Tek 465 scope, no display

[kb2crk]

Well I went and got the lot of stuff from my neighbor. Some good some not so good.
The Tek 465 powers up but the display does nothing. I am hoping it is something simple from it being in storage for a few years. Does anyone have an idea what to check?
I need to hook up the frequency counter and test it.

[N8YX]

What are the power supply voltages like?

Get hold of a service manual and verify each . Most Tek scopes of the era have +5, +/-15 and a +/-50v outputs off the main PSU header; all other voltages are derived from those.

Start by isolating the PSU board from the rest of the scope. If all checks out, reconnect the power headers and proceed with troubleshooting. If not...the likely culprit is a bad electrolytic filter cap.

For that matter, one of the many tantalum decoupling/despiking capacitors used on the various subassemblies may have gone bad and is drawing the respective supply line to ground.

That's what ails most of the Tek scopes I've worked on lately.

Check the supply and let us know what you find out.

[NY4Q]

Before you do anything, go here young man, go here :

http://www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_465_Oscilloscope/Tektronix-465_Service_Manual

[kb2crk]

What are the power supply voltages like?

Get hold of a service manual and verify each . Most Tek scopes of the era have +5, +/-15 and a +/-50v outputs off the main PSU header; all other voltages are derived from those.

Start by isolating the PSU board from the rest of the scope. If all checks out, reconnect the power headers and proceed with troubleshooting. If not...the likely culprit is a bad electrolytic filter cap.

For that matter, one of the many tantalum decoupling/despiking capacitors used on the various subassemblies may have gone bad and is drawing the respective supply line to ground.

That's what ails most of the Tek scopes I've worked on lately.

Check the supply and let us know what you find out.

I will have to do that. I got a bunch of radio parts in the lot also (caps, transistors and IC's) I might even have the parts to fix it when I find the issue...
I spent most of this afternoon setting up a board for model trains in the 11 yo's room. This morning was spent verifying that my daughters car was running right again.
Thanks for the starting points

[N8YX]

I will have to do that. I got a bunch of radio parts in the lot also (caps, transistors and IC's) I might even have the parts to fix it when I find the issue...
If you don't, I probably do - or can point you off to a source for them.

[X-Rated]

Have you pressed the beam finder button? If you press that and have the intensity up, I think it needs repaired.

[K7SGJ]

As stated above, a quick push of the beam finder will tell you a lot. If it works, it will confirm the HV is present, and most of the crt operating parameters are close. PS and HV section failures are where I have found most scope problems. And check it in a darkened room because you can see even the faintest phoper glow that you might miss in a bright room. And as Fred states, the power supply branches should be next. Once you can some light on the screen, you can work on the deflection and signal processing circuits, if needed. For what it's worth, over the years I've developed my troubleshooting techniques to begin with a thorough visual inspection with good lighting and some magnification. You will find you can fix a hell of a lot of stuff just by doing that. Obvious things like smoked parts, burned or cracked traces, shitty connections (that's a technical term) and stuff like that. On a scope or any crt equipment, after the visual, I try all the controls and push buttons looking for anything that feels suspicious, then head to the power supply and HV section. Also getting the readings around the crt is a good idea in case of a failure of something like a bias resistor, something in the brightness circuit, or something else that would keep the tube from from conducting. Once you get passed that it's just a matter of going through the sweep and vert circuits. Be sure to take advantage of the calibrated 1 vpp terminal used to put the scope probe to calibrate the vertical deflection. It makes a very handy signal source. Naturally, use a DVM or other scope to make sure the 1vpp or there abouts is present, first. Level isn't important until you go through the calibration. And that brings up another thing I've learned at the school of hard knox. Many times, just following the calibration instructions will get you in the right area. If as you are following the OEM cal sequence, (and block diagrams) you find something that is grossly off, you will find it a great place to start looking around, and then after a little detective work, you will be where you need to be. At this point, it behooves one to make sure the defective area doesn't share a common connection with another circuit, sometimes even on another board. This, in technical circles, is called chasing your tail; or, if you're a ham, frogging your dong.

Good luck with the challenge. You will prevail.

[kb2crk]

A challenge it will be. A dark room will be the first test. The garage with the door open and afternoon sun shining in was very bright. I was told it was working when put in storage between 5 and 10 years ago.
If I get it working and I can unload the amps and antennas I got in the lot I will have a scope on the cheap. I will start digging into it in the morning...

[N8YX]

Jerry's comment about the beam finder is definitely relevant, especially in light of:


I was told it was working when put in storage between 5 and 10 years ago.

