise there will be nasty surprises. (Yes, we girls, or rather the manufacturers, also use metallic or conductive additives, hehe). Hmmm just as info, the proper thing, like "Solder varnish SK10" or "PLASTIK 70" spray will cost around 12 bucks for 400ml ... which will be enough for some for 10 or 20 years.

[@loganjorgensen]

17:23 "That would probably cost as much as a new car.". ^_^ That is so true, people forget just how expensive memory ICs were in the past and how that size to cost ratio ramps way up the further back you go.

[@jonasneuhaus4717]

Fantastic fix. Youre the guy to have in a mad max world ;)

[@tomekrv942]

Great job.

[@tomasz89g]

Nice video. I like the attention you gave to quality, make sure it's done well, done right, and will last. I have a question: how do you know where things are supposed to be connected or go? You seem to know exactly where to stick the probes, what result to expect, how did you learn to diagnose? Thanks for the information sharing and effort in preparing these videos.

[@necro_ware]

Thank you! In this video the damage was mostly keyboard related. I already made multiple videos in the past, where I explained how the port is connected to the keyboard controller. It is a very common problem, because the battery is often located near the keyboard port.

[@therealjammit]

I had an old 8 bit video card I used for testing. I removed the metal bracket so it would sit flat and properly when I operated the board out of the case and flat on the desk. I had one too many screw ups trying to prop the edge of the board on something when testing with a video card with the metal bracket installed.

[@reidster87]

Very cool to see a board with the Cyrix/Ti L1 cache setting available in BIOS options!

[@wittonleung8732]

Great repairing show strike back! Oh one last thing，I use TL866II Plus EPROM programer to test SRAM IC and it‘s more intuitive， support up to 1024k bit chip.

[@michaelrose1814]

Keep it up

[@horusfalcon]

Neatly done! I would have used clear nail polish, but, hey, whatever works. The board certainly moves right along with that 486DLC, and I'm sure the MCP makes a bit of a difference, too.

[@freeculture]

Unless you used something like Autocad, not really. Since most people did NOT have one until the 486DX bundled it internally, most software was written for integer math and would not benefit from it. Most notably old games would not use it even when present.

[@BorgSwarm]

Love the video. I wish I had some old boards to work on but I cannot find them here so far. I am surprised that you did not go ahead and replace the battery with a coin cell. Perhaps in a later video. 🙂

[@harvaldi]

What do You prefer - assemble computer as close to original as possible (all parts from that era) or maybe to upgrade and mod it to something nicer in usage? I.e. quieter fans, mount some dust filter, mount dvd instead of cdrom.

[@krz8888888]

Solid board!

[@dominikschutz6300]

Excellent explanation of this old board, very informative to watch a video about this technology :)

[@SidebandSamurai]

Great video. Thank you for the insight

[@Roxor128]

Your test running Doom on this board reminds me of my teenage years playing Quake on a 486DX/33.

[@55goldrecovery61]

👍👏

[@JVHShack]

Excellent video as always Necroware! I hope that I can get a very similar mainboard working which I bought from a seller in The Ukraine 🇺🇦 on my live stream today.

[@user-rs8zg8ey2b]

I had a Mylex 486 main board, it was top of the line for it's time.

[@tspawn35]

My dos / win98 is using a shuttle hot Pentium 1 Baby AT motherboard. Love that thing. Has all the options I wanted. It was also released during the transition from at to atx power so it has both power options.

[@CaptainDangeax]

In the benchmark tools there is one showing a curve of memory speed, guessing how many cache and what size they are

[@VSigma725]

I have a system with a Shuttle HOT-307 board in it, which is very similar but slightly older (no 486 support) and also larger. Works just fine, I didn't have to do any repair work at all.

[@therealjammit]

Vinegar is an acid. We use the acid to "eat" off the corrosion. Using a strong acid will "eat" really fast, possibly too fast to stop it when it starts eating the stuff you want (copper traces). Using a weak acid will be slow but you'll have plenty of time to stop it before it gets too "hungry" and eats the stuff you don't want it to eat.

