Date   

Re: 7D15 internal trigger not working

Dan G
 

On Sun, Mar 21, 2021 at 01:26 PM, Steve Nossen wrote:

Measured the transistors and Q213 measures 30 ohms from C to E and E to C on
my SImpson 260. Much higher on a DVM but the same in both directions. Seems
leaky to me. Q203 measured more like a diode, conducts in one direction.
Q213 pins are connected to GND and +5V rails with very low value resistors, so
I would be suspicious of any in-circuit resistance measurements.

A non-invasive test of the basic health of these transistors is to
check the operating point voltages of Q203, Q213 and Q217, and compare
them against the expected values provided in schematic <1>. This check
should not need a signal applied to A20/B20, so the plug-in can be operated
in the vertical compartment for ease of access. (Unless, of course, you are
one of the luck few who have a nice 7000 plug-in extender.)

Also, did you remember to clean all attenuator cam switch contacts with
isopropyl alcohol? This would be the first order of business before
attacking the plug-in with a soldering iron.


dan


Re: 454 fireworks

Sean Turner
 

OK, I have the scope on the bench again for a closer look at all the components in the +75 supply. Obviously I haven't torn it apart to test out of circuit, but now that I tested it again, Q1197 seems to have an emitter-collector short. I don't *think* this would result from how it is connected. Am I missing something?

Looking at the mechanical bits, it looks to me like the power transformer has to be undone to get to nuts that hold the metal part that the pass transistors heat sink to.

Sean

On Mon, Mar 15, 2021 at 03:43 PM, John wrote:


Sean: If Q1197 isn't s/c it's 99% likely the drive circuitry, which at least
is accessible!
John


Re: 7A16A high frequency compensation.

Albert Otten
 

Ah yes, sorry Max, you mentioned both arrows some posts back.
I mentioned calibration of the PG506 since when calibrating the 7A16A you also try to compensate for pulse shape of the PG506.

Albert


Re: Beware of old AntiStatic foam

Dave Seiter
 

I have a number of plastic toy rail cars from the 40's (American Flyer, I believe) that were my fathers, and have a similar problem.  Either the plasticizer or mold release has resulted in white deposits (on both the plastic and metal parts) over the years that also smells like vomit.  Very hard to remove from the plastic.  I too have a set of Xcelite nut drivers that smell "weird".  Not like vomit, and there's no corrosion, but I like to let them air out before I use them.
-Dave

On Sunday, March 21, 2021, 11:49:23 AM PDT, stevenhorii <sonodocsch@gmail.com> wrote:



Another “plastic rot” question. I have a set of Xcelite tools. One of them,
a stubby Philips screwdriver, developed a white coating on it that was
impossible to remove without sanding it off. I could get some of it off,
but it kept re-developing this. None of the other tool handles has done
this. The handles, I believe, are a butyrate plastic that gives off butyric
acid as it oxidizes but they all are and this is the only one that
developed this white coating. The whole tool kit smells rather like vomit
(my wife refers to it as my “vomit tool case”) but this is common with
butyrate plastic-handled tools.


Re: Beware of old AntiStatic foam

Ken, WA2LBI
 

Those tool handles are another issue. I have a plastic fitted case for a
set of Xcelite nut drivers. They have quite an odor. I have to leave the
case open unless I'm traveling away from the workshop. I also have a number
of other tools, mostly screwdrivers, that have the same awful odor. I have
taken to inserting a block of wood in the toolboxes to keep the lids
slightly open so the odor can vent and I'm not blasted with a concentrated
"cloud" when I open the box.

Ken
WA2LBI

On Sun, Mar 21, 2021 at 2:49 PM stevenhorii <sonodocsch@gmail.com> wrote:

I think polyethylene foam instead of the black polyurethane foam does not
have the “get goopy and stick to everything” problem. Has anyone had
polyethylene foam degrade like the black stuff? I have not - either black
or white polyethylene has stood the “test of time”. I have seen foam rubber
turn to dust, but at least it does not (in my experience) get sticky.

Apparently the polyurethane foams also outgas as they degrade and this can
leave deposits on stuff - think camera optics as many camera carrying cases
use polyurethane foam.

