Check the wires in the plug those are crappy connections.  The board is more than capable of handling the load.  If you are getting burning it is caused by a thin wire where it is crimped or poor contact with the pins.  You really don't need or want an SSR for the extruder and if you should choose a bigger bed heater than an SSR would be needed.  When it comes to DC to DC relays you want to be rated close to double the rated load. 
A DC to AC Relay is not what you want unless (like in my case) the bed heater is actually running on AC.

ah OK, now I understand.  Guess I did jump ahead of the real issue and tried to solve something that is not an issue.  I actually bought a pack of MOLEX connectors to run from board to relays, those are rated to 250V / 2.5A, so calculate 625W - look better then stock feeding the bed so I will replace and make better connections, maybe solder all.  Will jump the PSU 3 pins as you noted - I saw pics of that while googling my issue last night.

Thank you very much for instant reply to my question.

No need for a relay then.  Just jump all three banks on the PSU and run one each black (-) and red(+) to the board.  The internal connections in the PSU are small so this will allow more current to flow.  A picture of your wiring may help with troubleshooting.

hmmm, maybe I jumped to a false conclusion but when I saw brown on connector from board bed heater, I speculated that was acting as a point of resistance so thought a relay would be better to take power direct from new PS.  Then I went all out and relayed the extruder as well.  Guess I should put the extruder back as stock but not sure about bed.

What bed heater do you have? Wattage

not sure.  As far as I know it is the stock heater.  Looks like pics I have seen online.

So I took Tin's advise from post above and ordered the supernight PS.  Arrived yesterday - for info of anyone reading this who has not converted - it is a nice unit, attaches nicely to back of SD3 by drilling four holes.

I decided that would also run extruder heat through it since it has 3 taps - 1 for motherboard, 1 for bed (the problem), and 1 for extruder.  Did not think about relays, just used the black box four post magnetic style.  I suppose you will know what happened - click click click, especially for the extruder, no so bad for the bed.  So back to Google - found discussions on this forum and elsewhere about SSRs.  Makes sense, should have thought of that.  A search on web shows 12V 10 amp or higher from $22 all the way to $50 - a bit much.  Found some relay suggestions that have output side for AC, confused about people running DC through those.  I'm a mechanical guy, I can get by for electrical but no expert.  Could use some advise for minimum cost to get the job done.

So questions:  What SSRs did you use?  Did you install a second for extruder or did you just leave it through the board?

ETA - so after all that, found that unit does not like a longer USB cord.  I tried 10ft, no go, tried 6 ft that came with it and works fine.  Need to reorg my area to accommodate.

the Supernight PSUs are good (and cheap!) I have a couple of them - no problems so far.

I have used Octave brand filament for a while now with pretty much no problems (other than they typical ABS issues of warping and/or cracking, and there are ways to reduce those), but it does get kind of expensive when you buy multiple colors...

Another filament I have had pretty good luck with is Hatchbox brand found on Amazon - a good bit cheaper than Octave, but seems to print just as nicely. I have a silver and a gold of that brand - both print well, but the gold prints just beautifully.

another source for decent filament at rock bottom pricing is Microcenter's house brand, called Inland. I have 3 spools from them, Black, Green, and a glow in the dark. Havent run the black yet, but the green and GITD both print very nicely.

https://store.solidworks.com/veteran/default.php

And as Ward said if you buy a PS go for a 30 amp will give room for upgrades.

Another good brand is MeanWell distributed by TRC electronics
IIRC a bit more money than supernight but lots of choices and good quality.
http://www.trcelectronics.com/View/Mea … 0-12.shtml
You may want to look at makergeeks for filament it is USA made .and a little cheaper than octave. A lot of the rolls are 1 lb so you can get variety easier if you like.
http://www.makergeeks.com/maker-filament.html
Glad to help
Tin

first of all welcome to the forum .

As far as a power supply 150 watts is correct. IIRC the unit should only pull about 120 max on warm up. but you want a little cushion.
looking at my factory ps  for my sd4 it is indeed 150 watts( 12v 12.5 amp ) center positive.

Some of the folks here have used the supernight PS off ebay
http://www.ebay.com/itm/SUPERNIGHT-12V- … 338a2e2c39

if you are not using or do not have a heated bed 120 watt should be ok.

Congrats on the citizenship! Good luck on the job hunting.
As far as resume padding and 3d printing you would do well to learn some parametric CAD. it is the difference in using the printer as a tool vs a toy. As a vet you can get a one year student licence for solidworks for $20, worth looking into.

I too am a vet 24 years national guard 6yrs Army electronics /communications. 11 yrs  as USAF  red hat/ RO  and the remaining time Aircraft Maint/Fabrication shop.
Not sure if I am an expert but have had my sd 4 for over a year, And have been here almost that long.

Tin

hello Tin; thanks for detailed reply.  Yep, I know CAD.  Cut my teeth on Fortran during degree (dating myself, and it was not CAD as we know it today, it was a compiler), used Autocad after left service, been using SolidWorks pretty much since it came out.  I will admit that I'm rusty because so called "promotions" past five years or so took me away from hands on into prg mgt so less CAD work.  Another good reason to get into printing, it will force me to practice CAD.  With all that said I did not know about $20 for vets - I am not a US vet but I'll ask if any vet counts, failing that I will check with Canadian distributor (not sure they can sell outside Canada, talk about a catch 22)

thanks again!

As always, Happy Printing.

As far as a power supply 150 watts is correct. IIRC the unit should only pull about 120 max on warm up. but you want a little cushion.
looking at my factory ps  for my sd4 it is indeed 150 watts( 12v 12.5 amp ) center positive.

Some of the folks here have used the supernight PS off ebay
http://www.ebay.com/itm/SUPERNIGHT-12V- … 338a2e2c39

if you are not using or do not have a heated bed 120 watt should be ok.

Congrats on the citizenship! Good luck on the job hunting.
As far as resume padding and 3d printing you would do well to learn some parametric CAD. it is the difference in using the printer as a tool vs a toy. As a vet you can get a one year student licence for solidworks for $20, worth looking into.

I too am a vet 24 years national guard 6yrs Army electronics /communications. 11 yrs  as USAF  red hat/ RO  and the remaining time Aircraft Maint/Fabrication shop.
Not sure if I am an expert but have had my sd 4 for over a year, And have been here almost that long.

Tin

Bit about myself -  originally from east coast of Canada, served with Air Force as an Engineering Officer for 14 years starting with my Mechanical Eng degree.  Got into electronics manufacturing after early retirement 21 years ago (government cutbacks), was with same company past 15 years, relocated to AZ 8 years ago with family (wife, son, dog, horse).  Became a US citizen this year.  Surprise, surprise - company eliminated my role earlier this year (last of engineering team, all work now offshore).  So I have been searching (first time in my life for this experience, not liking it).  Been thinking that the learning process to get into 3D printing will be good for my technical mind right now, heck maybe a resume padder!  So when good deal came my way I jumped.

Other hobbies - hiking (big mountain hikes, example - Humphreys few months ago, that was awesome), 4WD (03 TJ that my teenage son and I lifted and wrenched), competitive shooting (USPSA), also am a certified RO and do a lot of mentoring for new to the sport.

Anyhow, that's me - I look forward to learning from experts on here, and I hope to contribute one day soon!