Date   
Re: 1502 TDR project - using bench supply

Mark Pilant
 

Success.

After using the bench supply, and giving the unit a couple of minutes to warm up,
I started rotating the intensity control. As I swept to the upper end, I could see
evidence of a trace, although off the CRT. By adjusting the vertical position, I
was able to finally see the trace on the CRT.

I decided to check a couple of RG-58 test cables I had laying around, and the TDR
got them right.

So, here is a list of what I tried and whether or not it "worked":
1) Used the TekWiki cap/resistor replacement for the battery. Did not work.
2) Checked all the 470uf caps on the underside of the power supply board. Two
checked fine on my ESR/cap meter and one checked open. I replaced the
"open" cap with a new one. Not certain it "worked".
3) Power supply still not functioning, so I hooked the 1502 to a bench supply.
Success, all voltages correct.
4) I checked the supposed "open" cap out of circuit it checked fine. So I put it
back. Non-problem.
5) Left the 1502 powered up for a bit while I checked the power supply voltages.
After a bit (a minute or two) on a whim I tried rotating the intensity control and
saw evidence of a CRT trace.
6) Using the vertical position, intensity, and focus controls I was able to get a nice
clean trace on the CRT.

So now to figure out what I want to do about the battery pack and then put everything
back together (mostly put the case on).

Thanks for all the suggestions.

- Mark N1VQW

Re: 1502 TDR project - using bench supply

EB4APL
 

Greg,

After searching for your album, I realized that there is typing error in the name, "Tex" instead of "Tek"

Regards,

Ignacio

El 12/12/2019 a las 18:45, Greg Muir via Groups.Io escribió:
Mark,

If you are going to continue to work on 1502/1503 units in the future it is wise to build up an external bench supply power adapter for these units. I did the very thing and also built up an extender for the chart recorders as well.

For the connection to the banana plug in the battery compartment I modified a standard dual banana plug by cutting off the plug end, turning it around and attaching it to a handle. If you do this be sure that you mark the insertion position on the handle so as not to incorrectly connect it to the TDR. The other end is simply a dual banana plug for connection to a bench supply. Of course the negative side is indicated by the little flag on the side of that connector.

I just posted photos in the album section titled “Tek 1502/1503 Test Adapters.”

Greg

Re: 1502 TDR project - using bench supply

ehsjr
 

On 12/12/2019 11:59 AM, Mark Pilant wrote:
Hi Tom.
Got around to testing the 1502 using a bench supply.  As you suggested,
when hooked up, the 1502 power supply started operating as expected.  All
the voltages appeared to be to spec.  Although still no trace on the CRT.
I guess there may be some issues with the TekWiki suggested modification
of a 2200uf cap in parallel with a 270 10W resistor.
So now I need to figure out what to do.  I'm thinking of possibly using
a 12V 2A "wall wart" supply connected to the banana plugs instead of the
nor mal AC power cord.  The main problem is how to actually connect it
all up.
There is room on the rear panel for one of the ubiquitous coaxial power
connectors, but I'm a little reluctant to drill a hole for it.  I could
terminate the power card in the supply in a female banana jack attached
to some sort of "paddle" to make it easier to connect / disconnect; but
it would be "a bit" ugly :-)
Any other ideas out there?
Yes. First see Paul's reply. It's good for building a
battery pack AND for the cap/resistor mod AND for
mounting a jack for a 12V supply. NO internal mods
to the 1502.

Another way (but Paul's is better in my opinion) is
what I did years ago with a method a little different
than Paul's: two plates, connected by a threaded
rod and held apart by nuts on the rod. The distance between
the plates is adjusted so they exactly fit the depth of
of the battery compartment, then the nuts are tightened.
The inner plate has the dual banana plug and the outer
plate has the jack for the wall wart supply. There's
tons of room between the plates for the cap and resistor.

Inside Outside
Plate Plate
|............|
|==========={|}=
|............|

The = signs are the threaded rod, the {} are the nuts.
Ignore the periods - they are there to make the spacing
appear correctly for those with different font settings.

