Tektronix 475 oscilloscope - gone bad

[Urban]

Hi

Is there possibly anyone out there with a tech manual (as pdf) for this old beauty ?

I have no vissible sweep...

I think the supply has gone bad (or possibly just current limiting) I have +40V on the +50V regulated TP.

A scan of the PSU schematic would really be helpfull.

serial is: 101720


/Urban

 

[Sch3mat1c]

I've got the manual in 6.6MB of .PDF but it doesn't have a complete schematic anywhere, just segments.

Tim

 

[Greg Erskine]

Hi Urban,

I know this brief article is about the 465 but it may lead somewhere.

http://www.siliconchip.com.au/cms/A_101933/article.html

 

[AKSA]

Urban,

I've not pulled one down, but I have a 466 Storage Tek, beautiful CRO.

I'm led to believe that the power supply frequently falls over. I think it's a voltage tripler, and the caps are highly stressed. It's also used in a variety of other Tek CROs, and is therefore not too hard to fix.

Check the voltage tripler!

Cheers,

Hugh

 

[Urban]

I have found lots of goodies at: http://bama.sbc.edu/

Beware though the FTP is very slow, so you probably will have to try and try again.

Hmm. Voltage trippler. Will check. With one hand in my pocket...

/Urban

 

[tekman]

Try bama.edebris.com instead- much faster download, more simultaneous logins (= less long wait queue)

I've a 475 Service manual complete, so simply ask via personal mail ( PM ).

If really the HV multiplier failed, look for a junker 475 or 475A.

465, 485 won't work !

If you need more help, send a PM, may be I can help since we are both in europe located.

hth,

 

[Rahul]

Hi!

Try this link. You may have to register but lot of useful stuff is available for download.

http://teknetelectronics.com/srequest.asp

I got a manual for my 2565B here.

Regards

Rahul

 

[Urban]

Hi

Thanks for the links !

I finaly sorted my 475 out. The big cap in the +50V supply had gone to his maker. Rather basic perhaps but not too easy to find without a working oscilloscope and a manual.....

/Urban

 

[djQUAN]

Upping the ancient thread for my ancient scope...

Does anyone have a schematic for this scope (Tek 475A)

Mine just quit working and the mess of parts makes troubleshooting difficult. All fuses are good, the main supply caps have voltage but seems all the discrete regulators are dead as all regulated rails are 0V.

 

[djQUAN]

Sooooo..... some searching with google led me to Tek's site where I had to fill up a form and got a 64MB PDF file service manual with schematics and BOM for the 475 scope. Seems identical to my 475A but not exactly sure what are the differences between the two. But the boards and powersupply appear to be the same. I'll check my scope out this weekend.

 

[djQUAN]

Originally, this scope was made for long term reliability. It has only six electrolytic caps!

a couple hours of back and forth head scratching and looking at the service manual, the problem was caused by a 4.7uF tantalum cap that shorted the 50V rail to ground. Replaced with an electro from the junk bin and it worked at power on.