Date   
Re: Ebay Rip-off ? - "Global Shipping Program"

Colin Herbert
 

Fat chance, I think, Patrick. That would be far too much bother for them. I
daresay that both my complaint and the possible one from the original
purchaser of the watch were filed away in the waste-paper basket. Bigger
stick needed!

Colin.



From: TekScopes@... [mailto:TekScopes@...]
Sent: 08 February 2016 01:25
To: TekScopes@...
Subject: [TekScopes] Re: Ebay Rip-off ? - "Global Shipping Program"





Hi Colin,

I would have expected that the recipient of the 7B92A, expecting a blingy
watch instead, also would have complained to eBay. I'm wondering whether
eBay would then be smart enough to match the two complaints to recognize
your concern was honest and accurately stated?


Patrick Wong AK6C

Re: Ebay Rip-off ? - "Global Shipping Program"

David DiGiacomo
 

On Sun, Feb 7, 2016 at 10:12 PM, Sergey Kubushyn <@KSI> wrote:
Note, you no longer get any discount when you buy postage from USPS
(Click-n-Ship). It's better to use PayPal shipping.
Nope, I would not pay a single cent over that constantly growing fee they
already charged me.
Even though it would save you money?

Then, last time I checked (long ago but I seriously doubt they fixed it and
100% sure they added a ton of stupid bells and whistles since then) it did
_NOT_ work with Linux Firefox and did not offer USPS pickups.
PayPal shipping does work in current Firefox. I don't see why it
would be different on Linux.

You would have to request the USPS pickup on the USPS site.

As of discounts -- I shipped my last box something like 2 weeks ago and
still got a discount. When did this change?
January 17th. I was surprised too.

Re: Ebay Rip-off ? - "Global Shipping Program"

Malcolm Hunter
 

On 8 February 2016 at 14:57, Peter Gottlieb hpnpilot@... [TekScopes] <
TekScopes@...> wrote:

Yeah! I once got an eBay item for an overseas buddy who then decided he
didn't want it, so I was stuck with it and eventually had to deal with
selling it at a loss. Lesson learned!

​How I do it is I add my US friend to my ebay shipping details and select
her address when I checkout. If you do it this way, you have the item your
non-US friend has paid for until they pay you to ship it.

Malcolm​

Re: Ebay Rip-off ? - "Global Shipping Program"

Peter Gottlieb
 

Yeah! I once got an eBay item for an overseas buddy who then decided he didn't want it, so I was stuck with it and eventually had to deal with selling it at a loss. Lesson learned!


Peter

On Feb 8, 2016, at 9:36 AM, @Raymond [TekScopes] <TekScopes@...> wrote:

Dennis, >> In one case it was because the buyer refused to pay the customs duties so the package sat in
Customs but I had no way to know that. Then the buyer contacted Ebay to say I never sent it
and demanded his money back. I imagine that once he got his money refunded he would be happy to
pay the customs duty and keep the instrument.
Wauw...

Dennis,
I guess you ask full payment upfront since then, maybe "real" friends excepted...
We always do that on the local Dutch "MarktPlaats" (MarketPlace). Sometimes an extra amount for contingencies - or a beer...


Raymond

[Non-text portions of this message have been removed]

Re: Alternative SG504 head- lower cost, better function.

mosaicmerc
 

Hi David....
Yes, I got the gender flipped on the BNCs. Since it makes little sense to just make one, given all the re-engineering, I thought I'd make a few for those who wanted my 'improvements'.
My email about the prob, to you, is dated 27 Jan , 8:39AM. Titled 'bit of assistance pls.'

I haven't ordered any parts yet...so if you can share the gerbers. I can just remake one rather than doing the whole RF/engineering/VNA thing.

I can share the lemo replacement option with the forum though...as I have already designed that solution.

