Re: Tek 7904 In Pulse Mode Related to C1511 on LV Regulator


 

For sure don't replace the metal cased tantalums in the PSU. It's highly unlikely they have failed.

If the power supply is in burst mode (ticking), then my experience of fixing 485s strongly suggests looking for a shorted dipped bead tantalum hanging off one of the power rails as the first probable culprit. Sure there are other possible causes like the 120V Zener going low but that's not very common fault.

Is the PSU ticking?

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of David Campbell
Sent: 07 January 2021 00:59
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 7904 In Pulse Mode Related to C1511 on LV Regulator

This scope is 40 ( +) years old.* It is not a repair. It is a restoration.*

Replace ALL the caps in the PS. Try again.

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