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Re: 465B No Beam Problem
Rob Overman
Ben,
Thanks for your response. I took a break from troubleshooting the past day. Will restart in the next hour. Good idea about disconnecting the CRT. Will definitely do that. I sure hope it isn't the CRT because I threw out a good CRT a few months ago because I assumed I would not need it and don't like having junk laying around. I plan on using my current limited PS to feed the + 15 Vdc source - that is a great idea that I did not think of. I do have two other functioning 465Bs. Regards, Rob Sent from Yahoo Mail. Get the app
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Re: 465B No Beam Problem
bc
I'm not quite sure I understand the status now, but assuming that it still blows fuses but a $0.75 1A fuse will sacrifice itself to protect Q14009 whereas the Q14009 will protect a $0.75 1.5A fuse.
I think it's time to start using a current limited PSU or a low wattage light bulb instead of the fuse, it's hard to test (and expensive) when a fuse keeps blowing! (Do you have a LM317 and a ~5.6 ohm 1W resistor that you could wire up a current limiter that you can plug in to where the fuse sits, if you don't have an appropriate voltage, low wattage light bulb (perhaps two 12V, less than 12W lamps in series to cover 24V?). However the light bulb is *much* more useful than the LM317 as you get instant visual feedback on shorts!) Definitely also need to try to see if disconnecting the CRT will stop it from blowing fuses (anode and the round back connector). My 2465 will blow the HVPSU fuse with a bad CRT, and disconnecting the bad CRT stops it from blowing. Curious if you had another scope? As said in the past apparently (though I wasn't subscribed then) - the minimum number of scopes to own is 2, and I think that's right :) -Ben
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Re: Tektronix Type 109 Pulse Generator
Craig Sawyers <c.sawyers@...>
I got a small number of NOS mercury relays from the late great and much missed Deane Kidd. So I
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have enough to keep the 109, 110 and 067-0523-00 580-series cal fixture up and running for as long as it takes for me to also shuffle off this mortal coil. Craig
For a mercury wetted reed relay though, it still seems odd that it
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Re: Tek 466 -- Reduced deflection range
On 25 May 2016 23:16:16 -0700, you wrote:
Just checked a couple more things.8.12 volts is about right based on the network around VR434. R435 and R436 both measure 49.9 +/- 0.1 Ohms; R437 and R438 have the resistance of 616 and 617 Ohms. Which means, the current flowing into pin 1 is 0.195mA, while pin 5 is sinking 4.962mA. Neither is close to the expected 0.440mA, but the one going into pin 5 is particularly high. I certainly need to read up on transistor amplifiers, but I won't be surprised if the fault is caused by a drifted resistor... inside the IC.I do not see how you established this. Voltages around the bias trimpot do not look good either:The bias is suppose to be adjusted for maximum vertical deflection at high frequency. I'll spend some time tomorrow thoroughly checking the resistor networks near the IC, lifting every part that needs to be lifted, but I'm not getting my hopes up. I think it needs a new IC, so not really worth repairing. I'll post an update if I find anything.On 25 May 2016 00:03:50 -0700, you wrote: Hi David,These all seem sane. U464, pin 1: 0.305V (0.3V)Good. - pin 4: -0.8V (-0.4V)Whoa, that is not right. Either the input transistor at pin 5 is bad or its collector load is too small. - pin 16: 5.18V (5.8V)These are both a little low but not enough to be the problem. - pin 3: 4.94V (5.6V)Also a little low. I wonder if the R467, R465, and R466 divider has drifted. - pin 10: 10.9V (10.2V)Good. Q426, as well as the next transistor inside the IC, look suspicious, but I don't know if their failure could reduce the gain of the entire thing by roughly an order of magnitude.The input transistors of the hybrid work against each other so if one is bad, the gain of the other decreases as well. Voltages coming from the two resistor networks drawn "inside" the hybrid on the schematic are also off. Perhaps it is caused by a resistor that drifted in value? Or could it be the consequence of a problem in the lower half of the amplifier?I think we are down to the following possibilities. You measured the voltage across R438 and the value of R438 so you know the collector current of Q426. 1. Either there is an open between the junction of R436 and pin 1. 2. Or the input transistor at pin 1 is bad; it could have low gain. 3. Or the collector current of the transistor at pin 1 is low. The voltage at pin 6 is not low enough to explain this and seems to indicate that the collector current is good. If it were otherwise, then this voltage would be high instead of low. So it looks to me like the hybrid is damaged around the transistor at pin 1. I would check the connections between R436 and the hybrid to be sure. The good news is that I think this particular hybrid or the entire vertical amplifier is readily available.