Here's what the replacement of the Lemo looks like.
IMAG0022.jpg https://www.dropbox.com/s/u44t6av35ck3oye/IMAG0022.jpg?dl=0&preview=IMAG0022.jpg

https://www.dropbox.com/s/u44t6av35ck3oye/IMAG0022.jpg?dl=0&preview=IMAG0022.jpg

IMAG0022.jpg https://www.dropbox.com/s/u44t6av35ck3oye/IMAG0022.jpg?dl=0&preview=IMAG0022.jpg Shared with Dropbox



View on www.dropbox.com https://www.dropbox.com/s/u44t6av35ck3oye/IMAG0022.jpg?dl=0&preview=IMAG0022.jpg
Preview by Yahoo

Re: Ebay Rip-off ? - "Global Shipping Program"

 

Dennis, >> In one case it was because the buyer refused to pay the customs duties so the package sat in
>> Customs but I had no way to know that. Then the buyer contacted Ebay to say I never sent it
and demanded his money back. I imagine that once he got his money refunded he would be happy to
pay the customs duty and keep the instrument.
Wauw...

Dennis,
I guess you ask full payment upfront since then, maybe "real" friends excepted...
We always do that on the local Dutch "MarktPlaats" (MarketPlace). Sometimes an extra amount for contingencies - or a beer...


Raymond

Re: TDS 380 calibration and vertical scale problem

Siggi
 

On Sun, 7 Feb 2016 at 17:59 david.wilson92@... [TekScopes] <
TekScopes@...> wrote:

I think replacing the dc coupling 50 ohm smd should be doable, replacing
with part CRCW060350R0FKEA. Also going to replace 3 220uF 35 capacitors
with low impedance ones on the main board with part UHE1V221MPD. When these
parts come in I will pull ch2 hybrid and replace the 50 ohm dc coupling
capacitor and inspect for visual damage.
Hey David,

that message seems a little confused.
To reiterate; I don't think there's any evidence so far that any of the
soldered-in SMD parts on your attenuators are bad. The AC coupling
capacitor on CH2, in particular, seems to be just fine.

You do have two problems though:

1. Somehow signal is not getting from the BNC to the preamp in DC
coupling on CH2. This will likely be a burned trace, or a thick-film
resistitive element burned and gone open.
These resistive elements are not soldered in, those are laid down on the
hybrid structure, and will be under the "lumpy" spots of the blue coating.
2. On both attenuators it appears that you've lost a resistive element
that's part of the divider for the 500/200/100mV div pre-amp path. This
will likely also be a thick-film resistor that's suffered a gross overload
and gone open - another "lump" somewhere on the attenuator.

You should be easily able to trace the first problem, as you can simply
compare measurements between CH1 and CH2. Best case you have something like
a bad solder joint, though I expect that you'll find trace damage.

The second problem is going to be more difficult to fix, as we won't know
the value of the burned resistors - you've no good speciment to compare to.
So, you'll have to find the fault, then reconstruct the schematic of that
part of the attenuator before you can reason about what you need for
replacement.

Also
Capacitors->Farads, uF, nF, pF.
Resistors->Ohms

Good luck,
Siggi

Re: Ebay Rip-off ? - "Global Shipping Program"

 

Dennis, > In one case it was because the buyer refused to pay the customs duties so the package sat in
> Customs but I had no way to know that. Then the buyer contacted Ebay to say I never sent it
> and demanded his money back. I imagine that once he got his money refunded he would be happy to
> pay the customs duty and keep the instrument.
>
Wauw...


Raymond

Re: 2465B Power Supply Problem

Michael
 

David,

I can see the failure taking out the bridge. When something like that fails,
pretty much everything connected to it can fail because you never know exactly
what might happen during the failure or the exact timing which can make a big
difference. Since it didn't fail instantly, probably the blown C1016 partially
damaged the bridge, which then failed over the next few seconds.

Since I am now aware of that issue, I will replace the bridge as soon as
Mouser gets my parts here (supposedly shipping today).

My concern is that my "smoke" test may have also damaged the bulk storage
capacitors. I just replaced those and I hope not to need to replace them
again, so quickly! The bridge circuit that failed is the connection between
(-) and (~). That is connected to the bottom (-) of C1021. So when a positive
cycle is happening the negative side of C1021 would be lifted up. I am not
sure that it would cross the positive side, but since the input would be
unfiltered it might. But, it would also be discharging the capacitor which
might protect it.

