Date   

Re: Solder Sucker Recommendation?

Philip McIntosh
 

I recently bought an X-Tronic 9020-XTS rework station and that is what I have been using. I generally like it.

When I got it, I experimented on an old scrap board (not a Tek though) with the temperature and have been running it at about 352°C with a fairly large wedge tip. What temperatures are other people using?

Anything less than that and it does not seem to liquify the solder very well. I note that the solder on these 25-30 year old boards does not seem to melt as easily as it does on newer boards. I also touch up the joint with a little fresh solder before attempting to desolder. Maybe I need different solder. Recommendations on that would be welcome too.

I have some repair jobs coming up and don't want to dive in until I am sure of my method and materials.

Phil...
*****

--- In TekScopes@yahoogroups.com, larrys@... wrote:

What are you using for an iron?
-ls-


Re: Solder Sucker Recommendation?

Paul Kraemer <elespe@...>
 

Ditto my comments
One of the most useful de-solder devices ever made and one heck uv a big iron if you ever need one for serious heavy soldering
I've had mine for several years. Love it!
Paul K0UYA

----- Original Message -----
Sent: Tuesday, May 07, 2013 7:20 PM
Subject: Re: [TekScopes] Solder Sucker Recommendation?

 

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: 2465B - Error Codes

Nandagopal
 

Thank You very much, Mr Tom. I will try the same today.

snandu

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@...> wrote:

In the maintenance section, table 6-4. A limit error and a checksum error. Sounds like a dead battery in the NVRAM. What is the serial number? If greater than B050000, it is a Dallas memory module. You can unsolder it (very carefully - it is a multi layer board) and install a socket. For a sanity check, there is an image of a good ram chip that can be programmed into a new chip and plugged in. It should clear the error but the scope will not be calibrated (as it is now).

A search of the messages (A5 NVRAM, Dallas, etc) should give you a part number and source for the part.


Tom


----- Original Message -----
From: Nandagopal
To: TekScopes@yahoogroups.com
Sent: Tuesday, May 07, 2013 7:44 PM
Subject: [TekScopes] 2465B - Error Codes



Hi
I have been into servicing of an old Tekscope 2465B purchased in 1990.
I had power supply problem in both inverter section and Low voltage power supply problem. With the help of varous websites I resolved the power supply problem. Now the scope is working very fine. However during self test the error shown as "Test 04 Error 12". I think it is Checksum error in one of the calibration data stored in NVRAM. I donot find error code information in the manual. Can some one help?


Re: 2465B - Error Codes

vdonisa
 

bought in '90... my bet is a "low serial"....

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@...> wrote:

In the maintenance section, table 6-4. A limit error and a checksum error. Sounds like a dead battery in the NVRAM. What is the serial number? If greater than B050000, it is a Dallas memory module. You can unsolder it (very carefully - it is a multi layer board) and install a socket. For a sanity check, there is an image of a good ram chip that can be programmed into a new chip and plugged in. It should clear the error but the scope will not be calibrated (as it is now).

A search of the messages (A5 NVRAM, Dallas, etc) should give you a part number and source for the part.


Tom


----- Original Message -----
From: Nandagopal
To: TekScopes@yahoogroups.com
Sent: Tuesday, May 07, 2013 7:44 PM
Subject: [TekScopes] 2465B - Error Codes



Hi
I have been into servicing of an old Tekscope 2465B purchased in 1990.
I had power supply problem in both inverter section and Low voltage power supply problem. With the help of varous websites I resolved the power supply problem. Now the scope is working very fine. However during self test the error shown as "Test 04 Error 12". I think it is Checksum error in one of the calibration data stored in NVRAM. I donot find error code information in the manual. Can some one help?


Re: U950

vdonisa
 

Easy fix: remove the IC altogether, pics come back :-)

http://www.electronicspoint.com/tektronix-2465-dim-traces-and-no-vertical-movement-t60080.html

just kidding....

