Bourns Again - Bourns 601 Series RC Network T-Filters Replacement

[JDW]

I actually just did the model for exact replica of [the mounting bracket for Reset & Programmer's Switches].

JLCPCB can do stainless steel 3D printing now...

Holy cow! That's incredibly useful info! Thank you for posting that!

Personally, to bring down the cost in time and money of the SE Reloaded board I would love to see or do an updated board with surface mount components for all the resistors and capacitors. Theoretically the filters could also just be assembled on the board and maybe leave the footprint for the dip packages just in case. CR2032 battery holder would be nice.

I covered the 2032 battery in my video series, explaining it would get less battery life than the original, which is partly why I deliberately installed the stock holder instead of a CR2032 holder. So long as one could get the Reloaded PCB partly pre-assembled with those SMD passive components soldered onto it, at a cost (with shipping) of no more than buying and installing the discrete components., then I agree about there being a benefit But if one didn't get it assembled, it would become a problem, I think. SMD soldering even for someone experienced like me is no fun at all, and such would have taken me much longer because I don't have the right equipment (i.e., I don't have a US$500+ microscope like Bruce Rayne and Mac84 have). Even if I had a $500 microscope, most people buying the SE Reloaded board still wouldn't, so the difficulty associated with surface mount soldering for the masses remains. Also, if you accidentally pinch a teensy tiny SMD part such that it accidentally pops out from your hand and flies across the room, that component is gone for good! And yes, that applies to Mac Classic Reloaded because it's an SMD build. With thru-hole parts on the SE Reloaded board, you're not going to lose parts by accident, even if you accidentally toss a small part like a 1N4148 diode across the room.

Another issue is aesthetics and "the stock look." If somebody wants a board to look exactly like the original (maybe changing only the PCB color), then what we have now will allow for that. I've even been told the same about the PRAM battery. Some people know that battery carries with it more risk if left in there for more than 6 or 7 years, but they still want the stock look (and greater battery life).

Anyway, thank you for sharing this incredibly useful info!

 

[alxlab]

I covered the 2032 battery in my video series, explaining it would get less battery life than the original, which is partly why I deliberately installed the stock holder instead of a CR2032 holder. So long as one could get the Reloaded PCB partly pre-assembled with those SMD passive components soldered onto it, at a cost (with shipping) of no more than buying and installing the discrete components., then I agree about there being a benefit But if one didn't get it assembled, it would become a problem, I think. SMD soldering even for someone experienced like me is no fun at all, and such would have taken me much longer because I don't have the right equipment (i.e., I don't have a US$500+ microscope like Bruce Rayne and Mac84 have). Even if I had a $500 microscope, most people buying the SE Reloaded board still wouldn't, so the difficulty associated with surface mount soldering for the masses remains. Also, if you accidentally pinch a teensy tiny SMD part such that it accidentally pops out from your hand and flies across the room, that component is gone for good! And yes, that applies to Mac Classic Reloaded because it's an SMD build. With thru-hole parts on the SE Reloaded board, you're not going to lose parts by accident, even if you accidentally toss a small part like a 1N4148 diode across the room.

For me personally, my view of the SMD version of the board would be to have it pre assemble at the PCB manufacturer to reduce time and cost. With JLCPCB assembly service it would be cheaper with them than buying the parts from Mouser or DigiKey.

Mind you the footprint used for the SMD components can be the hand solder versions which have bigger pads if someone were so inclined to hand solder all the SMD components. I know at least a couple people who don't mind soldering 0603 components without magnification. Just like you I'm not one of those people who find it enjoyable lol.

For something with SMD components I've made a 3D printed stencil before to apply solder paste and then another 3D printed stencil to place the components. Then you just place it in an oven. I made the stencils manually in the past but I think I got an easier way to do it with Kicad that I need to investigate further.

If SMD is not your cup of tea and want a replica board then the current SE Reloaded board is the way to go.

I don't consider these two boards mutually exclusive. I'm all for options. They would both have their own benefits and downsides based on a persons wants and needs.