Do you think that it's likely to be damaged? My DMM is not terribly good at
testing capacitance and removing C1021 is real pain with the "extended" legs,
so I don't really want to do that. However, I aslo don't want to "spread" the
failure any further.


Mike

I have seen bridge rectifiers and safety capacitors fail together
before and in these cases, I wonder if it is the safety capacitor
which causes the diode failure. If the diode is conducting when the
capacitor fails, then the bulk storage capacitor can discharge through
the safety capacitor while the diode is in reverse recovery.

I was looking at the schematic and when the line input switch is set
to 120 volts, RT1016 and R1019 are not in the circuit. So when it is
set for a 240 volt input, the thermal resistor networks are in series.
>>I have discovered that the bridge is shorted, which is most likely my problem.
>>I am also preemptively replacing the surge protectors and thermal resistors. I
>>have replaced almost everything else in the preregulator circuit already
>>except for a single 75 ohm resistor. Might as well make a clean sweep. These
>>type of parts do age.
>>Additionally, I am preemptively replacing the surge protectors and the two
>>thermal resistors. I have identified the source of one and am talking
>>to the original manufacturer to determine the best match for the other. One of
>>them is off the shelf. It is 15% vs 10%, but that shouldn't be a problem. The
>>other may be a custom part.

Re: Ebay Rip-off ? - "Global Shipping Program"

tek_547
 

Hi Dennis, you said that sometimes you are bidding for friends in Holland. But I have a scope seen on ebay that I want to buy for the price the seller ask, so no bidding needed at all. The problem is for me that he is not willing to ship it overseas.
So is there a possibility that you can offer the same service to me what you did to others in Holland? I would be very pleased!
If you want you can mail me on r.kelbling at chello.nl

grtz, René

Re: Ebay Rip-off ? - "Global Shipping Program"

tek_547
 

Thanx Dennis, a pity but good to know ...

René

Re: Alternative SG504 head- lower cost, better function.

 

I never received the email asking for Gerbers. I've no clue why.

I don't get the 3" extension bit - are you connecting the Rigid coax to the PCB, then passing it through a gland and then have a BNC female on the end? (PS don't you mean BNC male here? BNC Female is what's on the front of most scopes.)

Dave

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: 08 February 2016 03:48
To: TekScopes@...
Subject: [TekScopes] Alternative SG504 head- lower cost, better function.

As we're discussing the SG504:
I broke my Partridge leveling head the other day, because the RG58 input and lemo cable are directly tied to the PCB, they got yanked cuz I was moving a nearby scope and cables tangled and bent/cracked the PCB.

I wrote David about trying to repair the PCB ..(asking for the layout files etc.) But I guess that's not gonna happen...no reply. Permittivity is probably screwed due to the cracks anyway.


So, now I have delved into reverse engineering the head myself with some improvements. The detector diode selection app note from HP (1999) does suggest the HSMS-282 series as optimal for >20dbm AGC signal management under 4Ghz.
Having traced all the signal paths and the method used by Tek to manage the signal strength I have come up with a couple cost & functional improvements. I noted significant fluctuations in the 'leveled' signal when using 3' RG58 patch cables (from the head) to reach a D.U.T. . This defeats the purpose of the remote head. So I moved the D.U.T to the head and used a shorter patch cable. When moving the D.U.T away from the head, the accident happened and here I am with no head.
An expensive accident.

So the plan is:
1) Do away with the lemo cable, remove the lemo bulkhead connector from the faceplate and use a custom bushing holding a simple 2mm, 2 row x 3 pin gold header & cable to connect to the SG504. Same arrangement on the Head.
2) Add a BNC-m bulkhead for the head input & output using a semi rigid
RG142 (3") to BNC Female . The input provides for strain relief and low loss cable upgrades for longer extensions eg. RG400.
3) The semi rigid pigtail output provides great signal integrity/flatness across the 1Ghz range and the Fem. BNC 'end' allows the head to connect directly to a 'scope or any device using a BNC-m connector directly with minimal loss.

