This freezing procedure has been done on a ship's main engine in Hong Kong 40 years back, there is a standard British book about marine diesels, the drawing is there as part of description of the procedure
I think it was Pounder's diesel engines, I read it long back.
They had to repair the crank pin, IIRC...argon tanker was parked on the dock, pipes down to engine room, freeze the area, separate the items, and so on.
The gas tanker looks like a toy, it was a Sulzer RTM120 IIRC, those things are more than 50 feet tall.
The alternate was to take the engine out of the hull, not easy.
120 means bore in cm...about 4 feet.
Standard stroke : bore is 3:1, 90 to 95 rpm, 118 gm / bhp-hr specific fuel consumption on heavy stock fuel on those engines.
A 6 cylinder engine in that series will be (off hand) about 45,000 HP.
https://en.wikipedia.org/wiki/Wärtsilä-Sulzer_RTA96-C
In my industry, the toggle pins in molding machines run inside graphite dimpled bushes, this is the normal method, less stress while fitting.
Special gloves are used, and inside an insulated chamber, argon gas is introduced, then pin goes in bush, and part is left in the open, to come back to room temperature.
The worker, wearing protective clothes, just slides the pin inside the bush, takes seconds.
I have seen this being done in machine builder's works, the defunct Mafatlal Micro Machines near Ahmedabad, and Goyani Machines in Makarpura, Baroda.
Just because you have not seen it or heard of it does not make it impossible...or hilarious.
We have a machine shop in Bombay, they machine ship main engine cranks to 0.007", max. length 60 feet or so, and throw max. 25 feet.
Also, a friend has a CNC shop, he has worked on India's biggest (known) lathe, 72 feet swing, made by Skoda, at the L & T works at Powai, now it is installed at their Hazira works.
If these figures make sense to you, stop your mocking.
You are not the only person here with heavy machine experience.
My uncle used to work in the deep water well driling business, sometime the drill pipes would separate 600 feet down...there was a skilled man in the team who could fish out pipes 600 feet deep inside a 10" bore...
And my father was in the oil business, first exploration and then cross country pipelines.
That is field experience, you may be hundreds of km away from a machine shop, you have to do it properly, sometimes in an innovative manner...
I think it was Pounder's diesel engines, I read it long back.
They had to repair the crank pin, IIRC...argon tanker was parked on the dock, pipes down to engine room, freeze the area, separate the items, and so on.
The gas tanker looks like a toy, it was a Sulzer RTM120 IIRC, those things are more than 50 feet tall.
The alternate was to take the engine out of the hull, not easy.
120 means bore in cm...about 4 feet.
Standard stroke : bore is 3:1, 90 to 95 rpm, 118 gm / bhp-hr specific fuel consumption on heavy stock fuel on those engines.
A 6 cylinder engine in that series will be (off hand) about 45,000 HP.
https://en.wikipedia.org/wiki/Wärtsilä-Sulzer_RTA96-C
In my industry, the toggle pins in molding machines run inside graphite dimpled bushes, this is the normal method, less stress while fitting.
Special gloves are used, and inside an insulated chamber, argon gas is introduced, then pin goes in bush, and part is left in the open, to come back to room temperature.
The worker, wearing protective clothes, just slides the pin inside the bush, takes seconds.
I have seen this being done in machine builder's works, the defunct Mafatlal Micro Machines near Ahmedabad, and Goyani Machines in Makarpura, Baroda.
Just because you have not seen it or heard of it does not make it impossible...or hilarious.
We have a machine shop in Bombay, they machine ship main engine cranks to 0.007", max. length 60 feet or so, and throw max. 25 feet.
Also, a friend has a CNC shop, he has worked on India's biggest (known) lathe, 72 feet swing, made by Skoda, at the L & T works at Powai, now it is installed at their Hazira works.
If these figures make sense to you, stop your mocking.
You are not the only person here with heavy machine experience.
My uncle used to work in the deep water well driling business, sometime the drill pipes would separate 600 feet down...there was a skilled man in the team who could fish out pipes 600 feet deep inside a 10" bore...
And my father was in the oil business, first exploration and then cross country pipelines.
That is field experience, you may be hundreds of km away from a machine shop, you have to do it properly, sometimes in an innovative manner...
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Ahhh, hold on a moment sunshine. I was not mocking you at all. You can throw all that big talk around all you want, but in this exact scenario, with a relatively heavy shaft inside a much lighter collar of the same material and an interference fit between them, it will almost certainly not work. As I said, have you done it?
The collar or race would attain almost the same temperature as the shaft only seconds afterwards. Of course freezing works in some cases and anyone in these industries knows of the technique. And when to use it.
Of course the technique is used to assemble parts, because you can easily attain a temperature differential. It works even better where the materials are different, like an aluminium alloy piston around a steel gudgeon/wrist pin. There is no value is saying it worked on some ship you read of somewhere and mine's bigger than yours so I win. It depends entirely on each application.
My reason for mentioning the workshop was only to put some context to our experience, not to show off. It is modest compared to some in the industry.
