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alright so i purchased 24vdc power supply and "Sunkee Solid State Relay SSR-25 DD DC-DC 25A 3-32VDC/5-60V DC SSR-25DD" from amazon. at first the ssr was working as intended, i set temp to 60c and it held it just fine. next i went to 100c and thats where it lost control... the temp kept rising until i had to pull power. i checked logic on the Rambo and indeed 0v was present on the bed wires, i even removed them from the ssr and the bed is still heating up. it looks like maybe the gate is stuck closed? I do have the cooling fin installed and it is quite warm to the touch. anyone else had this issue? i have a few more hours and i can get a Saturday delivery.

i do also have the 24v fused with 25Amp

I'm not following what you are doing. I have a 24V supply and a 12V supply hooked up to my RAMBo. There are separate terminals for the hot bed supply. The connectors from RAMBo to the Onyx out put 24V directly with no need for an SSR.

i had seen alot of posts on here where people were doing ssr insted of hooking up directly to RAMBo. would i need to increase the fuse from 15 to 25?

Changing the fuse is a good idea. I've been running mine like this for over a year now and it has been rock solid with 2 minute heat up times to 85°C with an 1/8" aluminum heat dissipator plate and borosilicate glass.

well balls

Michael, Cambo3D and I used the DC-DC SSR just as a form of protection, I still don't think it is a good idea to send close to 20 Amps through the traces on the Rambo when you
can buy the SSR for $15 or less. Gives me a feel better factor that does not cost much. That's why we did it.

Carl

[img]https://lh3.googleusercontent.com/-Ant8 ... 210925.jpg[/img]

this is supposed to be OL unless +3vdc is applied... i think its broke

Do you have another to try?

Eagle, good point and I do like to err on the side of safety/over engineering.

I was working from the info on the RAMBo wiki:

1.1b
change heated bed fuse from PTC to ATO (auto blade) fuse increasing heated bed rail max voltage to match others (24V max recommended PSU)

1.2c
iboard power inputs now support up to 35V

Been running for a year, no heat problems, no problems with the Onyx (there is also the concern that the Onyx won't handle the current).

Cheers,
Michael

mhackney wrote:Eagle, good point and I do like to err on the side of safety/over engineering.

I was working from the info on the RAMBo wiki:

1.1b
change heated bed fuse from PTC to ATO (auto blade) fuse increasing heated bed rail max voltage to match others (24V max recommended PSU)

1.2c
iboard power inputs now support up to 35V

Been running for a year, no heat problems, no problems with the Onyx (there is also the concern that the Onyx won't handle the current).

Cheers,
Michael

At the time it was a VERY big concern if the Onyx could handle the current. It has since been time established that it can handle the current.
The other big concern was not if the Rambo could handle the voltage, we know it can, it was whether the copper traces on the Rambo could handle
the close to 20 amps of current that would flow through them to the heating bed. We made the decision not to take the chance and inserted the
DC-DC SSR and let the current flow through that. You have proven that yes the Rambo can handle the current but I'm still glad that I made the
decision to use the SSR. Just one less thing to worry about and I would rather replace the $15 SSR than the $190 Rambo. Over-engineered, yes it is,
but I do not regret the decision to do it. Cheers to you.

Carl

bubbasnow wrote: this is supposed to be OL unless +3vdc is applied... i think its broke

You have to be cautious when buying those cheap chinese made relays. Its a hit and miss on quality. They're cheap for a reason.
I had that happen to me once before where the srr was stuck closed so the heatbed would keep heating. never again will i buy or use a chinese made ssr.

Opto22 makes some nice quality ssr relays that have a lifetime guarantee. I've never had any problems with their ssrs. I use them exclusively now for all my projects.
http://www.opto22.com/site/solidstaterelays.aspx

cambo3d wrote:

bubbasnow wrote: this is supposed to be OL unless +3vdc is applied... i think its broke

You have to be cautious when buying those cheap chinese made relays. Its a hit and miss on quality. They're cheap for a reason.
I had that happen to me once before where the srr was stuck closed so the heatbed would keep heating. never again will i buy or use a chinese made ssr.

Opto22 makes some nice quality ssr relays that have a lifetime guarantee. I've never had any problems with their ssrs. I use them exclusively now for all my projects.
http://www.opto22.com/site/solidstaterelays.aspx

It looks like 90% of that catalog is for controlling AC, could you give us the part number from Opto22 that will work in the 24V Rmax heatbed control.

I have bought and used the SSR type that you show in your picture.

I have over time used a fair number of them on project, both the AC and the DC varieties.

I have had 3 bad ones that arrived that way. I unfortunately did not test them when I originally received tham so I was SOL for returning them and getting functioning units. I have never had one fail that was in use and know to be good however.

I have the same setup as Michael with 24V going directly to the RAMBO rather than through an SSR. I tried the SSR's from Amazon and blew 2 cheap SSR's so gave up on them.

The problem I have had with the direct connection (no SSR) is with the molex connector that hooks the hotend to the RAMBO overheating and partially melting. I've had no issues with the traces on the RAMBO. I finally ended up desoldering the connector from the board and soldering a screw-on terminal directly to the board instead to get a really good connection. I believe the newer RAMBO's may have gotten rid of the molex connectors and replaced with screw-on terminals anyway.

alright I have Ran Several 10 hour prints with No Issues at 100 degrees I think less than 20 amps Is actually passing at any time, I installed a 20 amp fuse with nothing blowing.

bubbasnow wrote:alright I have Ran Several 10 hour prints with No Issues at 100 degrees I think less than 20 amps Is actually passing at any time, I installed a 20 amp fuse with nothing blowing.

http://forum.seemecnc.com/viewtopic.php ... =170#p7960
http://forum.seemecnc.com/download/file ... &mode=view