Blown my welder up.

[Retired]

Hi,

I agree Seadog; when a big cap decides to self destruct it certainly doesn't do it quietly; the ones I've seen blow didn't just suddenly explode there was a hort warning that something was amiss before the big event; they definitely grab full attention; the two caps going off in my welder did so in spectacular fashion and the welder was located behind me.

Thanks R Kraft for your information; I had noticed a relay on the board.

Many thanks Hood for your kind birthday wishes; Bron and I have just returned from a local garden center; I'm just passing a bit of time whilst awaiting the caps delivery. As I've a bit of time I thought I'd add a bit of what I get up regarding my many and varied hobbies just for a bit of interest. Please bear in mind I'm not electrically taught but over the years I've dabbled a bit.

Three of my winders; the front one is an AVO Wave Winder I fully restored from seized up scrap winning an award for the restoration. I made new parts for it here it's shown unfinished.

A pair of Aumann winders (German).

My manual AVO Douglas winder that I wound many coils on. All winders sold years ago when I gave up vintage radio restoration.

Mains vintage radios I could power up from my bench circuits but battery sets needed lots of different voltages in both positive and negative DC. The batteries haven't been available for many years so I designed and made my own bespoke power supply in fact I made two of these giving one to a friend. It's many years since I made this PSU but I wound two transformers; one each for HT & LT. The HT gave a range of volts from around 60 to 160 in steps of ten through a wafer switch; the steps were controlled by Zener diodes into the base of a power transistor ( BU508?). The LT was both positive and negative fully variable on each using regulators (LM317?) from memory. These gave variable DC to around 36V? Here the PSU is hooked up to Bush battery radio. I used to completely restore these old radios both chassis and cabinet; a fascinating hobby I enjoyed for about ten years directly after retirement to keep me interested during our long winters.

My vintage radio shack with the test gear I gathered over the years; scopes; sig gens and Lab power supply etc. The mug of tea was the most important item on the bench. I became so proficient at these restorations I lost interest and reverted back to other hobbies I enjoy like furniture making; wood turning; and all manner of DIY; I'm seldom still enjoying keeping busy.

I hope the welder caps arrive today and that they solve the problem because so far TIG welding has been nothing but a pain to me; the courier stated a timed delivery of the welder but it arrived a day later messing us around; the gas cylinder proved nothing but trouble which is posted elsewhere and still ongoing; setting the welder up buying tungstens; collets and collet holders plus purchasing aluminium; initially trying to weld with an helmet adjusted to shade #13 my fault entirely due to ignorance and now the welder has blown up; I've already explained to the welder I have a big sledge hammer as plan "B". At least my new Crystal 2.0 helmet is absolutely brilliant.

I hope this is of interest it just being a sample of my hobbies.

Kind regards, Colin.

 

[Seadog]

Very interesting Colin.

I used to have amanual winder, too. I hadn't reslized it was an Avo, but I sold it years ago. It came from my girl friend's uncle's workshop. He used to repair a lot of Mecablitz professional flash guns, judging by his notebooks. I never had ocassion to use it but had I had the room I would have kept it.

It was actually 2005 I sold it. It made £181 on eBay. I can only guess what it would fetch now.

 

[Retired]

Hi,

Thanks Seadog. I sold so much kit when I packed in with radios I've forgotten the amounts received; these AVO winders though are brilliant; mine was manual but the one in your picture looks to be powered? I used to enjoy transformer winding which isn't difficult once the basics are grasped. I started off winding small output transformers then progressed to mains transformer and field windings etc. The first mains transformer I wound I slipped up with; the rectifier needed something like 350V so I wound for 350V thinking that wasn't too bad at all; I had added for heaters and panel lamps but center tapped for the rectifier; I was very puzzled indeed why the radio had such low gain on volume until I checked voltages which were half what they should have been; I hadn't realized center tapping the transformer halved the output at each tap; I stripped it and wound on giving 700V then all was well; I found transformer winding easy to understand.

The AVO Wave Winder fully restored; missing parts I had to make including a full set of 45 cast iron change wheels that I made on my engineering lathe.

