Hi! I am new, but have several Tek scopes


Steven Bender
 

Steven here,

New to this Group, but not new to Tektronix, or various repairs.

I have and love my working Sony/Tek 335, and Sony/Tek 336 small Oscopes, may they show traces forever! I also have (4) not working Tek 2445 scopes that I need to repair, and a dual trace LeCroy 9450A that shows a trace on only one channel (these are on my really long TO DO LIST). In this time of COVID, I recently got three units that are taking up my time and attention, besides those that are just hanging around.

The latest three acquisitions include an off topic set - a Rohde & Schwarz UPL, (nice for audio) this one powers up with a blank white screen, no dos, no boot, no bios, no beep, so it’s problem is not the usual CCFL Failure. I think it runs either a 486DX or maybe an early Pentium 100/133. It has an internal power supply connector blackened/burned, and several of those smt glass cased diodes across the 9! Vregs from output to input, are looking kinda dark, and suspicious, some might be blown. So likely a PS failure (and hopefully nothing else ended up blown, as this unit is just loaded with boards)... (Any UPL owners/users among us????)

The other two recently acquired sets are: a Sony/Tek 335, and also a 336, both with VG cosmetics, but neither one shows a trace. The 335 I noticed has a broken Ch2 position pot, (R222 AB) Tek part 311-1795-00, a front panel .075/.125 shaft 10k/10k ohm dual control. As far as symptoms, the 335 shows a “low line” led, but that’s about it. The 336 will light up some of its push buttons, but also nada in terms of a trace.

I could use some suggestions, help, and that dual pot, there have to be some 335 parts donors still in existence, knobs are OK, just the outer shaft doesn’t connect to the inside part of the control.

Thanks, and you all stay safe!

Steven


 

Steven,

The first thing to try, with any ailing scope, is to check the power rails. For the scopes that aren't showing traces or otherwise failing to come up it's a good bet that one or more power rails are out of spec (remember to check both the voltage and the ripple) probably due to failed filter caps.

For the damaged pot there are several options: first is just to run the part number through eBay and Google and see what turns up, you may find something close enough. Some people on this group have had success taking apart damaged pots, straightening the bent shafts, cleaning the electrical contacts, and reassembling them.

Two commonly used parts suppliers are Sphere Research Corp. (www.sphere.bc.ca), and Qservice Electronics (www.qservice.tv), but there are others as well.

There is a good document from Tektronix titled "Troubleshooting Your Oscilloscope: Getting Down to Basics" https://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

You should post some pics in the photos section, so we can be appropriately envious.

Welcome, and good luck.

-- Jeff Dutky


 


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You do know that the EEVblog posts are 4+ years old don't you?

On Tue, Feb 23, 2021 at 9:18 PM Jeff Dutky <jeff.dutky@gmail.com> wrote:

There's also a fellow with a large collection of spare parts and a list on
EEVBlog forum:
https://www.eevblog.com/forum/buysellwanted/fs-new-test-equipment-repair-parts-hp-agilent-tektronix-fluke-etc/?fbclid=IwAR3MtFDHx2Y9AQ4ame6v6t3VRUqrFZH6uWvfQLn3NR3paAEGgEKsiu0qD58






 

I had not noticed that, but I think he's still trying to unload stuff: he just posted recently to a Facebook Tek scopes group, which is where I heard of him.