Date   
Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

 

On Thu, Oct 25, 2018 at 11:59 PM, lop pol wrote:


Its the trimmer for the A ramp 10us timing :/ am I going to run into issues
trying to use a ceramic trimmer there compared to air?
No issues to be expected at the frequencies involved. Any good-quality trimmer should do but you may prefer the looks and fit of an original...... As promised, I'll have a look on Tuesday but please, send me a PM if you haven't heard until 20.00 GMT.
If I'd have to send one from NL, shipment may be expensive, although it may be sent as a letter. Where would I have to send it to?

Raymond

Re: Anyone have a 5.5 to 18PF variable ceramic trimmer they would like to sell

Brendan
 

On Thu, Oct 25, 2018 at 03:53 PM, Raymond Domp Frank wrote:


On Thu, Oct 25, 2018 at 11:59 PM, lop pol wrote:


Its the trimmer for the A ramp 10us timing :/ am I going to run into issues
trying to use a ceramic trimmer there compared to air?
No issues to be expected at the frequencies involved. Any good-quality trimmer
should do but you may prefer the looks and fit of an original...... As
promised, I'll have a look on Tuesday but please, send me a PM if you haven't
heard until 20.00 GMT.
If I'd have to send one from NL, shipment may be expensive, although it may be
sent as a letter. Where would I have to send it to?

Raymond
Thanks for all the replies. The one in this link https://www.surplussales.com/Variables/Ceramic/CerCap3.html posted by Gary looks amazingly close. I'm going to see what else they have and make an order from them. Looks like an awesome site. Thank you for that. What I'm going to do it get the scope up and running with the trimmers that will be here tomorrow and then when the one from surplussales gets here I will put it in and calibrate the monster. Thanks guys.

Tektronix 067-0625-00 Peak to Peak Detector Battery

Craig Cramb
 

Anyone had to locate replacement batteries for this unit. Only marking on the battery is 1A.
Original Tektronix description is: 1.5V, 650MAH, Alkaline-Manganese Dioxide
Tektronix 067-0625-00 Peak to Peak Detector Battery
Pictures on link with dimensions required.

https://groups.io/g/TekScopes/album?id=76872

My 2465B has arrived + A5 Board leaky caps cleanup

tekscopegroup@...
 

This is a 2465B Sn 55K purchased off ebay, very good external cosmetics, almost pristine interior with only very few traces of dust and so far have not seen any signs of having been disturbed or repaired in the past. Seller was stating that a Test 05 Fail 40 error was coming up upon power up, and that the traces where showing a lot of vertical jitter and eventually would move off screen towards the bottom. I figured that price and shipping cost numbers where decent for a B version, with the front cover and storage pouch (<$250), given the description, which I figured could be related to the well known leaky caps problem, so went for it and won. Oh and somehow the blue filter was loose and almost fell out when I took off the front cover. Have to check the manual, but I figure the filter just needs to snapped back into the groves that seem to hold it in place? If it is so easy to fall off, no wonder so many scopes are being offered without the blue filter, gone missing.

But today upon arrival when I powered up the scope it does not show a trace at all, or even a readout, nothing at all on screen, so not sure how long ago it still had a live screen. The power up self test does stop at the "ADD" label, so as I understand this seems to match the reported Test 05 scenario error. In any case pulled out the A5 board and got started on the leaky cap mess cleanup following some very good suggestions from Chuck not to try to desolder the caps in one piece, but rather carefully chop them up to get to the pads. Well, I kind of cheated and very carefully lifted the single cap in the corner by desoldering it bit by bit by extremely gently rocking it side by side very little at a time while heating the (cleaned up) pads, as it looked easy to do it on that location. It came out fine. But then decided to heed the recommendations as the other remaining 3 caps looked more difficult to get at due to less space around them. I think in the end all went quite well, there was not too much corrosion damage on the pads, and I could not see any traces that where eaten away.

Off course still quite a few other affected parts with dull/greenish pads that will need to be cleaned or replaced (see pictures liked bellow), and I am guessing that in the case of the IC legs that show corrosion they will have to be cleaned thoroughly. Also once I am done removing the rest of the affected SMD resistors and caps, will wash both the affected areas of the board with dish soap and water with a soft toothbrush. Then its into the oven at 375 deg for 45 minutes. Just kidding... its really only 40 minutes that are needed.

Some A5 pictures here:
https://groups.io/g/TekScopes/album?id=76874

BTW the scope has a TEK U800 (not the less desirable Maxim part), and most ICs show a 1990 date code. The NVRam has a 9020 date code. Once I can sort out the most pressing issues with the inoperative display I'm thinking of going the FM16W08 route, to do away with the need of a backup battery for good. I only hope getting the A5 board back in shape will bring back the screen to life. If not once I'm done with it will start checking voltage rails at J119 as well.

