Honor Product Review
B&K Dynascan 1460 Oscilloscope
I have noticed that there have been several very nice reviews, on the forum, lately of some of the most up-to-date oscilloscopes. Every time I read one of these reviews I look over at my 40 year old B&K Dynascan 1460 and think how nice it would be to have one of those shiny new oscilloscopes with all the bells and whistles.
The fact however is that in all my years working with electronics I have never needed anything fancier than the B&K. I am not an Engineer and while I have claimed the title of technician you will not be able to google me and find any documentation to back up this claim.
I was 23 years old when I bought this 10 mHz single channel oscilloscope. At the time I was doing the service work for roughly 20 Radio Shack stores within a hundred miles of my home. There were times when the scope was a help but the truth is that most of my repairs were accomplished with a $20 analog multimeter. You can junction check transistors and diodes with the ohms X 1 scale. Resistors were straight forward and on the R X 10K range watching the needle deflection as the probes are switched forward and reverse on a capacitor you could get a pretty good idea if it was working properly.
Perhaps the B&K was more of a status symbol at the time than a practical instrument for the level of electronics I was doing. Even in the early 1980’s when I started servicing TRS-80 microcomputers I did not get to use the B&K very much. In order to do what I had to do to calibrate floppy drives and chase down gate problems it was necessary to buy a Dual Channel Tekronix scope. I still used the B&K scope for some of the audio electronics repairs but most of the time it sat patient and unlit. The Tektronix was very nice but it is long since gone. The B&K remains though.
Last night I was working late in my shop where I experiment and continue to learn electronics. After building a simple circuit the impulse hit me to look at the signal that was being generated. Therefore, I reached over turned on the B&K. Instead of the nice green line of a sweep I was greeted with a single dot of light. I rechecked all the settings and switches. I turned it off and on several times but still the ominous green dot was all that was visible. Had my old friend finally left me? I have never liked working on my own test equipment but here I was alone with little other options. The last time I had any contact with the factory was in 1975 when I had to take it in for a problem under warranty. Did the factory even still exist? Probably not.
I began to check out the scope by removing the three screws that held it’s 5 pound, one piece, metal case to the chassis. Next I identified the Horizontal Sweep generator circuit board. I turned the scope on and began to probe the many trim pots on the circuit board. It isn’t unusual for the wipers of the trim pots to become oxidized after 40 years. I also checked the condition of the solder joints on the board, carefully inspecting each questionable joint with a jewelers loop, (Old Eyes). The solder looked good and the wire wrap connections to the board were very solid.
After turning the scope off and unplugging it. I next grabbed my trusty $20 analog meter and began to test diodes and transistors. As I worked my way down the board I began to lose hope. Transistors and diodes are very stable devices for the most part and even after 40 years usually aren’t likely to fail. My feeling was that the capacitors are more likely to be the problem and I didn’t even want to think about trying to test or replace them. Finally the third to the last transistor that I tested had an open junction, base to emitter. I could easily read that it was a C458 with my loop. I remembered salvaging some C458s years ago and so I went to the proper bin and sure enough they were still there.
Since this was a matched pair transistor I removed it and replaced it with another C458 from a non-critical circuit on the B&K Horizontal board. When I touched my soldering iron to the old solder joints the aroma of 1970 vintage solder wafted into my nose. I am not sure what they are putting in the new solder but the old stuff definitely smells better. I installed the salvage C458 back into the non-critical circuit location.
As you can guess I had my trusty old friend back when I turned on the switch. At this point I realized that my B&K had a feature that is no longer available on the nice fancy scopes, repairability by me. It was at that point that I decided to write this review to honor my old friend the B&K Dynascan 1460 Oscilloscope.
John
