Given the weight of lead in a car battery... about
30 to 50lbs, and the weight of the lead in the tiny
amount of solder in a 1970's TV, you would to have a
forest of TV's dumped in a landfill before you equaled
the lead in one single car battery improperly disposed.

Out in the country, I see car batteries all over the place.
Many have degraded so much as to become almost become
invisible. They don't all get recycled.

LBJ once said,
"You do not examine legislation in the light of the benefits
it will convey if properly administered, but in the light of
the wrongs it would do and the harms it would cause if
improperly administered."


RoHs is one of those laws LBJ was talking about.

-Chuck Harris

On Thu, 9 Mar 2023 11:38:06 -0500 "Roy J. Tellason, Sr."
<roy@...> wrote:

On Thursday 09 March 2023 11:26:10 am Sam Reaves wrote:

Think about how much lead is in a car battery. I would bet that the
number of those in landfills far exceed the amount of lead used in
solder.

You would lose that bet. Car batteries are among the most recycled
products out there, with both the lead and the plastic cases being
recycled, as well as any electrolyte that may remain in them. I
don't recall the exact number but it was in excess of 90%.

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On Thursday 09 March 2023 11:26:10 am Sam Reaves wrote:

Think about how much lead is in a car battery. I would bet that the number
of those in landfills far exceed the amount of lead used in solder.

You would lose that bet. Car batteries are among the most recycled products out there, with both the lead and the plastic cases being recycled, as well as any electrolyte that may remain in them. I don't recall the exact number but it was in excess of 90%.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

Who needs tin whiskers in a car when you can have a Tesla with a loose steering wheel? Not that you need a steering wheel with Autopilot. Oh... hang on.. never mind ?

Wilko

Hi.

Re the Leaded/lead-free solder issue.

I didn't mention "Civilian Automotive" use, as I've heard conflicting information about that aspect.
But yes, I would have thought the regulations would have erred on the side of safety, especially with "driving control" systems. (Engine Management, Throttle controls, Electronically controlled Power Steering, ABS etc...)? But I don't know for sure.

Some of the info on that NASA site is truly scary!?? Components that were procured with a "No Pure Tin" clause in the purchase spec/agreement, but supplied WITH Tin, and problems ensued.? Not only, but also including Nuclear Power Station systems affected, causing unscheduled "incidents" and such.? (Reactor Scrams, and shutdowns!)

I also vividly recall the Mullard/Philips AF11x series of PNP transistors that would fail with a short to the (grounded) metallic can.? It was a common thing to cut the "Shield" wire, to restore normal service...

A quick and profitable fix, for a 13 year old at a school where many carried portable pocket AM radios (against all the rules!)

73.
??? Dave G8KBV.



--
Created on and sent from a Unix like PC running and using free and open source software:

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No wonder Lead Free solder is prohibited for Aerospace, Military, Medical and other "safety of life" systems.

But strangely (AFAIK) not for automotive systems which I would have though should be covered by the "safety of life" issue.

Or did I get that wrong?

D.

Hi.

If you need to resolder anything with a ceramic substrate (even SMD parts these days.)? Use one of the "eutectic" silver containing solders. ? That will help prevent later failure, and also has no "plastic" region in it's transition phase, so creating "dry" or "cold" solder joints is almost impossible.

Sn-Pb-Ag (62% tin, 36% lead, 2% silver; melts and solidifies at 179 degrees Celsius/354.2 Fahrenheit)
Sn-Ag (96.5% tin, 3.5% silver; becomes eutectic at 221 Celsius/429.8 Fahrenheit)
Sn-Cu-Ni-Ge (99.3% tin, 0.7% copper, 0.6% nickel, 0.005% germanium; 227 Celsius/440.6 Fahrenheit)

Perhaps you just disturbed some "Tin Whiskers", a known issue with many lead free soldered products.


Probably the definitive article on that subject!..

No wonder Lead Free solder is prohibited for Aerospace, Military, Medical and other "safety of life" systems.


Regards.
??? Dave G8KBV.

--
Created on and sent from a Unix like PC running and using free and open source software:

Today I spent some more time on it.

First attempt was to remove the hybrid, its pogo pin socket and clean all conact surfaces. So the hybrid gold plated contacts, the gold plated PCB contacts and both sides of the pogo pings. Once removed, everything looked very clean, so it was no surprise to find that the cleaning had no visible effect on the problem. Hmm..

Second I decided to touch-up all soldering on the white ceramic component (not sure what exactly is inside, input amp along with attenuator?) as well as resolder every solder joint that looked suspicious in the channel 1 input section. Good old Sn60Pb40 0.6mm. With the original RoHS soldering .. (never mind, you get my drift). And yes, it seems that this has finally cured the issue: on cold powerup a stable timebase line is produced. Also, mechanical stressing of BNC #1 has no longer any effect.

Will again keep the patient under observation but this looks promising to me.

Wilko

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Sounds like you’re heading in the correct direction. I would look for more solder issues also since the relay joints helped.

Although much better now that the relays have been resoldered, the problem is not completely gone yet.

It now takes approx 2 to 3 minutes from a cold start before the problem disappears, that was more like 10-15 minutes before the rework was performed on the relays.

So, I suspect there are some more, and likely similar, soldering issues to be resolved. The input hybrid runs very hot, its heatsink one can barely touch. Maybe the hybrid's socket has become temperature sensitive? I am a bit "chicken" about removing the hybrid, given its unobtainium status..

Wilko

Looks like the most relevant pictures never made it.

Retry below.

Thanks for everyone's suggestions.

I decided to crack it open for the 2nd time and go for a mechanical checkout on the BNC connectors and "everything connected to them in the close vicinity.

Although I initially suspected the non-optimal soldering of the central BNC pin that proved to be a red herring.
Getting the old stereo microscope gave, literally, a whole new perspective. I managed to take some pictures via the microscope and let them speak for themselves..

Interestingly enough only K700 and K800 were affected, the other 2 relays soldering appeared OK. In any case I resoldered all relay pins and that seems to have fixed it. Using real solder, the Pb/Sn version I mean, not that newfangled RoHS rubbish ??

I'll keep the patient under observation of course but for now it seems to have been cured. A user cal has been completed successfully.

Wilko

If you have another scope once opened you may want to inject a small signal into channel 1 and even channel 2 for comparison of signal at certain points along the circuit path. I can’t seem to find a schematic but that would definitely help follow the signal.

Andrew

It only occurs on channel 1, not on channel 2.

And once warmed up, channel 1 is also OK. Which points to something "reconnecting itself once warm". I guess I have to once again pull the mainboard, I have stared at it before but did not find anything out of the ordinary.

Wilko

If I had to guess I would say bad contact at some point. I haven’t pulled the schematic to see what the front end looks like but I’m thinking something loose. It only does it on channel 1 correct, channel 2 functions properly??

Andrew

It has been doing it for like 2 months or so. No abuse or measurement that triggered it (at least not something I recall, it has not been used much lately)

Wilko

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Did this just start out of nowhere or were you testing something?