A 6X4 vacuum tube can have a cathode to filament short and "still work" for a while. The only way to be sure the 6X4 is actually in good shape is on a vacuum tube tester with a good "shorts" test circuit.
Don Resor
-----Original Message----- From: jukebox-list-bounces@lists.netlojix.com jukebox-list-bounces@lists.netlojix.com On Behalf Of Jerold Kress via Jukebox-list Sent: Saturday, January 14, 2023 2:42 PM To: jukebox-list@lists.netlojix.com Subject: [Jukebox-list] FOLLOW UP TO SEEBURG TSU5 ISSUE
This is a follow up to my previous posting about issues with my Seeburg TSU5. I've isolated the problem to C514 over heating but so far have not determined the cause. I replaced C514 & C515 and R518 that bridges their negative ends. (I tested the caps to be sure they weren't shorted & the resistor's value is good.) C514 is connected to the -400V side of the 6X4 rectifier tube. I know this is a positive ground system so I was careful to replace the caps in their proper configuration, with both pos ends soldered to ground. I've switched out the 6X4 with 3 working replacements (all from working guitar amps) but C514 continues to overheat. (I shut down the system after a few seconds but in that time C514 is warm to hot.) I can test the voltage reaching this cap if that info will help in a diagnosis. Any insight into why this cap is overheating so quickly would be appreciated. Thanks!
jerold k
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