If you can see anything upon a press of the beam finder button I suspect dirty focus, intensity and trigger level pots, especially the latter if you don't have a sweep.

An FYI:

On many Tek scopes, the deflection, CRT filament and CRT high voltages are derived from a DC-DC converter which is powered from the 5V section of the supply. There is a very narrow voltage range in which the converter will oscillate properly and supply primary power to the HV transformer - from which all of those voltages are obtained. If the 5V supply is above or below those tolerances, you'll get nothing.

A quick way to see if all is in order with regards to that portion of the circuit is to remove the scope's covers and check for the presence of an illuminated CRT filament. If it isn't, start with the 5V supply. If it is, have a look at those pots. A little DeOxIt "FaderLube" will help restore operation.

Disclaimer:

There are voltages on the CRT anode which will kill your ass very dead should you come into contact with them. If you for any reason have to remove the HV supply and/or the CRT, be VERY mindful of Tek's procedure for disconnecting the anode lead and discharging the tube. And do so with the unit unplugged from the wall.

You may find the following to be of great help. It was written by your scope's manufacturer:

http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

[kb2crk]

Jerry's comment about the beam finder is definitely relevant, especially in light of:



If you can see anything upon a press of the beam finder button I suspect dirty focus, intensity and trigger level pots, especially the latter if you don't have a sweep.

An FYI:

On many Tek scopes, the deflection, CRT filament and CRT high voltages are derived from a DC-DC converter which is powered from the 5V section of the supply. There is a very narrow voltage range in which the converter will oscillate properly and supply primary power to the HV transformer - from which all of those voltages are obtained. If the 5V supply is above or below those tolerances, you'll get nothing.

A quick way to see if all is in order with regards to that portion of the circuit is to remove the scope's covers and check for the presence of an illuminated CRT filament. If it isn't, start with the 5V supply. If it is, have a look at those pots. A little DeOxIt "FaderLube" will help restore operation.

Disclaimer:

There are voltages on the CRT anode which will kill your ass very dead should you come into contact with them. If you for any reason have to remove the HV supply and/or the CRT, be VERY mindful of Tek's procedure for disconnecting the anode lead and discharging the tube. And do so with the unit unplugged from the wall.

You may find the following to be of great help. It was written by your scope's manufacturer:

http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

Powered it up last night in the dark and zilch, nada, nothing. I will start with checking the 5v supply in a few..
Thanks for the warning on the HV on the CRT. It is always good to have a reminder.

[X-Rated]

Odds are the thing is more trouble than what it's worth. Parts can be very expensive if you can find them. Mainly I am talking about the need of a new crt. Can you even find triplers for the thing?

[kb2crk]

I dont think it is trouble to take a look and see. It was part of a lot purchase along with power supplies, freq counter, B&W dummy load watt meter. bird meter and a bunch of other stuff. If it is something simple I will have a working scope. If I cant fix it I list it on the bay for parts or not working. I do believe it is worth the effort to look unless someone wants to make me an as is offer on it. I don't see that happening any time soon....LOL

[N8YX]

Odds are the thing is more trouble than what it's worth. Parts can be very expensive if you can find them. Mainly I am talking about the need of a new crt. Can you even find triplers for the thing?

I have an area ham friend who has a basement and garage full of Tek parts - including many from the 465/468 series stuff, along with complete scopes. There are a lot of commonalities across those model lines. One thing I don't hear him mention is the custom ICs in the 46x equipment going bad when compared to the failure rate of those used in the 24xx series.

We brokered a trade for a 468B once upon a time: I restored a piece of equipment for the gent and he gave me one of his rebuilt scopes. The scope in question was a frequent flier on my bench and after having helped repair many hundreds of pieces of gear it was subsequently passed on to another area ham...where it's still in use. IMHO, a 46x is definitely worth a rebuild effort.

I will study the schematic a bit later today and give you some things to check. This assumes that the power indicator and graticule illumination are both working, correct?

[X-Rated]

I have an area ham friend who has a basement and garage full of Tek parts - including many from the 465/468 series stuff, along with complete scopes. There are a lot of commonalities across those model lines. One thing I don't hear him mention is the custom ICs in the 46x equipment going bad when compared to the failure rate of those used in the 24xx series.

We brokered a trade for a 468B once upon a time: I restored a piece of equipment for the gent and he gave mean one of his rebuilt scopes. The scope in question was a frequent flier on my bench and after having helped repair many hundreds of pieces of gear it was subsequently passed on to another area ham...where it's still in use. IMHO, a 46x is definitely worth a rebuild effort.

