Hughes MCW-550 microwelder - looking for service manual / fu

Hello,

I'm try to fix very old Hughes MCW-550 microwelder that i rescued from being dumped and give it a second life for my use.

To fix it im in big need of service manual, schematic or any detailed manual (i found in Google some pdf-s but they have just technical details like advertisement) nothing about proper operation, calibration and testing if device is working properly.

Here is video that i shoot of this unit at my workbench:
https://www.youtube.com/watch?v=6dBmXFVgaxQ

I just finished fixing fuses holder and other small things that were smashed but still need right fuses values.

It's in creepy condition, some diodes are corroded so i will have to replace them anyway, i'm also going to poke every semiconductor and test it but right now im in point that i don't know how it should operate while it's 100% working. Without service manual or operator or schematic to help me understand what's going on it will tough to examine.


Right now i'm working on replace original dead 6V Sealed-Lead Cyclon acid battery using standard (4x in parallel )4.5Ah 6V gel battery.

If someone could share any experience it will be great.

Regards

 

electronicnoobblog@gmail.com wrote:

To fix it im in big need of service manual, schematic or any detailed
manual (i found in Google some pdf-s but they have just technical
details like advertisement) nothing about proper operation,
calibration and testing if device is working properly.

This one (which maybe you already found) has a little bit about operation
and calibrating the weld voltage.
http://www.karenmadison.com/HRW550.pdf *

Interestingly, it also claims that this device originally had NiCd
batteries, instead of Pb. (It does mention a "dry lead acid battery"
option for serial no. 2200 and up, which might be the Cyclon Pb
batteries you have.)

That business seems to buy and sell equipment like that; maybe they
would sell you a copy or scan of the manual.

It's in creepy condition, some diodes are corroded so i will have to
replace them anyway, i'm also going to poke every semiconductor and
test it but right now im in point that i don't know how it should
operate while it's 100% working.

It looks like it should provide a square wave, at the specified voltage
and duration, to the main output. When the main output is not on, it
should charge the batteries, to get ready for the next output.

It also looks like there are "sense" wires coming back from the weld
head to the "Voltage Fire" connector, to help the power supply maintain
the correct voltage at the weld electrodes. (4-wire measurement or
Kelvin connection). The scan above shouts very loudly that you should
not operate this device without those "sense" wires hooked up.

Matt Roberds

* This site seems to be more or less a duplicate of
http://www.rgleq.com/ . The "warehouse tour" video shows the same
building.

 

[JC]

On 9/20/2014 2:03 PM, electronicnoobblog@gmail.com wrote:

Hello,

I'm try to fix very old Hughes MCW-550 microwelder that i rescued from being dumped and give it a second life for my use.

To fix it im in big need of service manual, schematic or any detailed manual (i found in Google some pdf-s but they have just technical details like advertisement) nothing about proper operation, calibration and testing if device is working properly.

Here is video that i shoot of this unit at my workbench:
https://www.youtube.com/watch?v=6dBmXFVgaxQ

I just finished fixing fuses holder and other small things that were smashed but still need right fuses values.

It's in creepy condition, some diodes are corroded so i will have to replace them anyway, i'm also going to poke every semiconductor and test it but right now im in point that i don't know how it should operate while it's 100% working. Without service manual or operator or schematic to help me understand what's going on it will tough to examine.


Right now i'm working on replace original dead 6V Sealed-Lead Cyclon acid battery using standard (4x in parallel )4.5Ah 6V gel battery.

If someone could share any experience it will be great.

Regards

manual available for rent :
http://yourmanualsource.com/index.cfm?currentpage=651&fuseaction=page.Search%20Results&all_words=1

 

On Saturday, September 20, 2014 9:14:29 PM UTC+2, mrob...@att.net wrote:

electronicnoobblog@gmail.com wrote:

To fix it im in big need of service manual, schematic or any detailed

manual (i found in Google some pdf-s but they have just technical

details like advertisement) nothing about proper operation,

calibration and testing if device is working properly.



This one (which maybe you already found) has a little bit about operation

and calibrating the weld voltage.

http://www.karenmadison.com/HRW550.pdf *



Interestingly, it also claims that this device originally had NiCd

batteries, instead of Pb. (It does mention a "dry lead acid battery"

option for serial no. 2200 and up, which might be the Cyclon Pb

batteries you have.)



