Відео

I swear every time you have a shave you literally shave 10 years off your life, You look so much younger shaven.

Younger me in 1999, "Man, this visual basic 6.0 is hard!"

he has more experience with the centurion a rare bespoke system from the 1970s that costed over 100.000$ when it was new than dos something almost everyone who used a computer between 1981 and 2000 has used at least once .

Everytime he mentions Butler Tech it warms my heart! I went there and helped pull the drive out of the desk system, twice!

That UNI-T meter is a nice asset to have. 🙂 I have both the -E and the newer E-Pro. The -E is on my work as a measuring device for the Trucks I work on, and the E-Pro is my daily goto for electronics since it is quite a bit more sensetive in the mA range, and I have reprogrammed them both to start on DC on all ranges by default, switched off the Auto-Off for Backlight, and also switched off the Auto-Off on the meter entirely. 🙂

what would these computers have been used for originally? record keeping?

lmao, when I learned the 'an oscilloscope has to be isolated from mains when probing mains powered equipment' lesson, I didn't get the pleasure of just shorting out a diode; I had the probe blow up in my hand and the breaker trip a split second later. oops!

Yeah PDP time!!!

Ah yes, this is why I have an isolation transformer on my bench. It is incredibly easy to kill isolated electronics with a scope ground, and even if you don't kill anything, it will distort the signals.

You need a 1:1 isolation transformer for you scope in this kind of stuff. Think you can use a variac for that too.

7:55 "power suppies"??

Just a thought, but what is the voltage rating of the wire-wrap wire insulation?

Observe the rules of Mr. Carlson. Replace all caps. They're very cheap or relatively cheap and will not need replacing in your lifetime.

Doesn't your multi-meter had a diode test function?

ESD?

Something to be very careful about is that you probably want to use differential probes when looking at this power supply. You can approximate a differential probe by using two channels on your scope and using the subtractive math operation to display the signals. I've done lots of work on complex power supplies and this is a critical part of my approach. Having a precision DC load could also help you. I have a feeling that all of this will culminate in getting the DC supply on the Bendix up and running. It's fun to watch as always.

Your age goes up and down by about 20 years depending on your beard. Its honestly impressive

Great, ur clean shaven again, u look better w\o a beard

I had two of the 575 Super Eagles on a Sun 3/180 back around 1995. Had to spin up one drive at a time, THEN turn on the CPU else it would trip a 20 AMP breaker.

When using an oscilloscope you should always galvanically isolate the scope with an isolation transfo and not connect earth/PE. This makes it so that you can't short-circuit muliple gnds together and use a differential probe

COME TO JAPAN , I let you stay in my computer shed for vacation.. let me know

Wee bunny eating clover: sysbrk: unexpected reset in feelings.dll

When measuring and testing big diodes, capacitors, and other silicon, it is very helpful to use an analogue multimeter, instead of a digital DMM. The Analogue meter provides more voltage and current for the large component, and will more correctly show leakage, and conductance in those devices.

One would think that the clever DEC engineers would have made it easier to troubleshoot a power supply. Especially since this one is so complex.

I would have thought that if you shorted chassis negative to Earth ground, and the power supply was unhappy with that, there would have been an obvious "poof", lights flickering, and magic smoke being released. But, who knows... You're in the home stretch now. I was thinking the last problem would be a quick fix. Guess not. I guess we'll have to wait for the next episode.

Dave, remember, you should always be plugging the Power Supply into an isolation transformer and floating the oscilloscope with a ground lift plug. You are "lucky" you didn't fry your scope!

Since the module that is "broken" uses 35v and not 300v, it might be easier and safer to power it with a lab generator. Now I don't have the schematics, but it looks like you just need to recreate the 35v (probably it doesn't need to be that high, maybe 25-30v will do), Sync (60khz, 5v 1us pulse), +12v and "MEM DC ON (L)"

Are you dying your hair gray?

14:30 Hey! I got the same scope. I feel like a noob when I use the thing though. lol

I had a 386sx with an MFM hard drive, and I managed to talk to one of the last people at Kyocera that remembered the drive, who walked me through reformatting it RLL to take it from 20MB to 30MB storage capacity. This was in 1994, IIRC

Nice work! I would strongly suggest you get an ESR meter to check the capacitors in circuit. This is much much more reliable method than measuring the capacitance via a standard capacitance meter. And it would save you lots of time... Also, it might be a good idea to reform the caps "in situ" just by putting the bench power supply on the PSU outputs (while disconnected from the system)... I do this on vacuum tube stuff all the time, but there is even easier as the heaters are not powered on

Did you shave? It looks like someone else on the camera.