I will study the schematic a bit later today and give you some things to check. This assumes that the power indicator and graticule illumination are both working, correct?

I was assuming the crt was dead. I thought the whole thing was dark.

[kb2crk]

I have an area ham friend who has a basement and garage full of Tek parts - including many from the 465/468 series stuff, along with complete scopes. There are a lot of commonalities across those model lines. One thing I don't hear him mention is the custom ICs in the 46x equipment going bad when compared to the failure rate of those used in the 24xx series.

We brokered a trade for a 468B once upon a time: I restored a piece of equipment for the gent and he gave me one of his rebuilt scopes. The scope in question was a frequent flier on my bench and after having helped repair many hundreds of pieces of gear it was subsequently passed on to another area ham...where it's still in use. IMHO, a 46x is definitely worth a rebuild effort.

I will study the schematic a bit later today and give you some things to check. This assumes that the power indicator and graticule illumination are both working, correct?

All of the other illumination is working as far as I can tell. I am headed to the garage now to start looking at it closer.

[N8YX]

I was assuming the crt was dead. I thought the whole thing was dark.
Have a look at page 253 of the following. Then locate F450B and TP4009. I'm assuming (again) the 465B and 465 use a common power supply circuit. If not, the other manual can be found alongside at KO4BB's site:

http://www.ko4bb.com/Manuals/Tektronix/Tektronix_-_465_Oscilloscope/Tektronix_465B_ServiceManual.pdf

Tek did this one a little differently than their modular (SC50x, 7000-series) scopes. Rather than feeding the DC-DC converter with +5V regulated, they're supplying the converter straight from the +15V (unregulated) rail of the PSU and the CRT filament voltage is obtained from the secondary of the transformer.

15v (approx) at the fuse says that portion of the power supply is in working order, while a waveform at the test point indicates Q14009 is being driven properly by the oscillator section. If you don't have both, you won't have filament power. If you do have both, you're probably looking at a bad transformer.

Being that I'm a betting man of sorts, I'll bet that if you have no 15v at the input side of the fuse, C4521 (on page 254 of the same manual) may be shorted. The other possibility is U4411B or one of the pass transistors which it drives is bad.

This really sounds like a dried-out electrolytic, though. Problem is that you'll need a working scope to diagnose the DC-DC converter if your power supply voltages check out.

[kb2crk]

Found a blown fuse upon opening. 1A fuse was below the transformer. now to try to find another as I have plenty of larger glass fuses but have not found a 1A yet.

[kb2crk]

Found a new fuse and it blew right away. I have something shorted somewhere in it.

Definite short to ground somewhere. should prove interesting to find.

[NQ6U]

Filter cap, I'll bet. Them things love to short out.

[N8YX]

Which fuse is blowing?

[kb2crk]

Which fuse is blowing?
The fuse on the interface board. I was trying to look at the schematic but this old laptop is being a PIA.

[N8YX]

Is it labeled "F450B" by any chance?

[kb2crk]

I don't see a label on the board or the page I found it on in the schematic.

[N8YX]

Near the fuse should be a 3-pin connector that attaches Q14009 to the circuit. Remove that connector, install a good fuse and power up the instrument.

Do you have a multimeter with which you can perform some tests?

[kb2crk]

Near the fuse should be a 3-pin connector that attaches Q14009 to the circuit. Remove that connector, install a good fuse and power up the instrument.

Do you have a multimeter with which you can perform some tests?

I don't see a 3 pin connector anywhere near the fuse. I do have a multimeter (a couple of them) and have been checking some stuff on the board.

[N8YX]

Check C4006 - 47uF, 25v electrolytic. For that matter, put an ohmmeter of the side of the fuse that is away from the PSU circuit - after having removed the fuse. Is it shorted to ground, or reading less than 200 ohms?

[kb2crk]

It is showing a short to ground.

[N8YX]

It is showing a short to ground.
Either the capacitor I mentioned is bad or the DC-DC converter driver transistor is shorted. You really need to get a good look at both the board layout and the schematic to visualize where the parts are.

[kb2crk]

And yes the fuse is F450B

[kb2crk]

I am going to have to look at the schematic closely and check those components. Thanks for the help so far but I have to pull off of this for a bit to help with a train set.....
I told my 11 yo step son if he got all the old tacks pulled out I would work with him on the new layout.

[NQ6U]

Watching this this thread progress has been more fun than watching TV. I can't wait to see how it ends.