That business seems to buy and sell equipment like that; maybe they

would sell you a copy or scan of the manual.



It's in creepy condition, some diodes are corroded so i will have to

replace them anyway, i'm also going to poke every semiconductor and

test it but right now im in point that i don't know how it should

operate while it's 100% working.



It looks like it should provide a square wave, at the specified voltage

and duration, to the main output. When the main output is not on, it

should charge the batteries, to get ready for the next output.



It also looks like there are "sense" wires coming back from the weld

head to the "Voltage Fire" connector, to help the power supply maintain

the correct voltage at the weld electrodes. (4-wire measurement or

Kelvin connection). The scan above shouts very loudly that you should

not operate this device without those "sense" wires hooked up.



Matt Roberds



* This site seems to be more or less a duplicate of

http://www.rgleq.com/ . The "warehouse tour" video shows the same

building.

Exactly that's the "part" of manual that i got.
As You can see it's not full because scanned pages are 2,3 and 4. On page 4 there is say "see page 16" so maybe at end there was some kind of schematic or block diagram.

That's how battery looks like:
http://electronicnoobblog.com/wp-content/uploads/2014/09/DSC02664.jpg
http://electronicnoobblog.com/wp-content/uploads/2014/09/DSC02661.jpg
http://electronicnoobblog.com/wp-content/uploads/2014/09/DSC02662.jpg
http://electronicnoobblog.com/wp-content/uploads/2014/09/DSC02663.jpg

I never saw this before, it's single cell.
12 of them was stacked in parallel and series to get 6V 20Ah.

I replace them using four 4.5Ah 6V SLA Gel battery like this

https://images.search.yahoo.com/yhs/search;_ylt=A0LEVj4k2B9UUIMAJZsPxQt.?p=6V+4.5aH&fr=&fr2=piv-web&hspart=ddc&hsimp=yhs-linuxmint&type=__alt__ddc_linuxmint_com


Im pretty sure they have lower "short circuit" current than Cyclon but anyway in short period they should work just for test to give me indication how it's welding.


You have right, tt try to charge battery, i can see voltage putted on battery clamp but it's kind low like 6.x volts. That's not enough to charge 6V cell... it should be at last 7.2v.

I also found notice on battery "do not adjust charge voltage without batteries connected" but still i can't find potentiometer for that adjustment

That square wave and timing i should be able to test using oscilloscope but right now it's look like this:

When i hook up without head i can see around 6V on analog voltage indicator - we can assume that's battery voltage.

When i plug weld head - voltage on meter drop to 0.

That's question why is that happening, i do not press fire.

That's quite odd behavior... maybe there's short inside weld head... im going to test it but i have to open it (weld head) and do some measurement.


Website:
http://yourmanualsource.com

I can't access it... and manual for rent also look not good for me.
I'm from europe so borrowing paper copy it will be difficult.

Better option for me will be donate by paypal someone who have paper copy, to take pictures of it and share with me.

I'm going try write karenmadison.com maybe they have full copy of manual.

 

electronicnoobblog@gmail.com wrote:

That's how battery looks like:
http://electronicnoobblog.com/wp-content/uploads/2014/09/DSC02664.jpg
I never saw this before, it's single cell.

I first saw a battery like this in a mid-1980s rechargeable flashlight,
but I don't see them very often. They are made in several sizes, from
2.5 Ah to 25 Ah. The Pb plates are wrapped in a spiral @, not in
parallel || like most batteries.

I think they used to be more popular before switching power supplies got
popular; sometimes the power supply design was easier if you could have
multiples of 2 V, rather than 1.2 V (NiCd), 1.5 V (C-Zn, alkaline), or
6 or 12 V (Pb-acid).

Originally Cyclon cells were made by Gates, which mostly made rubber
products (water hoses and drive belts for cars, trucks, etc). In the
early 2000s they were made by Hawker, and are now labeled Enersys. One
of the factories is about 50 miles (70 km) away from me.

In the US, you can get car starting batteries made like this, with six
of these cells in series. Johnson Controls' "Optima" brand was the
original, but other companies make similar products now.

> 12 of them was stacked in parallel and series to get 6V 20Ah.

