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Re: Tek 465B woes
Kevin Crossett
Hi Bert. I do plan to open the scope up and take a look. At the very least
I think I can giggle some of the transistors in their sockets, and it sounds like I will be able to take general voltage measurements using my DMM. The high voltage stuff scares me a lot, and I don't want my wife and son to find me on the garage floor after a careless measurement, hi hi. I will report back any of my findings. On Wed, Dec 3, 2014 at 11:08 AM, Bert Haskins bhaskins@... [TekScopes] <TekScopes@...> wrote:
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Re: 7B80 not quite right
I have not seen this happen yet with a 7000 timebase but I would start by
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checking the horizontal calibration which is trivial. This will reveal if the sweep is short because the horizontal gain is low or because the sweep is being reset early. On 03 Dec 2014 09:32:18 -0800, you wrote:
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Re: Tek 465B woes
Where are you located? Maybe someone on the list lives near you and can help you learn this stuff.
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Regards ----- Original Message -----
From: Kevin Crossett kcrossett@... [TekScopes] To: TekScopes@... Sent: Wednesday, December 03, 2014 9:17 AM Subject: [TekScopes] Re: Tek 465B woes Thanks to everyone who has emailed the list with suggestions for me to try to cure my ailing scope. I have a copy of the service manual and have taken a look at the various schematics. To say I'm intimated is an understatement. Just looking at the voltages coming out of this unit scares me. I am just starting out on this electronics hobby path, and spend my time playing with low voltage DC circuits. To be honest, I'm not even sure how to go about checking the voltage within the unit, and forget about techniques to determine ripple on the supply. I have trouble really understanding what is going on in a typical RC circuit, and that's just running off a nine-volt battery. I'm afraid this one is over my head. It's a shame as I really like the scope, and I'm finally in a position with my family life that I can start fiddling with it. The scope had been in storage for about a year as I focused on my family and work. Again, thanks to everyone who gave some practical suggestions. I will file them away. And if I can't find someone who has experience with these scopes and who can take a look at it, then, one day, when I feel more confident playing with high-voltage equipment, I might drag it out and see about repairing it. OK, back to my lurking status. Kevin |
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7B80 not quite right
I was just going to use a 7B80 in a 7904 setup, but found that the horizontal sweep width is short by about 10-15 percent. At first I thought it was a mainframe problem, but swapping another timebase proved both slots are OK.
The 7B80 seems to work otherwise, except that the external trigger attenuator switch detent doesn't hold the in position - it's always out, so divide 10. This shouldn't affect the sweep though, and it's not needed anyway. This is a standard (non-option 2 X-Y) version, so I assume that shouldn't be an issue either. I've cranked the front panel "SWP CAL" pot to the max, and worked over all the controls lots of times, and rocked the ICs and transistors in their sockets, hoping to find something a little loose, but that all had zero effect. I looked at the manual, and there doesn't seem to be any other H adjustment inside, or anything else obvious to blame, so there must be something that's slightly off in the amplifier or the sweep gate comparator - I haven't made any measurements yet to narrow it down between those two. I hate it when something works but is just a little bit off - it could take a lot of diagnosis to find something slightly drifted out - I'd rather have it be a gross error that can be narrowed down quickly. I'm also tempted to just leave it as-is for now, since it's not critical, but it would be nice if I can find a quick fix. Has anyone seen this behavior on a 7B80, or other TB plugs, that may be a common problem? Am I missing anything? Ed |
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Re: [hp_agilent_equipment] NOT OT: manual for Kepco OPS-2000?
Hi Michael,?? Nice! ?I'm happy to scan it, and I can drop the results into dropbox or mail you an old-fashioned CD in the end, and dump to PDF as well before mailing the manual back.