[@necro_ware]

That's not quite right. Vinegar is an acid, that's right, but we don't use it to "eat" off the corrosion. We used it to neutralize the battery electrolyte, which is a base, to stop the chemical reaction, which leads to the corrosion. Acid reacts with the base (electrolyte) and turns it into water, but if the proportion of the acid is higher, then it starts to attack the copper again. That's why it is important to wash away everything as fast as possible. I made a video about this topic once in the past: kzbin.info/www/bejne/qYfbon94pZufZ8U

[@matthewday7565]

The fizz is the acid vinegar reacting with the dried alkaline electrolyte to neutralize it, like vinegar and baking soda

[@envoycdx]

Would love to see a follow up with this, more ram and some more tweaking. Bet we can see DooM in double figures :)

[@semifavorableuncircle6952]

Im currently trying to repair a huge, old (begin of 1988) 386 mainboard. Its quite incredible, with a full length memory card that has 72 socketed 1Mbit DRAMs on it. Thats 8Mb, in early 1988. Also the board has 2 leaky batteries for twice the fun and has integrated parallel/serial ports which dont work unfortunately. Also got some really nice and certainly equally expensive cards, like one SCSI controller with an 68010 on board, 2 working Hercules TIGA cards, 2 8bit VGA cards and 2 huge cards that seem to be controllers for a very old laser printer, with a 68000 and 3MB of ram on one, and a 68010 and 6Mb on the other.

[@markg3506]

Nice repair again 🙂

[@NJRoadfan]

This board with a (usually AMD) 40Mhz chip was THE budget door buster special in 1993. They could be had for much cheaper vs. even a modest 486 at the time, and provided a big boost if you were coming from a 286 machine. It ran Windows 3.1 decently enough in 386 Enhanced Mode, but like everything else from the period, Windows 95 killed these machines off if they didn't have the memory.

[@primus711]

You could absolutely get doom playable if you over clock and add more cache In my case with my bridge card in my amiga i used a faster ibm blue lighting

[@michaelwarner5277]

If you install more memory onto this motherboard, I'd recommend enabling all of the adapter ROM shadows in the BIOS. This is a trick I used to squeeze a bit more performance out of systems of this date. What it does is copy everything from ROM into RAM. Since ROM access time is much slower than RAM, this is going to cause systems of this vintage to improve performance.

[@necro_ware]

This makes only sense for addresses where ROMs are present. I made a video about it couple of year's ago in context of XTIDE. In this case I have no additional ROMs in memory, but the system and video BIOS and both are already shadowed.

[@madson-web]

This MOBO is beautiful. I wish I own one

[@tony359]

Nice little board and I think I have the exact same model or a very similar one. Same leak, same traces to be fixed and if memory serves, faulty cache as well! Nice video as usual!

[@robertbruce7686]

Another board saved and recusitated 😆👍

[@mogwaay]

Nice video, really getting into these old boards, quite fancy getting an old broken 286/386 one too to fix up someday too, if I can find one!

[@SaltyMeatHook]

This channel is great! Great work, nice compact 386 board. The one I had was gigantic compared to that.

[@raddaks2039]

I'm amazed you can work on those traces without a microscope. I'm not sure I could, and I'm not even 30 yet. Very nice work!

[@necro_ware]

As a software engineer I trained my eyes starring at computer monitors all my life ;) Jokes aside, I guess, I had good luck with my eyes so far.

[@Salamekleikum]

I have similar board DataExpert 367C with TI486DLC luckily my battery leak wasn't so bad, i like how small it is (Baby AT)

[@CaptainDangeax]

Hi. I own a TL866-II from XGECU and this device has a function to test those 61256, 62256 and other sram, along TTL and CMos circuits. I guess you've got one at hand to burn old Bios, maybe you could check ?

[@K10driver]

Unfortnatly i needet 14hrs between the notification and the view of the Video. Beside of the great content i like the music in the first half of the video much!

[@itstheweirdguy]

It's a good thing they started using coin cell batteries. A more modern board couldn't be fixed this way if you had problems in the wrong spot, so many layers and small traces, components. Amazing work. I'd like to see this thing souped up with 32 MB of ram and win 95 with the cyrix 486 that would be interesting, could you change the clock crystal out and squeeze a few more mhz out of the cyrix 486? Volt mod? I dunno.

[@necro_ware]

Yes, it is possible, but atheatos already made a lot of such stuff on his channel. Feel free to take a look, he always goes one step further.

[@AndreasKoepkeAU]

I think I need to do similar on my SOYO 486 motherboard. There is damage from a battery leak and a couple of weeks ago the onboard serial ports stopped working.

[@freeculture]

I learned the hard way in the 90ies to rip out any NI-cd batteries before storing things like motherboards away, as they would for sure leak and destroy. Thankfully the industry switched to the Lithium coin clock batteries that don't leak, they would just lose charge.