Enersys' selection guide
http://www.enersys.com/WorkArea/DownloadAsset.aspx?id=490
says that these cells have an internal resistance of 3.5 milliohm and
short circuit current of 570 A when fully charged. The battery of 12
cells would have had an internal resistance of approximately 2.6
milliohm (plus the resistance of the connecting wires), and a short
circuit current of about 2280 A (!!).

> I replace them using four 4.5Ah 6V SLA Gel battery like this

If you get good ones (like
http://www.power-sonic.com/images/powersonic/sla_batteries/ps_psg_series/6volt/PS-640.pdf_12_July_9.pdf
), the internal resistance for each battery will be 40 to 45 milliohms,
or 10 to 11.3 milliohms for four in parallel. The manufacturer doesn't
specify a short circuit current, but does give a 10 second discharge
current of 45 A. 180 A for four in parallel.

You have right, tt try to charge battery, i can see voltage putted on
battery clamp but it's kind low like 6.x volts. That's not enough to
charge 6V cell... it should be at last 7.2v.

Even if this welder was originally built for a NiCd pack, which probably
used 5 x 1.2 V cells, 6.x wouldn't be enough charging voltage. (It would
be for 4 x 1.2 V cells, though.)

When i hook up without head i can see around 6V on analog voltage
indicator - we can assume that's battery voltage.

When i plug weld head - voltage on meter drop to 0.

It looks like there are a couple of small "sense" wires that go back
into the control plug, in addition to the two heavy "main" wires that go
to the weld head. There might be some high value resistors (100k ohm?)
from the "main" connector to the "sense" connectors inside the welder,
to keep the power supply somewhat regulated when there is no weld head
plugged in. With the weld head plugged in, though, perhaps the supply
requires the "sense" wires to be there, and one of them might be open
or shorted.

I'm going try write karenmadison.com maybe they have full copy of
manual.

Good idea.

Standard disclaimers apply: I don't get money or other consideration
from any companies mentioned.

Matt Roberds

 

[Chris Jones]

On 21/09/2014 04:03, electronicnoobblog@gmail.com wrote:

Hello,

I'm try to fix very old Hughes MCW-550 microwelder that i rescued from being dumped and give it a second life for my use.

To fix it im in big need of service manual, schematic or any detailed manual (i found in Google some pdf-s but they have just technical details like advertisement) nothing about proper operation, calibration and testing if device is working properly.

Here is video that i shoot of this unit at my workbench:
https://www.youtube.com/watch?v=6dBmXFVgaxQ

I just finished fixing fuses holder and other small things that were smashed but still need right fuses values.

It's in creepy condition, some diodes are corroded so i will have to replace them anyway, i'm also going to poke every semiconductor and test it but right now im in point that i don't know how it should operate while it's 100% working. Without service manual or operator or schematic to help me understand what's going on it will tough to examine.


Right now i'm working on replace original dead 6V Sealed-Lead Cyclon acid battery using standard (4x in parallel )4.5Ah 6V gel battery.

If someone could share any experience it will be great.

Regards

Were the lead-acid cells really connected in series? The output voltage
(from that manual) was up to 1.99V, or 1.30V into 2 milliohms, so 650
Amps, which comes from the battery according to the manual. In that
case, the type of battery may be very important, as some batteries would
have much more internal resistance than the weld, and would prevent the
desired current from being achieved.

Perhaps it would be interesting to try replacing the lead-acid cells
with supercapacitors. You can buy a 3000 Farad 2.7V supercapacitor rated
for 1900 Amps and actually capable of quite a bit more, for about $65
from Digi-key. You would have to figure out whether the output voltage
regulating circuit of your welder can run from a 2.7V capacitor, or
whether it would need several capacitors in series due to the regulator
having too much drop-out voltage. You would also need a voltage
balancing circuit for the capacitor charger - which could probably be
built with a TL431 plus power transistor for each capacitor in the
series string.

I have been thinking of building a spot welder from supercaps, but I am
unsure how much voltage I will need. I think about 10 in parallel, for
19000A, should be enough to weld about anything I would want to, but
whether I need to stack them in series as well is the question. To
switch the current off after the weld, (and perhaps also regulate the
current, with a switched mode current source - if I can make suitable
inductors...) it seems like multiple 100A rated MOSFETs are about the
optimum amps per dollar. Getting low enough on-resistance is not the
limiting factor, as a much larger number of mosfets will be needed to
get the current rating high enough.

Chris