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Old August 8th 11, 09:12 AM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

We have about 10 Agilent 33120A frequency-generator / synthesizers
in our lab, and a few other similar synthesizers. They feature a
convenient digital frequency and amplitude programming knob that's
based on optical encoders. A pair of left-right pushbuttons sets
which decade you're adjusting with the knob, and over or underflows
operate on the next higher decade. There's a little indent near
the edge of the knob so you can spin it with your fingertip. You
can also use up-down pushbuttons or directly punch in numbers, but
the spinning knob is very convenient. Typically such encoders have
16 or 32 ticks per revolution. A very nice design feature.

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16

http://www.avagotech.com/pages/en/mo.../hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with identical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


--
Thanks,
- Win

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Old August 8th 11, 10:19 AM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

Winfield Hill wrote in message
...
We have about 10 Agilent 33120A frequency-generator / synthesizers
in our lab, and a few other similar synthesizers. They feature a
convenient digital frequency and amplitude programming knob that's
based on optical encoders. A pair of left-right pushbuttons sets
which decade you're adjusting with the knob, and over or underflows
operate on the next higher decade. There's a little indent near
the edge of the knob so you can spin it with your fingertip. You
can also use up-down pushbuttons or directly punch in numbers, but
the spinning knob is very convenient. Typically such encoders have
16 or 32 ticks per revolution. A very nice design feature.

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16


http://www.avagotech.com/pages/en/mo...cts/rotary_swi
tches/hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with identical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


--
Thanks,
- Win




Its probably patentable so is there a patent outline for them somewhere, to
show what the innards are?


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Old August 8th 11, 12:05 PM posted to sci.electronics.repair
JW JW is offline
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Posts: 519
Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

On 8 Aug 2011 00:12:54 -0700 Winfield Hill
wrote in Message id: :

We have about 10 Agilent 33120A frequency-generator / synthesizers
in our lab, and a few other similar synthesizers. They feature a
convenient digital frequency and amplitude programming knob that's
based on optical encoders. A pair of left-right pushbuttons sets
which decade you're adjusting with the knob, and over or underflows
operate on the next higher decade. There's a little indent near
the edge of the knob so you can spin it with your fingertip. You
can also use up-down pushbuttons or directly punch in numbers, but
the spinning knob is very convenient. Typically such encoders have
16 or 32 ticks per revolution. A very nice design feature.

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16

http://www.avagotech.com/pages/en/mo.../hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with idenical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


I have not seen a failure on the 33XXX series of generators, but the part
# is 0960-0892. Looking at the picture on the find-a-part website shows it
as a mechanical encoder.

http://www.home.agilent.com/myagilen...te=u4p3ex5iq_4

Which is obsolete and replaced by 0960-2545, also a mechanical one. It
looks like its the same as used on the 65XX and 66XX power supplies. I do
know that the older 65XX and 66XX do use the (obsolete) optical ones. It
is possible to use the mechanical ones to fix the obsolete optical ones
with a bit of hacking, but the mechanical ones need more turns to change
the output of the supplies for a given amount.

Are you sure it's an optical encoder you're looking for?
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Old August 8th 11, 02:47 PM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

JW wrote...

Winfield Hill wrote,

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16

http://www.avagotech.com/pages/en/mo.../hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with identical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


I have not seen a failure on the 33XXX series of generators, but
the part # is 0960-0892. Looking at the picture on the find-a-part
website shows it as a mechanical encoder.

http://www.home.agilent.com/myagilen...te=u4p3ex5iq_4


Indeed.

Which is obsolete and replaced by 0960-2545, also a mechanical one.
It looks like its the same as used on the 65XX and 66XX power supplies.
I do know that the older 65XX and 66XX do use the (obsolete) optical
ones. It is possible to use the mechanical ones to fix the obsolete
optical ones with a bit of hacking, but the mechanical ones need more
turns to change the output of the supplies for a given amount.


Thanks, great info!

Are you sure it's an optical encoder you're looking for?


No, and as you say, the service manual identifies the mechanical
one as the part, now that I bothered to look. Given the failures,
perhaps being mechanical makes sense. I had just assumed that
because HP long-ago developed and manufactured a fine optical part,
they'd use it in their expensive premium instruments. Heck, I've
long used their expensive optical encoder in my own designs!

