Digital Oscilloscope Usefulness

[Peter S]

Has anyone had experience with any of the lower price digital oscilloscopes that are offered on eBay for $50 or less? I'm interested in acquiring one for ignition system monitoring, so nothing terribly sophisticated is required. Just after reasonable accuracy and durability.

 

Peter sefton  

[TerryB]

Have you ever used an oscilloscope? Do you see using this on a modern car or antique?

Edited December 10, 2020 by TerryB (see edit history)

[Gary_Ash]

Try Circuit Specialists for a choice of digital storage oscilloscopes.  https://www.circuitspecialists.com/digital-storage-oscilloscopes

 

I bought a dual-channel Hantek DSO5202P, works well, though above your price point.  They do seem to have some simple ones for under $100, one even at $39.  Who knew? 

https://www.circuitspecialists.com/dso150_shell_oscilloscope.html

 

I remember using the old Tektronix ones that were as big as a dog house, cost a fortune.  One of them was capable of taking pictures of a single, 2 picosecond-long laser pulse from an experiment I was running.  That's 0.000000000002 seconds.  After two years of work, I still had less than 1 nanosecond of data, but it was good enough.  My friend Walt Simonson, now a well-known cartoonist, did this illustration for me.  It was the frontispiece of my thesis.

 

[edinmass]

I fixed a custom built modern car with one last week. The vehicle went to no less than four shops........all of them "the best".......and they got no where with the car. While the vehicle had multiple problems, it all started with a bad fuel injector.......which today the kids are too lazy to test each individual component on a scope. If the scanner doesn't toss a code, they are helpless. This was NOT OBDII but a unique platform running OBD 1 and had communication but only one way. Owner was told it needed a new engine, and one cylinder was down 50 percent on compression. I did what I always do, compression check first........everything was fine. Kept fixing known problems using the scope and a DVOM Fluke..........proved three sensors and a fuel injector bad. Fixed a vacuum leak and a lazy O2, all was fine. Very happy customer. It's not rocket science.......it is just time.

[Digger914]

1 hour ago, Peter S said:

Has anyone had experience with any of the lower price digital oscilloscopes that are offered on eBay for $50 or less? I'm interested in acquiring one for ignition system monitoring, so nothing terribly sophisticated is required. Just after reasonable accuracy and durability.

 

Peter sefton  

My experience with used O-Scopes in this price range is that they usually don't come with test leads and they all need calibration. For about $40 more than your starting budget, and about the price of 4 test leads and a well used scope,  the HANTEK1008C 8 Channel Automotive O-Scope from the link that Gary_Ash provided is a better scope investment.

 

 

  

[TerryB]

State of the art in 1962

[Peter S]

the snap-on is beautiful even as a piece  of shop furniture. will check on gary's post

[Bloo]

3 hours ago, Peter S said:

I'm interested in acquiring one for ignition system monitoring, so nothing terribly sophisticated is required.

 

An ignition scope and a lab scope are two different things. What are you planning on working on?

 

For ignition troubleshooting of antiques with distributors you want an ignition scope, and you want it to be ANALOG. Why? Because most digital ignition scopes sold for automotive diagnostics in that era (1980s-1990s) were close to useless.

 

For troubleshooting electronic engine controls, sensors, fuel injection etc. you want a lab scope. A digital one will be fine, and probably a better choice, as long as it is modern.

 

Some tools exist that are built for the automotive trade and are intended to do both. I have a fluke 98 that is a lab scope with attachments and modes to view distributor ignition patterns. It is a wonderful lab scope for automotive work, but isn't very quick to set up for distributor ignition. It is a far cry from pulling 3 leads out of an over head boom and having a pattern on the screen (as would happen with an analog automotive ignition scope). Once set up though, it works as well as analog.

 

 

[Mikefit]

First one I used had a screen about the size of a coke bottle and about useful. 

[m-mman]

4 hours ago, edinmass said:

I fixed a custom built modern car with one last week.

 

4 hours ago, edinmass said:

This was NOT OBDII but a unique platform running OBD 1 and had communication but only one way.

 

Since OBDII started in 1996 (24 years ago!) I dont know if the OBDI platform can be called "modern"?

But if you are used to fixing 80-100 year old cars, then I guess that 25 years IS a modern car. 

[edinmass]

Seems like OBDII came out yesterday! Then again, the same applies to CDI.

[Peter S]

I was mostly thinking of using the scope for a 1950s car with the OEM ignition, but it might be useful to have greater capabilities with my circa 2000 Toyota and Saturn with early OBDII

[edinmass]

The number one diagnostic tool needed is a test light that can load a circuit. 
 

