Tektronix 7000 series power supply, sluggish start

[Joerg]

The low and midrange Tek and Agilent scopes are made in China now. But
they cost 3-4x what the Rigols cost. The $1K Agilent *is* a Rigol.

Keithley is doing the same thing, buying a Chinese DVM and sticking
their name on it and doubling the price or so. Piece 'o crap.

What I found is that companies from China often aren't very good at all
when it comes to listening to their customers. If they'd ever learn how
to do that they could become really good.

 

[Joerg]

My $400 Rigol scope is pretty impressive. The user interface is good
and it's packed with features, like USB and digital filtering, that
you don't get on a $1400 Tek scope. The probes are very nice.

Same with the Instek here. Once a guy was rather surprised that his Tek
had higher noise and that storing a pic took only a second on the Instek.

But it does have things that are rather easily fixed. For example the
trigger level knob does not scale with the input divider, and it should.
So if you crank up the sensitivity your trigger level ends up at flight
level 410 and you need hundreds of encoder turns to get it back down.
Meaning you must set the sensitivity back where it had been before,
crank it to zero, then turn sensitivity back up. There is also no
accelerator function on this knob. Wrote to Instek but, as expected, no
answer. And no firmware fix. So I often press the blue "grandma button"
to avoid turn the knobs again.

Got a Chinese DDS generator here right now. That one has a serious bug,
phase jumps. Wrote to the guys, so far not much in terms of answers.

This is one of the reasons why in the medical electronics biz we are
fairly unafraid of Asian competition. Because in med you'll never reach
high-end without being at the customers all the time.

 

[Jamie]

My $400 Rigol scope is pretty impressive. The user interface is good
and it's packed with features, like USB and digital filtering, that
you don't get on a $1400 Tek scope. The probes are very nice.

John

Talking about Rigol, I don't have one of their scopes (yet) but I do
have a arbitrary function generator. I just wonder if they employ the
same power supply techniques in all of their euipment ? When I power
up the bench, because I like things to be dead when I am not around, The
unit's display flashes on and off along with the PSU relay.

Specially the DG1022 model. I just find it annoying..

Jamie

 

[JW]

My $400 Rigol scope is pretty impressive. The user interface is good
and it's packed with features, like USB and digital filtering, that
you don't get on a $1400 Tek scope. The probes are very nice.

For anyone who's looking for a good scope for cheap I'd recommend an
Agilent 54825N. 500MHz, 2GSa/s. I think the military has been
de-commissioning these for the last year or so. You can usually get 'em
for a grand or so on Ebay with a "power up test only, we don't know how to
test" etc. I've got five of them right now, that I'll move for 2K or more.

Yeah, it runs Windows, but that doesn't bother me much. In fact, I kind of
like it. Controls easily over the network, emails you on a trigger event,
and easy to customize.

 

[JW]

I'll keep my $900 TDS744--4 channels, 500 MHz, 2 Gs/s, no Windows. When
my ship comes in, maybe I'll plump for a TDS694C. One of the world's
most beautiful scopes. A bit hard to justify at the moment--for scope
stuff, there's not a lot I can't do with a TDS744 and an 11802 with
beaucoup plugins.

Got a TDS684B for sale if you're interested.

My only problem with that series of scopes (5XX through 7XX) is the CRTs.
Eventually they just fade out. The good news is that there's LCD
conversion kits that replace the CRT, you can get them for $550 each on
Ebay. They look great as well.

Attenuators also seem to fail quite often on the 1GHz and less versions of
TDS5XX through 7XX. Running a SPC and getting a compensation error is the
usual indicator. They can be re-built with off the shelf components
(relays) Just takes a steady hand (2 beers should do the trick), a long
tip on the soldering iron, and a microscope.

 

[Nico Coesel]

Got a TDS684B for sale if you're interested.

My only problem with that series of scopes (5XX through 7XX) is the CRTs.
Eventually they just fade out. The good news is that there's LCD
conversion kits that replace the CRT, you can get them for $550 each on
Ebay. They look great as well.

Or DIY:
http://forum.sparkfun.com/viewtopic.php?f=14&t=23147

I still need to update the VHDL part though.

Attenuators also seem to fail quite often on the 1GHz and less versions of
TDS5XX through 7XX. Running a SPC and getting a compensation error is the
usual indicator. They can be re-built with off the shelf components
(relays) Just takes a steady hand (2 beers should do the trick), a long
tip on the soldering iron, and a microscope.

Thats the capacitors leaking.

 

[Joerg]

Got a TDS684B for sale if you're interested.

My only problem with that series of scopes (5XX through 7XX) is the CRTs.
Eventually they just fade out. The good news is that there's LCD
conversion kits that replace the CRT, you can get them for $550 each on
Ebay. They look great as well.

Attenuators also seem to fail quite often on the 1GHz and less versions of
TDS5XX through 7XX. Running a SPC and getting a compensation error is the
usual indicator. They can be re-built with off the shelf components
(relays) Just takes a steady hand (2 beers should do the trick), ...

Two of these? Around 10 volts and (IIRC) 3/4 of a liter each:

http://greatbrewers.com/sites/default/files/images/Product - St Bernardus Abt 12.preview.jpg

[...]

 

[Joerg]

Bad caps in the switching power supply.

Either that, or as another poster in this thread mentioned the tantalums
on the backplane.

The weird thing is, it decided to repair itself and right now starts up
every single time. It is running right now.

 

[JW]

Or DIY:
http://forum.sparkfun.com/viewtopic.php?f=14&t=23147

I still need to update the VHDL part though.

