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AT&T 6300 Fan Replacement

alejack12001

alejack12001

Experienced Member
Joined
Jul 26, 2020
Messages
424
Location
Fredericksburg, VA
Most of all AT&T 6300's have a 110V fan on the back. I just wanted ask if that fan could be replaced by a 12 volt fan of roughly equal size?
 
Sure, just make sure to supply 12VDC to the fan. Applying 110VAC to it would let the magic smoke out.
 
The power supply does seem to have a very large power output with the bus control, controller and video bus requiring that AWG 10/1015 cable. So, just out of curiosity, how much current is being delivered to these buses based on the AWG cable size? There is two MFM ports on the power supply. I have one dedicated to the floppies and planned to power the fan from the other. As Chuck(G) said there is ample current here to power the fan and cool the system. Chuck(G) can you elaborate on another post of mine regarding the 16B series versus the 16 or 16A series power supplies. In other words do you know what the differences are?
 
No, sorry. But I'd definitely keep an eye peeled for a more modern replacement PSU. The M20/6300 is a very old design and the PSU uses some components (e.g. stud-mount schottky diodes) that would be hard to source today. As far as the wire size goes, it seems like more than a bit of overkill.
 
There's also a page I ran across with someone who simply took an ATX 12V power supply and incorporated it and included detailed instructions. (I'd have to search for the page now). The 12V PSUs tend to have beefy +12 lines as those are used to power the CPU regulator circuitry. He notes that you might have to include a ballast resistor to keep the +3.3 from kicking out.
Alternatively, you could adapt a regular dual-output switching supply (e.g. Meanwell) to fit; just make sure that the +12 line can supply 6 amps to stay compatible with the old one's ratings.
 
Thank you, if could locate that alternative; it would be appreciated. Trixter's doesn't design accommodate for the 14.7 volts needs for the video card port near the DB 25 connector. I know that voltage is used for the AT&T 313 monitor and is probably not used by the 319 of 318H monitors. Having enough current is necessary for the operation of the AT&T machines.
 
CSCS-14_Sams_pub PS.jpg
Chuck: If you observe the schematic I am posting here, you can see a 14.2 Volt connection at J7 which connects to the video card. My power schematic is for a 16 or 16A power supply. I guess there is a 16B, but there is no known schematic. So, the 16B may be different. I gave Trixter this AT&T 6300 schematic package and he has posted it to his Oldskooler website. Also, you can see F2 which according to the components list is some sort of thermal fuse. The terminal fuse is blown on at least 2 of my PS's. I don't know what this fuse is. It could a thermistor or an SCR.
 
Is your video card the standard video, or are you using the DEB? Interesting that the site posted seems to think that 12 volts is enough for everything.
 
Thanks for responding. Yes, I had found the Xerox 6060 power supply discussion before you replied. I will retry using the Xerox post to see if there would be a response from the forum regarding the board designed and where to acquire it. Of course, I could design my own, though I have never had much success in building my own PS units. I noticed that you had address the PS discussion on the 6060. Did you use Velario's process to make your own PS?
 
Chuck(G) said:
Is your video card the standard video, or are you using the DEB? Interesting that the site posted seems to think that 12 volts is enough for everything.
Click to expand...

The DEB has no special power requirements. I have a M24SP with DEB (Go329) and that is just is another (16 Bit) ISA card, addionally connected to the other card with a 50 pin flat cable. The GO329 has the same 15V pin for the power supply as the other graphics card to get directly those 15V prom power supply. But it is not connected and it makes no sense as only the monochrome monitors are supplied through the graphics card. Only stupid guys would connect a monochrome monitor to a Go329. But you can connect the monochrome monitor to the original card and the color monitor at the Go329 at the same time and it even makes sense, on the Go329 diskette is an example demo to show action on both monitors at the same time!
 
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