Ed


- Mark  N1VQW

Re: 1502 TDR project - number 2

Mark Pilant
 

Make that horizontal sweep set way too slow. (Not trace :-)

- Mark N1VQW

Re: 1502 TDR project - using bench supply

Paul Amaranth
 

The pack was missing on my 1502 and prices on those are silly (I paid $12 for
the 1502, I wasn't going to pay $50 for a dead battery pack). I made up
a frame out of sheet metal bent like this:

-+ +-
| |
+--+

to hold a couple of banana plugs and put in some subC nicads. Then I made
a cover plate that holds it all in. Works fine. I should put a little
slide switch on the cover plate to disconnect the battery when it's in
storage.

If you made up a bracket like that, there's probably room to put in a
small 12V power supply with an IEC connector on the back. Then just
swap in the battery when you need portability.

Paul

On Thu, Dec 12, 2019 at 11:59:25AM -0500, Mark Pilant wrote:
Hi Tom.

Got around to testing the 1502 using a bench supply. As you suggested,
when hooked up, the 1502 power supply started operating as expected. All
the voltages appeared to be to spec. Although still no trace on the CRT.

I guess there may be some issues with the TekWiki suggested modification
of a 2200uf cap in parallel with a 270 10W resistor.

So now I need to figure out what to do. I'm thinking of possibly using
a 12V 2A "wall wart" supply connected to the banana plugs instead of the
nor mal AC power cord. The main problem is how to actually connect it
all up.

There is room on the rear panel for one of the ubiquitous coaxial power
connectors, but I'm a little reluctant to drill a hole for it. I could
terminate the power card in the supply in a female banana jack attached
to some sort of "paddle" to make it easier to connect / disconnect; but
it would be "a bit" ugly :-)

Any other ideas out there?

- Mark N1VQW





!DSPAM:5df2721f306015243021362!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows

Re: 1502 TDR project - using bench supply

Greg Muir
 

Mark,

PS - I never have tried any of the passive component ":cheat" methods to trick the TDR into thinking it has a battery attached. The bench supply method works every time.

You also may be aware that there have been others who have come up with minor modifications to the TDR power supply circuitry itself to bypass the "battery present" detect circuit so that you don't need to have any connection to the battery compartment contacts whatsoever when operating the units off of 120V.

Greg

Re: 1502 TDR project - using bench supply

Greg Muir
 

Mark,

If you are going to continue to work on 1502/1503 units in the future it is wise to build up an external bench supply power adapter for these units. I did the very thing and also built up an extender for the chart recorders as well.

For the connection to the banana plug in the battery compartment I modified a standard dual banana plug by cutting off the plug end, turning it around and attaching it to a handle. If you do this be sure that you mark the insertion position on the handle so as not to incorrectly connect it to the TDR. The other end is simply a dual banana plug for connection to a bench supply. Of course the negative side is indicated by the little flag on the side of that connector.

I just posted photos in the album section titled “Tek 1502/1503 Test Adapters.”

Greg

Re: 1502 TDR project - using bench supply

Tom Gardner
 

On 12/12/19 16:59, Mark Pilant wrote:
Hi Tom.

Got around to testing the 1502 using a bench supply.  As you suggested,
when hooked up, the 1502 power supply started operating as expected.
:)

Repeat after me: Tom is wise and omniscient. If you repeat it enough times, maybe/I'll /start to believe it.


All
the voltages appeared to be to spec.  Although still no trace on the CRT.
Check all the voltages/ripple.

Suspect the EHT; those components can be easily replaced since they aren't potted.

I guess there may be some issues with the TekWiki suggested modification
of a 2200uf cap in parallel with a 270 10W resistor.
If you put a storage scope on the 12V line, then you can observe the switch-on transients. That will aid tweaking the R&C, but personally I think that's a waste of time.


So now I need to figure out what to do.  I'm thinking of possibly using
a 12V 2A "wall wart" supply connected to the banana plugs instead of the
nor mal AC power cord.  The main problem is how to actually connect it
all up.

