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Tektronix 475A failed during initial use

John Hensley #77659 开云体育 My 475A Oscilloscope powered up fine and as I was adjusting the trace, the scope just died, like a classic scope putting itself to sleep. ?I can still hear the power trans- former and the fuses on the rear panel are good (they are not blown). ? This is a scope which I have not had much time to use but because of its age I am very surprised it did this.? I'm going over some documentation that Dino Pappas kindly sent to me but I am? wondering if anyone has been through this and if so, what might be the issue? ?I am guessing the problem is with the A9 main board ? Thanks, John
Tom Jobe #77660 开云体育 Hi John, Taking your guess just a bit further, I would guess that one of those pesky tantalum capacitors is the problem on the mainboard. Check the resistance to ground of each low voltage supply at its test point to get started. The tantalums are multi colored "dipped"?capacitors, and the ones that often fail are in the 10uF to 47uF range. tom jobe... ? ? ? toggle quoted message Show quoted text ----- Original Message ----- From: John Hensley To: tekscopes@... Sent: Tuesday, June 26, 2012 5:50 PM Subject: [TekScopes] Tektronix 475A failed during initial use ? My 475A Oscilloscope powered up fine and as I was adjusting the trace, the scope just died, like a classic scope putting itself to sleep. ?I can still hear the power trans- former and the fuses on the rear panel are good (they are not blown). ? This is a scope which I have not had much time to use but because of its age I am very surprised it did this.? I'm going over some documentation that Dino Pappas kindly sent to me but I am? wondering if anyone has been through this and if so, what might be the issue? ?I am guessing the problem is with the A9 main board ? Thanks, John
Bruce Wilson All Messages By This Member #77674 Excellent answer. ?That's exactly what I found in one of my 475s that was DOA when I got it. Regards, Bruce W4BGW toggle quoted message Show quoted text On 26 Jun 2012, at 21:15 , Tom Jobe wrote: ? Hi John, Taking your guess just a bit further, I would guess that one of those pesky tantalum capacitors is the problem on the mainboard. Check the resistance to ground of each low voltage supply at its test point to get started. The tantalums are multi colored "dipped"?capacitors, and the ones that often fail are in the 10uF to 47uF range. tom jobe... ? ? ? ----- Original Message ----- From: John Hensley To: tekscopes@... Sent: Tuesday, June 26, 2012 5:50 PM Subject: [TekScopes] Tektronix 475A failed during initial use ? My 475A Oscilloscope powered up fine and as I was adjusting the trace, the scope just died, like a classic scope putting itself to sleep. ?I can still hear the power trans- former and the fuses on the rear panel are good (they are not blown). ? This is a scope which I have not had much time to use but because of its age I am very surprised it did this.? I'm going over some documentation that Dino Pappas kindly sent to me but I am? wondering if anyone has been through this and if so, what might be the issue? ?I am guessing the problem is with the A9 main board ? Thanks, John

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