The mechanical part looks much smaller than the optical one, which
might not fit as an upgrade replacement. Hmm, their mechanical part
looks a lot like the ones Spehro was selling as excess inventory.

BTW, as you can see at my Mouser link, the HRPG optical encoder
is not obsolete (yet). Hah, it costs $34 instead of $4.23.
Do we get what we pay for?
http://www.home.agilent.com/myagilen...mber=0960-2545


--
Thanks,
- Win
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Old August 8th 11, 03:39 PM posted to sci.electronics.repair
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Posts: 12,930
Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knobfailure


Winfield Hill wrote:

JW wrote...

Winfield Hill wrote,

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16

http://www.avagotech.com/pages/en/mo.../hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with identical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


I have not seen a failure on the 33XXX series of generators, but
the part # is 0960-0892. Looking at the picture on the find-a-part
website shows it as a mechanical encoder.

http://www.home.agilent.com/myagilen...te=u4p3ex5iq_4


Indeed.

Which is obsolete and replaced by 0960-2545, also a mechanical one.
It looks like its the same as used on the 65XX and 66XX power supplies.
I do know that the older 65XX and 66XX do use the (obsolete) optical
ones. It is possible to use the mechanical ones to fix the obsolete
optical ones with a bit of hacking, but the mechanical ones need more
turns to change the output of the supplies for a given amount.


Thanks, great info!

Are you sure it's an optical encoder you're looking for?


No, and as you say, the service manual identifies the mechanical
one as the part, now that I bothered to look. Given the failures,
perhaps being mechanical makes sense. I had just assumed that
because HP long-ago developed and manufactured a fine optical part,
they'd use it in their expensive premium instruments. Heck, I've
long used their expensive optical encoder in my own designs!

The mechanical part looks much smaller than the optical one, which
might not fit as an upgrade replacement. Hmm, their mechanical part
looks a lot like the ones Spehro was selling as excess inventory.

BTW, as you can see at my Mouser link, the HRPG optical encoder
is not obsolete (yet). Hah, it costs $34 instead of $4.23.
Do we get what we pay for?
http://www.home.agilent.com/myagilen...mber=0960-2545



Hello, Win. I haven't seen you around for quite a while.

The only failed optical encoders I've seen either had a failed
incandescent lamp (Very early type of encoder). The other was when they
were dropped on the shaft, which shatters the code wheel. These use a
thin glass disk that rotated through a pair of photo interrupters. The
shock of impact hit the disks at both photo interrupters, making it
unrepairable. A failed photo interrupter can be replaced in some units,
but it takes more time than it's usually worth.

The mechanical encoders are a lot smaller than the optical, so some
designs use them just to save space. I prefer optical encoders with a
fairly heavy knob so you can give it a spin, and stop it with your
finger when it gets close.


If you can get that part from Agilent for $4.23 I would get at least
half a dozen while they re availible.


--
It's easy to think outside the box, when you have a cutting torch.


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Old August 8th 11, 05:23 PM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

Winfield Hill wrote:

I'm wondering if anyone else has encountered this failure?


I bought a power supply E3647A and the encoder feels like very bad
quality. My boss bought the same power supply six month ago and the
encoder feels much better.

So I thought the quality of HP goes south and I bought the freq
generator from Rigol. When HP is selling the quality of
Rigol now, I dont like to pay the price for HP anymore!

Olaf




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Old August 8th 11, 05:51 PM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

On 8 Aug 2011 05:47:44 -0700, Winfield Hill
wrote:

http://www.home.agilent.com/myagilen...mber=0960-2545


That part looks very familiar. I'll guess that it's a mechanical
encoder made by CUI.
http://onlinecatalog.digikey.com/WebProject.asp?CodeId=7.4.4.28&pagelabel=2365#
I don't know the coding or counts per turn, so I can't find an exact
substitute. However, at $3.60 ea, you could probably buy an
assortment.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Old August 8th 11, 05:57 PM posted to sci.electronics.repair
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

On Mon, 08 Aug 2011 08:51:31 -0700, Jeff Liebermann
wrote:

On 8 Aug 2011 05:47:44 -0700, Winfield Hill
wrote:

http://www.home.agilent.com/myagilen...mber=0960-2545


That part looks very familiar. I'll guess that it's a mechanical
encoder made by CUI.
http://onlinecatalog.digikey.com/WebProject.asp?CodeId=7.4.4.28&pagelabel=2365#
I don't know the coding or counts per turn, so I can't find an exact
substitute. However, at $3.60 ea, you could probably buy an
assortment.