[kb2crk]

http://i338.photobucket.com/albums/n404/kb2crk/beufortandtek086_zps807b675c.jpg
http://i338.photobucket.com/albums/n404/kb2crk/beufortandtek085_zps06c7ea04.jpg
Just a couple pics

[NQ6U]

Wow, parts you can actually see. How nice.

[kb2crk]

Check C4006 - 47uF, 25v electrolytic. For that matter, put an ohmmeter of the side of the fuse that is away from the PSU circuit - after having removed the fuse. Is it shorted to ground, or reading less than 200 ohms?

Snipped a leg and tested for a short on C4006? had a short on both capacitors that were in that position on the board. Popped a fuse in for a quick power up to see and there was life in the CRT. I see only one cap on the drawing but I need better light that I had tonight to pull the iron out and then find the info on the parts (may need a magnifying glass). Looks like I have a project for the weekend....

http://i338.photobucket.com/albums/n404/kb2crk/b8affd7d-27d0-44b9-9d7e-66ca8b63f654_zps6fd9620f.jpg
In the red circle.

[NQ6U]

Kewl! Good luck with your project. I was serious when I said that following this thread has been more fun that watching TV.

[kb2crk]

I did no work on the scope yesterday after work because Top Gear was on BBC America. That is one show I enjoy.

[XE1/N5AL]

You probably already know this, but the two capacitors that are circled in red, in the lower right hand corner of your last photo, appear to be tantalum capacitors.

[N8YX]

You probably already know this, but the two capacitors that are circled in red, in the lower right hand corner of your last photo, appear to be tantalum capacitors.
And them things are the devil for going out in Tek equipment of that vintage.

Brother Eddie will testify to the virtues of a Sodr-X-Tractor when dealing with faulty parts on a densely packed, double-sided PCB.

[kb2crk]

The solder sucker is on the desk somewhere... what I have to find is one of my irons or the old weller gun.

[NY4Q]

...the old weller gun.

EASY NOW; there's already a thread covering those consarn things...

[NQ6U]

EASY NOW; there's already a thread covering those consarn things...

When soldering guns are outlawed...

They can take my soldering gun when...

Soldering guns don't kill people...

[X-Rated]

EASY NOW; there's already a thread covering those consarn things...

Lest we forget, "The Weller Debate - The one solder thread to rule them all..."

[NQ6U]

Lest we forget, "The Weller Debate - The one solder thread to rule them all..."

Or, the one wire to solder them all?

[kb2crk]

At least there are no puns yet....

[X-Rated]

I think it would be cool to have a club formed at Fort Meade called the National Soldermans Association dedicated to promoting and proliferating soldering equipment and solder techniques. Teach techniques like keeping that PC board from moving around, you could use a Solderleeza Vice.

[N8YX]

Start here:

http://www.youtube.com/playlist?list=PL926EC0F1F93C1837

Word to the wise:

Buy later-model Pace, JBC, Metcal or Etneo (if located in EU) equipment.

It's pricy if new, affordable if you know how to work the 'Bay and Craigslist and will outlast most of us if used in a hobby or low-volume production scenario. Heck, it'll probably outlast us if used in a high-volume production scenario. Heaters, pumps and tips are the only things which really go bad in normal everyday use.

I've been working the snot out of a PRC-2000/SX-70 combo lately, desoldering all of the through-hole goodies on two TS-930S main boards. They do such a good job of removing solder that the parts pretty much fall out if the board is inverted.

Hot Tip:

Pick yourself up an MBT-210 (2ch) or an MBT250 (3ch, also known as a PPS-85A) along with an SX-70 extractor, PS-80 or PS-90 Sodr-Pen, TT-65 Thermo-Tweez and TJ-70 Thermo Jet plus tips appropriate for your planned projects: SOT, PLCC, QLFP, SOIC, through-hole...whatever.

For $200-400 outlay (plus consumables) you'll be able to successfully rework 99% of the devices which come across your bench. As for me: For roughly the price of a new Weller WS3000M I got over $10K worth of commercial-grade equipment by selectively shopping.

Included in that outlay is a PRC-2000 (PPS-400), a PPS-85A, an MBT210 as a backup/parts unit and all of the handpieces which go with the -2000...along with consumables. I can now remove everything except large BGA devices and can even rework damaged boards if required.

[AE1PT]

Jog my memory--what is the difference between the 465 and the 465B?

I have the latter and it is a fine general purpose DT scope. You will be able to purchase it in several decades at my estate sale...