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Re: Tektronix Type 109 Pulse Generator
For a mercury wetted reed relay though, it still seems odd that it
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would ever wear out. The reed itself is under insignificant strain because the displacement in bending is so small and so evenly distributed. The mercury prevents arcing from damaging the contacts. That just leaves mechanical impact at the contact.
On 26 May 2016 11:51:59 -0700, you wrote:
Yes, they do wear out eventually. As I recall, they (and all electromechanical relays) have lifetimes in the millions of operations at rated load, so for general switching they can last a very long time. For high speed like in a pulse generator running at hundreds of Hz though, the operations count goes up pretty fast.
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Re: Tektronix Type 109 Pulse Generator
Ed Breya
Yes, they do wear out eventually. As I recall, they (and all electromechanical relays) have lifetimes in the millions of operations at rated load, so for general switching they can last a very long time. For high speed like in a pulse generator running at hundreds of Hz though, the operations count goes up pretty fast.
The wearout has two parts - the contact surfaces and the rest of the moving elements - that stuff can only bang between the states so many times. The load of course also affects the contact wear. Even though the Hg film makes and breaks the continuity, the hard contact parts still hit each other and wear out, even with no load. Ed
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Re: New forum and selling Tek stuff
Hi Bob,
Not sure what you mean exactly. I thought that you might want to sell the AM+P separately, since Dave Voorhis would like to buy just the TM. I already have TM (Too Many). Anyway, I'm afraid the total cost incl. shipment exceeds the budget that I have set for such a combination. Raymond
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Re: Tektronix Type 109 Pulse Generator
bobworsley92
Somewhere I have some mercury relay pulsers, came off of some TSN660 4.5GHz scopes I had. From memory they had a 250ps or so rise time.
I wonder if the reeds suffer from fatigue failure, they were used in telephone exchanges for the reason that their lifetime was essentially infinite. As far as I know the mercury is an addition, the reed is still pretty much the same. They do have to be used right way up as has been mentioned. Bob
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Re: New forum and selling Tek stuff
bobworsley92
Raymond
At the moment trefer to keep the TM501a with the AM503/P6302. The AM503 with the P6302 is 300GBP plus post, be cheaper within the UK because it will probably exceed the 2kg easy send international limit. Bob
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Re: New forum and selling Tek stuff
bobworsley92
Roger
The 7T11 with two 7S11/S2 plug ins is £400. [Non-text portions of this message have been removed]
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Re: 585A Not Powering On
Alex Brinister
Hi Albert, Yes, I did. I tried to do it the other way around, putting the plugin inside the 81. I didn't turn on the scope because the contact wasn't made very well and I didn't think it would work. I do have an instruction manual for the 81A so I followed that. Even before I reached for the manual, I realized the screw at the back of the 81 had to be screwed in before putting in a letter/1 series plugin for it to set into the scope properly. I never turned on the scope before setting both plugin and 81 adapter in the scope correctly though.
Would not following this procedure produce dead plugins? Thanks, Alex Brinister
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Re: 585A Not Powering On
Albert Otten
There happens to be a 585A on Ebay. The seller says
"Also Please Note - when using the 81A Plug In Adaptor, first insert the 81A by itself firmly into the scope, reach inside with a nut driver and tighten the adapter's own locking screw. Only then should you insert the letter or 1A plug-in that you want to use. Otherwise, you may not get a good connection between the plug in and the scope." Alex, did you "obey" this? Albert
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Re: Tek 2465B display shrinkage
I always measure to pin 7.
