Thanks for the review--I just picked up one of these kits myself as well to test out. It looks like the brightness of the displays is a pretty good match against the glass displays in the photos. Is that the case in person?

I agree with adding the IC sockets--that's simply good practice when working on PCBs.

I'll have to think about the locking header pins. I can see possible benefits and drawbacks to going either way.

I'd be curious of the current draw on one display. If you're interested, you could measure this by setting your DMM to read current (and usually you have to move the RED lead to another 'hole' on the meter).

Here's the part you won't like. Current has to be measured in line. So you'd have to pull the 5v contact out of the connector housing. Then connect one lead to 5v contact you pulled out, and the other lead to the 5v pin on the display.

I saw these a month or two ago on eBay. It's nice someone finally created kits for these so people that like to build things have a cheaper way to outfit their machines with LED displays. I had considered doing it myself, as it was my original intention with what ultimately became the Bally/Stern Bench LED Display that I sell. I'm still probably going to create a full size display for my own use and then depending on how numbers work out may make it available as a kit, but the current draw is the obvious issue with these designs. Replacing 1x display isn't a big deal, but replacing 4-5x displays there's definitely some testing/research that needs to be done to make sure you're not taxing the 5v regulator too much.

I've actually been meaning to at some point test current draw from some of these displays as I am truly interested in seeing the difference in Rottendog versus X-PIN versus my own design. What I created (bench led display) was of my own design after months of learning how the components worked and bread-boarding circuits.. learned a lot, but it sure would have been easier to just recreate someone else's design. Just not in my nature.

The Wolffpac displays look like a unique design to me, but from what I saw.. like the Rottendog, I'm not sure they incorporate a design with low current draw. First of all unlike Rottendog the Wolffpac use standard LED digits.. and I believe that's part of what could allow for a design like X-PIN.. and possibly Rottendog to some extent to operate on lower current to the leds but still allow for bright digits. On X-PIN the PWM (to also allow adjustment of brightness of digits) would also help with current draw (which Rottendog/Wolffpac are not doing either). Displays are already multi-plexed by Bally design, so that helps too.. a "PWM" in its own way, but even at that.. there's just not a lot of overhead on the original 5v linear regulator to play around with. So makes it important to conserve on current draw everywhere you can. Obviously a lot of people have bought and installed Rottendog displays and not had issues. Anyway I'm definitely interested in hearing some current draw measurements of these and other displays -- if no one else does it, when I get some time later this year and/or play around with my own displays I'll do some tests and report on them.

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

I like the pricing and simplicity of this kit, but current drawn by it could be a problem with the original Bally power supply.

Hope someone looks at the current draw though I might order one just as a bench tester

Just some additional thoughts on these..

What actually jumps out at me on these or the Rottendog are 100ohm resistors used on the segments. The ULN2003A has capability of up to 500ma current on its outputs, so that's not limiting current to led segments.. the 100ohm resistors are. Again, I get the multi-plexing.. but if you're at 100ohm resistor on a segment that's 50ma to each segment if they weren't being multi-plexed. It's been a while since I was doing this stuff, but say the 50ma becomes 10ma after the multi-plexing is considered (50ma / 5 displays = 10ma) that's 70ma per display if all 7 segments are lit on a digit. Worst case, all 8's lit up on the display. 70ma * 5 displays = 350ma extra current. That's adding quite a bit of current draw to the 5v regulator. Sure that scenario isn't likely where every digit on every display is all 8's.. so you have that and the multi-plexing helping tremendously in avoiding the worst-case current draw scenario, but it's still a consideration and possible for scores being displayed where most segments on each digit are lit.

Maybe there's a bit more to the multi-plexing and display service routines that help out additionally in limiting the current so the values don't matter as much.. and the obvious desire is to have the displays as bright as possible without risk of burn-out. Rottendog obviously has been selling their design for a while without many apparent issues.. so if they're still using 100ohm resistors on the led segments still then that says something. Just not sure why they wouldn't have used a higher value there.

These Wolffpac kits also look like they dropped some of the current limiting resistors on data signals from the MPU.. which will work, but then is more dependent on the max output current on the ICs feeding those to limit the current.. or the resistors on the MPU outputs to the displays. So that doesn't seem like it'd be helping with minimizing current draw on the regulator either. But perhaps it's minimal enough not to really worry about.