If I have some custom-fitted black foam in a transit case, I put the item
in a plastic bag and before putting it back in the case.

Another “plastic rot” question. I have a set of Xcelite tools. One of them,
a stubby Philips screwdriver, developed a white coating on it that was
impossible to remove without sanding it off. I could get some of it off,
but it kept re-developing this. None of the other tool handles has done
this. The handles, I believe, are a butyrate plastic that gives off butyric
acid as it oxidizes but they all are and this is the only one that
developed this white coating. The whole tool kit smells rather like vomit
(my wife refers to it as my “vomit tool case”) but this is common with
butyrate plastic-handled tools.

A comment on Duracell batteries. I am pretty sure there are counterfeits
out there - particularly the “bulk packs” with no Duracell label on the
outside. Here’s an article on fakes:


https://www.thecounterfeitreport.com/product/106/Duracell-Coppertop-AA---AAA-Batteries.html

When I have had Duracell batteries (the AA ones in particular) leak, on
checking, they were the ones I bought in unlabeled bulk packs. I generally
remove batteries from equipment I am not going to use frequently.

Steve Horii

On Sun, Mar 21, 2021 at 12:01 Harvey White <madyn@dragonworks.info> wrote:

As I've mentioned previously, the latest run of Duracell (guaranteed not
to leak before 10 years) does exactly that, and often in the package.

The good news is that they will often give you money to replace the
damaged item if you call them. Their warranty is "repair or replace",
but you do have to call.

I've had the foam in probe cases crumble, (both HP and Tek), anti static
foam corrode and crumble, etc...

Harvey


On 3/21/2021 9:50 AM, David Slipper wrote:
Nasty!! I wonder what other time-bombs are awaiting us!?

I'll certainly be checking my stock of bits and spares.

I always assumed that a famous brand of NiMh batteries were supposed
to be leak proof - Hah! I nearly lost a pair of nice walky-talkies and
a multimeter that way, so now cells get removed from rarely used items
and I make a point of checking torches and the like regularly.

Sadly not surprised at anything these days,
Dave


On 21/03/2021 13:07, - wrote:
Well, this thread just showed up on EEVBlog. This is exactly the
kind of
damage that I used to see happen to IC and to TE accessories that were
stored in the old antistatic foam.

<
https://www.eevblog.com/forum/chat/beware-of-old-antistatic-foam/?topicseen

















Re: Beware of old AntiStatic foam

Dave Seiter
 

Now you have me worried- I have a number of foam-lined trays of PET/CBM-era ICs that I haven't looked at in years.  Fortunately, they are in very dry storage.  One of my "special" chips (a 40 column VIC chip) has been in a conductive rubber socket since the 70's, and I know it's still fine (just checked!)
-Dave

On Sunday, March 21, 2021, 09:57:29 AM PDT, snapdiode via groups.io <snapdiode=yahoo.com@groups.io> wrote:

Yes I've gotten a dozen or so Commodore computer chips damaged that way, I just scraped off the residue with tweezers and hope that there isn't too much chemical residue left for damage to continue.


Re: Beware of old AntiStatic foam

stevenhorii
 

I think polyethylene foam instead of the black polyurethane foam does not
have the “get goopy and stick to everything” problem. Has anyone had
polyethylene foam degrade like the black stuff? I have not - either black
or white polyethylene has stood the “test of time”. I have seen foam rubber
turn to dust, but at least it does not (in my experience) get sticky.

Apparently the polyurethane foams also outgas as they degrade and this can
leave deposits on stuff - think camera optics as many camera carrying cases
use polyurethane foam.

If I have some custom-fitted black foam in a transit case, I put the item
in a plastic bag and before putting it back in the case.

Another “plastic rot” question. I have a set of Xcelite tools. One of them,
a stubby Philips screwdriver, developed a white coating on it that was
impossible to remove without sanding it off. I could get some of it off,
but it kept re-developing this. None of the other tool handles has done
this. The handles, I believe, are a butyrate plastic that gives off butyric
acid as it oxidizes but they all are and this is the only one that
developed this white coating. The whole tool kit smells rather like vomit
(my wife refers to it as my “vomit tool case”) but this is common with
butyrate plastic-handled tools.