Advantages:
1) Cut out the lemo connector costs. Using a 6 pin, keyed M22 gold header in a custom, round faceplate bushing. No alteration of the faceplate hole.
2) This allows for the DC level sig. cable to pull loose (from the
headers) if accidentally yanked (the lack of this killed my last head).
3) Allow simple cable length upgrades (user DIY) for both the RF sig and the DC level feedback sig. This adds bench top flexibility which does not now exist.
4) Improve level signal integrity by directly connecting the head to the D.U.T. (like a scope) with a 3" semi rigid pigtail and no adapter/ extension losses. Probably 1 to 2dBc of flatness benefit here.

As I now have a calibrated HP8753D 3Ghz VNA and a Kirby Microwave professional SOL cal. kit, I can assess the performance of the upgrades and tweak the design as required as per VSWR and transmission tests across the Ghz range.

This link:
http://www.taconic-add.com/pdf/technicaltopics--effects-of-solder-masks-and-conformal-coatings.pdf
shows that at the 1Ghz range, conformal coatings & copper surface finish have minimal effect on the transmission performance.

If anyone is interested in getting such an SG504 head, fully assembled, calibrated, conformal coated and VNA tested, complete with the custom
SG504 faceplate bushing and 6 pin DC, sig. level connector, let me know.
I can consider a group build. I figure the cost should be around $80 complete. A copper shielded custom acrylic housing as an option. You will have to replace the lemo bulkhead on the SG504 with the provided bushing & M22 connector but that is dead easy to do, desolder & solder 5 pins from a ribbon cable.

If you wish, after the upgrade, you can now 'sell' your lemo connectors etc. on EBAY for $35 and offset costs. Or sell your old working head etc. and 'earn' $$.







------------------------------------
Posted by: AncelB <mosaicmerc@...>
------------------------------------


------------------------------------

Yahoo Groups Links

Re: 7904 - Very Dim Trace

Marian B
 

*If* the X / Y deflection works as before, so calibrated time base steps
are still correct and calibrated vert amp steps, too, then you are
likely looking at a Z axis issue.

I'd recommend to check if the Z axis amplifier output is as expected. If
it is not, check the amplifier, if the amp is okay, check the Z axis logic.
If the amp output is okay, replace all HV caps and all diodes in the Z
axis DC restorer circuit.

Cheers, Marian

Re: Tektronix (7854 e.a.) Fan Controller revisited

 

On 07 Feb 2016 12:05:03 -0800, you wrote:

My new 7854 has a Guernsey S/N, something like 1....00175, I think (I'm not where the instrument is ATM).

Many parts and panels are marked 1986. Some June 1987, like the CRT + keyboard front panel.
The (PC-Style) fan is at least as loud as a TDS4xx, my 2465B/2467B, almost as loud as a TDS520/TDS680B.
Not bad bearing noise, just air and some normal mechanical noise.

David, does your RAM+ROM PCB combined version have a PC fan or the more traditional one?
It has a modern "Panaflo" tubeaxial box fan like you would find in a
PC.

The change notice that I have says the fan was changed starting with
B090000 which is before the RAM and ROM cards were combined starting
with serial number B100000.

Re: 2465B Power Supply Problem

 

I have seen bridge rectifiers and safety capacitors fail together
before and in these cases, I wonder if it is the safety capacitor
which causes the diode failure. If the diode is conducting when the
capacitor fails, then the bulk storage capacitor can discharge through
the safety capacitor while the diode is in reverse recovery.

I was looking at the schematic and when the line input switch is set
to 120 volts, RT1016 and R1019 are not in the circuit. So when it is
set for a 240 volt input, the thermal resistor networks are in series.

I have discovered that the bridge is shorted, which is most likely my problem.
I am also preemptively replacing the surge protectors and thermal resistors. I
have replaced almost everything else in the preregulator circuit already
except for a single 75 ohm resistor. Might as well make a clean sweep. These
type of parts do age.
Additionally, I am preemptively replacing the surge protectors and the two
thermal resistors. I have identified the source of one and am talking
to the original manufacturer to determine the best match for the other. One of
them is off the shelf. It is 15% vs 10%, but that shouldn't be a problem. The
other may be a custom part.

