Date   

Re: Fixed 7844 pic

Mark Wendt <mark.wendt@...>
 

On 05/08/2013 07:30 AM, Craig Sawyers wrote:
I've uploaded a pic of the finally (!) fixed and calibrated 7844, showing a
main feature of displaying the same signal at two different sweep speeds.

Craig
Nice! that is a really nice looking scope too!

Mark


Fixed 7844 pic

Craig Sawyers <c.sawyers@...>
 

I've uploaded a pic of the finally (!) fixed and calibrated 7844, showing a
main feature of displaying the same signal at two different sweep speeds.

Craig


Re: Very OT: Petition to veto the Internet sales tax bill

Jim <n6otq@...>
 

Hank,

You may be unclear on how politics works at the Federal level.  I won't discuss it here.  

As for sales tax, it's collected at the state. city, county, school district, road district, bridge district, and other local divisions.  Last time I had a verified count (about four years ago), there were more than 6,600 separate and individual taxing jurisdictions in the US.  I've heard that today there are 9,600, but I think that may be a typo.

The big danger here is that when the Feral government (NOT a typo) asserts authority, it's always a foot in the door for more Federal control and taxation.

Have a nice day, but PLEASE sign that petition and PLEASE oppose internet sales taxes.

73
Jim N6OTQ


From: HankC
To: "TekScopes@..."
Sent: Tuesday, May 7, 2013 7:34 PM
Subject: [TekScopes] Re: Very OT: Petition to veto the Internet sales tax bill

None of any sales tax $ goes to the Feds, so they would have no incentive to play politics.
Sales tax $ goes to the states (& some cities).
 
HankC, Boston
WA1HOS


Re: After 30 years, the modern and sophisticated digital oscilloscopes of today, ??

nowtotallyhackedoff
 

On Wed, May 8, 2013 1:57 am, iglesia_cristiana_arpas_eternas wrote:
After 30 years at least, the modern and sophisticated digital
oscilloscopes of today, will still work like our venerable Tektronix do
?.
Just that..what yours opinion guys?.
Gabriel
Well, if bad caps and tin whiskers don't get to them I expect that many
will be fine.

But scope** for repair will be much more limited than 'scopes that are 30
years old now, are today.


** pun not intended.
--
Paul


Re: U950

Mark Wendt <mark.wendt@...>
 

On 05/07/2013 08:32 PM, Tom Miller wrote:


Hey, that has happened to me before.
The worst case is to get a parts scope made up of all bad parts.
I think I have one of those now. :(.
Tom
Tom,

You just described my SC504 From Hell to a "T." It has now been relegated to the K-Ball bin. Every time I'd make a repair, something else would break.

It was a good learning experience though. I think I've completely memorized the entire set of schematics on that little beasty.

Ever have oscilloscope nightmares? ;-)

Mark


Re: Solder Sucker Recommendation?

Mark Wendt <mark.wendt@...>
 

On 05/07/2013 08:20 PM, Larry McDavid wrote:

<snippage>
Frankly, the Hakko 808 gun has *serious* suck! I've not found
anything better for through-hole de-soldering.

Larry
Larry,

Even better than the "Prince of Darkness" electronics? ;-)

Mark


Re: Solder Sucker Recommendation?

Mark Wendt <mark.wendt@...>
 

On 05/07/2013 07:28 PM, Philip wrote:
I have been using an old Soldapullt solder sucker I refurbished to work on boards. It has been working pretty well up until recently. It just doesn't seem to have enough umph to really pull the solder out of the holes. I end up getting most of it out but not enough to free the lead. I then heat it up some more and pull on the device from the other side. Then I put some solder on the land with the device removed and then the solder sucker will usually clean it out.

Is this as good as can be hoped for on these old boards and solder or is there a better way? Does any one have a recommendation for a good solder sucker or other desoldering method than I have described for removing components while preserving the integrity of the board and lands?

Thanks,

Phil...
Phil,

A few folks have gotten their hands on a Hakko 808 and like it. I've got an older Hakko 472 desoldering station, and it works very well for me. Check out the Hakko stuff on Ebay and see if you might be interested.

Mark


Re: Can a 7844 use two 7CT1N plugins at the same time? [2 Attachments]

Mark Wendt <mark.wendt@...>
 

On 05/07/2013 06:36 PM, Dennis Tillman wrote:
[Attachment(s) <#TopText> from Dennis Tillman included below]

Jerry Scheltgen loaned me a 2^nd 7CT1N so I was able to finally do this test several months ago. Here are two photos I took that cannot be done with any other scope except a 7000 series oscilloscope

The first photo shows what an actual load line of a Class B amplifier looks like. It was created by displaying the load line of an NPN transistor in one 7CT1N curve tracer and the load line of a PNP transistor in the second 7CT1N (thanks to Jerry) simultaneously. The load lines were lined up at the origin as they would be in a Class B amplifier.

