Thanks for posting this thread. Though I know nothing about your unit I appreciate seeing inside it.
And thank you for taking the time to read it. I am the same way, I love looking inside electronic stuff I never seen before and appreciate folks sharing
From the top deck of the main unit it looks logically laid out and pretty well designed. The below deck pears somewhat less organised. The CRT unit was likely robbed from another manufacturer as you have discovered. Far easier to use someone else's design than to build your own. It is, after all, a simple CRO assembly. Very well done for identifying the OEM. That must have been quite a challenge.
It reminds me of several engineering departments built each section separately and then brought it to the table to assemble lol. Like they never communicated with each other, and this was the outcome.
I cannot even remember how long I had this unit. But I know I have searched from day one only to find very little about it. As in my previous post there is schematics for the generator but were very poor.
Before the paper ID tag on the back fell off my serial number was in the high 10 thousands. So thinking there were quite a few of these built in the early 80's. I see a lot of 1981 to 1982 date codes on IC's and stuff. I did find a amateur radio operator (W9GB) that knows a lot about different things told me that the company has been long gone. So they were a fly by night company that produced these and disappeared.
So we now know that the scope unit is base off the BK 1405 5MHz scope. And yes this did take a long time to figure out. Surprised at how many scopes and equipment used this tube. When I ran into the BK1405 the circuit designed grabbed my attention. After looking it over I compared the unit and schematic and found I had a match. Even the silk screen on the board is the same as the schematic
As far as the RF generator section It was probably designed off one of the Wavetek units. The RF attenuator is also Wavetek branded and is still available for several hundred dollars.
With regard to documentation, I have often found that equipment that is pre-Internet and PC era does not have documentation available. It needs someone with the paper manual to scan and upload it. For rare and unusual equipment that sadly does not happen often.
Agreed!
And is another reason I like doing this. Get out as much information as possible through my research and repair of this unit. And if I can ever get it back to working condition then I can re-draw schematics with voltage reference and documentation. Sort of reverse engineer the thing so one day it may help others.
I see that no one else commented in this thread. I am interested though, so please continue to update this thread. Others can learn from it. Working with little or no documentation forces us techs to revert to basic principles and our knowledge of how a circuit or component should work. With your background you are obviously well qualified for the task. Others may learn from your experience on this equipment.
I will continue to keep an eye out for the LCD that you require.
All the best with the repair
Fraser
(Aurora)
I have found that no one replies to a lot of my post. But that is ok. I see hundreds of views on my own website but it is pretty much dead in activity. All that matters to me is folks finding something of use and that is helpful to them. The schematics I posted on my site have been downloaded many times. So I know folks are looking.
And again thank you for your interest in this. Just reading your reply helps fuel the fire with in to continue on this adventure. I can say if has been a tough one. I agree about working with no documentation. But it helps us to learn more in the long run AS soon as I am finished with the scope unit I will pull the LCD and see what the back side shows up. Maybe a id number if lucky
So as far as the scope unit since I have some documentation on it. Unidentified resistors have been replaced. The 4 oil filled caps that I removed some time ago have been replaced with ceramic style caps for the time being. I do not have any direct replacements in stock.
Just to get the circuit under test:
C123 and 126 were .1 @2KV and were replaced with .1 @2KV ceramics
C124 and 125 were .1 @1KV and replaced with .1 @1kv ceramics
Installed a new .5 amp fuse and powered the scope on. Nothing, no power LED, no bang, no smoke.
Starting with the mains connection to the transformer I found I had primary and secondary voltages. Checking DC power at the LED found it was blown. Replaced with a green LED.
No trace on CRT but I do have filament voltage on the board. Cannot see it in the tube but I know some are hard to see.
PS:
I also wanted to add. Since there is little information on equipment like this, take lots of pictures.
Of wiring connections, part placement, control wiring ect. Some wiring becomes brittle and will break loose. Leaving you with "where the heck did this go". This has already happened to me several times in the scope unit. There was a small red wire dangling from the power LED indicator. No where on the board could I find where it broke loose from. After reviewing some pics I took earlier I found the wire was attached to a resistor that has it's body raised off the board. So looks like this was an after thought for a connection point when the unit was built.
I feel I made some good progress today
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