But, since there's no SMD version of the SE Reloaded board right now, there's only one real choice currently.

 

[trag]

By the way, I bought my Bourns (shown in my video) from Mouser, just before Mouser terminated sales of that product; but man alive! I had to pay a whopping $6.15 per chip! And although UT Source sells them now, they charge $3.76 each with a min. order of 2pcs (keep in mind you need 4pcs for the SE board), and then you have to pay then $20 in shipping fees!

If you remember my old tantalum capacitor thread on 68kmla, going back to 2007, I added the Bourns filters in 2012. I still have a bunch of them. But shipping a few at a time to folks who don't need anything else is barely worth the effort at this point. Of course, the original purpose was always to help folks get the capacitors they needed, not to make money. After 15 years, I'm kind of glad most folks have figured out how to order them for themselves now....

Anyway, I don't remember how many I have but I found about $3 each to cover my costs. The problem now days is shipping is so expensive and I'm busier or older and more tired. Not sure which. I'd probably be open to selling off the ones I don't expect to use in my lifetime in one batch.

BTW, Digikey appears to still stock them, but again, more than $6 plus shipping. Looks like they have 342 and won't be getting more. If you order 100 at a time they're $4.16. These have the L suffix, which just means they're RoHS compliant.

https://www.digikey.com/short/ppd2mf

Regardless of any of that, I think this is a wonderful project. Inventing ways to replace these old parts as they become unavailable is important.

 

[JDW]

If you remember my old tantalum capacitor thread on 68kmla, going back to 2007, I added the Bourns filters in 2012. I still have a bunch of them....

My SE Reloaded Part II video is where I solder in the 4 Bourns filters, so if you would be willing to kindly help out the community with the sale of 4 or 8pcs at a time, feel free to post a comment under that video and I will make it a pinned comment for people to perpetually see. I feel that is important, despite the existence of this amazing recreation project, because right now the matter is about one's "total cost outlay." Build time is a cost consideration too because time is money. (You could opt for "assembly" at the PCB maker, but that too costs extra money.) And since PCB makers refuse to sell a single PCB panel (they require 5pcs of any PCB minimum), you end up with 120pcs when you buy 5 panels. That doesn't mean you need to build them all, but it does produce waste, since most people probably won't sell the leftover panels, and it's a bit of wasted money too on those unused panels. Most people probably just want a pack of 4 or 8 Bourns chips and that's it. That's where your excess stock of Bourns comes in. If you can sell those, it helps people out who otherwise may not wish to embark on building the Gerber files in this project.

But at some point, when DigiKey and other sellers run dry of stock, it then becomes more than just a cost and convenience issue. It becomes an availability issue. And at that future time, this Bourns filter recreation project becomes absolutely crucial, despite the fact you'll end up with 120 chips worth (5 panels). This project will end up being the only source of the Bourns DIP chips, which are needed not only for the SE Reloaded project, but also to repair other compact Macs like the SE/30 when a Bourns ends up getting fried for some reason. As such, @alxlab deserves mountains of praise for his work on this, and for his other nifty creations too!

 

[Elemenoh]

@alxlab I was trying to order but got this error on the BOM / Pick and Place page

Do you know what might be wrong? I followed the instructions on the readme and tried starting over, but got the same result.

 

[Elemenoh]

I clicked continue which seemed to be okay. Unfortunately the resistors themselves seem to be out of stock. I couldn't find an available replacement part. If you know of one please let m know.

 

[alxlab]

Yeah looks like the resistor is out of stock,. The other U1 error can be ignored.

 

[Peter Hirschberg]

Hello! I'm late to this party, but the Bourns filter (20 pin) on my SE/30 just went bad and was hoping to find a replacement. Is it possible to buy one of these already built/assembled? Thank you!

 

[bakkus]

Hello! I'm late to this party, but the Bourns filter (20 pin) on my SE/30 just went bad and was hoping to find a replacement. Is it possible to buy one of these already built/assembled? Thank you!

