Date   

Re: rare lot

leonard scheepsma
 

What a fantastic translation. Ramp generator into "catastrophe" generator into "disaster". Google translate without context.
I love it!


Re: USPS shipments comments

Steven Bender
 

Hi All,

A few years back, (not Tek equipment) I won a beautiful, museum quality cosmetics, Bang & Olufson linear tracking turntable, 1980’s Made in Europe, heavy, IIRC around $225. and the weight was about 40 lbs. It was coming from nearby, less than 50 miles away (next state over). The mailman carried it up the steps, walked over, (I was at the door watching) as he got near to me, he tossed it forward three feet onto the cement. He managed to break almost everything possible to break in the unit. I had taken out full replacement insurance, while I was eventually paid (minus $50. - no reason given). What can you do?

I’ve seen UPS do worse… a Sony TC-650 RTR arrived with a side of the box ripped open, trailing packing material, dropped so the metal frame warped so bad, unable to be repaired, the nice wood sides were a thousand tiny toothpicks, picked up again to go to the UPS Evaluation Center (likely it was dumped in some green recycle bin) and I got a massive $100. back, which was like a third of the cost before shipping.


Steven


Re: rare lot

Tim Phillips
 

'Disastergenerator' ? I have some of those lying around here !! <grin>

Wasn't this setup a replacement for the 160 generators when Tek were
getting into Biophysical market.?
I understood they rather took a hit on the product.

Tim


Re: Idle Question About the 485

 

Walter,

I don't see the fusible element in the 485 schematics, maybe you're thinking of the 7A19, or the 7A24?

My wife might not kill me if I got a 485, but I'm in the middle of a reorg of my bench and lab (making storage and organization for a bunch of plug-ins, and finding a reasonable way to arrange portable and bench-top scopes along side other instruments for use) and I'm already thinking that some of my scopes are surplus to requirements. A 485 would not make the project any easier.

The 7903 is clearly superior to the 485, unless you have to travel with it. My whole reorg is being done because I've become quite fond of a couple of 7600s (two 7603s and a 7633) in recent months. My bench was organized around a couple of portable scopes originally, which could be easily arrayed around my desk sitting upright on the floor, but the 7600s demand bench or shelf space. Having one 7600 on the bench as a tool doesn't leave much space for a second one as a patient.

I have not technical need for a 485. My only emotional connection is that I let a nice one slip through my fingers this past spring at a similar price. It had a blue phosphor CRT! I suspect that another member of this group might have bought it while I was napping.

-- Jeff Dutky


rare lot

Miguel Work
 


Re: 7704A - Delayed Sweep Intensity Too Bright

n4buq
 

Mark,

Yes, I believe the intent is to "highlight" part of the trace; however, mine is highlighting much to bright. I'll have to check those voltage levels in the Z-Axis circuit and see if the plugins are somehow providing the wrong voltages.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Mark Vincent" <orangeglowaudio@gmail.com>
To: "tekscopes" <TekScopes@groups.io>
Sent: Thursday, October 21, 2021 10:17:14 AM
Subject: Re: [TekScopes] 7704A - Delayed Sweep Intensity Too Bright
Barry,

See if having the A/B intensity turned up and the crt bias up (more negative at
the grid) helps. If your S/N is <210000, check Q320, Q322, Q420 and Q422. These
are in the two heatsinks on the right side top. If these are leaky, use
KSP10BU. I do not see any internal intensity control in this model. It may be
that the delayed signal is to be brighter to give contrast.

