Mesa MkV unusual problem

[bob p]

> Does anybody at these amp manufacturers think of MTBF?

you're kidding, right?

they think about getting as far as the warranty period and then you're on your own.

[Mick Bailey]

I'm interested in how other people remove the relays. The clearance between the pin and the through-plated hole isn't enough so that my desolder machine can break the sweat bond, so I remove what solder I can, apply flux and then Chipquik them off, but it gets through quite a bit of Chipquik which is expensive in the UK.

[Leo_Gnardo]

it gets through quite a bit of Chipquik which is expensive in the UK.

Chipquik - is that solder removal braid? I use a fair amount of braid although trying to limit its use due to expense. For me, the 0.100 inch wide variety. I was about to order another 100 ft. roll from Mouser last year when I found 4 x 25 ft rolls was a little cheaper. About a 2 year supply around here, for @ $100. Sometimes nothing else will work. Those dinky 5 ft rolls at Tandy/Radio Shack will pick your pocket empty. Good luck with those relays Mick.

[Jazz P Bass]

[QUOTE=Leo_Gnardo;309532]Chipquik - is that solder removal braid? QUOTE]

ChipQuik is a low melting point alloy that is really helpful when working with surface mount components.
How to Use Chip Quik > Main Section > SRA Soldering Products

[Leo_Gnardo]

[QUOTE=Jazz P Bass;309533]

Chipquik - is that solder removal braid? QUOTE]

ChipQuik is a low melting point alloy that is really helpful when working with surface mount components.

Welllll, I'll be dipped. In ChipQuik. 136F melt? Indium I thought at first blink but when I saw 136F it must be some bismuth alloy, a variety of Wood's metal. Like what's used in sprinkler systems for fire suppression.

Thanks Jazz P Bass, I learned something new today. Whoops on me for assuming it was braid & ya know what about assume so pin the tail on THIS donkey. I'm gonna get to work on some busted amps now, and mind my own bismuth.

[Mick Bailey]

I found the patent a while back (#5326016) and it contains 18% tin, 28% lead, 11% cadmium and 43% bismuth.

It's excellent for delicate situations, not just SMD. The problem is the price. I heard that there was a cheaper rival but couldn't find anything.

[Steve A.]

[QUOTE=Jazz P Bass;309533]

Chipquik - is that solder removal braid? QUOTE]

ChipQuik is a low melting point alloy that is really helpful when working with surface mount components.
How to Use Chip Quik > Main Section > SRA Soldering Products

Here is a video showing how to use the ChipQuik removal kit on those SMD chips with a hundred million pins. So for DIP relays do you need the alloy or just the flux?

SMD Removal using a Chip Quik kit - YouTube

Thanks!

I found the patent a while back (#5326016) and it contains 18% tin, 28% lead, 11% cadmium and 43% bismuth.

Your post has already shown up in a Google search for the patent. Wow!
Any suggestions for a good patent search site with PDF or TIFF files? I forget which one I used last...

Steve Ahola

[Tom Phillips]

...So for DIP relays do you need the alloy or just the flux?...

Yes. The flux they provide just helps it work but the alloy is the actual working part that blends with the existing solder to produce a new alloy with the very low temperature melting point. You can use other flux and just buy the Chip Quick alloy. However, the alloy is the expensive part.

[soundguruman]

I'm interested in how other people remove the relays. The clearance between the pin and the through-plated hole isn't enough so that my desolder machine can break the sweat bond, so I remove what solder I can, apply flux and then Chipquik them off, but it gets through quite a bit of Chipquik which is expensive in the UK.

"I found the patent a while back (#5326016) and it contains 18% tin, 28% lead, 11% cadmium and 43% bismuth."
Fumes from (heating, burning) cadmium soldering can cause DEATH upon inhalation. That's a FACT, JACK.
You are specifically, and SEVERELY warned.
Cadmium is EXTREMELY toxic and VERY dangerous. NO WAY that an inexperienced person should be handling something like this.

Inhale Cadmium Fumes, You Are DEAD.



Carefully BREAK the relay plastic case apart with a set of precision cutters. Dissect the guts with care, pull out the remaining plastic bottom remains.
Now all you have left is the 8 pins, soldered to both sides of the board. Carefully heat the pins one at a time, and push the pins thru the holes.

Clear the holes with solder wick... However, MOST consumer grade soldering irons do not have enough power to heat the board for de-soldering.
There is too much heat dissipation from the large copper pads.
For example, my Weller WD1 / WP 80 will suck these holes dry, in an instant. BUT a consumer grade soldering iron will fail, just about 100% of the time.
AND just let me warn you, that this board is VERY easily damaged, therefore only a VERY experienced person, with professional tools, should even attempt to complete this removal. This is NOT the board to LEARN on. You will be sorry.

