Tek 465B Magic Soot


CARL MESROBIAN
 

I bought a 465B as-is, etc. and thought I could get it up and running and discovered fuse 4508 was blown. I put a 1A in it's place and that blew also.



I decided to move this beast off my bench and while doing so discovered some magic soot on the inside of the case and on a CRT connection ? (red wire). also. Is this thing worth fixing? I have another scope that works, so theres no urgency to it.




https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205 https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205


 

The 465B is a fine analog scope.

Ok, first, the black soot is just that. It is attracted by the high voltage field around the red cable. It is just mostly carbon exhaust.

The fuse is in the unregulated +15 supply and _IF_ you are very lucky, it is just a shorted tantalum capacitor C4006. The capacitor is under the HV shield in the corner of the board and is a 47uF-35 volt dipped tant. You can just use a good quality 105°C aluminum electrolytic

The second most likely thing that blows that fuse is the HV multiplier module. They run around $50+ and it is a task to replace. The procedure is covered in the service manual.

Do you have the service manual?


Retards,
Tom

----- Original Message -----
From: cmguitar50@gmail.com [TekScopes]
To: TekScopes@yahoogroups.com
Sent: Thursday, November 09, 2017 6:43 PM
Subject: [TekScopes] Tek 465B Magic Soot



I bought a 465B as-is, etc. and thought I could get it up and running and discovered fuse 4508 was blown. I put a 1A in it's place and that blew also.



I decided to move this beast off my bench and while doing so discovered some magic soot on the inside of the case and on a CRT connection ? (red wire). also. Is this thing worth fixing? I have another scope that works, so theres no urgency to it.




https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205 https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205


CARL MESROBIAN
 

I have the Artek manual - it's searchable, too :)

I will check c4006 at some point - thanks!


CARL MESROBIAN
 

The cap measures 48.55 uF and ESR is .26.

I'll put this aside and think about digging deeper. I picked up a BK PR-28A in case I go further. I also have a variac and thought of bringing it up to around 70v as I saw in a tech training service manual


http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf



There seems to be a lot for me to learn on this , as I only dabble with tube amps for guitars, etc. This makes 500 VDC look like candy!


 

What is the resistance from the cap side of the fuse to ground? Ohmmeter lead + to the fuse.

----- Original Message -----
From: cmguitar50@gmail.com [TekScopes]
To: TekScopes@yahoogroups.com
Sent: Thursday, November 09, 2017 9:02 PM
Subject: [TekScopes] Re: Tek 465B Magic Soot



The cap measures 48.55 uF and ESR is .26.

I'll put this aside and think about digging deeper. I picked up a BK PR-28A in case I go further. I also have a variac and thought of bringing it up to around 70v as I saw in a tech training service manual


http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf



There seems to be a lot for me to learn on this , as I only dabble with tube amps for guitars, etc. This makes 500 VDC look like candy!


CARL MESROBIAN
 

It varies , but around 13-14 ohms

There's no fan either - don't know if that helps


and voltages on the PSU test points were


Should Be Actual


5V 3.5V
15 2.7
55 9.7
110 70