The collar or race would attain almost the same temperature as the shaft only seconds afterwards. Of course freezing works in some cases and anyone in these industries knows of the technique. And when to use it.
Of course the technique is used to assemble parts, because you can easily attain a temperature differential. It works even better where the materials are different, like an aluminium alloy piston around a steel gudgeon/wrist pin. There is no value is saying it worked on some ship you read of somewhere and mine's bigger than yours so I win. It depends entirely on each application.
My reason for mentioning the workshop was only to put some context to our experience, not to show off. It is modest compared to some in the industry.
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It works both ways, for assembly or dismantling, argon is preferred as CO2 and nitrogen can cause chemical changes in metals.
I mentioned those as they are easier to obtain, and in a vehicle the heat treatment level (hardness) is less than that in other applications. So less chance of damage.
My great uncle retired as the Chief Engineer at a navigation company, late 80s age, he has travelled the world on ships, I have some of his college texts, and he has told me to take his Zorki camera kit with extra lenses...he bought it on a trip to the Soviet Union.
His tales of repairs on the high seas were an inspiration, also of those in Dutch and Italian shipyards.
I ran a truck leaf spring plant when my uncle went on vacation, I have built, used and maintained hydraulic presses, mechanical presses, furnaces, and shot peening machines, among others. And electrical maintenance as well.
At the other uncle's factory, stone cutting and polishing machines.
At my plastic factory, motors, and many moulds, we use a small fly press if the insert is stuck.
So I can claim that I speak from experience.
I mentioned those as they are easier to obtain, and in a vehicle the heat treatment level (hardness) is less than that in other applications. So less chance of damage.
My great uncle retired as the Chief Engineer at a navigation company, late 80s age, he has travelled the world on ships, I have some of his college texts, and he has told me to take his Zorki camera kit with extra lenses...he bought it on a trip to the Soviet Union.
His tales of repairs on the high seas were an inspiration, also of those in Dutch and Italian shipyards.
I ran a truck leaf spring plant when my uncle went on vacation, I have built, used and maintained hydraulic presses, mechanical presses, furnaces, and shot peening machines, among others. And electrical maintenance as well.
At the other uncle's factory, stone cutting and polishing machines.
At my plastic factory, motors, and many moulds, we use a small fly press if the insert is stuck.
So I can claim that I speak from experience.
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I bought in a 1980's Maplin disco amplifier.
It worked but very distorted.
I checked all the components on the pcb and they checked out fine.
So powered it up and checked voltages.
I kept coming back to same transistor where voltages didnt seem right.
So diode checked it again and seemed fine.
Then it hit me the transistor was a pnp instead of an npn !
Someone had attempted a fix and messed it up.
Replaced transistor with npn and all was well.
I built up a model railway DCC controller.
Display wouldnt work so replaced it.
Still didnt work so replaced microcontroller.
Still didnt work so quick scan of soldered joints and all seemed fine.
Checked resistor values from top of pcb then noticed a blob of solder between a resistor and a via.
Removed it and pcb burst into life.
I must have dropped a blob of solder while building the pcb.
Display wouldnt work so replaced it.
Still didnt work so replaced microcontroller.
Still didnt work so quick scan of soldered joints and all seemed fine.
Checked resistor values from top of pcb then noticed a blob of solder between a resistor and a via.
Removed it and pcb burst into life.
I must have dropped a blob of solder while building the pcb.
I did that totally embarrassing thing on a previously pristine Kenwood KA3500 that had never been touched by a repairer. That thing we're always warned not to do by the repair experts.
I probed the circuit with open DMM probes to check bias, and then carelessly shorted one channel while removing the probes. I'm sure some of you might know that sinking feeling I had; 30 seconds not moving, staring at the circuit, expletives quietly emanating from mouth as the realisation sets in that you've just burned unobtainable parts. How quickly it can happen! 🙂
You always think you wouldn't be one of those numpties you read about on the net that make these stupid mistakes.
Guess what I bought later the same day? Yep, some Pomona Minigrabbers, Alas, too late for Kenny.
I probed the circuit with open DMM probes to check bias, and then carelessly shorted one channel while removing the probes. I'm sure some of you might know that sinking feeling I had; 30 seconds not moving, staring at the circuit, expletives quietly emanating from mouth as the realisation sets in that you've just burned unobtainable parts. How quickly it can happen! 🙂
You always think you wouldn't be one of those numpties you read about on the net that make these stupid mistakes.
Guess what I bought later the same day? Yep, some Pomona Minigrabbers, Alas, too late for Kenny.
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I had a similar issue with an amp project many years ago.
During testing one channel worked fine and the other was clean, but very weak.
Took a while but eventually found a hair-line solder bridge across the signal input connector pins on the board.
Not a dead short but the input impedance was so low it pulled down the signal.
Easy to fix but hard to find.
Casio fx-180P ate batteries, removed traces of copper made by on-off switch, and told owner to use only the soft start and auto off functions.
Lated for years after that.
Repaired some LED strips and their controller here in time for our festival. Mostly rework of solder joints.