The 2^nd photo shows two closely matched (but not perfectly matched) transistors. The traces from one beam of the 7844 are slightly brighter to enable you to distinguish one transistor’s characteristic curves from the other transistor’s curves.

Dennis.
Dennis,

That is very neat! What switch settings did you use to get both verticals to display like that?

Mark


Re: Lady Luck

Mark Wendt <mark.wendt@...>
 

On 05/07/2013 06:15 PM, metoorich wrote:
I should go to Vegas this week.... crazy. I responded to a Craigslist ad, a retired gentleman had some 'electronic test equipment' he was selling. He wasn't sure on the models, but had a couple of oscilloscopes. I met him in the parking lot of Cabella's, and to my surprise he had a Tek 475A and a 2467B. Probes, manuals, the whole enchilada. He sold them to me for $200 (total). I figured this is too good to be true, there must be something wrong with them. I figured the 2467B would cover my cost if I had to part it out. So I got them home just now and the work... I can hardly believe it. It still has the calibration report from 2000 in the pouch. This screen is bright.

I let the 2467B warm up and the screen has a slight case of the jitters... I hope that's not serious.

Photo:
http://groups.yahoo.com/group/TekScopes/photos/album/666236491/pic/664500579/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
The jitters are probably caused by that stack of 221's nearby on the bench... ;-)

Mark


Re: Solder Sucker Recommendation?

John Miles
 

ROFLMAO!  They should raise our fire insurance premiums just for visiting that page!

 

-- john, KE5FX

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Don Black
Sent: Tuesday, May 07, 2013 9:35 PM
To: TekScopes@...
Subject: Re: [TekScopes] Solder Sucker Recommendation?

 

 

I'm intrigued by how small they can now make a 420 watt power supply now. eBay item 280783317481.

Don Black.

On 08-May-13 10:20 AM, Larry McDavid wrote:

 

It is difficult to beat the performance of a Hakko 808 De-Soldering Gun,
available even on Amazon. With the vacuum pump located in the gun, there
is no air flow restriction within a long hose to a bench-mounted vacuum
source. Frankly, the Hakko 808 gun has *serious* suck! I've not found
anything better for through-hole de-soldering.

Larry

On 5/7/2013 4:28 PM, Philip wrote:
> I have been using an old Soldapullt solder sucker I refurbished to work
> on boards. It has been working pretty well up until recently. It just
> doesn't seem to have enough umph to really pull the solder out of the
> holes. I end up getting most of it out but not enough to free the lead.
> I then heat it up some more and pull on the device from the other side.
> Then I put some solder on the land with the device removed and then the
> solder sucker will usually clean it out.
>
> Is this as good as can be hoped for on these old boards and solder or is
> there a better way? Does any one have a recommendation for a good solder
> sucker or other desoldering method than I have described for removing
> components while preserving the integrity of the board and lands?
...

--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)

 


Re: U800 IC replacement available free, pcb only

m8jpk
 

Hi Thomas
I am intrested in this pcb
J Koria
56 Woodlands Drive
Stanmore
Middlesex
HA7 3PA 
United Kingdom


Re: Solder Sucker Recommendation?

Dave C <davec2468@...>
 

Phil,
Throw out (or into a drawer -- they're always useful in some situation) the hand solder sucker. Get a Hakko (or Chinese knock-off) vacuum desolder iron. You'll curse yourself that you didn't do it much sooner.

This is the type Hakko I have (with the pencil-type iron, not the pistol grip, but that's a personal preference):

http://www.ebay.com/sch/i.html?_odkw=hakko+%28472%2C473%29+-%28tip%2Cnozzle%2Cfilter%29&_sop=15&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=hakko+%28472%2C473%29+-%28tip%2Cnozzle%2Cfilter%2Chose%29&_sacat=0

I got mine for around US$100 on ebay.

It is so fast and simple to use it's ALMOST -- as someone else said -- fun!

Cheers,
Dave

-=-=-=-

On May 7, 2013, at 4:28 PM, Philip wrote:

Is this as good as can be hoped for on these old boards and solder or is there a better way? Does any one have a recommendation for a good solder sucker or other desoldering method than I have described for removing components while preserving the integrity of the board and lands?

Thanks,

Phil...


Re: U800 IC replacement available free, pcb only

 

Hi Thomas,

I' am interested in this pcb, count me in.

Juri Ghisio
Via Roma 95
13010 Stroppiana (VC)
Italy

Regards
Juri

--- In TekScopes@..., "thomas.lafay" <thomas.lafay@...> wrote:



Greetings.

I have a limited number of unpopulated U800 replacement modules, pcb only, for evaluation. Just add the components you purchase from the bom and replace your defective U800. I've decided that possibly someone else could help to improve the performance/cost and that's why I'm giving them to a good home. E-mail me your contact information and I'll send a blank pcb, bom and replacement guide. Yes, the performance is functional and at a minimum 95% of the original horizontal driver IC. It's better than a dead scope for sure.


