Hello. I like breadboards. I don’t quite build entire computers on them like certain people do,
but they come in quite handy for a quick prototype build or for testing unusual ICs. You had seen
my E&L Industries system in previous videos. They call it a “Digi Designer”. It’s quite convenient,
with its integrated power supply, debounced switches, LED indicators, plus a handy dandy
clock generator. It even sprouted an extension with 7-segment indicators in a previous episode.
But imagine my surprise when I found this bad boy on eBay. What? Quad breadboard, 3 adjustable power
supplies, 14 switches and 12 indicators, a full function generator with sine, triangle, square
and variable pulses, to a megahertz? I’m not sure why you’d design such a thing in the first place,
but I definitely had to have it! Hold on to your breadboards, Ben Eater, here I come.
So this is my latest prototype thingy. It's the monster prototype board from - I was just
talking to Ken - from eBay. And it has a function generator. Not just a clock, a function: sine,
square triangle. It has an extra pulse generator, three supply voltages, all adjustable. 0 to 10V 2A
5-30V volts 0.2A. [Ken] And are they bipolar? [Marc] They're not bipolar, but they are
intended to be one the plus supply and one the minus supply. You just have to hook them up the
correct way. And two meters, you see the Volts and the Amps. And, oh! Oh, that isn't working. Ten
inputs with three, four more push buttons. So it's like 14 inputs. And 12 LEDs - if they are
LEDs - or lights, whatever they are. Which I know from the other one, they have a little amplifier
behind, so they're actually high impedance things. Something where I can plug an HP card.
And then it's been somewhat broken in transport, but we'll repair that. There is the fuse.
Yes, it looks like we hit the jackpot and got the absolute top of the line Elite 2, which would have
cost you a whopping 1300 dollars in 1971, which Google tells me would be equivalent to $9,024.50
today. We are living the life. And it's the... Ooh!
Broken. [Ken] And the screw just broke? [Marc] The screw broke. [Ken] That's not supposed to happen!
[Marc] I see this one broke too. Something happened to them, they were pre-broken...
Tada! Wow!
This is much nicer than I expected!
[Ken] That's quite a lot of stuff! [Marc] A few friendly spiders. [Ken] Check out those
capacitors! [Marc] Yeah, a whole bunch of caps that could be bad! Here's my function generator on
this side. It's a complicated affair. Oh, look at all these ICs in this thing! [Ken]
That's kind of wild, the diagonal board. [Marc] I bet you they are the 7474s for the switches,
so you get a clean flip and a clean flop. And here are our transistors for the lamp drivers.
But they are actual lamps, oh my goodness. Neon lamps? Are they neon bulbs? Man, if they get
broken then... Yes, neon bulbs. [Ken] That's wild! [Marc] Wow, so those are the neon bulb drivers.
Master Ken, you have figured [out] something more, because there were five caps, and only three power
supplies that we could see. [Ken] Yeah, so that was kind of a puzzle to me: why are there five
capacitors, five power transistors, five independent power supply circuits that are
almost the same but slightly different, but only the three power supplies here? And Marc
suggested it might be two power supplies for the internal circuitry. And that totally makes sense.
So what I've concluded is, this power supply with the big rectifier is going to be for your
2 A power supply, these two with small rectifiers are going to be for the 200 mA power supplies,
and then these two are going to be for + and - to the function generator,
and to drive the lights. And these two have adjustments, because these two need to be
set at the factory for the internal circuitry. The other three are controlled by the knobs on
the panel, so they don't need an adjustment. And then there's two transformers. This transformer
powers the interior circuitry, and this transformer powers the user power supplies.
[Marc] So the user, if he screws up his stuff, it doesn't screw up the rest of the circuit. [Ken]
Right, if you mess up, put noise into the power supply, short it out, the rest of the circuitry
is still going to be powered. [Marc] This is way better done and better engineered than I would
have expected! [Ken] Yeah, so they put a lot of thought into this this design. [Marc] Yeah!
Then we have one, two, three bent switches and one broken one. So the broken one is the
one that really needs to be changed. And then a knob that doesn't turn. Okay, not too bad so far.
Okay, we need to replace the fuses and see if this comes up or just blows up in smoke.
I'm gonna get it. There we go.
Okay, jury-rigged two new fuse holders. They're not the exact right ones, but that will do until
I get the right ones. And here, the other thing you can see that's wrong, this doesn't work. And
it's pretty important, it's to check the voltage. I need to find how to fix that. Actually I think
it spins a bit, so I'm going to do the magic oil trick.
Oh! Why is it so hard?
Oh, man! So that thing has had this stuck problem for a long while. You can tell that they added
this screw ring to hold the dial, that the shaft is completely mangled. And then on the other side,
it's a construction where everything is connected to everything, which is a little bit scary.
Like, the strips here connect to the mount of the meters, which are directly connected to the pots.
