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7603 specifically and general refurbishment procedures of older oscilloscopes

 

Hello everyone,

I recently acquired a 7603 with 7L12 SA. I got the pair to use the 7L12 with my 7904A but I really like the large screen of the 7603. So I'm planning to use the '03 for audio work. The '03 seems to work when the 7L12 is installed but I can't get any kind of trace (except for readouts) when I use any of my 7000 series plug ins. I can't say I've tried every permutation but I've tried installing a 7A19, a 7A22, 7A26 in conjunction with a 7B92, 7B92A, 7B80 and a 7B85 with the "A" plug ins in the center & left slot and the "B" in the right with no joy.

Because of this problem I'll be opening up the 7603; if anyone has any specific suggestions on where to look I'd be grateful but otherwise are there any common procedures for the overhaul of an older scope? I have quite a bit of experience rebuilding older amplifiers and radios but I bought my 7904A refurbished, I have no experience on older Tek scopes. I thought I'd start by cleaning the plug in connectors and as many pots & switches as I could access. While open I will check voltages and have a good look at the caps.
Do you automatically replace all electrolytic caps or just ones that are showing signs of ripple or leakage?
A search of the files section implied that tantalum caps are usually reliable and do not require preventative replacement (other than obvious failures).
Are there any other common issues that need to be looked at? Any other suggestions?

This will take me a while to complete but in the meantime, thanks in advance for any help,

John
 

If it works with the 7L12 but not with known good regular plug-ins. More than likely don't have the right buttons pushed ( or a bad button) . Take a deep breath and check that you have the trigger selector set correctly for the channel your on and so forth.

Beam finder works correct?
Dave
manuals@...

On 7/23/2018 11:57 AM, johnasolecki@... wrote:
Hello everyone,

I recently acquired a 7603 with 7L12 SA. I got the pair to use the 7L12 with my 7904A but I really like the large screen of the 7603. So I'm planning to use the '03 for audio work. The '03 seems to work when the 7L12 is installed but I can't get any kind of trace (except for readouts) when I use any of my 7000 series plug ins. I can't say I've tried every permutation but I've tried installing a 7A19, a 7A22, 7A26 in conjunction with a 7B92, 7B92A, 7B80 and a 7B85 with the "A" plug ins in the center & left slot and the "B" in the right with no joy.

Because of this problem I'll be opening up the 7603; if anyone has any specific suggestions on where to look I'd be grateful but otherwise are there any common procedures for the overhaul of an older scope? I have quite a bit of experience rebuilding older amplifiers and radios but I bought my 7904A refurbished, I have no experience on older Tek scopes. I thought I'd start by cleaning the plug in connectors and as many pots & switches as I could access. While open I will check voltages and have a good look at the caps.
Do you automatically replace all electrolytic caps or just ones that are showing signs of ripple or leakage?
A search of the files section implied that tantalum caps are usually reliable and do not require preventative replacement (other than obvious failures).
Are there any other common issues that need to be looked at? Any other suggestions?

This will take me a while to complete but in the meantime, thanks in advance for any help,

John


--
Dave
Manuals@...
www.ArtekManuals.com
 

Hi John,

There are a few things you could do before opening the cabinet.
It's possible that the scope is working normally but showing no trace because of a fault in the (un)blanking circuitry. You might check the signals at the rear panel BNC output connectors (Vert Sig Out, Gate Out, Sawtooth Out) to see if there is activity inside.
An (un)blanking fault could be present in the path from 7B plugin to/through the main interface board. I think, but I have no 7603 to test this myself, that the CRT will be unblanked anyway when you try the 7603 in XY mode using two 7A plugins. (Try this unfocused to avoid phosphor damage.) The dot position should listen to position controls.

Albert

On Mon, Jul 23, 2018 at 05:57 PM, <johnasolecki@...> wrote:


Hello everyone,

The '03 seems to work when the 7L12 is installed
but I can't get any kind of trace (except for readouts) when I use any of my
7000 series plug ins. I can't say I've tried every permutation but I've tried
installing a 7A19, a 7A22, 7A26 in conjunction with a 7B92, 7B92A, 7B80 and a
7B85 with the "A" plug ins in the center & left slot and the "B" in the right
with no joy.

Because of this problem I'll be opening up the 7603; if anyone has any
specific suggestions on where to look I'd be grateful but otherwise are there
any common procedures for the overhaul of an older scope?
 

Thanks for the suggestions. I'm pretty certain I had all the buttons pressed correctly but I'll recheck that (wouldn't be the first time...!) and I'll try to check the unblanking circuitry.
What about capacitors and other aging components? As needed or change them all?

John
 

IMHO only replace electrolytic caps that have failed, those big Sprague caps are normally OK except when they go open-circuit.

Dave

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of johnasolecki@...
Sent: 24 July 2018 12:40
To: [email protected]
Subject: Re: [TekScopes] 7603 specifically and general refurbishment procedures of older oscilloscopes

Thanks for the suggestions. I'm pretty certain I had all the buttons pressed correctly but I'll recheck that (wouldn't be the first time...!) and I'll try to check the unblanking circuitry.
What about capacitors and other aging components? As needed or change them all?

John

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