CUI AZ16 data sheet:
http://products.cui.com/getpdf.aspx?fileID=6206

Catalog page:
http://products.cui.com/adtemplate.asp?invky=103924&brand=motion-control&catky=112362&subcatky1=994182&subcatky2=99 7832&subcatky3=953473

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Old August 9th 11, 12:02 PM posted to sci.electronics.repair
JW JW is offline
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

On 8 Aug 2011 05:47:44 -0700 Winfield Hill
wrote in Message id: :

JW wrote...

Winfield Hill wrote,

The optical shaft encoders were originally made by HP, but now of
course they're made by Avago. Sometimes they call these a digital
potentiometer or a "Panel Mount Optical Rotary Encoder". For
example, the HRPG-AD16 product line, about $34 each at Mouser.

http://www.mouser.com/Search/Refine....word=HRPG-AD16

http://www.avagotech.com/pages/en/mo.../hrpg-ad1616c/

Since they use an optical 2-bit quadrature grey-code (as opposed
to using a pair of switch contacts), they're supposed to be
extremely reliable.

But recently I've encountered two instruments with identical
tuning-knob failures, one in an elegant 33250A 80MHz model
that's on my bench, and the other in one of our standard
33120A 15MHz instruments.

In both cases the knob seems 'stuck" and not to work as you
turn it, except every now and then you'll get one or two
increments or decrements. Totally useless.

I'm wondering if anyone else has encountered this failure?


I have not seen a failure on the 33XXX series of generators, but
the part # is 0960-0892. Looking at the picture on the find-a-part
website shows it as a mechanical encoder.

http://www.home.agilent.com/myagilen...te=u4p3ex5iq_4


Indeed.

Which is obsolete and replaced by 0960-2545, also a mechanical one.
It looks like its the same as used on the 65XX and 66XX power supplies.
I do know that the older 65XX and 66XX do use the (obsolete) optical
ones. It is possible to use the mechanical ones to fix the obsolete
optical ones with a bit of hacking, but the mechanical ones need more
turns to change the output of the supplies for a given amount.


Thanks, great info!


You're welcome.

Are you sure it's an optical encoder you're looking for?


No, and as you say, the service manual identifies the mechanical
one as the part, now that I bothered to look. Given the failures,
perhaps being mechanical makes sense.


Could be, but I've yet to see a mechanical one go south unless there was
some abuse. Even then they are sometimes repairable. The bend over tabs
that hold the encoder together come apart a bit when the shaft is hit at a
right angle, which seems to happen all the time on the power supplies I
mentioned. I've lost count on the number of times I've repaired them.
After repair I solder two 24ga pieces of bus wire across the top from tab
to tab which helps sturdy them up a bit.

I had just assumed that
because HP long-ago developed and manufactured a fine optical part,
they'd use it in their expensive premium instruments. Heck, I've
long used their expensive optical encoder in my own designs!

The mechanical part looks much smaller than the optical one, which
might not fit as an upgrade replacement.


If you *do* have an optical one, it may depend on whether it solders
directly to a PCB, or is panel mounted. If the latter, it probably has a
cable which attaches to a PCB, and you should be able to adapt the
mechanical one. If you go that route, I've found that it is important to
ground the case of the encoder. You'll probably have to fiddle around with
the wires to get the order right. Trial and error...
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Old August 9th 11, 12:06 PM posted to sci.electronics.repair
JW JW is offline
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Default optical knob encoder: HP/Agilent 33120A freq generator, tuning-knob failure

On Mon, 08 Aug 2011 09:39:32 -0400 "Michael A. Terrell"
wrote in Message id:
:

The only failed optical encoders I've seen either had a failed
incandescent lamp (Very early type of encoder).


And what a pain in the butt to get to on a 6034A! I wish I could find a
"side firing" LED that would not only fit in that little slot, but also be
the right wavelength for it to work correctly. I've experimented a bit
with this, but never been successful.


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