Today, a logic probe and a DVOM and you can get through 98 percent of issues. With a good scope, you can watch the pintle pass through the winding of the injector. All fun stuff if you like computer control systems. The ultimate challenge is looking at a wiring diagram and knowing the symptoms and fixing the issue in just a minute.........with modern electrical problems..........thousands of hours of shop time is what gets you to the problem quickly.

Edited December 11, 2020 by edinmass (see edit history)

[Oldtech]

I fixed an '87 ( obd1) Ford 302 using a scope after the garages couldn't find it.  Seems there is no code that year for a bad pickup. Ha!

[Larry Schramm]

On 12/11/2020 at 2:36 PM, Oldtech said:

I fixed an '87 ( obd1) Ford 302 using a scope after the garages couldn't find it.  Seems there is no code that year for a bad pickup. Ha!

 

I thought that all cars had an ALDL (assembly line diagnostic connector) by that time.  I am not a Ford guy, but that would suprise me.

[Oldtech]

It had the ALDL connector. Just first year there was no code for failed pickup. - It may have been 86, I'm not sure. The next year there was. 

[Bloo]

You didn't just read a code in those days and have the scan tool tell you what to replace. I know it often works today, but back then it did not. I made a career of it for a while.

 

The code you read would just point you to which circuit to go looking at. Then, you would look at the part, the wiring, etc. Then you would investigate what the ECM saw (the computer was often called an ECM in those days) that it thought was bad enough to tell you about.

 

Example: Today if you see a code that says "oxygen sensor", there is a very good chance the oxygen sensor is bad. In the 80s and 90s there was about a 75-80 percent chance it would be something else.

 

Fords in those days had EEC-IV engine controls and, unlike the systems used on most other makes, the diagnostics routines were all built into the ECM. All a scan tool did was make it easier to trigger the internal tests.

 

Oldtech: If you mean the pickup in the distributor, there was a rash of bad ones. Back then if you looked inside the distributor and found one with a rubber plug that was colored black (instead of gray or beige or whatever) you were supposed to replace it on sight! Not easy to get out either, with the distributor gear pressed and pinned on....

 

.

Edited December 14, 2020 by Bloo (see edit history)

[Oldtech]

Yep, that pesky pickup on the distributor on a 302.

[edinmass]

Today with the multi directional scan tools and computers, the codes are much more reliable. That said, getting a technician that can still verify and repair the problem is a crap shoot. 
 

 

Interesting question to ponder........if you own a Tesla or similar car..........do you want a mechanic, a computer programmer, or an electronics technician to fix you car? 

Edited December 15, 2020 by edinmass (see edit history)

[37_Roadmaster_C]

3 hours ago, edinmass said:

 

Interesting question to ponder........if you own a Tesla or similar car..........do you want a mechanic, a computer programmer, or an electronics technician to fix you car? 

 

YES!!!

Edited December 15, 2020 by 37_Roadmaster_C (see edit history)

[TerryB]

The first thing that gets done is having the car connected to a computer to read what it’s thinking and doing.  Actually most repairs are simple and non tech, new tires new brakes, fix a broken door handle, take care of wind noise issue since no engine noise to cover it up.  Sometimes it’s software upgrades because the owners WiFi does not reach the garage.  Before Covid hit I had an opportunity to tour a local Tesla Service facility and speak with the service manager.  It was so quiet an environment compared to a typical service shop.  The one thing going on while I was there was installing a new conventional 12V battery for the car accessories power.  A deep cycle battery is used for that job.

[Larry Schramm]

I would add that a word of caution is needed when trying to find a problem with a car.  The knowledge and experience of the technician with UNDERSTANDING the vehicle systems is all important.  A simple "code reader" from the local auto parts store may not help a lot.

 

Example: You have a car that is getting poor fuel economy.  You may get an oxygen sensor code.  Depending on the vehicle it might just say oxygen sensor or maybe rich or lean sensor.  Only code that you have.

 

The cause of the code is not the oxygen sensor in this case.  The real cause of the light & code is a bad engine temperature sensor, but no codes for the temp sensor.  The reason for this is the operating temperature design specified range for the sensor readings would be between -40 F degrees to +256 F degrees.  The computer will not set a code between those two values.  At least on the vehicles that I am familiar with.   If the sensor goes bad and sticks at a value like -30 F degrees, the computer reads the value as still in the range of operation and adjusts the fuel accordingly.  With it being 90 degrees outside, the car is running very rich and sets an oxygen sensor code, but not engine temp code.

 

Same is true if it pegs at like 250 degrees. 

 

Live data is of all importance to make the diagnostics of the vehicle easier and more accurate.

Edited December 19, 2020 by Larry Schramm (see edit history)