[@Krivulda]

I love this chipset. 495SLC is a great chipset indeed. Bad thing my most beloved and precious board with this chipset started to die and I diagnosed it with bad chipset. I tried to replace it with another chip but managed to kill the chip totally. I don't know what should I do with it because finding spare chipsets is not fun at all...

[@dgnrlento]

Gracias

[@RetroPeKar]

Люблю такие миниатюрные поздние 386! С дорожками прям тонкая работа.. Интересно, что именно убило чип SRAM? Что-то замкнуло в позеленевшем сокете?..

[@reidster87]

Also, thanks for mentioning the shedding fibreglass pencils. I was thinking about using them, but getting tiny glass fibres stuck in my fingers is a hard pass!

[@MrFixiit]

so long as she dont find out you use her lipstick too it all good 😜

[@necro_ware]

LOL 🤣

[@ochykysh]

Doom on 386DX was playable if used in "window" mode, aka press "-" to decrease the size of the vision screen.

[@felixokeefe]

You could play Doom on it if you reduce the size of the view window. The minus key on the numeric keypad is I remember correctly.

[@LiLBitsDK]

of course Doom is playable but yeah you gotta make the screen smaller... we suffered through much back then... great times :D thanks for a great video, have fond memories of the 386-486 days :D my first OWN pc was a used 386sx 16MHz with 1MB later upgraded to 5MB and a whopping 200MB HDD :D later on I got a 486DX2 66MHz which I quickly upgraded to a 80MHz from AMD :D

[@DxDeksor]

Very nice repair. About doom however, I think the 486DLC actually makes the game playable. Of course not in the best conditions, like you could have with a 486DX2-66, but that was definitely the "high end" part. You can decrease the resolution slighly and reduce the details, and this should already speed up the game quite a lot to be in the playable area. Also, the game works with 4MB of RAM, but it's faster with 8MB ! Also you can probably tighten up the memory settings at 26:59 to make the system even faster (I think the board should let you use 0WS) I know I've done that before but I'm curious how a superspeeded 486DLC would perform with DOOM on this board :)

[@necro_ware]

Well, everyone has his own expectations of what is considered playable. If I squeeze everything out of this system it will get to 15 FPS when playing with full details and full screen only reduced by the bar on the bottom. The limiting factor is the ISA bus and with VLB it runs a lot faster, but I don't like to play Doom even on dx2-66 with VLB. You get to full 35FPS using DX2-80 and that is a machine, where Doom makes fun regardless how many enemies are on the screen. I never managed to play it through on a DX2-66, since on higher levels the CPU starts to stutter and it gets hard to fight the waves of monsters.

[@DxDeksor]

​@@necro_ware well yes, back then the game was demanding. I guess the most "high end" machine money could buy to play it was a Pentium 66 For the time I guess the game was playable even on a 386DX-40 with low details, but indeed was much more pleasant on a beefier machine. I wouldn't consider "stutterless experience" being the only way being playable, but of course it's the most pleasant one and now anything can run doom (quite litterally lol)

[@freeculture]

@@necro_ware That explains it, since i played with both the 386DX40 and the 486DLC40, with VESA local bus (yeah i have one for 386DX class), never saw anyone else with one, all the VLBs were usually in 486DX class mobos before the PCI age.

[@necro_ware]

@@freeculture VLB was introduced for a 486 and basically it is connected directly to the CPU, that's why it is so fast. There were some universal boards for 386 and 486 with VLB, but there the VLB was attached to the CPU through an additional bridge, otherwise it wouldn't work with a 386DX, since that CPU didn't know what VLB is. It was already definitely faster, than ISA, but such boards were slower, than a real 486 though. I have such board and I plan to make a big video about it and especially about Doom performance ;) I planned it for DOSember this year, let's see if I'll find time to do it.

[@jbinary82]

It would be a nice try to use Fastdoom project instead and see if performance is improved . It also has some funny options like CGA video.

[@M0UAW_IO83]

breathing those fibreglass 'needles' would also be a huge hazard to your health. I like the Dremel tools but I tend to use a model railroad track rubber, there are at least two types, the Peco one is too coarse IMO, I prefer the Guagemaster one, it does a really good job of cleaning stripboard, copper clad PCB and removing corrosion from electrolyte damaged boards.

