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2465B U400 Availability?
I'm looking at buying a 2465B that's supposedly needs a U400. Scope appears to work somewhat (calibrator trace looks good, etc.) and price is good.
I'm wondering what I may be getting into here. Are U400's very hard to find at a reasonable price? I see them on eBay but wondered if there's a better source (perhaps here?) for them. Also, is it "normal" for the 2465B to display any trace (e.g. the calibrator) when U400 is bad? In other words, I'm wondering if U400 is really the problem with it or possibly something else (apparently it won't calibrate). NVRAM maybe? Thanks, Barry - N4BUQ |
The U400 could cause problems in calibration but it is difficult to tell without testing.? However, it is possible to display a vertical trace?even when there are certain faults in U400.
Unfortunately, U400 is harder to obtain?than other parts and most sellers?(eBay?and otherwise) price accordingly. You could consider buying a low price "parts scope" to cannibalize for parts.? Most 2445 and 2465 parts will fit the 2465B.? The U400 fits them all.? Much of your decision depends on the credibility of the seller and the price.? Perhaps you can negotiate a price dependent on repair costs.? ??? From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Monday, March 28, 2016 3:34 PM Subject: [TekScopes] 2465B U400 Availability? ? I'm looking at buying a 2465B that's supposedly needs a U400. Scope appears to work somewhat (calibrator trace looks good, etc.) and price is good. I'm wondering what I may be getting into here. Are U400's very hard to find at a reasonable price? I see them on eBay but wondered if there's a better source (perhaps here?) for them. Also, is it "normal" for the 2465B to display any trace (e.g. the calibrator) when U400 is bad? In other words, I'm wondering if U400 is really the problem with it or possibly something else (apparently it won't calibrate). NVRAM maybe? Thanks, Barry - N4BUQ #yiv5855013699 #yiv5855013699 -- #yiv5855013699ygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;}#yiv5855013699 #yiv5855013699ygrp-mkp hr {border:1px solid #d8d8d8;}#yiv5855013699 #yiv5855013699ygrp-mkp #yiv5855013699hd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;}#yiv5855013699 #yiv5855013699ygrp-mkp #yiv5855013699ads {margin-bottom:10px;}#yiv5855013699 #yiv5855013699ygrp-mkp .yiv5855013699ad {padding:0 0;}#yiv5855013699 #yiv5855013699ygrp-mkp .yiv5855013699ad p {margin:0;}#yiv5855013699 #yiv5855013699ygrp-mkp .yiv5855013699ad a {color:#0000ff;text-decoration:none;}#yiv5855013699 #yiv5855013699ygrp-sponsor #yiv5855013699ygrp-lc {font-family:Arial;}#yiv5855013699 #yiv5855013699ygrp-sponsor #yiv5855013699ygrp-lc #yiv5855013699hd {margin:10px 0px;font-weight:700;font-size:78%;line-height:122%;}#yiv5855013699 #yiv5855013699ygrp-sponsor #yiv5855013699ygrp-lc .yiv5855013699ad {margin-bottom:10px;padding:0 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I have a 2465B in the process of being repaired. Mine displays all four channels, ch3 and ch4 display correctly but ch1 and ch2 distort as the vertical position is moved up and down. Square waves look fine until you watch them move!
All low voltage supplies look fine and looking here and elsewhere I guessed that U400 is the most likely culprit. A replacement is costing about half of the cost of the scope but I don't see an alternative. Everything else on the 2465 looks fine. Roger |
I would not buy a replacement for U400 without making sure that yours is bad first.
If you can wait while yours is tested, I'd send it to the Seller on eBay who sells them for $170. ?He will test yours for $5, plus the cost of return shipping. He also has a warranty on his used U400 if you choose to buy one and the $5 testing fee can be applied to the price of a replacement U400, if you buy one.. [Non-text portions of this message have been removed] |
It's a Craigslist sale and I don't know the fellow; however, he does seem to know more than simply "it powers on but don't know much more about it than that". From the ad, I think he may have tried to calibrate it (or have it calibrated) and discovered a fault in U400 but I don't know that for sure.
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I have a 2445 that I can try swapping U400 as a test. As far as price being commensurate with condition, it's well under $100 so I'm pretty sure I won't go wrong with it since it at least displays a decent calibrator trace and appears clean, etc. Thanks, Barry - N4BUQ ----- Original Message -----
From: "machine guy machineguy59@... [TekScopes]" <TekScopes@...> |
Regarding the U400, I've never pulled one of these. Are there any special precautions for pulling and/or reinserting these? I realize standard precautions for static, etc., but anything else?
