开云体育

On Friday, June 29, 2018, Albert Otten <aodiversen@...> wrote:

On Fri, Jun 29, 2018 at 07:35 am, musicamex wrote:

Does anyone have a clearer copy of the access board layout? Maybe an

actual

photo of that page? The only ones that I have downloaded so far are all

but

impossible to read. Thanks! Russ

Hi Russ, you mean board A9? I can send you 2 jpg's at 1200 dpi of about
6.5 MB each. Enlargeable until you have the screen almost filled with one
component number. When you reply via Private I have your e-mail address and
can send it as attachment.
BTW the original is rather vague also. There are several "partial" board
layouts in the manual at which components involved in the next schematic(s)
are shown in bold while other components are vague. Bad luck that Tek
didn't do so for the Power schematic.

Albert

On Friday, June 29, 2018, Harvey White <madyn@...> wrote:

On Thu, 28 Jun 2018 19:57:26 -0700, you wrote:

I'm so sorry that I havent kept up with all of the help here, Albert. I

wasn't expecting such a willingly helpful group when i joined the group.
This has been an exceptionally busy June for me. I'm recovering from
recent heart surgery and seem to be falling behind on my lab repair work
among other things. But i did get a bit of time [about 30 min] to follow
up on some of the suggestions here. The access board layout diagram is
pretty hard to read and not all that much is labeled on the actual board so
it is going slower for someone used to point to point and turret board
electronics. I have almost zip experience with transistors or pcb layout.
But I'm determined to get this figured out.

You might, for the sake of general learning, get some breadboard kits,
general purpose transistors, and start breadboarding some transistor
amplifiers and switches. It would give you a feel for the parts.

For PCB layout, consider that you are doing the same as wiring a
breadboard (the type with millions of holes). The rules, though, is
that the traces cannot cross each other on the same side (otherwise
they're the same trace). They must go from layer to layer through a
plated through hole called a via. On dual layer boards, you have
simply a top and bottom, and the vias go all the way through. On 4
layer boards, there's a top, bottom, and two inner layers. Frequently,
some of the layers are reserved for power and ground.

So PC boards are not all that bad.

One question: did you mean c1549 and cr1549? You were mentioning the

15v rail and c1559 and cr 1559 are on the 5v rail.

Re the video, it was the model and post sn 250000 that caught my eye an

invoked my comment. Misery likes company and to see someome trying to fix a
no screen problem gave me a bit of hope. There is not much other video
tutorial that I could find, good or bad, re what i have a problem with. I
am completely self taught in electronics and despite recognizing the less
than stellar technique, I actually learned a little about layout even if
nothing else was up to par judging from the comments.

I knew almost nothing about this 465 before I started this thread and I'm

gaining ground. Poco a poco andamos lejos.

You might want to look at linear supplies and how they work. The
principles between a linear regulator for tubes and transistors are
identical, but the different parts will give you different voltages on
the transistors (vs the tubes). Depletion mode N channel FETS are
most like tubes, once you get to that point. (triodes, thank you).

As in any such project, suspect the power first, then look at
functional blocks. I've had 468's with high voltage resistor network
problems, which will throw off the high voltage. There's a high
voltage divider network that's part of the feedback from the high
voltage output back to the regulator.

Harvey

Thanks again to all for the patience and wealth of info. I have a

birthday on Saturday. Maybe i will have time to spend a few more hours
figuring this out. Seeing a trace on the screen would be way better than
candles. ?

-------- Original message --------From: stefan_trethan <stefan_trethan@...> Date: 6/29/18 12:37 PM (GMT-06:00) To: [email protected] Subject: Re: [TekScopes] If you had $1, 000 to buy a 100 MHz scope...
I have a TDS544 at home, which is somewhat similar to the newer
TDS784D, and I really dislike the display, menu structure, and general
lack of responsiveness.
To me this is the point where Tek went wrong, and I have not liked any
Tek scope from this point on.
Often I prefer to fire up the 7d20 digitizer in a 7k mainframe, when I
know it's only slow signals and I don't need 4 channels.