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@...> wrote:

No pictures on the screen.


----- Original Message -----
From: vdonisa
To: TekScopes@yahoogroups.com
Sent: Tuesday, May 07, 2013 8:02 PM
Subject: [TekScopes] U950



Hi Tom,

What are the usual symptoms of such event (U950 fail)?

Thanks,
Valentin

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@> wrote:
>
> Hi Tom,
>
> Have you ever considered designing a replacement for U950, the Z-axis driver? I have seen 10 times more of them fail then the U800 chips.
>
>
> Regards,
> Tom
>
> ----- Original Message -----
> From: thomas.lafay
> To: TekScopes@yahoogroups.com
> Sent: Tuesday, May 07, 2013 2:25 PM
> Subject: [TekScopes] U800 IC replacement available free, pcb only
>
>
>
>
>
> 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: Solder Sucker Recommendation?

Larry McDavid
 

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

Dave Daniel
 

Now THAT is very cool.

DaveD

On 5/7/2013 4:36 PM, Dennis Tillman wrote:
 

Jerry Scheltgen loaned me a 2nd 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 2nd 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.   

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Dennis Tillman
Sent: Monday, May 07, 2012 2:36 PM

All of the discussion about the 7844 being two scopes in one got me wondering if I could insert two 7CT1N curve tracer plugins into it and direct one set of transistor curves to one beam and the other set to the 2nd beam. I can’t see whay it wouldn’t work And it would be interesting to then see if it was possible to do this on a conventional single beam 7000 scope too.

 

This may be more than an academic exercise if it turns out it can display a PNP and an NPN simultaneously I wonder if there is a way to combine the curves together to see what the load line or transfer curve for a class B amplifier looks like.

 

I have one 7CT1N but I don’t own two. Is there anyone in the Seattle area that has a 7CT1N who wouldn’t mind my bring over a 7844 with my 7CT1N and taking some pictures of it displaying two sets of transistor curves at the same time.

 

Contact me off line if you are interested and have a 7CT1N. I have the all the rest I need to do this.

 

Dennis



Re: Free CA plugin pay shipping!

Dave Daniel
 

Hi, Leonard.

Did you still want to come over to Lyons?

73,
Dave

On 5/1/2013 6:19 PM, Leonard wrote:
 

Sorry guys it's gone to the first reply and a local one at that. About 20 miles from me so no shipping problem. Whats great about that is my Hickck 1805, a Tek 545 equivalent that it fits in can go also because it's local to me. What makes it better to me is it goes to a retired volunteer firefighter and I'm a retired firefighter.
Leonard


--- In TekScopes@..., Dave Daniel wrote:
>
> I am at 303-823-5995, cell 303-775-3459. Getting together would be fun.
>
> I will defer to anyone else who can put either instrument to immediate
> use. My goal, as a collector of Tek equipment, is to save it from the
> dumpster.
>
> I didn't see mention of the Lavoie 'scope - what is that?
>
> DaveD
>
> Cheers,
> Dave
> On 5/1/2013 5:35 PM, Leonard wrote:
> >
> > That was fast! Send me an email with your phone number and maybe we
> > can get together and bypass the shipping. If you want the Lavoie scope
> > that it goes into, I'd be happy to include it.
> >
> > Leonard
> >
> > --- In TekScopes@... ,
> > Dave Daniel wrote:
> > >
> > > I'll take them if no one else does. Just as a backstop for them to not
> > > go into the dumpster. I'm at 80503.
> > >
> > > DaveD
> > >
> > > On 5/1/2013 5:26 PM, Leonard wrote:
> > > >
> > > > I have a CA plugin that I need to get rid of. If no one replies it
> > > > will go in the dumpster. I love Tek gear and I'd hate to do that.
> > > >
> > > > http://golddredgervideo.com/kc0wox/tekca1.gif
> > > > http://golddredgervideo.com/kc0wox/tekca2.gif
> > > > http://golddredgervideo.com/kc0wox/tekca3.gif
> > > >
> > > > I'll give it to the first one that replies by email if you pay the
> > > > shipping. Estimated less that $20.00 from 80513. You pay the actual
> > > > amount.
> > > >
> > > > First email at dredger@
> > > > gets it. I'm getting ready to
> > > > pick up a DSA 601a and a DSA 602a and the old stuff needs to go.
> > > >
> > > > Leonard
> > > >
> > > > http://kc0wox.com
> > > >
> > > >
> > >
> >
> >
>