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Thanks, Barry - N4BUQ ----- Original Message -----
From: "machine guy machineguy59@... [TekScopes]" <TekScopes@...> |
I haven't come across any special precautions for removal but there are warnings (in common with your 2445) about not operating the scope with the case removed unless you use an external fan to cool the hybrids on the main board.
Compared with prices in the UK, under $100 for a 2465B is a bargain. Mine was sold as not working and with no display, the usual corrosion from the electrolytics on the A5 board commonly makes the DAC reference voltage go way out of spec and this affects many sub-systems, trigger levels, beam vertical offset, brightness and probably many more. If 'yours' is suffering from a modest DAC drift it will almost certainly make it impossible to calibrate the scope. Mine had almost destroyed one of the thin film precision 10k resistors and had caused the beam to be invisible (and off screen anyway). If you have a 2445 to do the swap and test of U400 then you do not need to commit any further money until you are sure that U400 is the culprit. Replacing the resistors and capacitors on the A5 board is well documented and, at least in my case, not at all costly. Best of luck, Roger |
I bought the 2465B today. Nice physical condition on the outside but haven't had time to open it yet.
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Seems there's a bit of noise on some channels. I'm guessing power supply issues. Changing the vertical position of the trace definitely changes the height of the trace as I move from bottom to top. Looks like U400 is indeed problematic. Will know more once I dig into it. Thanks, Barry - N4BUQ I'm looking at buying a 2465B that's supposedly needs a U400. Scope appears |
I would not hesitate to buy?a 2465B with a trace for under $100.
Once home with this reassure I would measure all voltages and most likely replace all electrolytics.? Then borrow a U400 from my parts scope and go from there. From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Tuesday, March 29, 2016 7:14 AM Subject: Re: [TekScopes] 2465B U400 Availability? ? It's a Craigslist sale and I don't know the fellow; however, he does seem to know more than simply "it powers on but don't know much more about it than that". From the ad, I think he may have tried to calibrate it (or have it calibrated) and discovered a fault in U400 but I don't know that for sure. I have a 2445 that I can try swapping U400 as a test. As far as price being commensurate with condition, it's well under $100 so I'm pretty sure I won't go wrong with it since it at least displays a decent calibrator trace and appears clean, etc. Thanks, Barry - N4BUQ ----- Original Message ----- From: "machine guy machineguy59@... 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Depending on the history of your scope, the U400 pins may be corroded and make it hard to remove.? This isn't common nor likely, just possible.? So voe the screws that hold it in place and pry gently to lift it from the board.? If it doesn't come with reasonable pressure you may have to pull the A1 board from the scope and check the pin side of the board for corrosion.? But as I said, its not likely.
From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Tuesday, March 29, 2016 7:48 AM Subject: Re: [TekScopes] 2465B U400 Availability? ? Regarding the U400, I've never pulled one of these. Are there any special precautions for pulling and/or reinserting these? I realize standard precautions for static, etc., but anything else? Thanks, Barry - N4BUQ ----- Original Message ----- From: "machine guy machineguy59@... 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Bad voltages on certain supply rails can also cause the trace to distort as it is moved top to bottom.? One concern is if the distortion is the same on all channels and at the same place on the screen for all channels it could be the CRT.? That can be an expensive repair.? Check voltages first.? My 2465 had A and B channels that could not be mofed up and down more than an inch or so.? Turned out -8 volt rail was about -6.3 Volts.? Recapped and all is well.
From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Tuesday, March 29, 2016 2:22 PM Subject: [TekScopes] Re: 2465B U400 Availability? ? I bought the 2465B today. Nice physical condition on the outside but haven't had time to open it yet. Seems there's a bit of noise on some channels. I'm guessing power supply issues. Changing the vertical position of the trace definitely changes the height of the trace as I move from bottom to top. Looks like U400 is indeed problematic. Will know more once I dig into it. Thanks, Barry - N4BUQ I'm looking at buying a 2465B that's supposedly needs a U400. 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Got a chance to open up the 2465B tonight. Pretty clean and no obvious signs of capacitor issues (leakage, etc.). It's a 65K serial number and appears to have been made in 1994.
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Fan is broken. Two of the three spokes that hold the motor are broken and the blades were stuck against the back of the main frame. I managed to push those in place well enough to hold and the fan now runs; however, no telling how long it ran without that so heat damage could be a factor. Not sure, but the scope might have taken a small hit - enough to break that fan and cause the entire frame to be twisted just a tad. Reseated U400 just for fun but didn't cure the problem. Need to check voltages and ripple and possibly reseat some connectors as the controls and CRT seem to be intermittent with some apparent noise here and there. Also will want to try swapping U400 with my 2445 to see how much that cures. Neat scope! Thanks, Barry - N4BUQ ----- Original Message -----
From: "Barry n4buq@... [TekScopes]" <TekScopes@...> |
Its troubling that the scope ma have been dropped so hard.? Double check the CRT.? If all channels show similar distortion you may have a CRT fault.? Its repairable though.