The later TDS3000 series was extremely popular, but I just straight
out hate the darn things.
From that vintage on I really much prefer Lecroy, even a LC series,
with LCD screen if you can get it instead od the CRT, yes, I would
much prefer that over the Tek ones.
I used to have a Lecroy DDA125 as my main work scope until a year or
two ago, and it is _A LOT_ of scope which you may now get in the $1000
range (The DDA is the same as a LC684 only with special HDD options
added). Not as repairable as old Tek (but so is new Tek).

Now I have a HRO64Zi at work which I got a really good deal on when
they discontinued the series, but still well outside your $1k budget.
That is a fine scope, but _even less_ responsive than the TDS544 or
DDA125. It needs to think and calibrate itself _all the f-ing time_.
But you can so so much with it, it somewhat compensates for the lack
of responsiveness. And the 12 Bit, I wouldn't want to miss that.
It is not the best scope for random debug or fault finding, but for
analysis when you need to get numbers out, document or compare stuff,
it's great.

Anyway, that's well out of price range, all I'm saying is I do miss
using the old DDA125 some days.
So for me the decision for a used scope in the 1k range would be easy,
the DDA125 or something very similar any day.

But is it really better than a modern low end scope, like a Rigol?
Hard to tell. There is something those old "lab grade" scopes have
that you just don't get in a low end scope.
We have a Keysight 3000x at work that I use some times, and it always
infuriates me when you are limited by stupid things such as not enough
reference channels, or not enough math, or...
Also, on that Keysight you can't switch off analog persistence (just
like a Tek TDS3000) and I dislike that.

Of course a new scope will have convenient modern features you just
won't find on one made around the year 2000.
And it will be lightweight, easy to carry around, likely work reliably
without needing repair.

It is the same as with a car, do you prefer a used quality car, or a
cheap and cheerful new car?
I don't mind old, but I do like quality.

What I can say is that the new very lowest end Tek/Keysight/Lecroy are
_not_ worth the money in my mind.
You still pay extra for the brand, but you get nothing above and
beyond say a Rigol, less actually.
They try to capture that market by either re-labeling imported crappy
scopes, or building their own crappy scopes to the cheapest price, but
they can never beat a lesser brand with their high overheads.


So the choice for me would be between a Rigol 1000Z, or something, and
a DDS125, or something like it.

If you can still do that thing where you buy the low end Rigol and
they let you upgrade it to a higher end model, I'd be hard pressed to
make a choice.
Luckily, I don't have to.


ST


On Fri, Jun 29, 2018 at 6:45 PM, Pete Lancashire <xyzzypdx@...> wrote:

I'm trying to break the habit of buying old scopes. I'm looking for
suggestions 100 megahertz or better, 4 channels, supports a mode where
multiple pulses are shown over and over again and shows Distortion errors.
I would say that's the one unique thing.

So what would members of this is esteamed group suggest.

And older tek scope that is higher, TDS784D for example or a new Tek /
keysight / Regal

On Fri, Jun 29, 2018 at 10:57 am, musicamex wrote:

One step closer! C1549 looked like it might have been replaced with a mylar
cap. As soon as I unsoldered one side and turned on the scope, the fan came
on! So i replaced it with a 47mf 25 v electrolytic and now had a bit of a
trace but way off vertical axis. Good call Albert!

The voltages now are112.5, 55.66, 15.1, 4.9 and -6.4

I see that the vertical axis is associated with the -8 rail and read the
troubleshooting for vertical axis anomalies but before I go further I thought
I check for advice here first.

Thanks in advance, Russ

Le Albert Otten <aodiversen@...>, 29 juin 2018 8:04 PM a écrit :

On Fri, Jun 29, 2018 at 07:35 am, musicamex wrote:

Does anyone have a clearer copy of the access board layout?? Maybe an

actual

photo of that page?? The only ones that I have downloaded so far are all

but

impossible to read.? Thanks!? Russ

Hi Russ, you mean board A9? I can send you 2 jpg's at 1200 dpi of about
6.5 MB each. Enlargeable until you have the screen almost filled with one
component number. When you reply via Private I have your e-mail address
and can send it as attachment.
BTW the original is rather vague also. There are several "partial" board
layouts in the manual at which components involved in the next
schematic(s) are shown in bold while other components are vague. Bad luck
that Tek didn't do so for the Power schematic.

