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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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tektronix 465 repair
I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants |
#2
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tektronix 465 repair
On 12/20/2014 5:03 PM, Lee Gleason wrote:
I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? Re-capping the whole thing would be a good start, I expect. I have a 475 that I'll have to do that to one of these days. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
#3
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tektronix 465 repair
On 12/20/2014 2:03 PM, Lee Gleason wrote:
I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants I'd go check all the caps. Over the last few years, I've had more and more caps fail in tek stuff. Originally was the teardrop tantalums, but more recently, all types. I don't have a schematic handy, but if you can check the bleeder resistors in the HV supply, I'd do that. There should be HV test point that you can check with a normal multimeter. |
#4
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tektronix 465 repair
On 12/20/2014 4:03 PM, Lee Gleason wrote:
I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants There's a good TEK yahoo group that might be helpful. Mikek |
#5
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tektronix 465 repair
"Lee Gleason" wrote in message ... I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants I would recommend going through the adjustments section of the service manual. That will offer you a chance to find any out-of-spec parts. The Tek manuals are very complete and include a theory of operation section that will answer most questions. Pay attention to the ripple/noise specs on the power supply test points. The +55 volt rail serves as the main reference for the rest of the supplies. Regards |
#6
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tektronix 465 repair
On 12/20/2014 3:43 PM, Tom Miller wrote:
"Lee Gleason" wrote in message ... I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants I would recommend going through the adjustments section of the service manual. That will offer you a chance to find any out-of-spec parts. The Tek manuals are very complete and include a theory of operation section that will answer most questions. Pay attention to the ripple/noise specs on the power supply test points. The +55 volt rail serves as the main reference for the rest of the supplies. Regards That's a good idea, but concentrate on getting the numbers close by fixing busted stuff. I'd recommend against randomly tweaking stuff in an attempt to fix hardware problems. That assumes that the previous owner exercised similar restraint when he tried to fix it. |
#7
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tektronix 465 repair
Are the voltages on the vertical plates close ?
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#8
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tektronix 465 repair
On Sat, 20 Dec 2014 15:03:27 -0700, Lee Gleason
wrote: I have a crusty old TEK 465 I saved from going into the garbage a few years back. Finally got time to pull it off the shelf and see what's going on with it. I was told it was completely dead and not repairable when I salvaged it - I thought, I'll be the judge of that. Initially it was stone dead - no trace, no lights, no fan nothing. I found a 1.5 A fuse (F1419) blown, and when replaced, it would blow again immediately. None of the panel lights or the fan would come on, and all the power supply voltages were low. I found one bad capacitor that was grounding the +15, when it started smoking (some faults are easier to locate than others). Replaced it and then found another cap, C1419, that was shorted that was blowing F1419. Replaced it and now the lights and scale illumination and fan come on. When I press the beam finder, I get a large dot flash and then nothing. Letting off the beam finder and adjusting the controls for a normal trace, I noticed that the whole screen is sort of illuminated. If I slow the sweep way down, I see that a dim 3/4 inch wide by whole screen tall bar goes across the screen, at about the rate you'd expect on the slow sweep settings - so that looks like the HV and the time base stuff is more or less working. I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? -- Lee K. Gleason N5ZMR Control-G Consultants Did you ask the TEK group? I saw some detailed info go by there, often. |
#9
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tektronix 465 repair
On Sat, 20 Dec 2014 16:03:27 -0600, "Lee Gleason"
wrote: I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? These may help: http://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/ http://www.spurtikus.de/basteln/repair/tek465/index.html -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
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tektronix 465 repair
On 12/21/2014 10:59 AM, Jeff Liebermann wrote:
On Sat, 20 Dec 2014 16:03:27 -0600, "Lee Gleason" wrote: I'm guessing I have some sort of vertical amplifier problem. Before diving back into the schematics, I thought I'd ask, anyone ever seen this symptom before? These may help: http://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/ http://www.spurtikus.de/basteln/repair/tek465/index.html Great Links! Here's another that may be useful (see the first two items listed under "Documents"): http://www.hakanh.com/dl/ Happy Holidays, everyone |
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