From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Tuesday, March 29, 2016 9:47 PM Subject: Re: [TekScopes] Re: 2465B U400 Availability? ? Got a chance to open up the 2465B tonight. Pretty clean and no obvious signs of capacitor issues (leakage, etc.). It's a 65K serial number and appears to have been made in 1994. Fan is broken. Two of the three spokes that hold the motor are broken and the blades were stuck against the back of the main frame. I managed to push those in place well enough to hold and the fan now runs; however, no telling how long it ran without that so heat damage could be a factor. Not sure, but the scope might have taken a small hit - enough to break that fan and cause the entire frame to be twisted just a tad. Reseated U400 just for fun but didn't cure the problem. Need to check voltages and ripple and possibly reseat some connectors as the controls and CRT seem to be intermittent with some apparent noise here and there. Also will want to try swapping U400 with my 2445 to see how much that cures. Neat scope! Thanks, Barry - N4BUQ ----- Original Message ----- From: "Barry n4buq@... 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Only Channels 1 and 2 exhibit vertical linearity issues. Channels 3 and 4 appear to be okay. It won't be a big deal to swap U400 with my 2445 to see if it fixes the problem.
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I do notice the trace is not as sharp as I'd like/expect (my 2445 shows a bit crisper and I think they use the same CRT), so not sure if there's internal damage or just needs adjusting. There's a slight dent in the bottom rear of the cabinet and I think I can tell a small distortion in one of the frame pieces that meets up with the rear panel but the direction of that distortion seems odd (e.g. it would indicate an outward force rather than an inward force such as a strike to the rear panel, etc.). No telling just what/how it was hit. Overall, the frame seems twisted about 1/8" or more (doesn't sit flat on the bench). It's probably not too difficult to straighten this out. As for the broken fan, the way the fan "shroud" is designed, it presses against the center of the fan motor and it wouldn't really take very much pressure (with the cabinet removed) to break the small plastic supports that center the motor in the frame. I plan to CA glue those back in and see how that holds up. If not, a replacement appears pretty easy to find. The fan is slightly noisier than the other style fan in my 2445. I wish it had the same style fan in this model. BTW, as I mentioned, this appears to be a 1994 manufacture date and a 65k serial number. Was this pretty close to the end of production? I've looked for serial number correlation but not finding too much on that for this model. TekWiki just says "Produced from 1984 to ?". Thanks, Barry - N4BUQ ----- Original Message -----
From: "machine guy machineguy59@... [TekScopes]" <TekScopes@...> |
I have a CRT if needed (scavenged from a 2430A with bad CCDs, no screen burn). In the UK.
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Dave -----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] Sent: 30 March 2016 05:01 To: TekScopes@... Subject: Re: [TekScopes] Re: 2465B U400 Availability? Its troubling that the scope ma have been dropped so hard. Double check the CRT. If all channels show similar distortion you may have a CRT fault. Its repairable though. |
Only Channels 1 and 2 exhibit vertical linearity issues.? This is re-assuring for the CRT.? Since its only Channels 1 & 2 but its both channels in the same way, I suspect its a circuit problem and not likely the U400.? Keep in mind that bad supply rails can cause vertical distortion AND less sharp traces.? Its unusual for these scopes to have good supply rails after 20+ years.? Nearly all require re-capping the power supply and the A5 board as a minimum.This is the reason for my concern about being dropped.? This case is very sturdy, meant to be a portable scope.? I cant imagine how to distort the case with a normal blow.? I have an older rack mounted 2465 that was dropped hard, broke the CRT (at the neck, near the rear pins) and bent the screws holding it to the rack.? But the frame is still straight. As for the broken fanI have never owned?a 2400 series scope that didn't come with some kind of fan issue.? Yours seems minor compared to others.? From: "Barry n4buq@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Wednesday, March 30, 2016 8:11 AM Subject: Re: [TekScopes] Re: 2465B U400 Availability? ? Only Channels 1 and 2 exhibit vertical linearity issues. Channels 3 and 4 appear to be okay. It won't be a big deal to swap U400 with my 2445 to see if it fixes the problem. I do notice the trace is not as sharp as I'd like/expect (my 2445 shows a bit crisper and I think they use the same CRT), so not sure if there's internal damage or just needs