Regardless, it's neat to see someone do kits for these and offer them up for sale to the community!

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

Well, I figure they probably draw between 100 to 200 ma each, so around 1A max for full set. But I'd like to get someone to confirm that by measuring the draw on one.

It would be easy to put them on their own power supply. One simple and economical solution would be to rig up a LM7805 connected to the unregulated 12V supply.

Hi, I'm the guy making these kits. Thanks for the great write-up! I'm relatively new to pinball but I'm an engineer who has been doing design for more than 35 years. This board design came out of my own experience restoring machines and being shocked at the cost to replace dead displays.

The ICs themselves are CMOS so they draw negligible current. The 7-segment LEDs draw 20 mA per segment when on. The Bally pinball machine design has multiplexed displays, i.e. only one digit per display is actually on at any instant in time. So if every digit is showing an '8' (all segments lit) the display should draw about 140 mA. I would figure about 145 mA worst case when accounting for all other loads on the board. If some segments or digits are not lit the current draw will drop proportionately. (e.g. 1 digit showing an '8' = 25 mA, 6 digits showing a '1' = 42 mA )

Absolute worst case: If all 5 displays are on and every digit is showing an '8' they could draw as much as 725 mA total.

Always great to see the designer get involved in the discussion. Shows commitment and support of the product! Even better that you're also chiming in on the current draw estimates thrown around in this post & confirming some thoughts. I do wonder though what the actual head-room is on the 3A regulator in those machines. Have you ever done any in-machine load tests on the 5v line going to the rest of the boards to see how much "headroom" exists?

I bet this Rottendog isn't too far off that mark with their displays as far as current draw. The digits are custom and could operate brighter at less current, but if they're still using 100ohm resistors then they're probably looking at a similar worst-case load.. minus a bit of current saved on the data lines.

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

I have not tried measuring the actually current draw on the 5V supply. The schematics I have looked at imply that at least 3 different types of voltage regulators were used: LM323K, LAS1405 and 78H05. The 78H05 is rated at 5A and the other two at 3A continuous (and in my experience usually work well beyond the rating). All three have over current and over temperature protection so they should not be damaged if the load ever gets too high. The transformer is actually fused at 4A.

Without actually measuring the boards, it looks like the solenoid driver board is the biggest 5V power hog. Each driver channel looks to draw about 40 mA so about 800 mA. The CPU board about 500 mA, the lamp board a few hundred mA and the sound board less than 100 mA. So my guess would be about 1.6 - 2.0 A on the 5V supply not including the displays. Again, that's just my estimate looking at the schematics.

The inline resistors on the data lines don't actually change the current. They are there mostly for protection from being plugged in with power on and electrical noise. The voltage drop on LEDs is usually a function of the color. If Rottendog is using orange LEDs with 100 ohm resistors, they are probably also drawing about 20 mA per segment.

BY the way, I have been considering selling a 7 digit version of the display kit but sourcing LEDs with the comma is a problem unless I want to go semi-custom from China. Wondering whether people would be interested in a display that only had a decimal point instead of the comma?

I was working on a low-cost DIY display design just like this for my Comet, but ran out of time and ended up getting xpin displays. You put this out with boards and everything. Very nice work! Great idea making a kit.

I've seen tons of inexpensive numeric LED displays on eBay and whatnot (that is where I got mine from), but couldn't easily track down Alpha-numeric ones. Have you been able to source those?

I'd imagine anyone dropping DIY LED displays into their games cares more about function over form. At least I wouldn't care about a dot vs a comma.

For the comma, my thought was possibly some type of vinyl "overlay" that blocked out part of the dot and created a line (if using standard leds). Personally I'd rather not have the comma than a dot being there, unless the dot was made to look like a comma.

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

I would be okay with Euro-style (just say you've got a special European Bally )

XPin, Pinscore, and Rottendog were all somehow able to do it.

I did some poking around, but couldn't seem to find an LED display under 3" in size that had a comma.

e4c1e92884.png.jpg

I thought on the 7 Digit Displays, it was a function of the "spacing" not just the comma to fit off the shelf digits into the window of the backglass. Which is why others have had to have custom LED digits made.

As to total current draw, Let's also not forget that there are some games with more than 5 displays.