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? I would scan the pages at 600 DPI for posterity and compress the black and white pages to 32 shades of gray. ?That keeps the definition around the edges of the fonts while reducing the file size dramatically. ? As for schematics, I would have to scan 8x11" wide swaths and paste them together, which I am used to doing well. ?I've been storing my old scans of the Amateur Scientist column of Scientific American this way for years, so I have the capability and the storage space. ? Are the pages in a removable binder? ?If so I can do it in a couple days. ?If not, a couple weeks as it takes longer to do manually. ?I can send the schematic up front. ? Dan On Wednesday, December 3, 2014 11:00 AM, "Michael Noone nleahcim@... [TekScopes]" <TekScopes@...> wrote:
? Daniel - they accepted my order today so it looks like I'll be getting the manual shortly. I do not have the means to scan it... Is there anybody in this group that would be willing to scan? Thanks, Michael On Nov 25, 2014 5:50 AM, "Daniel Koller kaboomdk@... 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Re: Tek 465B woes
On 12/3/2014 9:17 AM, Kevin Crossett kcrossett@... [TekScopes] wrote:
This is a very easy thing to do: With the cover off and the the scope upside down the voltage test points are easy to fine and plainly marked. Even one of those ( free or $5 ) Harbor freight digital meters can show you if you have a major problem in the power supplies. Have you done the beam finder and X/Y operation tests?
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Re: [hp_agilent_equipment] NOT OT: manual for Kepco OPS-2000?
Michael Noone
Daniel - they accepted my order today so it looks like I'll be getting the
manual shortly. I do not have the means to scan it... Is there anybody in this group that would be willing to scan? Thanks, Michael On Nov 25, 2014 5:50 AM, "Daniel Koller kaboomdk@... [hp_agilent_equipment]" <hp_agilent_equipment@...> wrote:
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2465B Front Panel LEDs
I have a fully functioning and calibrated 2465B oscilloscope. It has only
one annoying feature. Whenever I push ANY of the front panel buttons, ALL of the unlit LEDs flash for less than 1 second. Does anyone know why this occurs? -- Gary Robert Bosworth grbosworth@... Tel: 310-317-2247 |
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Re: 465B random loss of -8 supply.UP
On 12/1/2014 4:27 PM, Bert Haskins bhaskins@... [TekScopes] wrote:
While babysitting this, I did my trick of wiping the case and pouch withSwapping U4206 (the opamp) restored the -8V and my 465B lives again. I hope!!, with intermittents it's hard to be sure. Note to the other poster: When the -8 supply is down, it's shuts off just about everything else. The |
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Re: Tek 465B woes
Kevin Crossett
Thanks to everyone who has emailed the list with suggestions for me to try
to cure my ailing scope. I have a copy of the service manual and have taken a look at the various schematics. To say I'm intimated is an understatement. Just looking at the voltages coming out of this unit scares me. I am just starting out on this electronics hobby path, and spend my time playing with low voltage DC circuits. To be honest, I'm not even sure how to go about checking the voltage within the unit, and forget about techniques to determine ripple on the supply. I have trouble really understanding what is going on in a typical RC circuit, and that's just running off a nine-volt battery. I'm afraid this one is over my head. It's a shame as I really like the scope, and I'm finally in a position with my family life that I can start fiddling with it. The scope had been in storage for about a year as I focused on my family and work. Again, thanks to everyone who gave some practical suggestions. I will file them away. And if I can't find someone who has experience with these scopes and who can take a look at it, then, one day, when I feel more confident playing with high-voltage equipment, I might drag it out and see about repairing it. OK, back to my lurking status. Kevin |
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Re: Zenith 36" problem!
Give Talon Electronics a buzz. George is an old-timer that understands TVs - and they will have your service manual, in PDF form. The B series were among the last Zenith sets made.
Talon is also the place to go for the old degaussing thermistors used in CRT televisions, glad I found them before buying on eBay. Taylor |
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Re: Tek 465B woes
Hi Kevin
Before you do anything, check your power supply voltages for correct voltages AND ripple. I have repaired hundreds of 4xx scopes, some with your problems, and almost all of them had severe ripple on one of the supplies. If your scope has been stored for a while, that's by far, the most likely problem. Keep us posted and good luck. Tad WA1FQO |
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2465A calibration memory
Hello,
My 2465A starts up with a TEST 04 FAIL 02 diagnostic error. I understand that this has something to do with a calibration value at is limit. Is there a way to find out which calibration is involved? And more generally, is there somekind of map available that shows the relation between the calibration location in memory (locations 00 to FFas shown in routine EXER 02) and the calibration values? In other words which memory location is related to which calibration? Regards, Jos, PA0JOZ |
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Re: Zenith 36" problem!