NO COLOR!??? Ack!

At one point I did find a source for the panel and panel controller that
would yield a color display. I contacted a Chinese OEM
http://www.promate.com/ that would sell the panel and controller for $173.

Here's the email:

Thank you for the detail information. Per your request here is what
Promate can offer for the G065VN01-V2 (LVDS Interface, LED backlight w/
driver included) + GB Driving Board kit (cables included):

1-99pcs: $173/pc
Lead Time : 4-6 weeks
This price is based on quantity ordered per Lot.


Thanks and best regards,

Andy Chen
Sales Marketing Engineer
PROMATE ELECTRONIC CO., LTD.
4F 32, Sec. 1 Huan Shan Rd., Nei Hu, Taipei 114, Taiwan
MOBILE: 0988-972-982
TEL: (02)2659-0303 ext.1296
FAX: (02)2658-0954
MAIL: andy_chen AT promate.com

Never followed up with it as I'd still have to have the sheet metal and
cables fabricated. I do have drawings of the sheet metal and
specifications on the LCD and controller if anyone is interested.

Thats the capacitors leaking.

Sometimes yes. The affected scopes I can remember working on off-hand are:
TDS520, TDS540, TDS520A TDS524A TDS540A TDS544A TDS640 TDS640A TDS644A.
I'm sure I've missed some...

I've cleaned and re-capped tons of those scopes, including a pallet full
that Rosenkrantz in Germany shipped to me. A number of them were
unrepairable as there were too many open etches and vias. Whoever owned
those scopes must have kept using them long after the caps started leaking
and the scope failed POST.

I don't recall whether any TDS7XX scopes were affected. At some point they
stopped using aluminum electrolytics on the ACQ boards, probably from all
the failures that occurred in early scopes. All the TDS7XX scopes I've
successfully repaired that were failing SPC needed attenuator re-builds,
although some of them were failing SPC for reasons unknown and I was
unable to fix.

 

[JW]

Two of these? Around 10 volts and (IIRC) 3/4 of a liter each:

http://greatbrewers.com/sites/default/files/images/Product - St Bernardus Abt 12.preview.jpg

Maybe only *one* of those! [licks lips]

 

[JW]

What kinda of price were you thinking?

$2400. Figure about $60 for shipping and insurance anywhere in continental
US. Has a nice bright CRT without cranking up the intensity, so it
couldn't have seen too many power-on hours. 30 day warranty.

 

[JW]

Either that, or as another poster in this thread mentioned the tantalums
on the backplane.

The weird thing is, it decided to repair itself and right now starts up
every single time. It is running right now.

Might have gotten lucky and blew a short in one on the tantalums.

 

[Joerg]

Might have gotten lucky and blew a short in one on the tantalums.

IME that always went the "exothermal" way: *WHADDABAM* ... followed by a
colorful puff of smoke and an evil stench.

 

[Nico Coesel]

NO COLOR!??? Ack!

At one point I did find a source for the panel and panel controller that
would yield a color display. I contacted a Chinese OEM
http://www.promate.com/ that would sell the panel and controller for $173.

The problem is that the monochrome scopes do not have a color
framebuffer.

 

[Nico Coesel]

Tek has the same feature on the older digital scopes I work(ed) with.

The asians tend to go for high-volume, low-margin products. I'm not
afraid of asian competition in my niche, either.

There is little to worry about the Chinese. If the volumes are big
enough you wouldn't have got the deal anyway. Over here a lot of
designers got scared though and dropped their prices to very low
levels. It is cheaper to hire an EE than a car mechanic.

 

[JW]

The problem is that the monochrome scopes do not have a color
framebuffer.

I had thought you meant to use the above DIY controller with the color
versions of the scope, which is what I was referring to when I mentioned
the LCD kit.

 

[Joerg]

Hmm, yes. I'd have to work on not feeling too dorky wearing something
like that, but I suppose a shockingly high heating bill would do so.

My main strategy when I was a single was to spend a lot of time at work,
school, or other places where heating and air conditioning were provided
to me without incremental cost.

Around the year 2000, after receiving a gas bill for $709 for just one
month, we had a wood stove installed. That instantly fixed the problem.
Best investment we ever made into the house.

 

[[email protected]]

Around the year 2000, after receiving a gas bill for $709 for just one
month, we had a wood stove installed. That instantly fixed the problem.
Best investment we ever made into the house.

Yikes! Though thinking about it, we used to get an oil delivery (225gal, or
so) every three weeks. Our largest electric bill this Winter was $175. The
smallest is around $100, so $75 for heat isn't too bad.

 

[Joerg]

Yikes! Though thinking about it, we used to get an oil delivery (225gal, or
so) every three weeks. ...

Almost 300 gals/mo? At today's prices that could set you back the same
amount.

... Our largest electric bill this Winter was $175. The
smallest is around $100, so $75 for heat isn't too bad.

In much of California electricity is mega-out for anything other than
lighting and stuff. Unless they get special deals new owners of electric
cars may be in for a rude awakening. Once you exceed a paltry baseline
quantity of kWh the price skyrockets. Which is also rather business
hostile because a li'l garage start-up shop might send the electric bill
right through the roof.

 

[Joerg]

Which is why Intel is expanding here (Ocotillo Campus) and shrinking
in Californica.

The Folsom campus 10 miles from here isn't shrinking AFAIK.

But Chandler sure is something special. I was visiting a company there
and right behind the building was a rather massive runway. We have that
as well, a few hundred feet from the house. But building something like
that in CA today is something I can't imagine right now.