Re: U950

 

No pictures on the screen.
 
 

----- Original Message -----
From: vdonisa
Sent: Tuesday, May 07, 2013 8:02 PM
Subject: [TekScopes] U950

 

Hi Tom,

What are the usual symptoms of such event (U950 fail)?

Thanks,
Valentin

--- In TekScopes@..., "Tom Miller" wrote:
>
> Hi Tom,
>
> Have you ever considered designing a replacement for U950, the Z-axis driver? I have seen 10 times more of them fail then the U800 chips.
>
>
> Regards,
> Tom
>
> ----- Original Message -----
> From: thomas.lafay
> To: TekScopes@...
> Sent: Tuesday, May 07, 2013 2:25 PM
> Subject: [TekScopes] U800 IC replacement available free, pcb only
>
>
>
>
>
> 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: Solder Sucker Recommendation?

Philip McIntosh
 

I completely cleaned it inside and out (I do that before every major job), replaced the o-ring and use silicone grease. I'll look into the Hakko stuff. Thanks.

--- In TekScopes@yahoogroups.com, Ken Winterling <wa2lbi@...> wrote:

Phil,

You say you refurbished the 'sucker. Did you clean the chamber, the metal
rod, "piston", and spring? How about replacing the rubber compression
ring? Did you lube the piston/compression ring? Replace the tip? I have
done all of those steps on mine that I have had since the 1970s and it
still works fine.

I recently acquired a Hakko 808 vacuum desoldering tool and several tips as
a birthday present (MUCH more useful than a neck tie!!!) . It is not
inexpensive but it is well worth the money if you do a lot of repair work.
It has the advantage of requiring only one hand to heat and remove the
solder and, in most cases, completely clean the through hole on both sides
of a PCB. Also, the barrel and tip of the '808 is about the same size as a
soldering iron so it can get into small spaces that would not accommodate
both a solder sucker AND a soldering iron side by side. I wish I got the
Hakko years ago...

Ken
WA2LBI


On Tue, May 7, 2013 at 7:28 PM, Philip <ndpmcintosh@...> 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...


Re: 2465B - Error Codes

 

In the maintenance section, table 6-4. A limit error and a checksum error. Sounds like a dead battery in the NVRAM. What is the serial number? If greater than B050000, it is a Dallas memory module. You can unsolder it (very carefully - it is a multi layer board) and install a socket. For a sanity check, there is an image of a good ram chip that can be programmed into a new chip and plugged in. It should clear the error but the scope will not be calibrated (as it is now).
 
A search of the messages (A5 NVRAM, Dallas, etc) should give you a part number and source for the part.
 
 
Tom
 
 

----- Original Message -----
From: Nandagopal
Sent: Tuesday, May 07, 2013 7:44 PM
Subject: [TekScopes] 2465B - Error Codes

 

Hi
I have been into servicing of an old Tekscope 2465B purchased in 1990.
I had power supply problem in both inverter section and Low voltage power supply problem. With the help of varous websites I resolved the power supply problem. Now the scope is working very fine. However during self test the error shown as "Test 04 Error 12". I think it is Checksum error in one of the calibration data stored in NVRAM. I donot find error code information in the manual. Can some one help?


U950

vdonisa
 

Hi Tom,

What are the usual symptoms of such event (U950 fail)?

