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#42
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Jerry Koniecki wrote:
Frank Miles wrote: Tektronix was, during that time, strongly discouraging all new designs from using tantalums. IIRC they had been taken to court over a case in which a 465 'scope (the original, not the plastic follow-ons) had spontaneously ignited and had resulted in an expensive fire. Forensics revealed that a tantalum power-supply bypass cap had started the conflagration. The drive to reduce tantalum usage was driven primarily by this liability issue, more than component cost. If you wanted to use a tantalum, you had to justify its usage to the component/design review committees -- which wasn't difficult if you had good reasons and your design was solid. Ah ha! I have a 465 (w/DM44) that I purchased in 1978 for personal use (no commercial abuse). Shortly after the warranty expired, it would not power up. I traced the problem to a shorted tantalum filter cap on the +15 volt line. But of course, it wasn't in the power supply, but rather on one of the boards. Pain to get to, IIRC. I can imagine. Tantalum caps are a real pain in the ass. If you reverse the polarity, they burn right through the PCB after a few months! We got a board in for repair last week with that problem. Luckily, everything on the board (yes, even the stickers with the serial numbers) is self extinguising. -- Reply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl |
#43
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Jerry Koniecki wrote:
Frank Miles wrote: Tektronix was, during that time, strongly discouraging all new designs from using tantalums. IIRC they had been taken to court over a case in which a 465 'scope (the original, not the plastic follow-ons) had spontaneously ignited and had resulted in an expensive fire. Forensics revealed that a tantalum power-supply bypass cap had started the conflagration. The drive to reduce tantalum usage was driven primarily by this liability issue, more than component cost. If you wanted to use a tantalum, you had to justify its usage to the component/design review committees -- which wasn't difficult if you had good reasons and your design was solid. Ah ha! I have a 465 (w/DM44) that I purchased in 1978 for personal use (no commercial abuse). Shortly after the warranty expired, it would not power up. I traced the problem to a shorted tantalum filter cap on the +15 volt line. But of course, it wasn't in the power supply, but rather on one of the boards. Pain to get to, IIRC. I can imagine. Tantalum caps are a real pain in the ass. If you reverse the polarity, they burn right through the PCB after a few months! We got a board in for repair last week with that problem. Luckily, everything on the board (yes, even the stickers with the serial numbers) is self extinguising. -- Reply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl |
#44
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Jerry Koniecki wrote in message ...
Frank Miles wrote: ..snippety... BTW, I did not get option 5 (TV sync separator). I wonder if it is feasable to install it myself? Documentation is listed as 465 option 5 supplement 070-2191-00. Anyone have this info? Yes, you can install it youself. The OPt.5 is a small extra board, basically a video clamp circuit. There is a small ek special IC on the board, but when you analyze the circuit you will recognize that a quad op-amp of gain-BW 5 MHz will work well. At least at mine it does so. Scopes with option 5 have a differnt front panel layout. So, you might get in trouble to realize this with your non-opt5 scope. But basically: Yes, it can be field installed. hth, Andreas |
#45
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Jerry Koniecki wrote in message ...
Frank Miles wrote: ..snippety... BTW, I did not get option 5 (TV sync separator). I wonder if it is feasable to install it myself? Documentation is listed as 465 option 5 supplement 070-2191-00. Anyone have this info? Yes, you can install it youself. The OPt.5 is a small extra board, basically a video clamp circuit. There is a small ek special IC on the board, but when you analyze the circuit you will recognize that a quad op-amp of gain-BW 5 MHz will work well. At least at mine it does so. Scopes with option 5 have a differnt front panel layout. So, you might get in trouble to realize this with your non-opt5 scope. But basically: Yes, it can be field installed. hth, Andreas |
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