[N8YX]

Jog my memory--what is the difference between the 465 and the 465B?

Without looking at the user manuals, I believe the 'B came with a waveform storage option.

[K7SGJ]

Jog my memory--what is the difference between the 465 and the 465B?

I have the latter and it is a fine general purpose DT scope. You will be able to purchase it in several decades at my estate sale...

Decades? Too long to wait. It would be worth more now if you can move the estate sale up a little. However, we would miss you. Never mind.

[AE1PT]

Decades? Too long to wait. It would be worth more now if you can move the estate sale up a little. However, we would miss you. Never mind.

There are lots of times I think about having it right now. All of it--the radios, test gear, and parts. I would keep the hand tools, as they are useful for other things. All of the money I could pour into finishing the darkroom and getting back to silver based photography. As my primary hobby...

What causes me to think this way are questions like the one presently in the Yahoo Amateur-Repairs reflector. It involves how to bend a ground plane antenna radial to 45 degrees. Listening to >3.8Mhz for more than an hour can also trigger the selling reflex, unless I am half in the bag myself. :cheers:

[K7SGJ]

There are lots of times I think about having it right now. All of it--the radios, test gear, and parts. I would keep the hand tools, as they are useful for other things. All of the money I could pour into finishing the darkroom and getting back to silver based photography. As my primary hobby...

What causes me to think this way are questions like the one presently in the Yahoo Amateur-Repairs reflector. It involves how to bend a ground plane antenna radial to 45 degrees. Listening to >3.8Mhz for more than an hour can also trigger the selling reflex, unless I am half in the bag myself. :cheers:


Or as someone posted a few weeks ago, where to put the drip pan to catch the grid leak.

[kb2crk]

So much for fixing it today. In all the parts I have I don't have the caps I need. I do have a bunch of crystals, transistors, and proms.......

[N8YX]

What do you need in the way of parts?

[kb2crk]

All I know of right now is the 2 caps. I know that one is the 47 Microfarad 25 v. The one right next to it I need also but I need to find my magnifying glass to see what it is.

[N8YX]

Figure out the other part you need then let me see if I have them. I'm pretty sure there's a new 47uF/25v tantalum floating around here.

[kb2crk]

http://i338.photobucket.com/albums/n404/kb2crk/DSCF4072_zps66f2cf7a.jpg (http://s338.photobucket.com/user/kb2crk/media/DSCF4072_zps66f2cf7a.jpg.html)
http://i338.photobucket.com/albums/n404/kb2crk/DSCF4074_zpsc68ffc79.jpg (http://s338.photobucket.com/user/kb2crk/media/DSCF4074_zpsc68ffc79.jpg.html)

These are the 2 tants I found bad. they are run in paralell in the 465.

[X-Rated]

Glad they don't look like our capacitors.

[K7SGJ]

http://i338.photobucket.com/albums/n404/kb2crk/DSCF4072_zps66f2cf7a.jpg (http://s338.photobucket.com/user/kb2crk/media/DSCF4072_zps66f2cf7a.jpg.html)
http://i338.photobucket.com/albums/n404/kb2crk/DSCF4074_zpsc68ffc79.jpg (http://s338.photobucket.com/user/kb2crk/media/DSCF4074_zpsc68ffc79.jpg.html)

These are the 2 tants I found bad. they are run in paralell in the 465.

Ya need a pair? caps, that is

[kb2crk]

I sure do need a pair of caps.... I can even trade some CB finals for them.....

[K7SGJ]

I sure do need a pair of caps.... I can even trade some CB finals for them.....

No need for a swap. Am I reading 22@35 tant? And is space an issue. If not, I'll send you a couple of 22@50. They aren't much larger but sometimes space is critical. If you have space, a little head room is nice, especially saince you already lost a pair. So to speak

[kb2crk]

The room is there so those should work. Losing one pair is quite enough

[K7SGJ]

I'll try to get them out tomorrow. I'm not sure if I still have your address, are you good on the ZED?

[kb2crk]

Eddie
I am good on the zed although you should have my address from a previous shipment...LOL
Thanks Paul

[K7SGJ]

Eddie
I am good on the zed although you should have my address from a previous shipment...LOL
Thanks Paul

I found it. Boy, those were some outstanding picutres. Using one of those high end professional models with the big buck lens?

[KG4CGC]

Beer at FD?
http://hamradionation.com/poll.php?user=kc9ih&poll_id=719

[WØTKX]

Red Solo Cup, Or Blue Solo Cup?