Thanks,
Valentin

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@...> wrote:

Hi Tom,

Have you ever considered designing a replacement for U950, the Z-axis driver? I have seen 10 times more of them fail then the U800 chips.


Regards,
Tom

----- Original Message -----
From: thomas.lafay
To: TekScopes@yahoogroups.com
Sent: Tuesday, May 07, 2013 2:25 PM
Subject: [TekScopes] U800 IC replacement available free, pcb only





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: Solder Sucker Recommendation?

Ken, WA2LBI
 

Phil,

You say you refurbished the 'sucker.  Did you clean the chamber, the metal rod, "piston", and spring?  How about replacing the rubber compression ring?  Did you lube the piston/compression ring?  Replace the tip?  I have done all of those steps on mine that I have had since the 1970s and it still works fine.

I recently acquired a Hakko 808 vacuum desoldering tool and several tips as a birthday present (MUCH more useful than a neck tie!!!) .  It is not inexpensive but it is well worth the money if you do a lot of repair work.  It has the advantage of requiring only one hand to heat and remove the solder and, in most cases, completely clean the through hole on both sides of a PCB.  Also, the barrel and tip of the '808 is about the same size as a soldering iron so it can get into small spaces that would not accommodate both a solder sucker AND a soldering iron side by side.  I wish I got the Hakko years ago...

Ken
WA2LBI


On Tue, May 7, 2013 at 7:28 PM, Philip <ndpmcintosh@mac.com> 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...


Re: Can a 7844 use two 7CT1N plugins at the same time?

doswoodman@ymail.com <rgwood@...>
 

I knew there was a reason that is my favorite scope.
Now that is some fancy tinkering.
Cool stuff
Rob

--- In TekScopes@yahoogroups.com, "Dennis Tillman" <dennis@...> wrote:

Jerry Scheltgen loaned me a 2nd 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 2nd 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.



From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Dennis Tillman
Sent: Monday, May 07, 2012 2:36 PM



All of the discussion about the 7844 being two scopes in one got me
wondering if I could insert two 7CT1N curve tracer plugins into it and
direct one set of transistor curves to one beam and the other set to the 2nd
beam. I can't see whay it wouldn't work And it would be interesting to then
see if it was possible to do this on a conventional single beam 7000 scope
too.



This may be more than an academic exercise if it turns out it can display a
PNP and an NPN simultaneously I wonder if there is a way to combine the
curves together to see what the load line or transfer curve for a class B
amplifier looks like.



I have one 7CT1N but I don't own two. Is there anyone in the Seattle area
that has a 7CT1N who wouldn't mind my bring over a 7844 with my 7CT1N and
taking some pictures of it displaying two sets of transistor curves at the
same time.



Contact me off line if you are interested and have a 7CT1N. I have the all
the rest I need to do this.



Dennis


Re: Lady Luck

metoorich
 

I totally agree. We had already agreed to meet again because he has more test equipment for sale in storage. He said he used to own a fiber optics backbone manufacturing company that he sold. He fishes and hunts now. I have lots ammunition reloading gear (dies, primer, powder, brass, bullets, etc) that he's very interested in, so I will have the chance to show my appreciation.

--- In TekScopes@yahoogroups.com, "J. L. Trantham" <jltran@...> wrote:

Looks good from here.



In the spirit of 'commit random acts of kindness' you might want to contact
the seller, let him know that all was well, and give him a 'tip'.



Congrats on a great addition to the bench.



Joe



From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of metoorich
Sent: Tuesday, May 07, 2013 5:15 PM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Lady Luck





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=
<http://groups.yahoo.com/group/TekScopes/photos/album/666236491/pic/66450057
9/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
&mode=tn&order=ordinal&start=1&count=20&dir=asc


2465B - Error Codes

Nandagopal
 

Hi
I have been into servicing of an old Tekscope 2465B purchased in 1990.
I had power supply problem in both inverter section and Low voltage power supply problem. With the help of varous websites I resolved the power supply problem. Now the scope is working very fine. However during self test the error shown as "Test 04 Error 12". I think it is Checksum error in one of the calibration data stored in NVRAM. I donot find error code information in the manual. Can some one help?