The alternative is to use a de-soldering vacuum, such as PACE, which is powered from an external air compressor. These are also VERY expensive. These also require a great deal of professional skill, to avoid damage to the circuit board. The type of desoldering vacuum, with built in air pump, is generally NOT powerful enough. I like to see about 90 PSI from a compressor, to power the vacuum.

After removing the relay, and cleaning / defluxing the the board, the pads should look just like a new board. Not ONE trace of damage.
I prefer to install an ALCO machine pin gold plated socket. The socket should be installed so that it is approximately 3/32" from the board surface. Long tail pin sockets may be helpful, in leaving a space between the board surface and the bottom of the socket. There is a reason for leaving this space under the socket.
Now, carefully plug in your new relay. I mean, that socket is going to hold TIGHT. Now, use a MINI wire zip tie, under the socket, loop it around the relay, and tie it.
NOW you have a nice clean relay install, secured by a zip tie, which can be easily removed and tested or replaced, in about two minutes!
Heck, I might even try some different types of solid state relays....who knows?

What it "SHOULD" have been is a mercury whetted contact vacuum relay. But hey, a little expensive.

[pdf64]

Some useful guidance on the US safety data sheet http://www.jameco.com/Jameco/Product...heet(MSDS).pdf
Note the recommended use of respirator with HEPA filter!
On the flip side, the boiling point is quite high, so it may be that at normal soldering temperatures, very little cadmium etc becomes released to air.
However, it definitely seems worth taking control measures such as local extraction, proper mask, gloves wash hands.
Pete

[soundguruman]

Some useful guidance on the US safety data sheet http://www.jameco.com/Jameco/Product...heet(MSDS).pdf
Note the recommended use of respirator with HEPA filter!
On the flip side, the boiling point is quite high, so it may be that at normal soldering temperatures, very little cadmium etc becomes released to air.
However, it definitely seems worth taking control measures such as local extraction, proper mask, gloves wash hands.
Pete

A normal respirator mask will not protect you against cadmium. Should be SCBA (self contained breathing apparatus) with isolated O2 supply. That's an air tank, folks.
The proper equipment is a welding fume extractor, which is specifically approved for cadmium fumes.
These extractors have 6-10 filters, including a HEPA filter. They typically cost $3000-$5000.
A normal solder fume extractor (cheap kind) is useless.
If you take chances with cadmium fumes, you are suicidal. Don't be an idiot, please.

If I can remove the relay with normal solder, and solder wick, so "could" you.

[Jazz P Bass]

Some useful guidance on the US safety data sheet http://www.jameco.com/Jameco/Product...heet(MSDS).pdf
Note the recommended use of respirator with HEPA filter!
On the flip side, the boiling point is quite high, so it may be that at normal soldering temperatures, very little cadmium etc becomes released to air.
However, it definitely seems worth taking control measures such as local extraction, proper mask, gloves wash hands.
Pete

Where does it say, in the MSD, that there is cadmium in the product?
True enough it is in the patent formula.
From the MSD:
Tin 12%
Lead 18%
Bismuth 49%
Indium 21%
Not that any of the chemicals are good for you if you breath/ injest them.
Still.
Unfounded, unwarranted, scaremongering BS about the cadmium.

[wizard333]

Why does Mesa make these two traces run so close is a mistery to me but it sure is a recipe for problems...

See my thread about a DC3 recently. The hole for the 'ground' side of a few of the Cks is right next to, and I mean RIGHT NEXT TO, about .02" or less from, the pin for the heaters. Stupid. Add the lava like amount of heat these little 4xEL84 with 6 preamp tube amps kick up, and that will short, just a matter of when.

Good thing they use thick copper traces at least. If that happened on a new Fender, 10" of thin aluminum trace would evaporate instantly. But then I don't recall Fender putting a ground connection micrometers from the heater pins either.

[pdf64]

Maybe it was an early formulation which contained cadmium?

[soundguruman]

Where does it say, in the MSD, that there is cadmium in the product?
Trye enough it is in the patent formula.
From the MSD:
Tin 12%
Lead 18%
Bismuth 49%
Indium 21%
Not that any of the chemicals are good for you if you breath/ injest them.
Still.
Unfounded, unwarranted, scaremongering BS about the cadmium.

"I found the patent a while back (#5326016) and it contains 18% tin, 28% lead, 11% cadmium and 43% bismuth."
That IS the post that I replied to. Oh, but you weren't paying attention....were you?

"Unfounded, unwarranted, scaremongering BS about the cadmium."
Everything I said about cadmium was true, and verifiable.
The only BS here is YOURS.

Now go out and inhale some cadmium fumes....and find out (first hand) just what "scaremongering" is.