Oscilliscope sparkie Testing

Dad has been gone for almost 2 years now, and I had been thinking about getting rid of this thing for a while, when I heard somewhere that you could test "sparkie" output with just such a device. Now, I know that there are a few electrical engineers out there, and I was wondering if ya'll could help me figure out how to go about doing this. I would love to put this thing to good use, as I remember distinctly that dad told me that the company that he worked for spent a bizillion dollars having a few hundred thousand of these units refurbished, only to throw them in the dumpster 3 months later when a newer model came out. At the very least, this thing is full of vacuum tubes, so it oughta be worth something.....right? Thanks in advance for any suggestions!!!----Rob

It seems as though, along with that investment came the EPA rulings about underground fuel storage tanks. The original tanks and pumps were probably sold to the property owner for $1.00. He thought that was a great deal, at the time.

We did have one really dorky looking guy that we called in to read the patterns when some other problem than a fouled spark plug was suspected. He could also discipher Egiptian hiroglyphics and sand script etc. :O)

The flight engineer mostly just looked at it and tapped it with his finger before take off to be sure it was on. Must have worked because they always got off the ground!

Zane

Mark

You'll need an external horizontal sweep trigger from the points or #1 cylinder sparkie. Otherwize, you'll just gitta parade of spikes across the scope sweep that you can't slow down so you can "read" the scope.

Hint: drop by a real automotive tune-up shop and watch their BIG tune-up 'scope. What, they donnna know how to use it eather? Sure looks impressive to the customer. There are really few reasons for using it and generally, its cheaper for the customer, and faster for the mechanic, to "wholesale" replace ignition parts, than to hook-up that impressive TV screen.

For a more thourgh discourse on using Ignition Scopes, do a web search, or stop-by your local library..... ....Dell

Jim Cox
Tube Tinkerer at large

The problem in analysis is determining that all plugs are firing equally. Well to do that you have to have some sort of equilizer (we call it calibration) so that you know you are "capable" of picking up equal level signals (if the ignition system cooperates and gives them to you). This is a pain and that is why I didn't recommend it earlier.

The horizontal sweep rate can be changed so that you can use this as a tach. Just remember that the plugs fire every rev even though the engine only wants to use the "fire" on compression cycles. Count the time between the spikes and divide it into 1 and the result will be revs per what ever your units are. Time for one minute (like in rev's per minute...rpm) is 60 sec. 1/60 is .0167 seconds or 16.7 milliseconds. Since the N is a 4 cylinder, each cylinder fires once x 4 cyl's = 4 spikes on your scope per rev. so the spikes are 16.7/4 or 4.2 milliseconds apart. If your tractor is running at 1000 rpm, then the spikes are 1/1000 of what they were at 1 rpm (above) or 4.2 micro seconds (us) apart. Put the time base on 1us and count 4.2 cm on the face and that is where the spikes should be....course you have to sync the scope to the signal and that's another story.

Tach check.....use the tach in your truck to calibrate your scope just like you checked your tractor....just remember for a v8 you will have twice as many spikes for the same rpm, so 1000 rpm will be 2.1 usec apart.

Enough of that.

Mark

Regards
Gary

The cam runs 1/2 as fast as the crank so that the intake works on the intake stroke and the exhaust on the exhaust stroke.

Firing order would be 1324 and the plug wires are routed to the dist in that order. The only thing that knows whether it's intake or exhaust time is the cam. It takes 720 degrees of crank rotation to completely rotate the dist and that is the time to complete 2 combustion cycles.

So that's what that gear is for on the camshaft..(grin)...amazing what time does to the brain....Must be my magneto driven lawn mower I am thinking about or my 2 cycle Mercury outboard with a dist.

I stand corrected sir.

Mark

(I didn't know people read this stuff) LOL.

I

If it was a dual trace scope.. that would be even better for spark comparisons...