Mark



Re: 7704A - Delayed Sweep Intensity Too Bright

n4buq
 

Stephen,

I'll have to check that. I think the problem is seen for other time-bases so not sure if it's a problem with the plugin but it could be.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "SCMenasian" <scm@menasians.com>
To: "tekscopes" <TekScopes@groups.io>
Sent: Thursday, October 21, 2021 11:04:37 AM
Subject: Re: [TekScopes] 7704A - Delayed Sweep Intensity Too Bright
Barry,

Maybe the discussion of Aux Z axis Control and Aux Z Axis Out on pages 3-16 and
3-17 of the 7B53A manual will give a clue. It describes the Z-Axis interface to
the mainframe. Since the 7B92A has a front panel contrast adjustment, the
interface probably has the ability to control intensity via a voltage level.
Perhaps a bad component in those sections of your 7B53A has that level pegged.

Stephen Menasian



Re: Idle Question About the 485

Ozan
 

Hi Walter,

On Thu, Oct 21, 2021 at 09:14 AM, walter shawlee wrote:
50 ohm protection on the 485 is a fusible ceramic element in the attenuator
chain, a rare and hard to find object.
---
485 has an active protection circuit that flips input relay to 1M-ohm setting to protect the 50-ohm attenuator. There could be a fusible element as well although I can't see it in the schematic or the pictures I took on my unit. Perhaps it was on certain serial number range.

Ozan


Re: Debugging begins: Tek 606

toby@...
 

On 2021-10-17 11:12 p.m., toby@telegraphics.com.au wrote:
Hi,
Was testing my Tek 606 yesterday, and after power on and the next few minutes it made about five "snap" discharge sounds with fluctuations in brightness. After the last one, I lost trace permanently.
Checked LV rails and all are spot on except for the +30 and +120 unregulated, which are off the HV transformer secondary. Before I go any farther, does anyone have a good idea of what the discharges might mean?
The next step seems to be to power the board to investigate further.

The HV section is basically this (but my unit shows some updates as mentioned previously): https://imgur.com/gtO35ue

Can anyone comment on whether it will be safe to operate this topology onnected to the LV supplies but with the CRT disconnected completely (grids, filament, cathode)? Or should I test with the CRT connected?

Either way I think I will probably be able to do this with the HV safety shield in place until I reach a point where I need to measure the HV itself.

--Toby



--Toby


Re: Idle Question About the 485

 

Jeff,

50 ohm protection on the 485 is a fusible ceramic element in the attenuator chain, a rare and hard to find object.
having said that, the 485 scope is very nice, but quite complex (especially in the vertical section) AND old, not a great combination today.

I was surprised at the relatively good condition of that 485 unit on ebay, it looks like a worthy overhaul candidate to me, especially considering the brightness of the unobtainable CRT. I was tempted myself, but aside from the fact susan would almost certainly kill me on its arrival, I have two (R)7903's which I far prefer for fast analog work. THAT is a great scope, and not adequately appreciated.

all the best,
walter
sphere research corp.


Re: 7704A - Delayed Sweep Intensity Too Bright

SCMenasian
 

Barry,

Maybe the discussion of Aux Z axis Control and Aux Z Axis Out on pages 3-16 and 3-17 of the 7B53A manual will give a clue. It describes the Z-Axis interface to the mainframe. Since the 7B92A has a front panel contrast adjustment, the interface probably has the ability to control intensity via a voltage level. Perhaps a bad component in those sections of your 7B53A has that level pegged.

Stephen Menasian


Re: USPS shipments comments

Dave Seiter
 

My brother-in-law worked for a law firm that specialized in maritime law.  He tells a story that happened at the port of Oakland- someone was importing two old MIGs, and they had survived the trip thus far without a scratch.  A team was supposed to move the planes (I would assume the fuselages at this point) onto flatbed(s) with forklifts.  They dropped the first one almost right away, thought they had figured out what they had done wrong (I guess, or didn't care), and then proceeded to drop the second one.  The customer was NOT happy, to say the least!
-Dave

On Thursday, October 21, 2021, 06:01:31 AM PDT, stevenhorii <sonodocsch@gmail.com> wrote:

I’ve been to quite a few warehouses to pick up stuff I had delivered by
freight. It’s a lot cheaper to pick it up compared with home delivery since
they need to dispatch a truck with a lift gate for most home deliveries
(unless you have a truck dock!) I have had to uncrate stuff in the customer
parking area when the crate was too large for my SUV.