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----- Original Message -----
From: 'Matt Hofmann' mhofmann@sbcglobal.net [TekScopes] To: TekScopes@yahoogroups.com Sent: Thursday, May 26, 2016 8:35 AM Subject: RE: [TekScopes] Tek 2465B display shrinkage I found the table for power supply voltage tolerance in the manual and the pins on J119, the test connector, on the main board. What it doesn't show is where the ground reference is that I should be measuring these voltages from. I am sure someone knows where to reference these reading from. From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] Sent: Wednesday, May 25, 2016 12:11 PM To: TekScopes@yahoogroups.com Subject: Re: [TekScopes] Tek 2465B display shrinkage Do a search of the archives for A5 controller smt capacitor problem. In summary there are four SMT electrolytic caps on the A5 controller card that leak and damage the PC board. You will need to inspect, clean, and repair that problem first. Then have a look at the LV power supply caps. Regards ----- Original Message ----- From: 'Matt Hofmann' mhofmann@sbcglobal.net [TekScopes] To: TekScopes@yahoogroups.com Sent: Wednesday, May 25, 2016 11:56 AM Subject: [TekScopes] Tek 2465B display shrinkage Hello all; I am new here and I have a 2465B that has suddenly given me problems. After about a 5 minute warm-up, the image on the screen contracts to about 2/3 normal size and it jitters so that it is unreadable. I am a long-time Tektronix user (more than 40 years), but new to digging inside to see what is wrong. Any ideas of where I should start? Should I look for bulging electrolytics? Thanks! Matt
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Re: New forum and selling Tek stuff
Roger Evans
Bob,
For some reason I missed the list first time round. I am certainly interested in a 7S11 and a 7T11 or 7T11A. Maybe you could quote some prices before I send off cheque for the 24xx handle. Thanks again, Roger
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Re: Tek 2465B display shrinkage
Matthew Hofmann
I found the table for power supply voltage tolerance in the manual and the
pins on J119, the test connector, on the main board. What it doesn't show is where the ground reference is that I should be measuring these voltages from. I am sure someone knows where to reference these reading from. From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] Sent: Wednesday, May 25, 2016 12:11 PM To: TekScopes@yahoogroups.com Subject: Re: [TekScopes] Tek 2465B display shrinkage Do a search of the archives for A5 controller smt capacitor problem. In summary there are four SMT electrolytic caps on the A5 controller card that leak and damage the PC board. You will need to inspect, clean, and repair that problem first. Then have a look at the LV power supply caps. Regards ----- Original Message ----- From: 'Matt Hofmann' mhofmann@sbcglobal.net [TekScopes] To: TekScopes@yahoogroups.com Sent: Wednesday, May 25, 2016 11:56 AM Subject: [TekScopes] Tek 2465B display shrinkage Hello all; I am new here and I have a 2465B that has suddenly given me problems. After about a 5 minute warm-up, the image on the screen contracts to about 2/3 normal size and it jitters so that it is unreadable. I am a long-time Tektronix user (more than 40 years), but new to digging inside to see what is wrong. Any ideas of where I should start? Should I look for bulging electrolytics? Thanks! Matt
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Re: Need a handle for a Tek 2430A
Roger Evans
Bob,
I would be very happy to send you a cheque for £14, I think that would still be a bargain. If you e-mail me using my group ID at yahoo.com and give me an address then I will get a cheque in the post. Many thanks, Roger (very.....logic, can't find underscore on the phone keypad!)
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Re: New forum and selling Tek stuff
Any chance you’d sell a TM501 on its own, and if so, for how much?I'd possibly take an AM503/P6302, without TM501, depending on price. Shipment to NL. Possibly, another TekScopes forum member in the UK, who has shown interest in your stuff and whom I know may pick up or relay for me. I'm in the process of contacting him about this. Raymond
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Re: New forum and selling Tek stuff
Dave Voorhis
On 24 May 2016, at 18:42, eng@bwelectronics.co.uk [TekScopes] <TekScopes@yahoogroups.com> wrote:
… AM503/P6302/TM501 ...Any chance you’d sell a TM501 on its own, and if so, for how much? [Non-text portions of this message have been removed]
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Re: New forum and selling Tek stuff
Malcolm Hunter
On 24 May 2016 at 18:42, eng@bwelectronics.co.uk [TekScopes] <
TekScopes@yahoogroups.com> wrote: Ignoring standard amplifiers and timebases, there are six 7S11 with S2 How much are you looking for? I might be interested in the 7L14s and 7CT1N. I'm in Peterborough. Malcolm
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Re: Tek 466 -- Reduced deflection range
Vladimir _
Just checked a couple more things.
Emitters of Q416 and Q426 sit at 8.12 and 8.13V respectively, and their collector currents (through R437 and R438) are virtually the same -- 6.27 and 6.17mA. R435 and R436 both measure 49.9 +/- 0.1 Ohms; R437 and R438 have the resistance of 616 and 617 Ohms. Which means, the current flowing into pin 1 is 0.195mA, while pin 5 is sinking 4.962mA. Neither is close to the expected 0.440mA, but the one going into pin 5 is particularly high. I certainly need to read up on transistor amplifiers, but I won't be surprised if the fault is caused by a drifted resistor... inside the IC. Voltages around the bias trimpot do not look good either: pin 14: 10.84V (9.5V) pin 15: 10.23V (9.5V) pin 7: 11.25V (9.5V) pin 8: 11.92V (9.5V) top side of R471: 0.893V (0.8V) I tried to adjust the trimpot and, while I was able to get 10.2 on pin 10, it didn't help with all other voltages. I'll spend some time tomorrow thoroughly checking the resistor networks near the IC, lifting every part that needs to be lifted, but I'm not getting my hopes up. I think it needs a new IC, so not really worth repairing. I'll post an update if I find anything. Thanks, everyone!
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