Soundguy

Soundguy

It would take some explaining and experience for you to set it up so that you could watch your"sparkies". One of the big problems is that it likes to watch signals that are just a few volts high, like in a transistor radio driven by a 9 volt battery.

Your engine's spark plug fires anywhere from 18,000 volts to as much as 50,000 and there are 2 or 4 or 6 or 8 wires to measure. Basically what you would want to measure is the shape of the signal and relative amplitude (relative to the other plugs). Well if you bought high voltage adapters and some hootus to hold everything still so that you could compare apples to apples you have a fighting chance..... ..(like the $20,000 or so engine analyzer at the local repair shop). But for most of us those specialized adapters don't exist and to "see" your engine run is just a novelty. Besides you usually can fix er up just dandy without all those gadgets.....don't get me wrong, I have worked with them (at my paying job) for a lotta years and know that of which I speak.

Besides when elect equip sits for long periods, the components deterioriate and who knows, it may not even power up.

Sorry, but that's the way it looks from here.

Mark

The biggest problem I saw with old equipment was caps that dies.. tube sockets that coroded, and pots that got dirty.. also dust on the CRT back behind the yoke, here the safety caps are.. etc.. also up near the altar ( 2nd anode )... lots of arcing with the dust.

I pretty much concur.. Like I said.. it will be a 'task' to teach someone o-scope 101 via email.

If he does ever get it fired up.. I have a 50's era signal gen he can use to tune it up... Has a big oil pot built in to the top to cool the tubes.

Thinkg must weight 100 pounds.. good into the upper khz range.

We used to play around and inject an autio signal into the input.. like from a ( turntable pre-amp).. then modulate. Made a great low-power am radio xmitter.... with a long wire antenna run out the window and along the clothesline..

Soundguy

Mark

Well, if you've got the bench space, and you are inclined... setup one of those siggens, and the o-scope and putz around with it. Won't be long before you can do something.. assuming it works.

You can either build a heavilly attenuated probe using a high value resistor.. or use an inductive pickup / coupling like JC suggested.. etc..

have fun... and don't get electrocuted..

Watch out for broken tubes..Keep in mind that some of the power tubes, and maybee rectifier tubes can have special property gases in them.. not just vacume... Some radioactive I've heard.. not sure if those are the purple ones or not?
Anyone have the skinny on that?

Soundguy

In the eeeee eeeee eearly days, they used mercury vapor rectifiers in the low voltage power supply but I am unaware of any radiation associated with that. When selenium rectifiers came out, they went into the trash along with a lot of heat produced by the filaments.

The closest thing to a radioactive tube that I know was the 6BK4 shunt regulator for the RCA TV chassis high voltage section. As I recall, the voltage was high enough to emit gamma (I think)rays off the cathode. They put a tin shield around it to help keep them away from you. Also think the picture tube was a problem too....but color tv solved that....used a "shadow mask" to help focus the red blue green guns on their respective phospors.

Mark

I remember those big selenium rectifiers. I repaired a big battery charger way way back that used them.. huge heatsinks..etc.

Soundguy

But in industrial applications like dc welders and battery chargers (as you mentioned), it was tops....no filaments with their problems, but like vacuum tubes, it could take an overload and come back swinging where the latter 2 materials would get mad and go home if you smacked them a good whack. I bought a Miller AC/DC Stick welder a couple of years ago....the last stick the welding supplier had. ....opened her up and sure nuf, still using selenium with the little fan.

Mark

Mark

I had an old heathkit tube type 1mhz trace scope. I built a 10 meg attenuated probe for it... was neat to play with.. especially helpfull on tv repair.. let you see the colorburst curve.. etc. ( I'll have to run to my parents to see if that thing is still in the shed..)

Some of the old units had a banna/binding post setup for the probe, instead of BNC connection.

Will make some difference if it has a curve lock function to 'freeze' a trace.

Let us know. ( Dell might be even more help here.. I only got to play on tube scopes our lab had solid state ones when i was in school )

Soundguy

good luck

Soundguy