A comment on Duracell batteries. I am pretty sure there are counterfeits
out there - particularly the “bulk packs” with no Duracell label on the
outside. Here’s an article on fakes:

https://www.thecounterfeitreport.com/product/106/Duracell-Coppertop-AA---AAA-Batteries.html

When I have had Duracell batteries (the AA ones in particular) leak, on
checking, they were the ones I bought in unlabeled bulk packs. I generally
remove batteries from equipment I am not going to use frequently.

Steve Horii

On Sun, Mar 21, 2021 at 12:01 Harvey White <madyn@dragonworks.info> wrote:

As I've mentioned previously, the latest run of Duracell (guaranteed not
to leak before 10 years) does exactly that, and often in the package.

The good news is that they will often give you money to replace the
damaged item if you call them. Their warranty is "repair or replace",
but you do have to call.

I've had the foam in probe cases crumble, (both HP and Tek), anti static
foam corrode and crumble, etc...

Harvey


On 3/21/2021 9:50 AM, David Slipper wrote:
Nasty!! I wonder what other time-bombs are awaiting us!?

I'll certainly be checking my stock of bits and spares.

I always assumed that a famous brand of NiMh batteries were supposed
to be leak proof - Hah! I nearly lost a pair of nice walky-talkies and
a multimeter that way, so now cells get removed from rarely used items
and I make a point of checking torches and the like regularly.

Sadly not surprised at anything these days,
Dave


On 21/03/2021 13:07, - wrote:
Well, this thread just showed up on EEVBlog. This is exactly the
kind of
damage that I used to see happen to IC and to TE accessories that were
stored in the old antistatic foam.

<
https://www.eevblog.com/forum/chat/beware-of-old-antistatic-foam/?topicseen













Re: Beware of old AntiStatic foam

Dave Seiter
 

A few years ago, I found a very nice set of lab glassware in a fitted case at an estate sale.  When I got home, half the foam had disintegrated into dust from just driving around, and the rest did when I touched it. At least it wasn't gooey!
-Dave

On Sunday, March 21, 2021, 09:01:10 AM PDT, Harvey White <madyn@dragonworks.info> wrote:

As I've mentioned previously, the latest run of Duracell (guaranteed not
to leak before 10 years) does exactly that, and often in the package.

The good news is that they will often give you money to replace the
damaged item if you call them.  Their warranty is "repair or replace",
but you do have to call.

I've had the foam in probe cases crumble, (both HP and Tek), anti static
foam corrode and crumble, etc...

Harvey


On 3/21/2021 9:50 AM, David Slipper wrote:
Nasty!! I wonder what other time-bombs are awaiting us!?

I'll certainly be checking my stock of bits and spares.

I always assumed that a famous brand of NiMh batteries were supposed
to be leak proof - Hah! I nearly lost a pair of nice walky-talkies and
a multimeter that way, so now cells get removed from rarely used items
and I make a point of checking torches and the like regularly.

Sadly not surprised at anything these days,
Dave


On 21/03/2021 13:07, - wrote:
Well, this thread just showed up on EEVBlog.  This is exactly the
kind of
damage that I used to see happen to IC and to TE accessories that were
stored in the old antistatic foam.

<https://www.eevblog.com/forum/chat/beware-of-old-antistatic-foam/?topicseen









Re: Battery holder spring corrosion (was:Re: [TekScopes] Beware of old AntiStatic foam)

snapdiode <snapdiode@...>
 

I think batteries are able to spit out chemicals from their seals as they age. I have this Radio Shack Model 100 portable computer that has extensive (almost not repairable) corrosion near the battery pack, but also has odd single pin corrosion clear across the PCB, the only reasonable explanation is a tiny droplet being spit out the battery seal. It's not just leaking like a slow seeping of fluid across a barrier, I'm guessing there's also times when gas pressure builds up, part of the seal gives, a droplet flies out, the pressure is relieved, the seal forms back, and the cycle slowly continues and might take another year for the next droplet.