Re: Solder Sucker Recommendation?

 

Maybe it is time to refurbish the vacuum source or the heating
capacity is low. I have been using a Weller DS227 vacuum desoldering
head to great effect. It takes 3 to 4 seconds per pin on any size DIP
part which just falls out when I am done.

On Tue, 07 May 2013 23:28:05 -0000, "Philip" <ndpmcintosh@mac.com>
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...


Re: Solder Sucker Recommendation?

Abdul Nizar
 

While the Hakko 808 is not cheap, it works like a charm, and makes the process almost fun.

 

http://www.hakko.com/english/products/hakko_808.html

 

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Philip
Sent: Tuesday, May 07, 2013 4:28 PM
To: TekScopes@...
Subject: [TekScopes] Solder Sucker Recommendation?

 

 

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...


Re: 2235 going into protect and burning R786 & R776

 

I would feed in a current limited voltage to the W954 jumper (out) so you can look for a shorted device in the H output amp. That or just look around with an ohm meter. Are the deflection plate leads clear from any grounds?
 
Tom

----- Original Message -----
From: kb1pgf
Sent: Tuesday, May 07, 2013 7:05 PM
Subject: [TekScopes] 2235 going into protect and burning R786 & R776

 

Hello All,

I apologize if I have missed an obvious solution to my problem, this is my first foray into repairing anything as complicated as a scope so I'm a little lost as to what to look for.

I purchased a 2235 (my first scope!) on ebay and upon receiving it discovered it attempt to power up and fail about once a second (my fault for not understanding the description correctly). I was able to get the power supply up by removing W954 from the +100v power rail. From there I found both R786 and R776 to be burned in the circuit for the horizontal deflection plates - one had gone from 1.33k to 330 ohms! Re-installing W954 and removing both damaged resistors allowed the power supply to come on without tripping, but installing a new R786 (actually 3 smaller resistors in series, I don't have any 1.33k resistors on hand) resulted in smoke a few seconds after applying power.

Any suggestions on what I should look at testing would be greatly appreciated, I'm quite lost as to what to do next.

FYI all I have on hand for testing is a DMM, so I'm a little limited on methods of testing.

Thanks,
Andy


Re: 2235 going into protect and burning R786 & R776

Tom Jobe <tomjobe@...>
 

Hi Andy,
The guys who actually know what they are doing will probably be along soon, but in the mean time, remove your new R786 and start probing around Q789. Something is going straight to chassis ground, and the closest thing I see going to ground is C787.
tom jobe...
 
 

----- Original Message -----
From: kb1pgf
Sent: Tuesday, May 07, 2013 4:05 PM
Subject: [TekScopes] 2235 going into protect and burning R786 & R776

 

Hello All,

I apologize if I have missed an obvious solution to my problem, this is my first foray into repairing anything as complicated as a scope so I'm a little lost as to what to look for.

I purchased a 2235 (my first scope!) on ebay and upon receiving it discovered it attempt to power up and fail about once a second (my fault for not understanding the description correctly). I was able to get the power supply up by removing W954 from the +100v power rail. From there I found both R786 and R776 to be burned in the circuit for the horizontal deflection plates - one had gone from 1.33k to 330 ohms! Re-installing W954 and removing both damaged resistors allowed the power supply to come on without tripping, but installing a new R786 (actually 3 smaller resistors in series, I don't have any 1.33k resistors on hand) resulted in smoke a few seconds after applying power.

Any suggestions on what I should look at testing would be greatly appreciated, I'm quite lost as to what to do next.

FYI all I have on hand for testing is a DMM, so I'm a little limited on methods of testing.

Thanks,
Andy

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