shitty chinese psu kit

[Kleinstein]

hope the corrected pdf files help if anyone is planning on building one of these.

With the circuit divided in 3 files the plan is a bit hard to read.
The last version still has the voltage regulation messed up somewhat - the divider for the main feedback is somehow missing. The lables between the files also don't match.

[m3vuv]

Hopefully this should fix it,as it is it works flawless upto 36v and 10 amp output,it will do more but melts my test leads and my avo8 and flule 83v breakout into a sweat over 10 amps,its just the no output when its been on a few hours and is hot,i hope the big heatsink on u3 fixes it,at least it wont be cooking the tl431 voltage ref ic,fingers crossed,getting short of room in the enclosure now tho with 2x transformers a 22000 uf cap + 50a bridge heat sink!

[m3vuv]

hope the corrected pdf files help if anyone is planning on building one of these.

With the circuit divided in 3 files the plan is a bit hard to read.
The last version still has the voltage regulation messed up somewhat - the divider for the main feedback is somehow missing. The lables between the files also don't match.

Have a look yourself :https://gswagner.com/35%20V%205%20A%20Supply/

[m3vuv]

well 1hr and its looking good at 4v+ 4a so far!

[m3vuv]

neres a couple of pics of it.loaded thru my avo into a 1 ohm resistor.

[m3vuv]

and another pic.

[m3vuv]

a few more to come,hassle with the filesize limit tho as cant be assed to resize them.

[m3vuv]

and another,sideview of the guts of it - the main transfo + filter cap, bridge + 7812 heatsink,they are all in the main case,the aux tranfo+ pcb,pass transistors+ pc heatsink and fan are all on the front panel,it started life as an old pc speaker sub woofer.

[m3vuv]

last one so far untill the next blowup lol.

[m3vuv]

I lied lol,heres a summary of changes to the original pcb etc,firstly the original bridge rectifier removed and replaced with screw terminals to mount a 50a bridge offboard,secondly r4 replaced with a 1 watt resistor,one of the filter caps has had terminals fitted to its legs to allow connection to a 22000uf 68v cap offboard,a bigger heatsink added to u6,the original tip 3055 transiistors replaced with 4x BUW49 transistors with a 30amp max collector current each,along with .22 ohm 5 watt emitter resistors,u3 mounted offboard an a 2x2 inch heatsink,i think thats it,im happy the constant current mode works well and max vout is 36v and tested so far at 10a max as thats the limit of my test gear.Hope this helps others who want to build this/uprate this. 73 de m3vuv.

[m3vuv]

this is the link for the kit i got: https://www.aliexpress.com/item/32986139693.html?spm=a2g0o.cart.0.0.3e143c00nN48NA&mp=1

[not1xor1]

well i left this running overnight charging a car battery at 14v 1 amp,woke up this morning to find zero output,left it disconnected for an hour and its working againe,could that be the 7812 shutting down thru heat?,if so i plan on building this and fit offboard,is that a good plan?or just fit the existing reg offboard on a bigger heatsink?

Unless you attached the wrong schematic or are just trolling that circuit will never work because you will never get 14V and 1A out of 2 78L12 ICs.

"m3vuv" is suspecting that the LM7812 supplying the 12V control rail is shutting down.

and so ... ? Probably those are 2 LM7812 unlike the L type ones of the schematic he posted.
In any case I can't see how he can get 14V with just a single diode in series with the common.
Besides that I do not see any current regulation so where does that 1A come from?

This is the beginner section. Do you want to make beginners waste time and components with such an outrageously wrong schematic     .

[xavier60]

well i left this running overnight charging a car battery at 14v 1 amp,woke up this morning to find zero output,left it disconnected for an hour and its working againe,could that be the 7812 shutting down thru heat?,if so i plan on building this and fit offboard,is that a good plan?or just fit the existing reg offboard on a bigger heatsink?