Coil winding underway and it's amazing what comes out of a small transformer once its stripped to be rewound. As usual I always did things the hard way; I used to count every turn on these transformers until I realized all I needed to count was a secondary winding say heaters or panel lamps; if there were 24 turns of wire and a panel lamp was 6V I then knew the turns/volt ratio to be 4 to one. I could then wind on 960 turns for primary at 240V then 2,800 turns for the rectifier at 700V. I learned everything the hard way through mistakes and research. I always take lots of digital images for future references.

I'm never bored.

Kind regards, Colin.

 

[sako243]

You want a big bang I've witnessed bigger versions of these capacitors blow up:

They go off with a spectacular bang, someone accidentally dropped a small spanner across the terminals - half was turned into plasma and vanished, the other half went through the ceiling tiles


(edit)link appears to be being re-written by the forum, have a look from 10 minutes onwards(/edit)

 

[Seadog]

You're quite right, it was moptor driven, hence the motor in the photo

 

[slim_boy_fat]

It's my birthday today aged a young 72

A bit late to the party, but many Happy Returns!

 

[Hood]

I have dabbled in coil winding myself. It was not for me personally but rather a client who did all sorts of interesting things for detecting in the oil, gas and water industries.
I made a coil winder for him but it was CNC and as I had never seen a coil winder before I basically just made it like a simple lathe. The design brief was that it had to be able to wind coils of any size from tiny to about 500mm long and 100mm diameter.
I recently sold on the coil winder as my client retired and it was sitting unused in my plasma shed and plasma particles are not the best environment for electronic things

Here is a pic of the smallest coil I made, I had to fit a secondary spindle in place of the tailstock so that I could hold the core under tension to wind the wire onto it.
The core was 0.5mm diameter Mu metal and the wire was 0.1mm diameter, if I recall it was about 8000 turns.

 

[Seadog]

Funny you should say that

Field winding for my old toolpost grinder. Replaced the pair but still overheating. I really don't fancy doing the armature

 

[Hood]

This is a pic of the machine I made.

That is using the secondary spindle which basically replaced the tailstock. That and the main spindle were set as Master/Slave and it worked well. The coil in it is bigger than the one pictured above but I think the core was of a similar diameter.

I also used to wind the small coils of aluminium wire on my CNC lathe, it was much cheaper to buy a 7Kg reel of wire and wind it onto the 0.5Kg reels and as it was CNC I didn't really have to spend much time as it got on with it whilst I did other things. Pic of the lathe below.

 

[R Kraft]

I can actually smell the burnt transformer, just by looking at the photo .

 

[Hood]

I can actually smell the burnt transformer, just by looking at the photo .

The smell from the RC networks that were across the contactor coils on my CNC lathe used to give up the ghost every now and then. They were after all over 30 years old, but the smell that greeted you when one went was frightening

 

[Retired]

Hi,

Thanks for your interesting replies and pictures; coil winding is a big industry in its own right. I used to buy big drums of enameled copper winding wire; the special silk covered winding wire though was far too expensive of the kind used on my wave winder. Resistance wire too is very expensive.

During my 24 years working at Brook Motors we used to have enameled copper wire arrive by the wagon load of pallets; these were run through the works by fork truck into the bonded store; I believe this was to save paying duties on the wire until it was actually released for use.

Nice winder Hood; I'm impressed.

The counter looks very much like the AVO counters Seadog; what's your lathe? I used to own a Colchester Triumph; now I own a Record DML 24" and a Union graduate both woodturners and my Lorch Schmidt engineering lathe; I think it fair to say anyone who has owned a lathe won't be without a lathe?

The caps haven't yet arrived; boo hoo.

Kind regards, Colin.

 

[R Kraft]

Some of them use resistors instead of inrush limiters, this is just an example.

 

[Retired]

Hi,

I'm delighted to receive the circuit diagram R Kraft; many thanks for posting it; I've only glanced at it at the moment but it does indeed look similar to what I've already seen especially in it having the two bridge rectifiers; my board has six electrolytics whereas I can see four on this example shortened diagram.