Tech tip - if your power supply can measure the leakage current of a cap - it's bad!! Your power supply only shows down to 10s of mA. Leakage current (once everything is charged) should be a lot less then that. I'm reading 100nA/rated volt. So at 55V, that's still way, way under 1mA, even allowing for aging.

Awesome tech! And I totally agree with you; the fun is in the complete package. My passion is in slightly newer computers (c64, c128, Amiga) but Original hardware, floppies, CRTs etc.

As Meat Loaf might have said: "Don't be sad... 'cos five out of six ain't bad..." 😇

I didn't know that the Moomin's had made it to the US - you'll get the reference ;-)

You learned a valuable lesson about scopes - that ground lead is connected to the scope's power AC ground, which is probably connected to other things in the circuit under test. You really need to be careful about where you connect scope ground. Some people learn it the hard way connecting the scope to a "hot chassis" set and left the magic smoke out of everything including the scope!

Hah always throws me off when David shaves clean… I’m like “did he post a video from 5 years ago?” Lol Anyway, looking forward to the next videos on this machine. PDPs are awesome

TBH, i'd actually swap out all these regulators with modern snt modules but that's just me. imho it ain't worth blowing up a rare machine by tacking together slowly failing PSUs. just my $0,02 on, i've seen switchmode PSU going bad in many ways. some just stop working, some start producing ripple and some start running up their output voltage. also some regulators like to get instable when the caps go bad. i had at least two instances of only the crowbar saving a one of a kind piece of equipment At least always test all the (easily reachable) caps, and do that first, if you want to keep them original where possible

So the psy is now 85%ok well that's at least a good start

kool

Thanks for all the great videos! I'm sure you've thought of this, but just in case you haven't or it hasn't occurred to anyone else reading the comments, having a little portable battery powered scope is really great! I have a Zoyi ZT-703S and it's an incredible value! I think around $90 USD? Sure, it's not going to be as good as a bench scope, and there are portable scopes with better features, but this thing I have... wow. It's quick and easy and works so well - well enough to poke around and see what's going on during a repair. It's got a built-in rechargeable battery, that I believe is easy to replace, but because of that you don't have to worry about having an accident like what you had in this video. It's not going have a ground that connected to earth ground when it's running on batteries, so you can't short out something to earth ground by accident. I believe in your situation having an isolation transformer and a bench scope might have helped avoid this, but just having a little battery powered scope has been a game charger. Nobody is sponsoring this comment I just have one and I didn't think it would have the positive impact it has. The convenience of having a battery powered scope just on my bench ready to roll means I'm way more likely to just grab it and use it. That's had huge benefits! I love it and wish I got one years ago!

EEVblog #279 - How NOT To Blow Up Your Oscilloscope It's worth watching.

I'm not impressed with the 74 series TTL IC's. I worked with and fixed DGC computers from the NOVA 800, NOVA 1200 to the ECLIPSE computers, and of course 2.5MByre Diablo HDD and DGC hard drives. (And the huge 300 MByte CDC SMD drive Readers must know that almost any computer manufacturer then made his own peripherals.

That fan sound brings back great memories of ‘my’ 11/44! That’s how it should sound!

Have you thought about feeding your own +12 into that pin? If you have a variable power supply you should see the circuitry trying to compensate without having to plug it in to the "scary voltage".

Thank you for not being in the camp of "replace all the caps". This so annoys me when I see this. Awesome video. I'm sure you'll figure out the missing 12v soon.

Great video. Two comments: Firstly: TIc-Tic sound coming from switch mode power supply is almost always overcurrent protection. And please, get a new caps + decent component checker for leaks and ESR. Secondly: Ground loop with Oscilloscope, been there, done that. Can get nasty with high power systems. Using isolation transformers at AC is a good idea. Or Diff-probe ..

electrolytics WILL have a certain amount of remaining DC current even if good , i'd say 10ma for a high capacitance low voltage is good, but important thing is esr , especially on a switch mode psu, if it regulates by sensing dc off a cap, high esr can result in high dc pulses to the sense circuit, making output low or even shutting it off if it has overvoltage trip out protection, i had this issue with a philips crt tv in the mid 1990s .. reformed caps can seem ok but still have poor esr, its not so critical with linear/ac line frequency power supplies but switch mode circuits can be picky..

its not always good to use a bulb as a load as they have far lower resistance when could, the current surge could've popped the diode...