Re: Beware of old AntiStatic foam

snapdiode <snapdiode@...>
 

On Sun, Mar 21, 2021 at 11:06 AM, Bert Haskins wrote: Yep they used something like this in drive belts also.

Yes my TEAC X-3 just had a "belt melt", it is hard ti understand why they can't be made in silicone rubber now. That should be practically eternal in comparison to my lifespan....


Re: 7D15 internal trigger not working

Mark Vincent
 

Steve,

If you get the KSP10BU transistors, these have a pinout of BEC. They are not the common EBC or ECB pinout. I suspect all of your 0402 transistors are leaky from what you already checked. Checking them out of circuit will confirm leakage or not. If you want to have some fun, use a battery of 9 or 12V, a series resistor of about 1000 ohms or so and treat the transistor as a diode (E and C used) and see what voltages you get across each device. Reverse the battery connections or E and C connections and see what happens to the voltages across each of the two. This is done with the transistor out of circuit and base not connected.

Mark


Re: Beware of old AntiStatic foam

snapdiode <snapdiode@...>
 

Plastics in general aren't eternal. I have two P6032 probes that are melting and the smell is nauseating. I have to open them up and air them out as soon as I can crack a window open here.


Battery holder spring corrosion (was:Re: [TekScopes] Beware of old AntiStatic foam)

Brad Thompson
 

Renée wrote on 3/21/2021 1:17 PM:

unfortunately I too have had the same experience. foam-lost a bunch of microprocessors and assorted items that I thought were in safe place....
and regarding Duracell---lost a couple pieces of test equip..now this was a long time ago-their answer was "send it in we will fixit"...well I did that with one item and then they said not repairable and it is too old to replace
<snip>

Hello--

Thank you for the heads-up regarding Duracell's discard service [sic].

I've noticed that battery holders for, say, AA cells that feature coil-spring contacts
for the cells' negative ends eventually experience corrosion of the springs, even though
there's no sign of leakage from the cells. This occurs when manganese-alkaline cells are used
and it doesn't appear to be brand-related..

This may be related to "black wire disease"...

http://www.hangtimes.com/black_wire_disease.html

...But that phenomenon seems to relate to NiCd cells and not alkaline cells.

Is there a corrosion chemist in the house?

73--

Brad  AA1IP


Re: OT: MC12080 prescaler chip weirdness

Michael Dunn
 

Maybe I'll try pre-baking the next one also. I've read claims that it's unnecessary for hand soldering, but...


Re: Beware of old AntiStatic foam

Bert Haskins
 

On 3/21/2021 12:18 PM, Ken, WA2LBI wrote:
That old foam is awful stuff. I’ve had headphone head bands and ear pads
crumble to dust. I’ve also lost ICs that were pressed into the foam.
Foam-lined storage cases have damaged or destroyed stored items. Old
microphone inserts become dust. There are many other examples...

A few years ago, after many leaking batteries - some still new in the
package, I removed every Duracell battery from every device I own. I’ve
lost a number of flashlights, kid’s toys, remote controls, etc. The worst
is the damage done to my electronic test gear. I switched to Energizer and,
since then, have not had a single device device damaged by battery leakage.

The other item to check is the stick on feet used on so much equipment. As
we know, they turn to a slimy, sticky mess that also gets on the adjacent
surface and is difficult to remove. At the very least, over time, they
“migrate” from their original position and leave a slimy trail.

<rant off>

Ken
WA2LBI
The one I really remember is a "Pyle Driver" speaker that used some sort of a foamy glop to anchor the speaker cone.

I really liked this speaker because it had a nice upper mid range presence but then one day I plugged in my guitar and was greeted to some really awful sounds.

The speaker cone had totally come off the frame and there was no sign of the glop.

They are still selling this brand of speakers, I can't begin to guess how they got away with it.

" As we know, they turn to a slimy, sticky mess" Yep they used something like this in drive belts also.

And the very worst one is a black semi hard foam that was used in boat fuel lines!
Over the years this stuff would shrink, become tight and then break.
In many cases the fuel line burned up in the resulting fire so the true cause was never known.