I know why they generally do not allow customers to walk around the
warehouse. It’s dangerous. The forklift drivers zoom around and are not
expecting inexperienced folks to be on the floor. I have been allowed on
the floor when they were having trouble finding the crate I was expecting.
They did find it with my help - it turned out that it got moved to a
staging area for a later pickup day than I had told them.

I got talking with one of the foremen about the hazards of the fork lifts.
He told me that they are usually very good and that accidents with
shipments are few (but he would say that). He did tell me about a couple of
incidents with the driver running the forks through a crate. One of them
was a large screen flat-panel TV (in those days it meant a large insurance
payout). Things falling off the forks is another problem, but the drivers
usually know when they start to lift a pallet or crate if it is not far
enough back on the forks. I worried a little when they used a lift to get
my crate into my SUV. I could imagine the forks going through the rear
bumper or something. But the guy got it in and then raised the forks so the
ends of them were at the wood frame around the rear of the crate. He then
very slowly pushed it all the way into the back of the SUV managing to
avoid pushing into the backs of the front seats (I had folded the rear
seats down). These guys can be careful when they need to be.


On Thu, Oct 21, 2021 at 07:03 Michael A. Terrell <
terrell.michael.a@gmail.com> wrote:

That sounds like a Drew Carey show episode where Oswald smashed the scanner
in shipping while playing on a forklift.

On Wed, Oct 20, 2021 at 12:19 PM Jim Ford <james.ford@cox.net> wrote:

Wasn't there a Dilbert strip like that where the company provided beer
for
the employees to loosen things up?  They ended up jousting with the
forklifts in the warehouse!  Jim Ford Sent from my Verizon, Samsung
Galaxy
smartphone
-------- Original message --------From: Ken Eckert <eckertkp@gmail.com>
Date: 10/20/21  8:51 AM  (GMT-08:00) To: TekScopes@groups.io Subject:
Re:
[TekScopes] USPS shipments comments My wife worked for a while in a BC
Liquour control board warehouse, guys would drive the forks into a pallet
just for a giggle............









Re: USPS shipments comments

Michael A. Terrell
 

I have driven forklifts and worked in a workbasket from one. That time, the
idiot driver who was assigned to the job kept disappearing. It ran out of
propane while I was working near the roof, running cables. He replaced the
tank, and opened the valve. It was leaking badly. I yelled to close the
valve. He just shrugged and said, "It'll stop", and walked off. My yelling
got the attention of the plant manager. They stopped the leaking propane,
and went to find him. The jackass could have destroyed the building and
killed over 100 production workers with a single spark. It took hours to
get the odor out of the building. They could only open all the doors to let
out the gas, because the contactors on the motors would have set off an
explosion if the machines were shut down.

On Thu, Oct 21, 2021 at 9:01 AM stevenhorii <sonodocsch@gmail.com> wrote:

I’ve been to quite a few warehouses to pick up stuff I had delivered by
freight. It’s a lot cheaper to pick it up compared with home delivery since
they need to dispatch a truck with a lift gate for most home deliveries
(unless you have a truck dock!) I have had to uncrate stuff in the customer
parking area when the crate was too large for my SUV.

I know why they generally do not allow customers to walk around the
warehouse. It’s dangerous. The forklift drivers zoom around and are not
expecting inexperienced folks to be on the floor. I have been allowed on
the floor when they were having trouble finding the crate I was expecting.
They did find it with my help - it turned out that it got moved to a
staging area for a later pickup day than I had told them.