adjusting. There's a slight dent in the bottom rear of the cabinet and I think I can tell a small distortion in one of the frame pieces that meets up with the rear panel but the direction of that distortion seems odd (e.g. it would indicate an outward force rather than an inward force such as a strike to the rear panel, etc.). No telling just what/how it was hit. Overall, the frame seems twisted about 1/8" or more (doesn't sit flat on the bench). It's probably not too difficult to straighten this out. As for the broken fan, the way the fan "shroud" is designed, it presses against the center of the fan motor and it wouldn't really take very much pressure (with the cabinet removed) to break the small plastic supports that center the motor in the frame. I plan to CA glue those back in and see how that holds up. If not, a replacement appears pretty easy to find. The fan is slightly noisier than the other style fan in my 2445. I wish it had the same style fan in this model. BTW, as I mentioned, this appears to be a 1994 manufacture date and a 65k serial number. Was this pretty close to the end of production? I've looked for serial number correlation but not finding too much on that for this model. TekWiki just says "Produced from 1984 to ?". Thanks, Barry - N4BUQ ----- Original Message ----- From: "machine guy machineguy59@... 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Two points:
Barry's 2465B and mine have very similar issues with non-linearity on ch1 and ch2 but ch3 and ch4 OK. At least on my scope the power rails are ok for voltage and ripple. I also checked the power supplies where they have common decoupling to U100 and U200 and so far have not found anything amiss. There are threads here and elsewhere suggesting U400 as a possible cause and it's price is consistent with it failing frequently! I haven't yet checked U400 bias current or the voltages on the channel select inputs. Secondly, Barry has several noisy analogue controls, DAC stability could be a common cause. Do the y and t cursors move smoothly? If they don't then it would be well worth checking the DAC output, there is setup procedure near the beginning of the calibration section of the manual that puts the DAC output on one of the DIP header pins and it responds to cursor movement - should be a good test. Meanwhile my replacement U400 has been stuck in transit for over a week en route to the UK! Roger |
You are right, it could be U400.? But I would try the other things first, lol.? In Barry's case, he has a source for an alternate U400.? I would try that AFTER?verifying all voltages are in spec.? No need to damage the alternative U400 with bad supply voltages.?
I am waiting to hear that your "new" U400 corrects your problem. From: "very_fuzzy_logic@... [TekScopes]" <TekScopes@...> To: TekScopes@... Sent: Wednesday, March 30, 2016 3:21 PM Subject: Re: [TekScopes] Re: 2465B U400 Availability? ? Two points: Barry's 2465B and mine have very similar issues with non-linearity on ch1 and ch2 but ch3 and ch4 OK. At least on my scope the power rails are ok for voltage and ripple. I also checked the power supplies where they have common decoupling to U100 and U200 and so far have not found anything amiss. There are threads here and elsewhere suggesting U400 as a possible cause and it's price is consistent with it failing frequently! I haven't yet checked U400 bias current or the voltages on the channel select inputs. Secondly, Barry has several noisy analogue controls, DAC stability could be a common cause. Do the y and t cursors move smoothly? If they don't then it would be well worth checking the DAC output, there is setup procedure near the beginning of the calibration section of the manual that puts the DAC output on one of the DIP header pins and it responds to cursor movement - should be a good test. Meanwhile my replacement U400 has been stuck in transit for over a week en route to the UK! Roger #yiv2028227971 #yiv2028227971 -- #yiv2028227971ygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;}#yiv2028227971 #yiv2028227971ygrp-mkp hr {border:1px solid #d8d8d8;}#yiv2028227971 #yiv2028227971ygrp-mkp #yiv2028227971hd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;}#yiv2028227971 #yiv2028227971ygrp-mkp #yiv2028227971ads {margin-bottom:10px;}#yiv2028227971 #yiv2028227971ygrp-mkp .yiv2028227971ad {padding:0 0;}#yiv2028227971 #yiv2028227971ygrp-mkp .yiv2028227971ad p {margin:0;}#yiv2028227971 #yiv2028227971ygrp-mkp .yiv2028227971ad a {color:#0000ff;text-decoration:none;}#yiv2028227971 #yiv2028227971ygrp-sponsor #yiv2028227971ygrp-lc {font-family:Arial;}#yiv2028227971 #yiv2028227971ygrp-sponsor #yiv2028227971ygrp-lc #yiv2028227971hd {margin:10px 0px;font-weight:700;font-size:78%;line-height:122%;}#yiv2028227971 #yiv2028227971ygrp-sponsor #yiv2028227971ygrp-lc .yiv2028227971ad {margin-bottom:10px;padding:0 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