Albert

On Fri, Jun 29, 2018, 10:35 AM John <John@...> wrote:
My 575 mod 122C arrived at the weekend. It did basically work when
brought up gently on a variac. I've been through most of the valves and
replaced a few which were well down on emmision, including the 6AQ5 /V810.
Similarly, most of the paper caps have been replaced with polyester 600V.
I've just been through the cal. procedure and everything seems fine, but
there is now a slight dot-pattern on the trace which I don't recall
noticing when it had the "old" caps and "old" valves in place. As there
doesn't appear to be any Z-mod capability, I'm wondering what might cause
this? Or is it normal? I've checked the -1700V with a P6015 probe, and it
looks clean. There's small amount of ripple on the +2300V anode, but only
c 20V p-p.
Photo album uploaded under "575 dot-pattern trace"
John

On Fri, Jun 29, 2018, 10:35 AM John <John@...> wrote:

My 575 mod 122C arrived at the weekend. It did basically work when
brought up gently on a variac. I've been through most of the valves and
replaced a few which were well down on emmision, including the 6AQ5 /V810.
Similarly, most of the paper caps have been replaced with polyester 600V.
I've just been through the cal. procedure and everything seems fine, but
there is now a slight dot-pattern on the trace which I don't recall
noticing when it had the "old" caps and "old" valves in place. As there
doesn't appear to be any Z-mod capability, I'm wondering what might cause
this? Or is it normal? I've checked the -1700V with a P6015 probe, and it
looks clean. There's small amount of ripple on the +2300V anode, but only
c 20V p-p.
Photo album uploaded under "575 dot-pattern trace"
John

On Fri, Jun 29, 2018 at 6:45 PM, Pete Lancashire <xyzzypdx@...> wrote:

I'm trying to break the habit of buying old scopes. I'm looking for
suggestions 100 megahertz or better, 4 channels, supports a mode where
multiple pulses are shown over and over again and shows Distortion errors.
I would say that's the one unique thing.

So what would members of this is esteamed group suggest.

And older tek scope that is higher, TDS784D for example or a new Tek /
keysight / Regal

On Fri, Jun 29, 2018, 9:13 AM Richard Solomon <dickw1ksz@...> wrote:

I picked up a working 1502 a few years
ago on that auction site.

The batteries were shot, but I found a
paper on using a resistor and a big cap
to fool it into thinking it had batteries.

I think I have used if less than 5 times
over the years, but for the price it was
a nice addition to the test equipment
pile.

It didn't hurt that I had an original manual
for it.

73, Dick, W1KSZ

On Fri, Jun 29, 2018 at 4:11 AM, Tom Gardner <tggzzz@...> wrote:

I really like 1502 (not a, b, 1503 etc), and have some I ought to sell.

There are two principal weaknesses other than the usual PSU caps:

* the tunnel diode is relatively fragile, and can be destroyed by a DC
voltage
on the cable or even a static charge in the cable - hence the special
shorting BNC connector. Having aid that, all 5 that I have seen are
intact
* the battery pack must be present before it will switch on: the PSU
detects
missing and uncharged batteries. All 5 that I have seen have had

faulty

batteries. There are ways of faking a battery, or they can be replaced
by
new sub-C NiCds or NiMH. With NiMH be very careful with "Chinese
capacity
specifications" and the trickle charging current.



On 29/06/18 04:09, Pete Lancashire wrote:

Yeah if you need the short distance performance the 1502 is the only way
to
go. The newer models which have LCD redoubt if the LCD has not gone bad
now
it will. And the unfortunate part is the LCD was custom.

keep your eyes open a lot of sellers don't know what they have but like
another member said make sure the tunnel diode is good.

A few people have looked at the ex Soviet tunnel diodes but as far as I
know no one has found a substitute.

To me sounds like a perfect project to use a modern pulsar there are an
awful lot of 1502s out there.