Ed;
You are right about the horizontal deflection circuitry in many of the late generation CRT TVs. The government was pushing for greater efficiency of electronic equipment to reduce power demands on the electric power industry. Most of them changed to LV power supplies that eliminated large power transformers and in turn used the horizontal deflection/HV power supply section as a switching power supply and added multiple secondary windings on the flyback transformer to derive other voltages to supply circuits in the rest of the set. Many sets had remote controls that remained on after the set was turned off and the push was there to reduce that to a flea-power level in the standby mode. Those late generation CRT TVs can be a real bear to work on. Most of the manufacturers recommended using an isolation transformer with voltage step-down/up capability to aid in troubleshooting and provide some additional protection against electrical shock. CRTs can hold HV for days and weeks when the set is turned off. There is a recommended way to discharge the CRT HV for each type set before servicing HV circuitry. If someone is not educated in how to safely do this, an appropriate service technician should be called. Many CRTs use a HV to achieve proper focus and that voltage can be around 4-5KV too. CRT screen grid voltages can be around 800-1.5KV. There are many locations in CRT type sets that can give a nasty shock. One thing about changing from a CRT based set to a modern flat screen set is the difference in the aspect ratio versus the size of images on the new sets. We changed from a 32" CRT set to a flat screen LCD type years ago and found that we had to go up to a 42" wide LCD set to achieve images that had the same size vertical display as the old CRT unit. Count on up-sizing about 31 to 32% in order to still see things the same apparent size on the screen. Joe KC5LY |
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Re: Tek 465B woes
Mark Wendt
On 12/02/2014 10:10 PM, Jim Popwell jpopwell@... [TekScopes] wrote:
Siggi’s right… get the proper manual….artek’s are very good….Yeah, and it's been a while since we've had a good troubleshooting thread. I learn from all of them! Mark |
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Re: Tek 465B woes
Jim Popwell
Siggi’s right… get the proper manual….artek’s are very good….
read the manual…. Tek has been very very good about teaching you HOW it works and then letting you trouble shoot it. The 465b is a very good scope to work on. take the feet off of the back and the two center screws and then carefully slide the whole cover off. LOOK!….. study the manual and see where things are and where the dangers are and where to make your test measurements. most of the 465 has individual transistors making things a lot easier to test. from the look of your video 1/2 of the horizontal amp is not working. first just for fun…wiggle any of the transistors on the horz bd that are in sockets…. you could get lucky…. then as Siggi suggested, check your power supply voltages. go slow and read as you go..you’ll get done…there is plenty of help here… jim On Dec 2, 2014, at 6:44 PM, siggi@... [TekScopes] <TekScopes@...> wrote: [Non-text portions of this message have been removed] |
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Re: Tek 465B woes
One more thing. It appears Artek Manuals have three different 465 scans for different serial ranges < >. You may want to buy the one that matches your scope's serial number (on the front of the scope, I believe). Dave's scans are going to be better quality than the free one on bama, and OCR-ed too.
Feel free to shoot questions and observations as you go, someone may notice trouble you miss in the heat of the moment. In addition to tinkerers like me, there are real-life experts hanging out here, but they seem to reserve themselves for the tougher problems :). Have fun, Siggi |
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Re: Tek 465B woes
I just took a quick peek at the horizontal deflection circuit schematics. Doesn't look too frightening, first step would be to check the DC supplies. A common failure is failing or drooping supplies. Horizontal seems to use 110V, 55V, 5V and -8V. Measure the DC level, and if you have a decent DMM, measure AC for signs of ripple too. If those check out, it's to the DC levels in the schematic to see where those are at.
You'll probably be closer to a cause with that already. Good luck, Siggi |
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Re: Tek 465B woes
Hey Kevin,
Welcome to the group. Start by grabbing the sevice manual, which can be found online. Here < > is one place. Give it a read, take a deep breath, then dive in to diagnosis and repair. These old service manuals are amazing. Now, I don't have a scope from this era myself, but I understand the transistors may be socketed. This may help as it's easy to pull them out for testing, and to swap them around. Do you have access to a second scope for troubleshooting? Siggi |
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