6 Million $ Man, Medusa and Vector come to mind.

Although also rated at only 3 amps, maybe it would be a good idea to consider using the following to replace the LM323K when using LED displays:

http://www.ezsbc.com/index.php/psu5.html#.VhK9mMvn-1s

But it may not be as much about taxing the Regulated 5 volts as it is the unregulated 11.9VDC.

The ones I picked up on eBay for the Comet DIY LED display project I never finished seemed to be the right width.

Awesome work! I love building such things myself. Also, I'd definitely buy right now if you had DIY kits for a 7 digit upgrade to 6 digit displays.

Yeah those are all entirely custom digits.. basically contact an LED manufacturer, pay for tooling costs (pretty expensive).. give them specs, font design, etc.. you can create anything on the led digits at that point. I *think* it was going to be like $4k to have custom digits done in by a US company. Something like $3000 tooling and $1 per digit with 1000x digit minimum order. I may be fuzzy on the details but something like that when I had looked into it 3 years ago. Then additional orders would be $1 per digit (no additional tooling fees). So someone that's selling a lot of these just has to bare the cost once and then they can have nice digits of their own design, with commas. Might just be a matter of time for a China seller to offer them if someone has a Chinese plant make digits with commas and they see a need for it though. So who knows.. maybe in a few more years.

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

Explains why those 'name brand' displays are a little more expensive...

Yep, no doubt. If you really take a look at it too.. Rottendog 6-digit set is $185 *I think*.. that's $37 per display. Just knowing what I do now about PCB costs, component costs and either time to hand-assemble or cost per pad to have it factory assembled, even in China.. I wouldn't want to touch that. The kits seemed the only way to go. The $200ish display sets are actually pretty darn reasonable and I really don't know what kind of margins they have selling to distributors, but yeesh.. my guess would be $10'ish profit **BEFORE** accounting for boxes/packaging material, inserts, shipping expenses, Uncle Sam and probably a load of other things. Definitely have to count on the direct sales via shows / website.

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http://www.pinitech.com - "Pinball Inspired Technology"
Kits, upgrades and test equipment for pinball machines

I put one of these together over the weekend. It took a solid 2 hours. Next time, I may just order the assembled kit if I get more since it's only a $10 difference per display.

However, in putting it together, I made one "oopsie". Since the leads on the axial caps at C1 and C2 need to be bent so close to the actual cap because the spacing isn't very generous between the through-holes, I ended up cracking one if them.

Since I didn't have any left in my parts area, I'll have to remember to include it on my next parts order so I can finish it up. It's a common cap that I need to have in stock anyway.

If you do enough axial resistors,capacitors,diodes,etc -- watch ebay for one of those black metal OK-Industries LB-300 lead benders. Awesome for perfect bend every time, even up close. Don't buy one of the plastic ones, they suck...

Lb300a.jpg

Interesting...

I tried looking for a demo video, but I couldn't seem to find one. How do you set the spacing for the bends?

Knob on the near end in photo is for setting width.
Notice the black pointy end in the middle pointing down? There are two of those. You turn the knob until the two points go into the holes where the part goes -- then your width is set. Knob on top far end is a locking knob, once you set your width and don't want to change it for awhile, turn that knob to keep you from accidentally changing width.

Thanks for the explaination. I can see how that would be a very handy tool. It's now on my want list

I'm keeping a look out as well, Looks like an interesting way to spend yet more money

Well glad to hear you tried them out Bob.

The two biggest pros to me where soldering practice and cost savings.
I wanted my twelve year old to put together but he was showing no interest. And we have already done a few other kits together like a LED matrix cube. So in comparison this kit is super easy. First one may take a little longer of course but after the first one just cut that time by at least 70%.

Of course looking as close to original is always preferred. But in the case of a comma. Don't see that as a deal breaker at all.
my Flash doesn't have comma(s) it never bothered me.
A dot would look dumb to me.

Yes another good idea mentioned having one or two just for your test bench. No need to worry about glass ever breaking.

In person the LED are a tad brighter. I only needed one display so I used mine in the ball credit position. A dimmer adjust would be an ideal improvement.
As well as the 90 degree locking tab as seen in the xpin close up. I guess if head upside down in transit the digit board could separate or fall off. ????
Maybe on next gen wolfdp?

I did not put the foam strips on ethier. To help block side light ?? Or prevent back glass damage ???

Still think it is a superior option $ wise for anyone in the market. And the logo is cool!