I got talking with one of the foremen about the hazards of the fork lifts.
He told me that they are usually very good and that accidents with
shipments are few (but he would say that). He did tell me about a couple of
incidents with the driver running the forks through a crate. One of them
was a large screen flat-panel TV (in those days it meant a large insurance
payout). Things falling off the forks is another problem, but the drivers
usually know when they start to lift a pallet or crate if it is not far
enough back on the forks. I worried a little when they used a lift to get
my crate into my SUV. I could imagine the forks going through the rear
bumper or something. But the guy got it in and then raised the forks so the
ends of them were at the wood frame around the rear of the crate. He then
very slowly pushed it all the way into the back of the SUV managing to
avoid pushing into the backs of the front seats (I had folded the rear
seats down). These guys can be careful when they need to be.


On Thu, Oct 21, 2021 at 07:03 Michael A. Terrell <
terrell.michael.a@gmail.com> wrote:

That sounds like a Drew Carey show episode where Oswald smashed the
scanner
in shipping while playing on a forklift.

On Wed, Oct 20, 2021 at 12:19 PM Jim Ford <james.ford@cox.net> wrote:

Wasn't there a Dilbert strip like that where the company provided beer
for
the employees to loosen things up? They ended up jousting with the
forklifts in the warehouse! Jim Ford Sent from my Verizon, Samsung
Galaxy
smartphone
-------- Original message --------From: Ken Eckert <eckertkp@gmail.com
Date: 10/20/21 8:51 AM (GMT-08:00) To: TekScopes@groups.io Subject:
Re:
[TekScopes] USPS shipments comments My wife worked for a while in a BC
Liquour control board warehouse, guys would drive the forks into a
pallet
just for a giggle............













485 input attenuation circuit protection modification

Mark Vincent
 

For those that have a 485, look at the S/N to see if it is in the lower range. At one point it was changed to protect the round IC from pluses from the relay coil when switching from 50 ohm to 1meg input. You can modify the circuit by adding the parts of the higher S/N to the lower to protect the IC. I did this in mine. The schematic will show both versions. The NPN transistor that is added is a 2N3904. A 2N2222/A or other will work.

There is also a 12V axial tantalum that is for the 9V filtering on each input. I removed the tantalums and put in a ULD 16V to prevent those tantalums from shorting. There is a 13V circuit that has 15V tantalums that will short. I used 47mfd 25V ULD types in this circuit.

Mark


Re: 7704A - Delayed Sweep Intensity Too Bright

Mark Vincent
 

Barry,

See if having the A/B intensity turned up and the crt bias up (more negative at the grid) helps. If your S/N is <210000, check Q320, Q322, Q420 and Q422. These are in the two heatsinks on the right side top. If these are leaky, use KSP10BU. I do not see any internal intensity control in this model. It may be that the delayed signal is to be brighter to give contrast.

Mark


Re: Idle Question About the 485

Tom Gardner
 

No disrespect taken :)

Looking at the circuit diagrams, the 485 has two separate attenuators, one 1Mohm and one 50ohm. A relay connects the BNC input to the relevant attenuator. Overload causes the relay to switch to the 1Mohm attenuator.

OTOH, the 24x5 has a single 1Mohm attenuator, and a relay simply puts a 50ohm resistor in parallel with that.

Using a NanoVNA to (imperfectly) measure the VSWR of my 485 shows it is between 1.00 and 1.03, rising to 1.04 at 350MHz.

OTOH, my 2465 varies between 1.01 and 1.15, and is 1.12 at 350MHz.

On 21/10/21 15:06, Jeff Dutky wrote:
Tom,

no disrespect intended, but I'm looking directly at my 2465, and it has five input coupling positions for channels 1 and 2, labeled in order: 1MΩ AC, 1MΩ Gnd, 1MΩ DC, 1MΩ Gnd, and 50Ω DC (with a red border around the 50Ω DC label). It also has, according to the manual, overload protection in 50Ω DC mode, and will revert to 1MΩ Gnd position in such a case. The precise mechanism of the overload protection seems to be more direct in the case of the 2465, which appears to have a thermal sensor that triggers the switch back to 1MΩ input, but the effect is the same.