There is room on the rear panel for one of the ubiquitous coaxial power
connectors, but I'm a little reluctant to drill a hole for it.  I could
terminate the power card in the supply in a female banana jack attached
to some sort of "paddle" to make it easier to connect / disconnect; but
it would be "a bit" ugly :-)

Any other ideas out there?
Remove the transformer. Mount an 240Vac - 12Vdc brick on a PCB in place of the transformer, and connect it to the IEC socket and the battery "pins" or similar. No case mods required.

Keep the transformer in case you want to revert the mod and use tagged NiCd cells. Over here they are ~£30 for 9.

Re: TM503 in scope cart

Greg Muir
 

Would be rather handy indeed for those who have to move from bench to bench for tests and don’t want to drag everything along behind them.

Greg

1502 TDR project - number 2

Mark Pilant
 

Thinking I might find a use for a 1502 parts unit, I picked one up. Although
it was "parts only" I decided to see what kind of shape it was in.

NiCd batteries shot, and starting to leak a bit. So I tried connecting it
up to my bench supply (I'm using for my other 1502). After a bit of warm up
I get a nice horizontal trace on the CRT. Beam intensity and focus work fine.

So I figured, that the heck, I'll connect up a short piece of coax with a
50 ohm terminator. When I to this, the trace changes, but strangely. With
the coax connected, I see a nice "fat" trace, whose width changes with various
control settings.

The "fat" trace reminds me of looking at a high frequency signal on a scope,
with the horizontal trace set way too slow.

Just what I need... another project :-) :-) :-) Although maybe I'll be able
to may one working 1502 out of the two of them.

- Mark N1VQW

Re: 1502 TDR project - using bench supply

Mark Pilant
 

Hi Tom.

Got around to testing the 1502 using a bench supply. As you suggested,
when hooked up, the 1502 power supply started operating as expected. All
the voltages appeared to be to spec. Although still no trace on the CRT.

I guess there may be some issues with the TekWiki suggested modification
of a 2200uf cap in parallel with a 270 10W resistor.

So now I need to figure out what to do. I'm thinking of possibly using
a 12V 2A "wall wart" supply connected to the banana plugs instead of the
nor mal AC power cord. The main problem is how to actually connect it
all up.

There is room on the rear panel for one of the ubiquitous coaxial power
connectors, but I'm a little reluctant to drill a hole for it. I could
terminate the power card in the supply in a female banana jack attached
to some sort of "paddle" to make it easier to connect / disconnect; but
it would be "a bit" ugly :-)

Any other ideas out there?

- Mark N1VQW

Re: 577 AC collector supply not reading zero on display

DW
 

I would like to thank everyone here for their help and especially advice. In this case we noticed sometimes it is good to let things be and I have personal experience before from this. Given this advice I immediately up on that option.

Re: 465B soft start?

n4buq
 

Done my share of restuffing caps and considered doing that to the 465B; however, that requires both desoldering and soldering to the board, each time risking damage. I decided to only desolder the old ones, solder small jumper wires as needed, and use an auxilliary board. If the new caps ever need replacing, it won't involve soldering/desoldering to the main board. I have some of the discs which would have worked, but if the caps ever needed replacing for those, it would still involve work to the main board. Not pushing my boards, just explaining my reasoning.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Tom Green" <xman143@...>
To: TekScopes@groups.io
Sent: Thursday, December 12, 2019 9:38:05 AM
Subject: Re: [TekScopes] 465B soft start?

Old caps:

https://www.youtube.com/watch?v=WOlH5hVajco

https://www.youtube.com/watch?v=IYtu_2psK2I

There are many other videos on there as well.

Tom

On Thu, Dec 12, 2019 at 10:19 AM n4buq <n4buq@...> wrote:

I designed a board to help with this:

https://groups.io/g/TekScopes/album?id=64929

I have some of the boards if you're interested.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Andrew Stanworth via Groups.Io" <andrew.stanworth=
ntlworld.com@groups.io>
To: TekScopes@groups.io
Sent: Thursday, December 12, 2019 8:42:36 AM
Subject: Re: [TekScopes] 465B soft start?