Re: Ebay Rip-off ? - "Global Shipping Program"

Michael
 

I have ordered many dozens of various items from eBay. Not once have I
received the wrong item. Some orders from Asia have taken a very long time,
but they got here and within or around the estimated time. When I purchased
my 2465BCT as a "working" scope, it DID work - for about 5 minutes. I told
the seller that I intended to keep it and they voluntarily refunded me $50.

One time I received the wrong order from a seller on Amazon (shipped from
China). They apparently couldn't tell one garlic press from another (at least
without the photo I sent). But, we negotiated a price at which I was willing
to keep the press I received and they promptly refunded the difference.

I know that some people have had bad experiences, but I don't think that is
true for most.

I do think that cases where somebody refuses to pay customs duty, gets a
refund and then pays the custom duty for a "free" item suck big time for the
seller. But, if the item is really pricy, why wasn't tracking & insurance
included for the SELLER's protection? If you're selling a $1000 item and the
extra $5 or $10 for tracking / insurance makes the deal unprofitable then
probably you shouldn't be selling it for that price.


Mike

Many times I've received the wrong item and not once did I ever end up receiving
the correct one. Not ever. Ebay's rules have improved a bit, so lately when
that's happened I got a full refund, but previously I've had to ship the wrong
item back (at my expense) and even then didn't always get refunded. I don't
know about now, but back then if a seller "left the system" ebay would tell you
there's nothing they could do and you lost the money.

Re: Tek 555 part needed.

Morris Odell
 

I agree that the burn on the transformer doesn't look good but OTOH if the rectifier filaments are glowing and you have enough PDA voltage to make the upper trace look normal then it's likely that the transformer is working. Where are you measuring the -864 volts? The PDA voltage comes from an overwind on the same winding that supplies the CRT cathode. If the voltage of the cathode supply is low I would check the components associated with it. The cathode supply might be being loaded down by leakage to ground. Alternatively there could be some fault in the feedback circuit. Try measuring the voltage at pin 1 of V900. If it's high - around 200V or more - than the feedback circuit is trying to raise the HV output but the supply is working into an excessive load - i.e leakage to ground. If it's low, 90V or less, then the feedback circuit is trying to throttle back the oscillator because it's seeing too positive a voltage on pin 2 of V914. Pin 2 of V914 should be at about -155 to -160 volts. Check R950 & C942 and also check that the HV adjust pot R952 isn't leaky to ground. I have certainly encountered that fault in the past. Also the 0.01 uf ceramic caps are usually very reliable but you never know when one might go leaky.

Morris
________________________________________________________________________
Re: Tek 555 part needed.
Posted by: lbfulton@... zerousair
Date: Sun Feb 7, 2016 5:38 pm ((PST))

Yes, all the filaments in those small diodes seem to be of equal brightness in both supplies. Haven't checked for arcing there with the lights off, but there's only a very faint burnt odor and I believe whatever damage was done stopped without completely destroying the transformer. It has to working after some fashion as -864 vdc is maintained on the output side.

Re: Tek 555 transformer

ykochcal
 

A second thought:

Looked at the picture again, did you clean the area where the burn is?
That looks like the terminal by the burn is for the PDA HV that connects to
C932, and the transformer does not have the same dust coating like the
tubes. Is it possible that it was dirty, arced and then and someone had
cleaned it before you to fix the problem?

Are both CRT pin 11 and 12 too low a voltage? Or is one of those working and
one not?
How do they compare with pin 4 and 2 voltage?

John

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Sunday, February 07, 2016 5:39 PM
To: TekScopes@...
Subject: RE: [TekScopes] Re: Tek 555 part needed.

Yes, all the filaments in those small diodes seem to be of equal brightness
in both supplies. Haven't checked for arcing there with the lights off, but
there's only a very faint burnt odor and I believe whatever damage was done
stopped without completely destroying the transformer. It has to working
after some fashion as -864 vdc is maintained on the output side.





