Dc power supply in cnc not working

[stj]

Re: Dc power supply in cnc not working

there is a french guy who was reverse engineering stk modules a while back!

[shelby5041]

Re: Dc power supply in cnc not working

i may be the only person that has genuine sanyo STK4191 V modules

i bought a retired audio video repair shop inventory

as i said he bought them new about 25 years ago from sanyo

not fakes

made by sanyo..not just stamped sanyo

[sam_sam_sam]

Re: Dc power supply in cnc not working

I doubt that Jameco would be selling fakes ( knowingly) but you never know anymore

[shelby5041]

Re: Dc power supply in cnc not working

sanyo is not a cpmapny anymore and hasnt been for many many years..the last sanyo real stk was made about 20 years ago

anybody or any company who sells a new stock stk that is stamped sanyo or marked with a sanyo part# on it is just a fake knockoff period and are junk compared to the original sanyo made stk....go to youtube and search fake sanyo stk and you will see a guy who took them apart and see the difference.

[redwire]

Re: Dc power supply in cnc not working

U1 LM338T with R3 and R2 make up a 5V regulator no way it can do 5A with such a tiny heatsink, even 1A would cook it.
U2 7812CT makes up a 12V 1A regulator
U3 not in pics

I think there is no 42V reg, it was just the raw DC off the big filter cap?
Looks like a wire is missing if there is no big fat take off wire from the filter cap(+). There's two black wires (bridge rect. and load) but only one red wire (bridge rect.) musta been a copper thief lol

[sam_sam_sam]

Re: Dc power supply in cnc not working

I was talking about the LM338 regulator ic chip

[eccerr0r]

Re: Dc power supply in cnc not working

Looks like around a 44 volt regular based on what I can see. It should not be dropping much voltage and thus not dissipating that much power either. Nothing wrong with this regulator, except that the circuit prohibits it from self preservation if things go awry. LM338/LM317's usually can protect themselves from certain death - this circuit cannot.

[shelby5041]

Re: Dc power supply in cnc not working

hi if he say regulator good then where else should i check why no 42v at connector but yes 45v at big big cap?

from the cap to the connector are only a few components..a few diodes and resistors

no copper thief..machine worked fine last time i used it and has been stored in my garage.since then untouched,,,.nobody but me has access to machine

[eccerr0r]

Re: Dc power supply in cnc not working

Regulator will be damaged if it's only 1.4 volts on its output.
You still need to make sure that it's still not shorted.
Tried swapping the board with one of your other ones and kill those too? Then you'll know if it's shorted or not at least ...

[shelby5041]

Re: Dc power supply in cnc not working

yes there is only 1.4v at output connectors that should be 42v as was last time machine was used by me

i guess i will replace the tm338 and see what happens

i dont want to swap boards from my other machines and create a worse situation since they are both running fine..

im sure it can be fixed and im sure its a simple issue ..as long as the big cap has 45v then i know everyhting before it is working fine and there isnt much after it ..its possible when i was messing with the new potentiometer on the other board the new potentiometer was bad and created an issue / surge with electronics elsewere



thanks

[sam_sam_sam]

Re: Dc power supply in cnc not working

yes there is only 1.4v at output connectors that should be 42v as was last time machine was used by me

i guess i will replace the tm338 and see what happens

i dont want to swap boards from my other machines and create a worse situation since they are both running fine..

im sure it can be fixed and im sure its a simple issue ..as long as the big cap has 45v then i know everyhting before it is working fine and there isnt much after it ..its possible when i was messing with the new potentiometer on the other board the new potentiometer was bad and created an issue / surge with electronics elsewere



thanks

I am going ask you something and do not want you to take this the wrong way but where did you get the information about hooking the potentiometer to this board and was it made to be done the way you want to hook it up

The other thing you can not run the LM338 at 45 volts ( maximum voltage is 40 volts) it is not designed to run at this voltage for very long you will fry it after a short period of time and if you heat sink is not big enough that is going to be a problem as well

Here is an example of what can go wrong with something that you have bought for a purpose and find out there are issues and it will not last very long because of the issue it has

Right now I have a battery charger for a tool that the charger has a design issue the switching transformer ( over heating ) is not big enough to push 3 amp like the manufacturer claimed it supposedly to be able to do so I have to decide how and what I am going to do to be able to use this battery operated air compressor that I just bought

[shelby5041]

Re: Dc power supply in cnc not working

Hi samsam
I hooked potentiometer up per manual and have dome same on otherc2 identical mschines with no issues

The LM338 is what the msnufscture used so i will replsce it...if it doesnt fix issue i will let u know

[shelby5041]

Re: Dc power supply in cnc not working

potentiometer schematics per manual

[shelby5041]

Re: Dc power supply in cnc not working

Update

Nevermind...this thread done

I put board bsck on to test voltage regulstor voltages and within 1minute the lsrge blue cap exploded .

Power supply is trash

Im not sure what i dod wrong as this machine is same as other 2 but i really messed it up and now its going to be a huge expense..i may just scrap the machine.

Whst could cause the huge blue csp to explode?

[eccerr0r]

Re: Dc power supply in cnc not working

connected backwards.

[shelby5041]

Re: Dc power supply in cnc not working

Yep thats what i did.....is that huge cap even replaceable if it dodnt blow everything else in circuit

Unfort im just having bad days with this damn machine.

[CapLeaker]

Re: Dc power supply in cnc not working

Yep… no problem. Just match something up at Digi-Key, mouser etc.

[shelby5041]

Re: Dc power supply in cnc not working

Yrah but this cap is huge like 75mm tall and 45mmdia
It mist cost a fortune

[eccerr0r]

Re: Dc power supply in cnc not working

as it's just a line frequency filter and a burned out lm338 you'll likely just damage the capacitor and nothing else. Maybe the rectifier or fuse. Much less damage than APFC SMPS primary capacitors blowing.

pics for "what not to do"?

BTW makes me sad when I see caps and equipment blown up this way Also makes me mad when people screw up equipment like this, including myself. I hooked up a 8mm video camera backwards by mistake and fried stuff. *sigh*

Also a quick search on mouser: a 75V 7800uF capacitor (1.75" diameter) costs $25 ... Others around that can cost up to $50 a piece or so. But yeah not cheap...

[shelby5041]

Re: Dc power supply in cnc not working

i just removed the capacitor

its 75v 4800uf

80mmx50mm with screw terminal type 22mm span