Re: After 30 years, the modern and sophisticated digital oscilloscopes of today, ??

iglesia_cristiana_arpas_eternas
 

Hi David, I mean if they will still be providing good service, as today we provide the venerable old Tektronix!.
My first 422 still works like the first day, and keeps a pristine beam in the new home, sold it a few years ago.
Gabriel.

--- In TekScopes@..., David <davidwhess@...> wrote:

Why wait 30 years? They do not work that way now and even their
resemblance to early DSOs is fading.

If I designed a DSO from scratch, it would resemble an old DSO more
than a new one by preference.

On Wed, 08 May 2013 00:57:27 -0000, "iglesia_cristiana_arpas_eternas"
<iglesia_cristiana_arpas_eternas@...> wrote:

After 30 years at least, the modern and sophisticated digital oscilloscopes of today, will still work like our venerable Tektronix do ?.
Just that..what yours opinion guys?.
Gabriel


Re: 2465B - Error Codes

m8jpk
 

Hello Nandgopal
I would also ckeck all the smd caps 10uF and 33uF on the board.
Have you tried to calibrate it?
Before you go to changing the NV ram TRY and go thru 
the complete cal procedure. 
Regards M8JPK


Re: Solder Sucker Recommendation?

 

A triac can control many watts and does not take up much space. Plus, it is a 240 volt unit so the current is not that high. Just look at the size of a lamp dimmer.
 
-Tom
 
 

----- Original Message -----
Sent: Wednesday, May 08, 2013 12:50 AM
Subject: Re: [TekScopes] Solder Sucker Recommendation?

 

They just need a few watts at low voltage for the fan and control circuit, the heater voltage is fed straight through.

ST

On Wed, May 8, 2013 at 6:35 AM, Don Black <donald_black@...> wrote:


I'm intrigued by how small they can now make a 420 watt power supply now. eBay item 280783317481.

Don Black.


Re: Solder Sucker Recommendation?

stefan_trethan
 

They just need a few watts at low voltage for the fan and control circuit, the heater voltage is fed straight through.

ST


On Wed, May 8, 2013 at 6:35 AM, Don Black <donald_black@...> wrote:


I'm intrigued by how small they can now make a 420 watt power supply now. eBay item 280783317481.

Don Black.


Re: Solder Sucker Recommendation?

Don Black <donald_black@...>
 

I'm intrigued by how small they can now make a 420 watt power supply now. eBay item 280783317481.

Don Black.

On 08-May-13 10:20 AM, Larry McDavid wrote:
 

It is difficult to beat the performance of a Hakko 808 De-Soldering Gun,
available even on Amazon. With the vacuum pump located in the gun, there
is no air flow restriction within a long hose to a bench-mounted vacuum
source. Frankly, the Hakko 808 gun has *serious* suck! I've not found
anything better for through-hole de-soldering.

Larry

On 5/7/2013 4:28 PM, Philip wrote:
> I have been using an old Soldapullt solder sucker I refurbished to work
> on boards. It has been working pretty well up until recently. It just
> doesn't seem to have enough umph to really pull the solder out of the
> holes. I end up getting most of it out but not enough to free the lead.
> I then heat it up some more and pull on the device from the other side.
> Then I put some solder on the land with the device removed and then the
> solder sucker will usually clean it out.
>
> Is this as good as can be hoped for on these old boards and solder or is
> there a better way? Does any one have a recommendation for a good solder
> sucker or other desoldering method than I have described for removing
> components while preserving the integrity of the board and lands?
...

--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)



Re: Ebay seller Mountop

ROLYNN PRECHTL K7DFW
 

Looks like they had two units. One working and parts unit. Did they ship the wrong unit?

==================================================

It appears the two listings are for the same unit as the seller ended the first one ("This listing
was ended by the seller because there was an error in the listing.") and apparently cobbled the
unit to re-list it.

The entire listing description of only 14 words is a little too vague for me to have any
expectations of receiving a 100% working and calibrated instrument. Especially for $177.14 to my
front door.

"Unit powers on. Power cable included. Small damage on back side. Testing seems accurate."

The word seems doesn't give me any confidence. Two channels connected to the cal output was
probably the extent of their "testing".


RP


Re: Ebay seller Mountop

G. K. <glkinst@...>
 

Looks like they had two units. One working and parts unit. Did they ship the wrong unit? - George

From: jerry massengale
To: TekScopes2@...; tekscopes@...
Sent: Tuesday, May 7, 2013 7:22 PM
Subject: [TekScopes] Ebay seller Mountop
 
Hi,I received a 2246A that was supposed to be fully functional with power cord and it did not have the power cord. It does not pass self test and does not autocal. The seller asked me if I wanted a refund for the power cord. Does anyone know these guys?

Jerry Massengale

101881 - 101900 of 193798