- Bert




On Sun, Mar 21, 2021 at 12:01 Harvey White <madyn@dragonworks.info> wrote:

As I've mentioned previously, the latest run of Duracell (guaranteed not
to leak before 10 years) does exactly that, and often in the package.

The good news is that they will often give you money to replace the
damaged item if you call them. Their warranty is "repair or replace",
but you do have to call.

I've had the foam in probe cases crumble, (both HP and Tek), anti static
foam corrode and crumble, etc...

Harvey


On 3/21/2021 9:50 AM, David Slipper wrote:
Nasty!! I wonder what other time-bombs are awaiting us!?

I'll certainly be checking my stock of bits and spares.

I always assumed that a famous brand of NiMh batteries were supposed
to be leak proof - Hah! I nearly lost a pair of nice walky-talkies and
a multimeter that way, so now cells get removed from rarely used items
and I make a point of checking torches and the like regularly.

Sadly not surprised at anything these days,
Dave


On 21/03/2021 13:07, - wrote:
Well, this thread just showed up on EEVBlog. This is exactly the
kind of
damage that I used to see happen to IC and to TE accessories that were
stored in the old antistatic foam.

<
https://www.eevblog.com/forum/chat/beware-of-old-antistatic-foam/?topicseen
--
Ken
WA2LBI

Sent from one of my mobile devices




Re: OT: MC12080 prescaler chip weirdness

Michael Dunn
 
Edited

Thx for the replies, tho, believe it or not, I *can* read and follow a datasheet, usually... ;-}

https://www.ebay.com/itm/153648250450
Looks like a good board...

Admittedly, I'm not using a great layout...it's built on a little "Surfboard"(?) thingy. Vcc was kinda noisy at first, but that disappeared once I tacked a second decoupler as close to the pins as possible. Still divides by 2.

I'm heartened by one of the posts I read, where he'd tried a couple chips from Chinese sellers, which divided by 2, then one from a UK source, which worked. I've ordered a couple from Greece(!), so I'm sure they'll be good...???


Re: Beware of old AntiStatic foam

Eric-K0ELB
 

This is well known in the gun community, people buy those nice hard shell plastic gun cases with the foam inside and leave their guns in there for years, and corrosion always results.

They found out that the real problem is the type of foam. Open celled foam will absorb moisture and thus corrode anything that's stored in it for a length of time. Even if it's covered in oil like a firearm usually is. The more humid the area you live in the worse it is, obviously. The trick is to never leave anything you want to use again in foam.

For storing things like IC's, I would use something like a small hard plastic case and no foam at all. And check them at least once a year.


Re: FG502 doesn't start at some specific settings

Ozan
 

I don't have this equipment but here is my feedback in addition to Mark's suggestions:

Digging around I found that the triangular generator stays in a state where is
happy (I can provide all voltages in significant points of the schematic)
Are +17V, "+17V (DCPL 1)", -17V, "-17V (DCPL 1)" on sheet <1> stable when cold (not working)?

In the happy non-working state what are the voltages (partial list is OK if you don't have them all):
1) at the gate of Q200, and collector of Q292.
2) bases of Q230A and Q230B
3) bases of Q290 and Q292
4) emitters of Q140 and Q175

In case gate circuit is acting funny: Voltage at collectors of Q325 and Q315

until it decides to start working. I'm attaching two pictures of a normal
start and the delayed one. In the second one (4018-1) note the Ch4 (blue)
baseline is at the top of the display screen.
What are the test points for the different traces?

Ozan


Re: 7D15 internal trigger not working

Steve Nossen
 

Dan and Mark,

Thanks for the tips. I had the covers off a few times and removed the -5 V board. Never noticed the socket pins allowing perpendicular mounting.

Measured the transistors and Q213 measures 30 ohms from C to E and E to C on my SImpson 260. Much higher on a DVM but the same in both directions. Seems leaky to me. Q203 measured more like a diode, conducts in one direction. I'll add some transistors to my next order. The 1 uF caps both measure 1 uF and D of .02 at 1KHz, about 3.3 ohms. The 2.2 uF caps measure 2.3 uF and D of .1, about 7.2 ohms. I'll start with a transistor swap.