Comments and suggestions very welcomed about any follow up tests to make sure I have possibly not missed anything on the A5 cleanup, any know suspect VIAs to check, or hidden traces to verify they have continuity to another part, etc. Any other obvious possibilities besides the A5 mess on why the screen is non-op?

BTW, noticed that one of the 3 caps had two very fine traces between the pads to which the cap is mounted. I see these traces on one side go to what looks like two test points, but on the other side they seem to end nowhere, and don't seem to be connected to the capacitor pads either. Out of curiosity, anyone know what they are meant for? Thanks for any input.

Alex

Re: My 2465B has arrived + A5 Board leaky caps cleanup

 

Alex,
Very nice cleanup job.

I'd just like to jump in here about removing SMD caps with minimal chance of pad damage.

Every technician has his own favorite method of removing SMD capacitors.

My favorite method is to grip the capacitor from above with a pair of pliers, push DOWN, and simultaneously firmly twist the capacitor in the horizontal plane, about 120-180°.

NEVER pull the capacitor in an upwards direction.

The correct horizontal twisting action will break the capacitor leads at their weak point, and the capacitor will separate from the PCB.

If this method is done correctly, it will never cause damage to the solder pads on the PCB.

Re: Tektronix 067-0625-00 Peak to Peak Detector Battery

Craig Sawyers <c.sawyers@...>
 

I have two of these. The batteries are used for is to provide a DC offset "bucking voltage" of 0.3V
via a resistor network and adjustable resistors R8/R9 that sets zero output at 1.2V p-p.

If R10/R11, which are usually 120k at 1.5V are increased to 348k then the common 3V tagged cells could
be used with the same sensitivity of adjustment of R8/R9.

Having just worked that out, I've just worked out how to resurrect my own!

Just need to find a suitable tagged 3V battery that can take 7.5uA draw 24/7.

Craig

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Craig Cramb
Sent: 26 October 2018 03:52
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 067-0625-00 Peak to Peak Detector Battery

Anyone had to locate replacement batteries for this unit. Only marking on the battery is 1A.
Original Tektronix description is: 1.5V, 650MAH, Alkaline-Manganese Dioxide Tektronix 067-0625-00
Peak to Peak Detector Battery Pictures on link with dimensions required.

https://groups.io/g/TekScopes/album?id=76872

Re: Type G plugin versions

Dave Seiter
 

Wow- my G is s/s 9934, so it's just after the change.  Strange that they didn't change the sheet metal right away.
-Dave

From: Albert Otten <aodiversen@...>
To: TekScopes@groups.io
Sent: Thursday, October 25, 2018 12:44 PM
Subject: Re: [TekScopes] Type G plugin versions

According to the later manual Type G switched from UHF (131-012) to BNC (131-277) at S/N 9480. No idea in which year that was.
Albert

On Thu, Oct 25, 2018 at 08:17 PM, Dave Wise wrote:


I don't know the G serial number at which Tek switched from UHF to BNC*, but
the 1962 catalog shows UHF while 1963 is BNC**.  I think I have a newer manual
at home, I'll try to remember to look.

There was a mod kit for converting instruments in the field.  I have at least
one modded scope and plugin.  Yours too, most likely, as Tek would not have
sold instruments with such an obvious bodge.

Dave Wise

* For what it's worth, the 535A mainframe switched at 31260.
** Some old models were not updated.

Re: Tektronix 067-0625-00 Peak to Peak Detector Battery

Kerry Burns
 

Hello Craig

I've recently had to replace the original 1.35v mercury batteries in my 067-0625-00. I used 1.5v alkaline A1PX-BP1 batteries. Readily available and they are an exact fit - but you do need to have the battery supplier spot weld tags on to them for soldering. I got mine from my local 'Battery World' store, but you can get them from various online suppliers, such as 'Battery Direct' (https://www.batteriesdirect.com.au/shop/product/12224/a1px-bp1.html).

I've put two photos of my device with the new batteries ( both wrapped in black tape to reduce the chance of shorting) in the album 'Tektronix 067-0625-00 Peak to Peak Detector Battery'. I also had to replace the 50ohm input resistor in mine as a previous owner had broken this trying to remove the RF input section (contrary to the instructions in the manual).

Mine seems to work OK now, but I haven't yet checked it right out to 500 MHz.

Kerry

Re: Tektronix 067-0625-00 Peak to Peak Detector Battery

Craig Sawyers <c.sawyers@...>
 

That is really neat! Apparently available in Australia and NZ. But so far no luck finding in the UK or
Europe.

I'll try out my solution and report back what the result is.

Craig

Hello Craig

I've recently had to replace the original 1.35v mercury batteries in my 067-0625-00. I used 1.5v
alkaline
A1PX-BP1 batteries. Readily available and they are an exact fit - but you do need to have the
battery
supplier spot weld tags on to them for soldering. I got mine from my local 'Battery World' store,
but
you can get them from various online suppliers, such as 'Battery Direct'
(https://www.batteriesdirect.com.au/shop/product/12224/a1px-bp1.html).