Let people know where in the world you're located - makes it easier to find out if someone is close

 

[Peter Hirschberg]

Oops, sorry about that. I'm in Reading, PA.

 

[fred1212]

Anyone know if these are a suitable replacement for the M/C 8849L and 8850L on a plus board?

 

[Rule5]

Regarding the filters in particular, it would take someone to step up to actually take the trouble to sell these. This means breaking the panels into individual pcbs, cutting the 2.54mm pitch headers (if needed), packaging and shipping. I was thinking that maybe $1 - $1.50 CAD would make sense for the un-assembled (headers not soldered) filters? I strongly believe these need to be cheaper than the real 4120R-601-250/201 chips or else what's the point? Shipping will surely cost more than the four filters needed for a single Macintosh SE board but I guess the same would go if you bought the filters from utsource.net or the like.

The filters are sort of a special case since they can't be hand soldered so in order to be economical a batch needs to be made to spread out the assembly costs per unit.

Actually the header can assembled by JLCPCB as well but I've never actually tried their hand assembly and I'm not 100% sure of the cost. Likewise if you use other manufacturers they might be able to assemble the whole thing and separate all the individual board from the panel for you, Having to manually separate the panels into individual pcbs is a limitation of JLCPCB's manufacturing process. I've always found JLCPCB to be the cheapest to make the PCBs for my projects but for making a final commercial version of the Bourns filter it might might sense to look elsewhere.

Regarding the licensing of the Bourns filter, I actually made it CC-BY on purpose to make it easier for people to make and sell these commercially. I considered these a basic component so it should be as open as possible to help it spread. I still spent time doing the design though, hence the attribution part of the license so people can see the other projects I've done.



In general I think most people that mark their projects as non-commercial are not against selling the projects commercially. It's more of a way to add some protection from people from selling their projects for a profit without compensating them. Usually it just takes contacting the project owner first to reach an agreement for commercial sale.

Personally I would be open to allow people to sell any of my projects commercially if they contact me first.


I do intend to open up an online store on my website at some point to help recoup some of the costs from all these projects. I would consider it like giving a donation but you get stuff in return . In the mean time though I could sell stuff if I'm messaged directly.


I think @JDW highlighted all the possible cost issues associated with doing and SE Reloaded board. The sum of the parts would end up being more expensive than just buying a replacement SE board. Even you just wanted to transfer all the parts from a working SE board to the SE Reloaded board the time cost is high. For me personally even the time cost is to high to justify. Now that being said, I think that the SE Reloaded in the current market only make et more for people who understand the component and time cost and are willing to do it anyhow since it's a hobby or they want learning experience.



@JDW I think the fact that making a video that shares all the knowledge around doing a SE Reloaded board, along with the caveats you mentioned above, is actually a great service to Mac hobbyist community. It brings a deeper understanding for the tools, processes, work and costs involved with such an endeavor. By highlighting the issues you ran into hopefully it will bring new solutions from people with different skills and experience.

I got sucked into all this Mac stuff about a year ago when I wanted to replace the 1/2 batteries in my dad's Mac SE. That lead to seeing the need for an alternative the 1/2AA batteries. That then ended up in the creation of the 1/2AA to CR2032 adapter which was my first time using Kicad and actually manufacturing a pcb. Since then I've learnt component assembly with the Bourns' filter and done many more projects thanks to the support and knowledge of people in the Mac community like you.



Well if you wanna help me I guess the best thing to do would be sending money Seriously though just sharing my projects or website would be more than enough. By sharing I'm hoping new ideas and solutions can stem from them. I'm also alright if you mentioned that I'm selling these filters. I guess the easiest way to contact me for buying stuff is on this forum or the TinkerDifferent discord.


Went through a lot of different thoughts and topics in this post. Hopefully what I wrote isn't too disjointed.

I know this is an older post, did you ever make some of these for sale? I’m restoring a Macintosh SE FDHD and may need a set based on the amount of battery barf under the current filters.