Steve


Re: PS 5010 troubleshooting (no negative, erratical display)

ditter2
 

Hello Martin,

The main voltage reference used in the PS5004 is a National Semiconductor LM399. These references are thermally stabilized, and after about 6 months of aging through normal use, have a stability which rivals standard cell primary voltage references. However, the IC process did not support laser trimming, so the only downside to these otherwise great parts is they have about a 5 % initial voltage tolerance – a challenged to adjust to the precision required for an instrument with target accuracy of 0.01%. This is way beyond the acceptable adjust resolution of a 20 turn trimmer pot. I ended up with a bank of binary weighted resistors in the leg of a voltage divider to pre-select the voltage to be in range that can be adjusted by the 20 turn trimmers. Initially these were to be controlled with a DIP switch, but this would require the user to correctly enter the 4 bit binary code for each “try and miss” step during calibration. I found the cam operated DIP switch we ended up using, which simplifies this step by doing the proper binary coding for each increment/decrement.

As the manual reads, you would only need to perform this step when replacing the reference IC, as any aging drift should be adjustable with the range of the 20 turn trimmer. To set this coarse pre-selector switch, you need to adjust the span trimmers to the center of their range, which is a lot of turns for a 20 turn pot. The trimmers don’t have positive stops at the end, they just keep turning and a small “click” is felt in your screwdriver when you get to the end. So centering a 20 turn trimmer first requires turning to the end more than 20 turns (to assure you are at the end, then backing up 10 turns. This is why you see these span trimmers being adjusted so many times in the Cal procedure.

Second question:
If this is quoted directly from the manual (I don’t have access to my copy right now), it looks like there is a missing word that would help.
“Connect the PS 5004 OUTPUT to the digital voltmeter input using a BNC cable and a pair of BNC-to-banana plug adapters. The shield side of the BNC is connected to the PS 5004 OUTPUT terminal, and the voltmeter Low input.”
Should read:
Connect the PS 5004 OUTPUT to the digital voltmeter input using a BNC cable and a pair of BNC-to-banana plug adapters. The shield side of the BNC is connected to the PS 5004 - OUTPUT terminal, and the voltmeter Low input.” (add a minus sign between “PS4004” and “OUTPUT” - these should be Bold type face to indicated these are the connection point names)

A challenge in manual writing is that everyone, the engineers, technicians, and even manual writers themselves, are “too close” to the equipment we are writing about, and procedures are the same as we have all used over and over. So it is easy to assume the reader already knows something that we all know – but only because we are “insiders”. What this step is trying to say is to use a shielded BNC cable to measure these precision DC voltages, and make sure the shield is connected to the PS5004 negative output terminal, and the DMM low / guard terminal. It is important to drive the DMM Guard input and not leave it floating.

Third question: These are 20 turn trimmers, so needing to two resolutions is possible, especially if the instrument is being calibrated the first time after many years of storage. I think the need for the coarse adjustment is described above – it is necessary to get the range covered by the 20 turn span trimmers close enough to account for a 5% initial tolerance in the initial voltage reverence.
On this topic – if you are calibrating a PS5004 or any high precision instrument (Fluke DMM etc.) that has been not used for a decade or more, you should probably first power it up and let it run for a week or more. Large drifts from aging may be moisture absorption in components and circuit boards.

Final question – there is interaction between the span and zero adjustments. This results because Zero volts output is not actually zero. Studying the schematic, see the output has an active load on it that can sink small currents below 0 V. So the supply can be adjusted to negative output. In fact, the original design would allow precision adjustment of the output to minus 100 mV, but the supply can only sink a few mA in the negative direction, as it is not q four quadrant supply (only single pass transistor). The application would be measuring input offset in DC amplifiers, etc. I thought it would be quite useful, We did some customer trials with an engineering prototype, and the users found the feature to be confusing because of the current limitation when the output went negative. So we pulled it out. This feature is implemented only in the firmware – no hardware changes were made. Thus the supply actually has some output voltage when adjusted to Zero, which is removed by other offsets in the circuit. Thus the gain action of the coarse and fine span trimmers will move the zero output setting, which requires an iterative adjustment procedure.

Steve

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