Date   

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

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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


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
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
would ever wear out.


Re: Tek 466 -- Reduced deflection range

 

On 25 May 2016 23:16:16 -0700, you wrote:

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.
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:

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.
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.

Thanks, everyone!
On 25 May 2016 00:03:50 -0700, you wrote:

Hi David,

I have the late version manufactured in 1982.

The resistances between the emitters are pretty close to expected values:
* Q412 and Q422 is 75.7 Ohms (expected between 72.5 and 76 Ohms)
* across R457 in-circuit: 134.5 (expected 134 Ohms)

Using the rest of the scope as a power supply for the vertical amp, I measured the following DC voltages (correct values given in parentheses):
Q412, collector: 3.94V (4V)
Q422, collector: 4.01V (4V)
Q416, collector: 4.19V (4.3V)
Q426, collector: 3.89V (4.3V)
Q416, Q426, base: 7.34V
These all seem sane.

U464, pin 1: 0.305V (0.3V)
- pin 2: -0.498V (-0.4V)
Good.

- pin 4: -0.8V (-0.4V)
- pin 5: 62mV (0.3V)
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)
- pin 6: 5.10V (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)
- pin 11: 12.8V (12V)
- pin 13: 14.74V (15V)
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.


Re: Tektronix Type 109 Pulse Generator

 

For a mercury wetted reed relay though, it still seems odd that it
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.

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.


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


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


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


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


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]


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


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


Re: Tek 2465B display shrinkage

 

I always measure to pin 7.

----- 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


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


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


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!)


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


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]


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
samplers, two 7T11, one 7T11A, 7CT1N, 7D20, two AM503/P6302/TM501, one
AM503/P6302. All these should work, not calibrated though. Also two 7L14,
one was looking good until it tripped the scope PSU, cap I assume, one sort
of did things but no sensible trace. I really ought to get it out and power
it all up again, was 6 or so years ago last tested. The P6302 all seem ok,
just tested them and had a good square wave at 16Hz so that should mean the
Hall sensor is ok. Several 134/P6021 current probes, all were working.
Several Fluke Y8100 AC/DC low frequency current probes, all dead if you
want a job?

​How much are you looking for? I might be interested in the 7L14s and
7CT1N. I'm in Peterborough.

Malcolm​


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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