[@gozi9423]

OMG I GOT THE SAME MAINBOARD :)

[@osgrov]

Beautiful trace repair! The few times I've had to do that I used wires.. Looks really cheap. ;) Next time I'm definitely going to use your method! On a side note: happy to see some 386 love. It feels like the forgotten platform many times - lots of people are into the 8088s and 286s, lots more with the 486s and early Pentiums, but not so many "in the middle". :)

[@AJComputerServicesUK]

Classic At: 11:03 “So to give it a little bit more stability I always cover such places with some Nail Varnish which I initially have STOLEN from my Wife but as she realised it the Robbery was turned into a grateful donation” 😂🇬🇧

[@AJComputerServicesUK]

Necroware, What can we call you instead of Necroware as it just doesn’t sound right? Could you have a look at fault finding an AM3+ Motherboard one day please? 😂

[@nep-nep6575]

I have that same motherboard in a generic AT clone with a 40mhz AMD 386DX from the factory. It’s a neat little board and makes for a good Win3.1/3.11 PC! Oh, also Doom is playable on it, as long as you lower the graphics quality and screen size.

[@No1BRC]

The first time I played Doom was on an Escom 386DX/33. See, as a kid that played Wolfenstein as a first 3D Shooter ond 286, Doom was a giant step- and I probably didnt care about the low fps 😂 Again, a very entertaining video 😊

[@SianaGearz]

Yeah I first played Heretic on a 386, several frames a second, I didn't care. My ZX Spectrum clone at home could do 3D games at one frame every 2 seconds or so.

[@ayan.debnath]

You are AWESOME! I sent you a email regarding my Retro Motherboard. Pls reply....

[@nm0490]

Another great video from Necroware! Can you please provide an info on what kind of dioxide spray you use and what contact spray did you use when cleaning cache DIP sockets? Would WD40 work for cleaning DIP contacts?

[@necro_ware]

I use German "Kontakt" Spray. You shouldn't use the usual WD40, that would attack the PCB, but WD40 also makes a special contact cleaning spray.

[@jk180]

That is a nice board. Thank you for saving it. I'd like to see if swapping the math-coprocessor, tweaking the bios settings, and maybe a slight overclock (not sure you could do it with that clock generator) would get you over 15 frames in Doom. Still not really playable, but something that could show how well designed the Cyrix chip was for its day.

[@menotyou8369]

Doom doesn't use floating point math, so the FPU doesn't make any difference. Quake would show a difference, but probably run at less than a frame per second, if it ran at all.

[@jk180]

@@menotyou8369 I agree with you, but if your going with an upgrade, I say go all the way. I’m rebuilding some old computers that I wish I could have built, but didn’t have the money for back in the day. It’s been fun getting old stuff working again such as an Everex Step with a 386/33 Cyrix , AST Premium II 486/66 DX2 and now a customer built Intel pentium 233MHz

[@xPLAYnOfficial]

I am *definitely* interested in seeing how much you can push that 386 board with the Cyrix Level 1 Cache support. Perhaps you can even get Doom to 15FPS XD

[@RetroTinkerer]

Hello, It's always a pleasure watching your repair videos, these CPUs only require to enable the L1 to enable their full potential? They don't feature any special instructions like the socket 3 Cyrix 5x86?

[@necro_ware]

There are some minor additional settings, which can be set using a utility, but it's more about compatibility, than performance.

[@freeculture]

It behaves like a 386 and that was intentional, it was meant to upgrade your 386 like you saw in this video. There was even a variant that would clamp on top. SLC to upgrade from SX, and DLX to upgrade from DX. (It gets confusing with the later 486DX, so ignore that)

[@chris-n7z1t]

Nice work. Since you needed to replace the AT-style keyboard connector, I started wondering if there is actually a PS/2-style replacement with the same footprint and pin-outs available that could be used as a substitute? I know retro purists would probably frown upon this idea, but it would mean one less converter cable 🙂

[@freeculture]

Converter cable? There are adapters that are just one solid small piece. If you want to be purist, just use a proper AT keyboard.

[@cdoublejj]

have you tried UV curing solder mask for trace repair?

[@Px4164]

I had no problem with Doom on amd K3 386, but don't remember rest of the config ;)

[@ricdintino9502]

Are you going to add a button battery adapter?

[@freeculture]

Rather than adapter most motherboards do have a 4 pin plug where only the extremes are used for non rechargeable batteries, sometimes with a jumper in the middle pins, which is what you would use if you rip out the NI-cd but don't want to set the clock every time you turn the machine on. LOL found one of these boards, the 4pin is next to the bios and it does have the middle jumper, i think you were supposed to remove it? Need to find the manual heh, i still have it, somewhere... They sold a plastic thing where you put 4 AA batteries and plug that there, it only has wires in the extremes so yeah, its meant to be removed that jumper otherwise it wouldn't fit.