Unless you attached the wrong schematic or are just trolling that circuit will never work because you will never get 14V and 1A out of 2 78L12 ICs.

"m3vuv" is suspecting that the LM7812 supplying the 12V control rail is shutting down.

and so ... ? Probably those are 2 LM7812 unlike the L type ones of the schematic he posted.
In any case I can't see how he can get 14V with just a single diode in series with the common.
Besides that I do not see any current regulation so where does that 1A come from?

This is the beginner section. Do you want to make beginners waste time and components with such an outrageously wrong schematic     .

The "battery at 14v 1 amp" refers to what the PSU's output was set to, to charge a battery. The circuit with the two LM7812 regulators was intended by "m3vuv" to power the PSU's control circuitry with 12V, nothing to do with 14V.

Also, through the thread I have pointed out the mistakes in the schematic. Which schematic?

[m3vuv]

my good god even i am getting lost now! lol.

[m3vuv]

well i left this running overnight charging a car battery at 14v 1 amp,woke up this morning to find zero output,left it disconnected for an hour and its working againe,could that be the 7812 shutting down thru heat?,if so i plan on building this and fit offboard,is that a good plan?or just fit the existing reg offboard on a bigger heatsink?

Unless you attached the wrong schematic or are just trolling that circuit will never work because you will never get 14V and 1A out of 2 78L12 ICs.

"m3vuv" is suspecting that the LM7812 supplying the 12V control rail is shutting down.

and so ... ? Probably those are 2 LM7812 unlike the L type ones of the schematic he posted.
In any case I can't see how he can get 14V with just a single diode in series with the common.
Besides that I do not see any current regulation so where does that 1A come from?

This is the beginner section. Do you want to make beginners waste time and components with such an outrageously wrong schematic     .

The "battery at 14v 1 amp" refers to the what the PSU's output was set to, to charge a battery. The circuit with the two LM7812 regulators was intended by "m3vuv" to power the PSU's control circuitry with 12V, nothing to do with 14V.

Also, through the thread I have pointed out the mistakes in the schematic. Which schematic?

maybe should understand what i am talking about and not troll!!!!,looks like norx1 whatever his name is, is not quite switched on with this??

[xavier60]

my good god even i am getting lost now! lol.

To clear this up, what was the intention of the circuit that you attached in  Reply #216?

[m3vuv]

was that the one with two 7812 regs?

[xavier60]

was that the one with two 7812 regs?

Yes, that one.

[m3vuv]

That schematic was thoughts on a possible solution to the 7812 shutting down,ie share the load and cut down the heat of the probblem 7812,mounting the original on a heatsink offboard seems to of fixed it tho,unless it was the heat soaking to the 431? ic tho as how they are on the pcb, means the 431 is hard against the 7812 heatsing,just a shitty layout!.

[not1xor1]

That schematic was thoughts on a possible solution to the 7812 shutting down,ie share the load and cut down the heat of the probblem 7812,mounting the original on a heatsink offboard seems to of fixed it tho,unless it was the heat soaking to the 431? ic tho as how they are on the pcb, means the 431 is hard against the 7812 heatsing,just a shitty layout!.

OK... so it is just a matter of misunderstanding... I haven't followed the whole thread and had understood you were charging the battery with that L78L12 circuit. 
(I link the image below)
I apologize.

[m3vuv]

its ok,we are only human,i didnt build the circuit as moving the 7812 offboard fitted on a 2"x2" heatsink seems to of cured it shutting down.time will tell.

[m3vuv]

I have just noticed,if i switch this on with any load connected i get zero output,if i disconnect the load and turn it on then reconnect the load its fine,any ideas whats causing this? TIA.

[xavier60]

Measure the voltage on all pins of U1 with respect to the + output terminal.

[m3vuv]

when do i do that,when it wont output with a load connected or what ?.

[xavier60]

when do i do that,when it wont output with a load connected or what ?.

While it's in the fault state, Watch out for the fault clearing while the pins are being probed.