Miller Two Fifty Manual needed, not found in manual download section

[Stefen7]

I have read the posts on this site and it has been extremely helpful. Thank you to all those who have posted very useful information.

I need help finding the Operating Manual for a used welder I am looking at. The seller has not provided the serial number, but it looks identical to this one which I believe is called the “Miller Two Fifty.” But the manuals listed for “Two Fifty”; O313 (Two Fifty Twin, 1973); and OM-119 (Two Fifty AC, 1974) are from a different machine with only one selector handle (vs two in the photo), and has an open grille at the top of the front, (vs no vent in the photo). I even tried the serial number for the unit in the photo (71-560949), and nothing came up. Any help would be appreciated.

Secondly, if the rectifier diodes in an old machine fail, can they be replaced with parts for a current Dialarc unit?
Thank You.

[H80N]

PLS Doublecheck & repost the serial #....................

ALSO a better picture of the front panel would help...

[Stefen7]

71-560949

[Stefen7]

Sorry, this is my first time posting and still figuring out how the site works.

I have a larger photo but the site will not allow me to load it, I am trying to sort that out.

Serial number for that machine is 71-560949.

The manual OM-313, August 1973, starts with serial number 72-612483, so presumably this machine predates 1973.

[Stefen7]

[Stefen7]

[Aeronca41]

"Secondly, if the rectifier diodes in an old machine fail, can they be replaced with parts for a current Dialarc unit? "

As long as the current and voltage ratings of replacement diodes are = or greater to the originals they will work. Just need to be careful about polarity-there are generally two "positive" and two "negative " diodes (assuming a bridge rectifier design-most common, but not always. If there are only two diodes, it is a "non-bridge" full wave rectifier design, with a center tap on the transformer secondary winding, in which case the diodes are likely identical) sometimes called straight and reverse polarity diodes on old machines. The difference is whether the mounting stud is the cathode or the anode of the diode. Some applications use insulated mounting and all 4 are the same but I don't think that is very common. Need to check the schematic diagram against the physical construction. Not good if you mix up the diode types when replacing them. Makes a potentially expensive short circuit.

[Aeronca41]

If H80N doesn't find you a manual (he almost always does-definitely a guru at finding info) just call miller. I went through the same issue with an old Millermatic 200 manual and they had the correct manual in my email box in an hour. Super people.

[H80N]

Sorry, this is my first time posting and still figuring out how the site works.

I have a larger photo but the site will not allow me to load it, I am trying to sort that out.

Serial number for that machine is 71-560949.

The manual OM-313, August 1973, starts with serial number 72-612483, so presumably this machine predates 1973.

Your machine appears to be a 1971 version per the chart

https://www.millerwelds.com/support/serial-number-chart

Since it seems to predate the manuals posted online.... try calling the literature dept 920-735-4356 or 1-800-4-A-Miller (1-800-426-4553). Manuals not online are likely still in their library

They may be able to Email the correct version... or sell a hardcopy

[H80N]

BTW if rectifier diodes are defective.... they should be easily cross referenced to currently available by referencing the diode industry #

usually or at least often a 1NXXXX #

[Stefen7]

Sorry, trying to post a better photo of the unit tied up my connection for 30 minutes, and still did not load, (slow rural dial-up). I'll give Miller a call. Thank you for the info about the diodes.

[Stefen7]

A better photo of the front for anyone looking for information on a similar machine.

[Stefen7]

I called the literature dept (920-735-4356), and they e-mailed me the manual. For anyone else looking for the same manual, it is:

IOM-312A - 6/69

Models:
250 AC/DC (900 941)
250 P AC/DC (900 950)
250 AC/DC-HF (901 122)
250 P AC/DC-HF (901 129)

Thank you to H80N, Aeronca41 and the team at Miller for your help.

[H80N]

I called the literature dept (920-735-4356), and they e-mailed me the manual. For anyone else looking for the same manual, it is:

IOM-312A - 6/69

Models:
250 AC/DC (900 941)
250 P AC/DC (900 950)
250 AC/DC-HF (901 122)
250 P AC/DC-HF (901 129)

Thank you to H80N, Aeronca41 and the team at Miller for your help.

Glad that worked for you.....

Do you have a problem with it....??? symptoms... ??

[Stefen7]

Sorry for the delay in replying, I was at work. There is a used one I am going to look at this weekend, and I needed all the info & help possible. Thank you for asking.