So that the whole thing doesn't remove well, unless you remove the whole
entire front panel controls. And I need to get access to the shaft to figure out why it's stuck.
Okay, I had to remove all sort of things. but then I was able to get
the whole mess of spaghetti [out]. And I still can't get it unstuck. But I might
be able to remove the wafer, and get just the shaft and the holder mechanism.
Huray, I got this stuck part out. So now I have just to figure out
what went wrong with this guy. So we know what's wrong: the shaft is just frozen in its bushing.
Which could be that the shaft is bent, or that there's something between the
shaft and the bushing. If it's just frozen with grease, I might be able to get it with Nye oil.
All right, I'm making some progress. I removed the retaining ring, got it in two vices,
lots of oil in there. And it's moving.
I think I'll be able to remove the shaft,
which means it's probably not bent. It's probably just all grease in there. All right,
got it! Classic case of grease having congealed. Ao once I cleaned it up, you go here, and voila!
And I marked the position of everything before I took it apart, so hopefully I'll be able to
put it back together as it was. So this should be like this.
I think it's repaired. I reattached everything. Then I have to change those four switches:
this one, this one, this one, this one. Those two actually are broken in the back. And I have
a similar switch, not exactly the same: this is a double pole double
throw. But that should work. So let's go, let's see what's happening back
here.
Yeah, this one is... Those two are destroyed. So this one is broken broken, and this one also
has been semi-broken. And the other one just so much bent, the switch might not work anymore.
Okay.
Oh my, so much unnecessary mechanical damage. It had been tossed around quite a bit. Fuse
holders were smashed, switches shafts completely bent, and they even managed
to break the green connector at the right. Poor thing. It got no love at the recycler.
Okay, all the switches have been replaced. And actually I can confirm, these are 7400
NAND gates arranged in an SR flip flop. This is what this is. So it's an SR flip-flop, two
NAND gates, the output of one is circled back to the input of the other. And the
inputs are to the switch. So this will flip it one way, this will flop it the other way.
And there is also a little RC to smooth things out. So this is what I expected.
And this surprised me: these are 710 op-amps. So it's an op-amp plus a transistor driver over here.
I guess they went a little bit overboard here.
We won't complain about it! And I have in my collection of replacement of the connector here.
There we go. That's really almost the exact same thing. Last one in...
Okay, pile of bad parts out, new parts in! This works.
Then, question is, will it turn on and give us something?
And a one, and a two. Yes! I have 5 volts!
But it does not agree with me here. So I have something on the dial,
but I have nothing on the output. This says zero millivolt DC.
Okay. Oh, I know why!
Because there is a standby and operate button. Operate? Uh,
well, except it's not exactly what we want. It's 0.3 volts DC, that is not the 5 volts
indicated. And if I move to the other one... Oh yes, up to 15 volts!
And here I have 15 volts too. Does it show up on the output or not? No.
It's unhappy with that.
And let's try the other supply.
And this was more of the same,
the third power supply didn’t have any voltage at the output either.
So, not great so far . The meters seem to indicate a bit of power supply life,
but it sure does not make its way to the output.
Let's see about the function generator, if we get anything there.
So we seem to have nothing.
Well, I shouldn’t call it nothing, we have a rippely +10V
on the output. But no generator output, but no generator output.
Zippo,
zero. Let's see we have anything on the pulse generator.
Aha!
We have life! Okay, we have some wobbly... Okay, the width does something,
amplitude does something, it's not at zero. Okay, that does something.
There is a little bit of hope. And I can change the width
and the amplitude. My zero is pretty high. Can I do one shot? Click.
Yeah, I saw it actually. If I get it really slow. Poink! One shot.
Okay, so that works.
So there is a little bit of hope. It says POS out, but it seems to be the negative pulse.
If I do the other one... Oh the negative out doesn't work, okay. Ah! The negative low works.
Except it's not at zero.
Right. Function generator, not great either.
Maybe my lights and switches will work? They are a bit complicated though.
Okay, all the switches here appear to have a little bit of life. This one works.
And the inverse here. Okay, the 7400s are still working.
Okay, so those switches do work.
All our switches work, okay, so that's something.
All right, we appear to have one lamp that works. I just had this one going.
Okay, that's cool. And a
one.
This one works, this one works, this one works. So we have our neon bulbs, they are super reliable.
Okay, we have 12 working lights! Very very very nice.
Deep deep deep deep deep. All right, very excellent.
Okay, so we have to figure out what's wrong with the power supply first, and then
what's wrong with the generators later. All right, a little bit of life in it.
Yes, unexpectedly, the lights still work. Neon bulbs for the win. But that’s about
the only thing that works. Let’s be honest, this is another eBay disaster.
Fortunately I have Master Ken on the problem, and we’ll see if he
can reverse engineer the very complicated generator with over 40 transistors in it,
so we can attempt a full repair. Many, many, many faults await in the next episode. See you then!