-- Jeff Dutky




Re: 7704A - Delayed Sweep Intensity Too Bright

n4buq
 

Mark,

Intensity settings for normal traces are about right. The main intensity is somewhere near mid-range and the A/B intensity controls are in the 9:00 to 12:00 range (or less).

I'm using a 7B53A and when I pull the time/division knob to its outward position for a delayed sweep, the delayed trace is very bright. I presume the intensity of the delayed sweep is an independent setting from a normal trace in the main frame but not sure.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Mark Vincent" <orangeglowaudio@gmail.com>
To: "tekscopes" <TekScopes@groups.io>
Sent: Thursday, October 21, 2021 9:55:27 AM
Subject: Re: [TekScopes] 7704A - Delayed Sweep Intensity Too Bright
Barry,

It sounds like the time base you are using is the source of the delayed sweep.
Some have an intensity control for the delayed sweep. A 7B92A is an example.
The 7704A has two main intensity controls, the one at the top and two above the
plug-ins. One of the two could be turned up. I have the two about 70% up and
adjusted the crt bias so that the main intensity is about at the 11 o'clock
position to get a trace visible. Controls in the Z circuit were adjusted. Those
will alter intensity and focus.

Mark



Re: 7704A - Delayed Sweep Intensity Too Bright

Mark Vincent
 

Barry,

It sounds like the time base you are using is the source of the delayed sweep. Some have an intensity control for the delayed sweep. A 7B92A is an example. The 7704A has two main intensity controls, the one at the top and two above the plug-ins. One of the two could be turned up. I have the two about 70% up and adjusted the crt bias so that the main intensity is about at the 11 o'clock position to get a trace visible. Controls in the Z circuit were adjusted. Those will alter intensity and focus.

Mark


7704A - Delayed Sweep Intensity Too Bright

n4buq
 

The delayed sweep intensity is way too bright in my 7704A. If I understand it correctly, a time-base sends a signal to the mainframe to indicate the delayed sweep is active and the mainframe knows to make that a higher intensity trace.

Is there a separate adjustment for that intensity? I haven't attempted to set the CRT grid bias and that could be part of the problem but it appears a signal standardizer may be required for that and I don't have one of those and am hoping that I can at least reduce that excessive brightness just a bit without having to get one of those first.

I know this might sound like a "golden screwdriver" sort of thing but if I could just reduce that intensity for now, it would be a big help.

Thanks,
Barry - N4BUQ


Re: Idle Question About the 485

 

Jean-Paul,

I have already lucked out on a 2465 in January of this year, which cost slightly less than this 485 ($120 before shipping). I'm not really interested in the 2465A or 2465B, both because the controls move further and further away from direct control of the instrument on the A and B models, and because of a certain fellow in California who sells disfigured 2465As as 2465Bs, so I'm unsure if I can trust any second-hand 2465Bs I would find in the wild.

I did notice the deterioration of the upper trigger slope knob, but the rest of the unit looks to be in fairly good condition, considering its age. Also, this is a scope from exactly the period that I most like (which includes the 475 and the 7000-series). I also noticed that the hinge covers on the handle seem to be quite faded, which makes me worry that they are about to go brittle, and there is some damage to one of the rear feet. The serial number is B010156, which I think means that it is a very early production unit indeed.

For being so old, most of the knobs appear to be in excellent shape, and the CRT looks quite strong (the intensity is set at less than the half way mark and the traces look nice and bright). Still, your warning is heard and heeded.

Actually, on a second examination of the images, it appears that the CH 1 and CH 2 VOLTS/DIV knobs don't match, which means that one (probably CH 2) had to be replaced, and all they could find was a knob from a much later instrument (a knob without the black insert at the top).

teamlarryohio,

That is a very small button for trigger view. Even in the close-up of the CRT section (second picture) I can barely tell that's actually a button.

-- Jeff Dutky

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