whacky oscilloscope!

gain-wire · 15th May 2009, 03:38 AM

Hey people check this out:

http://cgi.ebay.com/LEADER-325A-OSCI...3A1%7C294%3A50
the trace is totally out of whack!

I wonder what the heck happenned... could have something to do with the fact it was dropped.

infinia · 15th May 2009, 03:48 AM

Quote:

Originally posted by gain-wire

I wonder what the heck happenned... could have something to do with the fact it was dropped.

yikes... CRT yoke assy most probably fubar-ed. Seller doesn't say exactly was dropped but is implied with rubber foot damaged that badly.

gain-wire · 15th May 2009, 04:15 AM

An oscilloscope has a Yoke? hunh?

I thought only televisions and computer monitors had yokes...

infinia · 15th May 2009, 06:06 AM

Quote:

Originally posted by gain-wire
An oscilloscope has a Yoke? hunh? I thought only televisions and computer monitors had yokes...

Some do an some don't, anyways the deflection looks wonk'd.
The shorter neck CRTs usually have coils, anyways here the service manual ftp://bama.sbc.edu/downloads/leader/lbo324/ your guesses as good as mine.

Enzo · 15th May 2009, 07:06 AM

If it doesn;t have a yoke, certainly the deflection plates inside the CRT could be bent out of alignment by dropping.

And make sure the power supply filter caps haven't come loose.

DRC · 15th May 2009, 02:54 PM

its eletro-static deflection.

almost certainly a broken support inside the tube - this can usually be seen with just the timebase running and altering the vertical position.

you may even be able to hear the bits rattling around inside the tube ...

gain-wire · 15th May 2009, 05:03 PM

Yeah, I did check the service manual, and there is no yoke coil. Just deflection plates. I suppose the tube is a fairly common one, for a japanese product it's a 95TB31. Funny, it does not appear to be mentionned in the parts list.
Anyway, could there be a possibility thet it could be the "trace rotation" coil? I thought this was usually done by simply rotating the crt.

Mark Allen · 6th October 2009, 04:18 AM

Most likely a power supply problem. Check with the aid of yet another scope for AC leakage on the DC rails, be careful! Bent deflection plates wold not cause this sort of odd trace but AC leaking through would.

MArk

15th May 2009, 04:15 AM	#3
gain-wire diyAudio Member Join Date: Nov 2004 Location: NCR	An oscilloscope has a Yoke? hunh? I thought only televisions and computer monitors had yokes... __________________ Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig

15th May 2009, 05:03 PM	#7
gain-wire diyAudio Member Join Date: Nov 2004 Location: NCR	Yeah, I did check the service manual, and there is no yoke coil. Just deflection plates. I suppose the tube is a fairly common one, for a japanese product it's a 95TB31. Funny, it does not appear to be mentionned in the parts list. Anyway, could there be a possibility thet it could be the "trace rotation" coil? I thought this was usually done by simply rotating the crt. __________________ Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Need help with oscilloscope	error0	Equipment & Tools	2	6th April 2008 02:22 AM
Oscilloscope	XTAL	Parts	0	18th March 2005 06:05 AM
PC or USB Oscilloscope	owel	Parts	9	31st March 2004 09:55 PM
How to use an oscilloscope	SimontY	Equipment & Tools	15	16th September 2003 11:46 AM
oscilloscope	Kilowatt	Digital Source	12	22nd January 2002 01:30 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

15th May 2009, 07:06 AM	#5
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	If it doesn;t have a yoke, certainly the deflection plates inside the CRT could be bent out of alignment by dropping. And make sure the power supply filter caps haven't come loose.

15th May 2009, 02:54 PM	#6
DRC diyAudio Member Join Date: Jan 2003 Location: UK (south west)	its eletro-static deflection. almost certainly a broken support inside the tube - this can usually be seen with just the timebase running and altering the vertical position. you may even be able to hear the bits rattling around inside the tube ...

6th October 2009, 04:18 AM	#8
Mark Allen diyAudio Member Join Date: Jan 2008 Location: Bountiful, You-Taw	Most likely a power supply problem. Check with the aid of yet another scope for AC leakage on the DC rails, be careful! Bent deflection plates wold not cause this sort of odd trace but AC leaking through would. MArk

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)