On Thu, Jun 28, 2018, 1:00 PM Harvey White <madyn@...>
wrote:

On Thu, 28 Jun 2018 11:02:57 -0700, you wrote:

As Stefan said, how fast a step pulse you need and how much scope

bandwidth you need both depend on how much resolution you need. Do you
happen to have sampling plug-in set for your 7000 series mainframes?

If

not, how much scope bandwidth do you have available? Also, how fast a
risetime can you generate in a pulse?

Also as Stefan mentioned, if you can get down to a nS, you should be
able

to get pretty close!

I'd recommend (for the long term) that you keep an eye on ebay for a
good

deal on a Tektronix 1502 TDR. One of the handiest units I have. A
person
can't have too many TDRs though! Check out a 7S12 when you have time.
Absolutely delightful! :-)

The 1502 (not a/b/c) certainly has a tunnel diode in it for the main
generator. It is difficult to impossible to get ahold of when damaged
(and it damages easily since it's right across the input). If you do
get a 1502, make sure that the TD is working.

I don't know anything about the 1502 A/B/C, so I cannot speak of the
tunnel diode (if any) in it.

A 1503 does not have a TD to generate the pulse, has 10 times the
distance at effectively 1/10 the resolution, that is, if the 1502
would be good to 1 cm, the 1503 is good to 10 cm.

Harder to damage, though.

Harvey


Best of luck with the cable!

Tom

On Fri, Jun 29, 2018 at 4:11 AM, Tom Gardner <tggzzz@...> wrote:

I really like 1502 (not a, b, 1503 etc), and have some I ought to sell.

There are two principal weaknesses other than the usual PSU caps:

* the tunnel diode is relatively fragile, and can be destroyed by a DC
voltage
on the cable or even a static charge in the cable - hence the special
shorting BNC connector. Having aid that, all 5 that I have seen are
intact
* the battery pack must be present before it will switch on: the PSU
detects
missing and uncharged batteries. All 5 that I have seen have had faulty
batteries. There are ways of faking a battery, or they can be replaced
by
new sub-C NiCds or NiMH. With NiMH be very careful with "Chinese
capacity
specifications" and the trickle charging current.



On 29/06/18 04:09, Pete Lancashire wrote:

Yeah if you need the short distance performance the 1502 is the only way
to
go. The newer models which have LCD redoubt if the LCD has not gone bad
now
it will. And the unfortunate part is the LCD was custom.

keep your eyes open a lot of sellers don't know what they have but like
another member said make sure the tunnel diode is good.

A few people have looked at the ex Soviet tunnel diodes but as far as I
know no one has found a substitute.

To me sounds like a perfect project to use a modern pulsar there are an
awful lot of 1502s out there.

On Thu, Jun 28, 2018, 1:00 PM Harvey White <madyn@...>
wrote:

On Thu, 28 Jun 2018 11:02:57 -0700, you wrote:

As Stefan said, how fast a step pulse you need and how much scope

bandwidth you need both depend on how much resolution you need. Do you
happen to have sampling plug-in set for your 7000 series mainframes? If
not, how much scope bandwidth do you have available? Also, how fast a
risetime can you generate in a pulse?

Also as Stefan mentioned, if you can get down to a nS, you should be
able

to get pretty close!

I'd recommend (for the long term) that you keep an eye on ebay for a
good

deal on a Tektronix 1502 TDR. One of the handiest units I have. A
person
can't have too many TDRs though! Check out a 7S12 when you have time.
Absolutely delightful! :-)

The 1502 (not a/b/c) certainly has a tunnel diode in it for the main
generator. It is difficult to impossible to get ahold of when damaged
(and it damages easily since it's right across the input). If you do
get a 1502, make sure that the TD is working.

I don't know anything about the 1502 A/B/C, so I cannot speak of the
tunnel diode (if any) in it.

A 1503 does not have a TD to generate the pulse, has 10 times the
distance at effectively 1/10 the resolution, that is, if the 1502
would be good to 1 cm, the 1503 is good to 10 cm.

Harder to damage, though.

Harvey


Best of luck with the cable!

Tom