On Wed, Dec 11, 2019 at 10:20 AM, DaveH52 wrote:


I should have mentioned before that the capacitor can completes part
of the
circuit. So if you don't want to add some jumper wires, use a tubing
cutter
to cut the base off the old capacitors and use that as an interposer
between
the new caps and the circuit board. I don't recommend putting the can
back
over the new caps because it will hold in heat.
Interesting. I have been considering the options for replacing the PSU
caps
on this scope too - although currently mine seem to be working ok
(haven't
got around to measuring ripple yet but like a good boy scout wanted to
'be
prepared'!). Desoldering those cans from the pcb seems pretty tricky with
almost inevitable track damage from the inordinate amount of heat
required.
I was going to attempt this and then use those circular adapter boards
you
can get to mount the new caps. How easy is it in reality to cut the cans
with a tubing cutter (I presume you mean like plumbers use to cut pipe?)
-
is there enough clearance to get a tool like this around the cans? Other
suggestions I have read about include the use of some sort of saw (eg. a
cutting disc in a Dremmel) but that would produce a lot of metal filings
and
swarf - not ideal in this enviroment! Also, how much gunk in the form of
electrolyte etc comes out of these things when cut? Is it liquid or paste
and is it manageable? Any photos of or links to this process would be
interesting to see!







Re: 465B soft start?

Tom Green
 

On Thu, Dec 12, 2019 at 10:19 AM n4buq <n4buq@...> wrote:

I designed a board to help with this:

https://groups.io/g/TekScopes/album?id=64929

I have some of the boards if you're interested.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Andrew Stanworth via Groups.Io" <andrew.stanworth=
ntlworld.com@groups.io>
To: TekScopes@groups.io
Sent: Thursday, December 12, 2019 8:42:36 AM
Subject: Re: [TekScopes] 465B soft start?

On Wed, Dec 11, 2019 at 10:20 AM, DaveH52 wrote:


I should have mentioned before that the capacitor can completes part
of the
circuit. So if you don't want to add some jumper wires, use a tubing
cutter
to cut the base off the old capacitors and use that as an interposer
between
the new caps and the circuit board. I don't recommend putting the can
back
over the new caps because it will hold in heat.
Interesting. I have been considering the options for replacing the PSU
caps
on this scope too - although currently mine seem to be working ok
(haven't
got around to measuring ripple yet but like a good boy scout wanted to
'be
prepared'!). Desoldering those cans from the pcb seems pretty tricky with
almost inevitable track damage from the inordinate amount of heat
required.
I was going to attempt this and then use those circular adapter boards
you
can get to mount the new caps. How easy is it in reality to cut the cans
with a tubing cutter (I presume you mean like plumbers use to cut pipe?)
-
is there enough clearance to get a tool like this around the cans? Other
suggestions I have read about include the use of some sort of saw (eg. a
cutting disc in a Dremmel) but that would produce a lot of metal filings
and
swarf - not ideal in this enviroment! Also, how much gunk in the form of
electrolyte etc comes out of these things when cut? Is it liquid or paste
and is it manageable? Any photos of or links to this process would be
interesting to see!





Re: 465B soft start?

n4buq
 

I designed a board to help with this:

https://groups.io/g/TekScopes/album?id=64929

I have some of the boards if you're interested.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Andrew Stanworth via Groups.Io" <andrew.stanworth=ntlworld.com@groups.io>
To: TekScopes@groups.io
Sent: Thursday, December 12, 2019 8:42:36 AM
Subject: Re: [TekScopes] 465B soft start?

