Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Junk room revisited

Status
Not open for further replies.

jrz126

Active Member
Hard to believe that it's been a whole month since I posted about my junk-room adventures...

I am finally able to purchase 3 of the oscilloscopes (at $0.10/lb! :shock: )
I dont know if i will be able to get any probe leads with them, So where is a good place to buy those?

Also, where would I find some info to determine if the scope is still calibrated/working properly?

I'm getting a tek-465, which seems to be functioning properly, a tek-7834 which is a rather large unit, and it isnt working. and then a tek-2430A. I believe this might be a digital scope. it's got something wrong with it, but I may be able to fix it.

Well I'm off to pick up my new goodies.
 
If the 7834 has a bad CRT, you're screwed since that was Tek's high-end analog storage scope. Pray tell, where the heck are you finding treasure like this for 10¢ a pound? At that price, shipping must be $100/lb!

Dean
 
The 7834 would just click about 1 or 2 times a second, like it was trying to come on but it didnt have enough power.

I just went down there to get the serial numbers, and I looked at the 2430A, the sticker on it said it wont store the settings, and something was messed up with the trigger levels. hopefully it can be fixed or still can be used. but the price is definitly right...a digital scope for ~5 bucks.

It's a junk room at work..so shipping is free :D I'm betting I wont have to pay more than 20 bucks for all 3 scopes. :D
 
I must have missed that first post. So, where do you work. And, well... do they have anymore good stuff? :eek: :eek: :eek: :eek: :eek:
 
So I went down to the junk room again to pick up my scopes and take them to the salvage building.

I was looking around some more and I found this guy on one of the back shelves.
2440-bb118-9-full.w.jpg


The screen was pointed towards the wall which is why I didnt notice it before. The tag says uncalibrated, unrepairable, and "R+C Probe Comp Bad" what does this mean? the scope comes on just fine and all of the self tests pass.

:shock: WHOA! a quick ebay search shows this scope selling for +$3,000.00 ....yeah umm... for that price, I may just take it :twisted: .

Oh yeah, I figured out why the 7834 wouldnt power up, one of the removable dual trace units was bad, pulled that up and it powers up just fine

Oh yeah, here's a link to the old post https://www.electro-tech-online.com/threads/dtmf-reciver-n-transmitter.13131/
 
Last edited by a moderator:
Jeff, the 7834 (and most of the other 7000-series, the 485 and the later serial numbered 434) has a heaven-sent power supply. The "ticking" you were hearing was the sound of the switcher trying to come up but finding an imbalance on one of the many supplies in the mainframe (+50, -50, +15, -15, +5), usually caused by a short to ground, typically because of a shorted bypass or filter capacitor. Obviously, you found the problem, and the errant vertical preamp has such a fault in it.

The 7834 supply is constantly checking for all of the linear regulated supplies to be at the proper voltage, for proper primary current on the switching transformer and for zero crossing of the line voltage.

To troubleshoot a "ticking" 7000-series, just let it tick and connect a scope probe to each of the regulated supplies in turn. You should see good supplies hop up to or near their proper voltage and a bad supply won't.

Dean
 
I asked about the TDS 540, and they are keeping it for parts :cry:

Anyhoo...I got some more info on the digital scope. It fails the Trigs/repet* self test.

Another problem I noticed is it will display the calibration trace just fine, then after about 20 seconds ~ 2 minutes, it will just pause. only way to get it to read the trace again is to push the "aquire" button.
I think it only does it when you have a probe connected.

I'm researching how to fix this now, any suggestions?

oh yeah, it's the 2430A scope

Is it possible to connect this scope to my PC? (It has the GPIB bus)
 
Well, I just purchased them today...only took a month Typical GE Transportation timelyness :) turns out they charge $.25/lb for electronics equipment.
The cost:
TEK-7834 =48 lbs =$12.00
TEK2430A = 29 lbs = $7.25
TEK-485? = 25 lbs = $6.25

So in the end, I got 3 oscilloscopes for $25.50 :D

Now I think I'm gonna ditch work early and go play with my new treasure :D
 
-off topic-

I've been wondering for a long time, and I finally have to ask: What is the cat attacking in your icon?
 
I found a site that had like some 400 photoshopped pics that used this cat.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top