I've put two photos of my device with the new batteries ( both wrapped in black tape to reduce the
chance of shorting) in the album 'Tektronix 067-0625-00 Peak to Peak Detector Battery'. I also
had to
replace the 50ohm input resistor in mine as a previous owner had broken this trying to remove the RF
input section (contrary to the instructions in the manual).

Mine seems to work OK now, but I haven't yet checked it right out to 500 MHz.

Kerry

Re: Tektronix 067-0625-00 Peak to Peak Detector Battery

Craig Sawyers <c.sawyers@...>
 

OK - the correct physical size is 1/3 AA. Although tagged batteries of that size are available, they
all seem to be rechargeable 1.2V.

But, the physically smaller 1/3 N (11.6mm dia, 10.8mm long) at 3V and solder tags is Varta
https://uk.farnell.com/varta/6131201501/battery-lithium-cr1-3n-170mah/dp/1781983

At 170mAh that should give about three years life at 7.5uA drawn. That is about half that of the
original battery, which should have given 7-8 years' service (although Tek suggested that they be
replaced yearly).

Craig

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Craig Cramb
Sent: 26 October 2018 03:52
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 067-0625-00 Peak to Peak Detector Battery

Anyone had to locate replacement batteries for this unit. Only marking on the battery is 1A.
Original Tektronix description is: 1.5V, 650MAH, Alkaline-Manganese Dioxide Tektronix 067-0625-00
Peak to Peak Detector Battery Pictures on link with dimensions required.

https://groups.io/g/TekScopes/album?id=76872

Re: My 2465B has arrived + A5 Board leaky caps cleanup

BryanByTheSea
 

That's a excellent tip for removing SMD caps, thanks for sharing.

Re: My 2465B has arrived + A5 Board leaky caps cleanup

Roger Evans
 

Alex,
There is a vast amount of information around about the A5 corrosion problem. The corrosion usually causes two 10k precision resistors to change their value. These set the voltage reference for the DAC that controls most of the operating points for the scope, including trigger levels (that causes the Test 5 failre) and also the brightness levels of trace and readout. There is a high probability that the screen will be OK after you replace the damaged components. Before I did my A5 repair I also had nothing visible on screen, I adjusted the Grid Bias pot before repairing the A5 board as a confidece measure to see that the rest of the scope was OK.
Roger

2465B leaky voltage

 

This morning, I was working with my scope, and I touched the CH1 BNC socket - ground side.
BZZZZ.

I thought I was dreaming.

I measured the voltage to AC Ground - 113VAC!!!

So something's leaking somewhere.

This is a 3 wire AC system - Live, Neutral, Ground.

I immediately checked my Signal Generator, on the same outlet - just fine, so it's definitely the scope.

Before I start poking around, does anyone have some fast pointers, to zero in on?

Menahem

Re: 2465B leaky voltage

ppppenguin
 

Are you sure the scope is properly grounded? Measure it rather than assuning it's OK because another peice of kit doesn't give any trouble. Just stray capacitance can cause an ungrounded chassis to feel a bit lively and measure at half mains voltage (I'm assuming you're in a 220V/230V/240V country). However there's little current available as you'll find if you try a lamp between the scope ground and actual ground.

As far as I can see, there aren't any "Y" capacitors between live or neutral and ground. But C1020 and C1051, both 2200p, are from ground to parts of the power supply that are ahead of the main isolating transformer.

Re: 2465B leaky voltage

 

Correct on the 230VAC assumption!

I've checked that it is "grounded" - there are Y capacitors in the sealed EMI-filter unit - right at the AC input, and I'm beginning to suspect those of failure.

All the caps are new, so those 2.2nF's are not suspect.

The 113VAC voltage exists, even if the machine is switched off.

Re: 2465B leaky voltage

ppppenguin
 

Shalom Menachem. I've just looked at your profile and note you're in Jerusalem.I've been amused when visiting Israel to find some high current applainces connected using our old British BS546 15 amp plugs and sockets.And landline phones using the same connector as in the UK, though with different pinout as I discovered the hard way.

I've certainly had a Schaffner mains inlet filter fail badly. It was on a Tek 1755A Vectorscope. It got hot enough to melt solder before an RCD tripped.

The question still remains, is the chassis just floating at half mains or is there real current available? Easily tested with a lamp or resistor to true ground or neutral. If there are Y caps in a mains input filter then loss of ground will definitely cause the chassis to float at half mains. Once you're sure that it's just floating rather than with real current available then I'm pretty certain you've got a missing ground. In the scope itself, in the mains lead or at your power outlet.