------------------------------------
Posted by: lbfulton@...
------------------------------------


------------------------------------

Yahoo Groups Links

Re: 7904 - Very Dim Trace

 

On 07 Feb 2016 19:15:56 -0800, you wrote:

Guys, this is my first post here. I've been tinkering at Tek scopes for along time - since I first bought a 531A in the late 70's. I'm looking for some tips on a 7904.

I picked this one up at an auction, and at first, it looked pretty good. Good enough that I've been scrounging plug-ins for it, and generally cleaning it up, and adjusting it. I switched it off one night, and the next day, I had no trace. Zilch. Beam finder, maxing the intensity controls - no help. Even in a darkened room, no light at all.

The filament is lit.

All LV supplies check out OK.

I don't have a HV meter to allow me to measure the anode supply. I know there's decently high voltage there, judging by the length of the spark when I discharge the electrostatic charge, however.

The 2950V measures high, about 3250V. Yet, curiously, the cathode supply regulator (U1635) isn't railed - in fact, based on my DC measurements in this area, I think the regulator is actually regulating - just at too high of a voltage. Weird. I wish I knew what the cathode supply measured before the issue popped up...
I assume you measured the output of U1635 and found it to be within a
couple volts of ground.

A high cathode voltage could be produced by leakage through CR1639
which protects the non-inverting input of U1635. U1635 could also be
bad.

On a whim, I tweaked the CRT grid bias (R1674) and can now get a faint trace. It's well focused, just dim. Pushing Beam Find does not h elp - it just gets blurry, reduces the sweep span, but it's still dim.
If the cathode voltage is high then the horizontal and vertical
deflection sensitivity should be proportionally lower. Is that the
case? You can check the calibration using the probe calibrator output
signal.

I would defocus the beam before conducting further tests in case you
fix the problem so that the CRT phosphor does not get burnt.

Re: Tek 555 transformer issues

ykochcal
 

First I have a 555 that I have not gotten to yet so I am no expert on them,
but I am interested in your progress, and some thoughts:

It does seem odd that you could get more or less full filament, and voltage
out of the other windings and only a fraction of the HV on one winding if
the transformer was bad, as in shorted windings.

Have you looked at the primary side to see if it is heavily loaded? Which
would indicate a more of a shorted winding. Luckily you have the other beam
that is almost identical to compare. Say on the 6CZ7 pins 1 and 3

I had a 647 that had the feed back loop open and was running a full throttle
which is at a considerately higher voltage, for some time and it had a spark
from the HV winding to the core, but that was epoxy. And I did not find it
was repairable. Note the resistor in the feed back measured fine with the
leads clipped on each resistor, it was only after I did the measurements the
nth time that I realized that the weight of the clip was making "twist" on
the leads and a connection inside the resistor but if I clipped on the leads
of the resistor before and after, so there was no "twist" on the leads of
the bad resistor that it was open.

So I could imagine a condition where say something like the feed back pot
was open for a while and it arced but now the pots back working and the
transformer is running at a lower voltage and is not arcing, but it does not
seem too likely to me.

As someone already more or less said there are a lot of HV capacitors that
could be dragging things down, and 5642's that could be leaking on the
reverse cycle and pulling the voltage down down.

Do you have a probe that can look at the plate voltage?

But if you do take the transformer out you can pop it in a toaster oven and
heat the core to take the core off then see if you could grind out the board
if it's charred and try to re insulate it.

Be sure to keep the core even if it's bad for future rewinding.

Thanks for the pictures.
Good luck and please keep us updated on your progress.
John

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Sunday, February 07, 2016 5:39 PM
To: TekScopes@...
Subject: RE: [TekScopes] Re: Tek 555 part needed.

Yes, all the filaments in those small diodes seem to be of equal brightness
in both supplies. Haven't checked for arcing there with the lights off, but
there's only a very faint burnt odor and I believe whatever damage was done
stopped without completely destroying the transformer. It has to working
after some fashion as -864 vdc is maintained on the output side.