And stuck a 9 watt driver on board circuit in place of a chip on bord circuit that failed, I used a metal filled epoxy in place of thermal glue. Circuit was 20 cents...direct 220V, no separate driver.
Computer failed with blue screen...oil in CPU and SMPS fans after a blower service has restored operation, fans were slow, heat related shut down...
Lated for years after that.
Repaired some LED strips and their controller here in time for our festival. Mostly rework of solder joints.
And stuck a 9 watt driver on board circuit in place of a chip on bord circuit that failed, I used a metal filled epoxy in place of thermal glue. Circuit was 20 cents...direct 220V, no separate driver.
Computer failed with blue screen...oil in CPU and SMPS fans after a blower service has restored operation, fans were slow, heat related shut down...
I had a small but significant buzz from the tweeter in one of my active speakers. I suspected my wiring in the psu was not optimal. I had a single pair of 22,000uF smoothing caps and I thought it might be charging pulses causing the issue.
I added a couple of small 2,200 caps bypassed with 22uF and 0.1uF almost directly on the bridge and rerouted the 0V cable so there would be negligible charging currents flowing around my 0V point.
I now have to put my ear to the speaker to hear any noise.
A huge improvement, but I think I need to rebuild it from scratch as I’m pretty sure this can be eliminated completely if done really well.
I added a couple of small 2,200 caps bypassed with 22uF and 0.1uF almost directly on the bridge and rerouted the 0V cable so there would be negligible charging currents flowing around my 0V point.
I now have to put my ear to the speaker to hear any noise.
A huge improvement, but I think I need to rebuild it from scratch as I’m pretty sure this can be eliminated completely if done really well.
That 0.1 uF “almost directly across the bridge” needs tweaking. Change of value, adding some series R. 0.1 uF is as good a starting point as any given NO other measurements. Almost always the source of a “buzz” as opposed to “hum”. You would see a small burst of RF every 8.3 milliseconds - and the fix is a snubber on the diodes. Giving all 4 diodes their own RC snubber is often better. A band aid people use to fix this is to use uber-fast diodes, but that is as likely to make it worse as better. And creates other problems.
And believe it or not, a class 2 ceramic is the right type of capacitor to use. How’s that for phlying in the phace of audiophoolia?
And believe it or not, a class 2 ceramic is the right type of capacitor to use. How’s that for phlying in the phace of audiophoolia?
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Yeah, I don’t have one of Mark’s Quasimodo “Bell Ringers” so I’ve no idea what the best snubber value is, so I’ll stick some trusty X7Rs on the bridge.
I have some 100ohm 100 Watt resistors to use as a dummy load so I can experiment a bit and look at it on the scope.
I do already have a X-Cap in series with a 10R on the winding, but that is clearly not optimal in my case.
So-called "audiophile" capacitors are often a terrible choice for anything but what they're intended for ie crossovers. For high frequency bypass in an electronic circuit, ceramic capacitors are exactly what is called for.
I thought all proper Audiophiliacs on DIY audio ONLY use Schottky rectifiers and nothing less. If im planning on selling the piece I use gold caps wherever I can. Those Nichicon Golden tune or Muse and any other with Gold inscriptions and expensive look🙂
If schottkys work they’re actually pretty good as they have a lower forward voltage drop too. Problem is they get leaky as hell at any real voltage so i have to stick with conventional normal recovery types at the voltages I work with. Won’t spring for silicon carbide, and their forward voltage is back up where conventional Si rectifiers are anyway.
The mistake most make is using ultrafast epitaxial types. This is just plain wrong for a number of reasons. There are places to use them and a 60 Hz power supply is not it. They dont cause transformers to ring any less than regular ones do. They just raise the RF frequency of the ringing. Sometimes enough to achieve damping, other times not. But they don’t handle 200+ amp 8.3 millisecond long pulses near as well as regular diodes do. That happens every time you plug it in.
The mistake most make is using ultrafast epitaxial types. This is just plain wrong for a number of reasons. There are places to use them and a 60 Hz power supply is not it. They dont cause transformers to ring any less than regular ones do. They just raise the RF frequency of the ringing. Sometimes enough to achieve damping, other times not. But they don’t handle 200+ amp 8.3 millisecond long pulses near as well as regular diodes do. That happens every time you plug it in.
Hey, what happened to @wiseoldtech?
It says account closed...
He was off the forum for about six months, then back, then account closed.
Any idea why? Was he sick?
It says account closed...
He was off the forum for about six months, then back, then account closed.
Any idea why? Was he sick?
Last weekend I replaced the "bulgin" plug on one head of an old pair of B&W 801 Series 80 speakers. I also cleaned up the surfaces of mid-range and tweeter which had accumulated some dust over the years and repainted the tweeter screen black with an airbrush as the original paint had turned to a patchy brown color in a few spots. I'm looking to eventually offload these if anyone in the Seattle area is interested. Cabinets are in fair condition with some superficial scuff marks and they have the stands as well. I just don't have room for these behemoths in my home.