Re: My 2465B has arrived + A5 Board leaky caps cleanup

 

Alex,

The filter gets put back in after you put on the front panel. Just make sure the metal clip is installed on the front panel at the top of where the filter goes. You just slip the filter in starting at the top and the spring tension will allow it to snap into the side and bottom groves.

Manuel

Re: My 2465B has arrived + A5 Board leaky caps cleanup

Siggi
 

On Fri, 26 Oct 2018 at 01:13 <tekscopegroup@...> wrote:

Comments and suggestions very welcomed about any follow up tests to make
sure I have possibly not missed anything on the A5 cleanup, any know
suspect VIAs to check, or hidden traces to verify they have continuity to
another part, etc. Any other obvious possibilities besides the A5 mess on
why the screen is non-op?
A5 problems are a sufficient condition for no screen. On my 2467 a clamping
zener on the -1.25V reference had gone short, causing no display at all.

You've probably read up on this already, but the resistor network that sets
the DACs reference current is your prime suspect for the no display
condition. In your shoes, I'd buzz out all the traces and the resistors
involved there - this is everything connecting to pins 14 and 15 on the
DAC. Note that if you need to replace R2012/R2013 that they're precision,
low tempco resistors, so ideally you'd want to replace them with like -
especially if you intend to calibrate the scope. The little trimpot is a
frequent casualty of capacitor leakage, so give that a good look. I
wouldn't worry about jiggling it or replacing it, you'll have to go through
the DAC calibration procedure either way. It's a simple enough procedure,
and I think it's safe to assume that bringing the DAC into spec will bring
you nearer calibration than wrecking it.

There was a recent thread here discussing the +1.36, -1.25 reference
voltages and how they derive directly from the DACs reference current. I
don't think on your A5 board they will be brought to a test point, but if
you hunt them down, they allow you to assess the wellness of the DACs
reference, which is otherwise difficult to measure.

Re: 2465B leaky voltage

Chuck Harris
 

Let's gather some solid evidence:

The bond wire in the IEC style power cord goes
directly to the chassis by way of the mains power
line filter module.

It is a belt and suspenders system. The filter
module is in a metal can that has a metal mounting
flange that is screw mounted to the scope's chassis.

Inside of the can is a strap that goes from the bond
wire pin of the socket directly to a terminal on the
back of the can. The terminal is riveted to the
can.

The ground terminal on the back of the can has a green/
yellow wire soldered to it. The green/yellow wire has
a crimped on closed ring lug that is affixed with a nut
to a riveted threaded stud on the rear panel of the scope.

The rear panel of the scope is screwed to the chassis
using multiple screws.

The BNC connectors on the 2465 are directly (mechanically)
connected to the chassis at the front panel beneath the
bezel ring. Each has its own torx screw.

Assuming that the scope is the problem is a poor idea.
First do some measurements.

Connect a good low ohm meter to the offending BNC connector's
shield connection. Measure ohms to the front panel ground
banana socket. Measure ohms to the bond pin on the rear
IEC power connector.

If either of these measurements is not very near zero ohms,
you have a problem within your scope. Most likely inside of
the rear power filter... usually a burned out strap due to
a very, very high current path from the filter bond pin to
the filter hot mains lead... or possibly a manufacturing
defect.

By very near zero, I mean less than 1/4 ohm.

Next, unplug your power cord from the wall outlet, and
plug it into the IEC connector on the back of your scope.
Measure from the bond wire pin of the cord to the
front panel ground banana socket.

If it is not very near zero ohms, you have a bad power cord.

By very near zero, I mean less than 1/2 ohm.

If these grounds are correct, your problem is likely in your
bench power, or your house grounding system.

-Chuck Harris

M Yachad wrote:

Correct on the 230VAC assumption!

I've checked that it is "grounded" - there are Y capacitors in the sealed EMI-filter unit - right at the AC input, and I'm beginning to suspect those of failure.

All the caps are new, so those 2.2nF's are not suspect.

The 113VAC voltage exists, even if the machine is switched off.



Re: 2465B leaky voltage

ppppenguin
 

Chuck, thanks for laying out, step by step, what I was summarising.

The 113V reading is about what you would expect using a DVM with high (10M) input resistance with the scope's ground disconnected. It's simply the pair of Y caps in the filter acting as a potential divider. I don't know the value of the Y caps but from memory the maximum current that's allowed to flow from live to ground is about 250uA for a Class II (double insulated) appliance, somewhat more for a Class I (grounded) appliance. Even 250uA will give you a tingle, I've felt this many times when handling kit that isn't grounded.

If 1 of the Y caps in the filter was faulty I would expect the voltage reading to be either close to zero or close to full mains. The fact that it's close to half mains strongly suggests that the filter is OK and the scope's ground is missing. Also if one of the y caps was faulty I would expect a 30mA RCD (aka GFI) to trip. Assuming your lab is protected by one of these, and I really hope it is.