On Wed, Dec 11, 2019 at 10:20 AM, DaveH52 wrote:


I should have mentioned before that the capacitor can completes part of the
circuit. So if you don't want to add some jumper wires, use a tubing
cutter
to cut the base off the old capacitors and use that as an interposer
between
the new caps and the circuit board. I don't recommend putting the can back
over the new caps because it will hold in heat.
Interesting. I have been considering the options for replacing the PSU caps
on this scope too - although currently mine seem to be working ok (haven't
got around to measuring ripple yet but like a good boy scout wanted to 'be
prepared'!). Desoldering those cans from the pcb seems pretty tricky with
almost inevitable track damage from the inordinate amount of heat required.
I was going to attempt this and then use those circular adapter boards you
can get to mount the new caps. How easy is it in reality to cut the cans
with a tubing cutter (I presume you mean like plumbers use to cut pipe?) -
is there enough clearance to get a tool like this around the cans? Other
suggestions I have read about include the use of some sort of saw (eg. a
cutting disc in a Dremmel) but that would produce a lot of metal filings and
swarf - not ideal in this enviroment! Also, how much gunk in the form of
electrolyte etc comes out of these things when cut? Is it liquid or paste
and is it manageable? Any photos of or links to this process would be
interesting to see!



Re: 465B soft start?

Andrew Stanworth
 

On Wed, Dec 11, 2019 at 10:20 AM, DaveH52 wrote:


I should have mentioned before that the capacitor can completes part of the
circuit. So if you don't want to add some jumper wires, use a tubing cutter
to cut the base off the old capacitors and use that as an interposer between
the new caps and the circuit board. I don't recommend putting the can back
over the new caps because it will hold in heat.
Interesting. I have been considering the options for replacing the PSU caps on this scope too - although currently mine seem to be working ok (haven't got around to measuring ripple yet but like a good boy scout wanted to 'be prepared'!). Desoldering those cans from the pcb seems pretty tricky with almost inevitable track damage from the inordinate amount of heat required. I was going to attempt this and then use those circular adapter boards you can get to mount the new caps. How easy is it in reality to cut the cans with a tubing cutter (I presume you mean like plumbers use to cut pipe?) - is there enough clearance to get a tool like this around the cans? Other suggestions I have read about include the use of some sort of saw (eg. a cutting disc in a Dremmel) but that would produce a lot of metal filings and swarf - not ideal in this enviroment! Also, how much gunk in the form of electrolyte etc comes out of these things when cut? Is it liquid or paste and is it manageable? Any photos of or links to this process would be interesting to see!

Re: TM503 in scope cart

Oz-in-DFW
 

Tek made a cart for the USG that had 7K/5K plugin storage in the cart. This looks to be one of these.

Re: TM503 in scope cart

Dave Seiter
 

I too have a K213 cart with a TM504 that lives on the upper of two shelves.  It is really just extra storage space, but it fits nicely.
-Dave

On Wednesday, December 11, 2019, 06:35:50 PM PST, Harvey White <madyn@...> wrote:

I have a scope cart with a TM504 attached (no plugin slots for scope
plugins in a separate rack, I've seen them).


On 12/11/2019 7:35 PM, Kurt Rosenfeld wrote:
This scope cart seems to have a TM503 mounted in it: https://www.ebay.com/itm/264244929767

Was that an official mod, or was it just something the owners did to their scope cart?

thanks, -Kurt




Re: TM503 in scope cart

Glenn Little
 

The TM503 modules could be to power up and provide stimulus to a unit under test where the TM series scope displays and feature were just not enough.
This would give all of the required test equipment on one cart.

Glenn

On 12/11/2019 7:41 PM, ArtekManuals wrote:
Hopefully just something the owner did to his cart ...either that or he has no clue what he is doing ...which is very scary

I either case he is delusional if he thinks he will ever get� that much money for it all... even at 1/3 that price would be a bit high IMO.
Dave




On 12/11/2019 7:35 PM, Kurt Rosenfeld wrote:
This scope cart seems to have a TM503 mounted in it: https://www.ebay.com/itm/264244929767

Was that an official mod, or was it just something the owners did to their scope cart?

thanks, -Kurt


--
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Re: TM503 in scope cart

John Griessen
 

On 12/11/19 6:35 PM, Kurt Rosenfeld wrote:
TM503 mounted in it:https://www.ebay.com/itm/264244929767
Was that an official mod, or was it just something the owners did to their scope cart?
Looks very tidy, but with no cooling openings, seems like not factory.
But wait, the last photo of the back shows matching ribbed aluminum bump out
to accommodate the TM503... with a big opening, so maybe yes factory.