All I need is a tip and I'm nosy;

https://www.google.com/search?rlz=1...kAhWbQkEAHXwtD14QsAR6BAgJEAE&biw=1920&bih=969

Kind regards, Colin.

 

[Seadog]

what's your lathe?

It's a Boxford AUD of 1963 vintage. I'd love something larger but I just wouldn't be able to get it through the house

 

[Retired]

Hi,

Thanks Seadog. I owned a Boxford years ago. Bron and I pass the factory in Elland many times. We also pass the 600 lathes (Colchester) site in Heckmondwyke but I've just had a web browse and see they are now in Elland; I've been out of touch for a while so wonder if both companies are now joined together in Elland; Brooks where I worked supplied the motors so I knew the companies well.

Kind regards, Colin.

 

[Retired]

Hi,

I've just been looking at the schematic you kindly posted R Kraft; it occurred to me there might be a supply input fuse but I can't see one; I connect the welder to a 32A socket supplied from a "C" type mcb and further protected by RCD; I've just checked and the mcb has tripped; pity it didn't trip before the explosion though?

I've contacted Parweld via their website;

https://www.parweld.co.uk/

I've briefly explained the welder blew up and sent a link to this thread; I've asked if they can supply a schematic saying the new welder expiring like this isn't a good advert for Parweld; I'll be interested in the reply? I don't want anything for nothing and I accept Parweld do not transfer warranties.

Many apologies eddie49; I missed replying to your question regarding how long the welder ran before going bang; I initially tried using the welder but couldn't see the tungsten or puddle so gave up very quickly indeed actual welding time perhaps less than a couple of minutes; the second attempt at welding using my new Crystal 2.0 helmet must have lasted less than five minutes so in total less than ten minutes actual welding time which is abysmal. I've checked RS and the delivery quoted is allow up to five days; the rate I'm going now at 72 I wonder if I'll live long enough to do any TIG welding at all; so near and yet so far with problem after problem.

Thanks Hood for your kind birthday wishes.

Kind regards, Colin.

 

[R Kraft]

Quite a few possibilities , part of a bridge diode may have gone short or a capacitor that looks good may have gone short.
A fused shut relay may be trying to charge capacitors instantly.

 

[R Kraft]

When you work on chinese type welding equipment, they tend to use 2 or 4 or 6 , small cheap components in parallel to add up to the capacity of one large expensive component.
You end up with circuits, that on the surface are unique, but that are the same as countless others.
The parts may be mismatched enough to cause some to heat and blow out.

 

[Retired]

Hi,

A belated thanks Slim for your birthday wishes.

Today has started well, no Internet connection; no email and even the TV wouldn't log onto YouTube so everything's normal.

Thanks R Kraft. It's possible as you say there are a number of caps in parallel and could explain why there are six of the same on the board; the two that have blown could be the first two to suffer inrush hence they blow first? If all six are involved then this changes values; I've forgotten how it works but I think however connected the voltage remains the same but series capacitors the value remains at the lowest uF but in parallel the values add up so in this case I think the 200V is constant but the value could be 1200uF in series or 3600uF in parallel. It's a long time since I played with caps and resistors. A correct schematic would be useful.

A short while ago I asked Bron of she fancied a trip over to RS in Gelderd Road Leeds? I've got four of these caps due for delivery but given the bad luck right from the start with this wayward welder I thought time to take control and either fix it or destroy it so pop over to RS and collect six caps allowing me to replace the lot at one go? With my constant bad luck I just knew if we set off to Leeds we would have problems so in anticipation I opened a chat line with RS and asked a delightful Diana if we could pop over and collect six of the caps this morning; I was asked which branch and replied Gelderd Road please; after a pause allowing Diana to check I was informed these items are not available for collection. I thanked Diana and closed the chat so my bad luck continues but I'm used to it so opening the chat line saved more hassle and frustration.

It's only 6 miles to our recycling center and that would solve the problem because TIG welding so far for me has just been one huge expensive wind up. This mower petrol tank is proving challenging; perhaps I should have made it from 1/4" steel plate and used my Oxford welder which is bullet proof without all these electronic circuits?

Kind regards, Colin.