18VDC PSU has dropped to 10v - ZD-915 desoldering station

[phreak97]

My ZD915 desoldering station lost fan speed, pump speed, and peak heating ability yeaterday. Today I did some investigation and discovered the 18v psu is only outputting 10v. Now, I know the basic idea of how a switching pau works but not well enough to quickly diagnose the faulty component. I know the transistor controls the pwm via the opto-isolator, and how the pwm drives the transformer, but I haven't the faintest idea what part is likely to cause the output to almost halve.

Any ideas what I should check?

Here's a photo of the pcb: https://drive.google.com/file/d/12Bm...w?usp=drivesdk

[stj]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

most likely possible suspects,
bad caps causing ripple/spikes,
bad opto isolator
bad voltage reference - probably marked "431"

[R_J]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

Does E3 look slightly bulged on the top? I would also replace that small electrolytic in the primary circuit

[redwire]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

ZD-1565 V2 same psu was discussed here: ZD-915 Desoldering Station when on the blink

[sam_sam_sam]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

I have 6 of these unit

Try this first hook up two 12 volt MR16 50 watt bulbs or (two 1157 automotive light ) in series and see if the power supply is shutting down and restarting

I had one of them that the mosfet had issues with it and was pulling the power supply down
This is reason for having you check the power supply by it self do not run this power supply with out the heat sink installed you will fry the switching power supply regulator ic chip if you do with a load on it

If it is do the following

The first you need to do is is replace the switching regulator ic chip this is the ic chip that has 5 or 6 pins to it and replace of the capacitors on this board ( I have had to change a few of them before on these units


Look at the switching power supply regulator ic chip it hard to tell in that picture if it has a crack at the top of it or not

as mentioned earlier about the optic sensor ic chip and the voltage reference ic chip it would not hurt to maybe replace that as well or at least check it to make sure it is working correctly or not

The next thing is if you have a lab power supply power the temperature controller board with ( only 12 volts not 18 volts that it normally works at ) with out the Desoldiering Gun hook to the controller board and measure the current of the board it should not be more than 30 or 40 milliamperes if it higher than check the surface mount capacitors on that board for any of them are getting real warm it has happened to me before

Also check the fan controller board and see if it has resistors in it or has an ic chip in it there are two versions of this unit the earlier version and the later version

One note about this switching power supply it claims to able to put out 15 amps me personally it would be lucky on a good day to put out maybe 10 amp with out straining

[sam_sam_sam]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

If you are thinking about running this off of another 18 volt switching power supply
PLEASE read this post first

You can however you need to supply it with + 5 volts and - 5 volts for temperature controller to work right ( this switching power supply does some weird things ) that if you try to run it off of pure 18 volts dc power supply you will have problems if use the setup for the heater controller mosfet and the pump controller mosfet

You can however use a PWM power supply controller and a 3D heater bed controller which has to be modified to work off 3 volts not 12 volts for the optic sensor and use one for each of the heater element and the vacuum pump

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

I have 6 of these unit

Try this first hook up two 12 volt MR16 50 watt bulbs or (two 1157 automotive light ) in series and see if the power supply is shutting down and restarting

I had one of them that the mosfet had issues with it and was pulling the power supply down
This is reason for having you check the power supply by it self do not run this power supply with out the heat sink installed you will fry the switching power supply regulator ic chip if you do with a load on it

If it is do the following

The first you need to do is is replace the switching regulator ic chip this is the ic chip that has 5 or 6 pins to it and replace of the capacitors on this board ( I have had to change a few of them before on these units


Look at the switching power supply regulator ic chip it hard to tell in that picture if it has a crack at the top of it or not

as mentioned earlier about the optic sensor ic chip and the voltage reference ic chip it would not hurt to maybe replace that as well or at least check it to make sure it is working correctly or not

The next thing is if you have a lab power supply power the temperature controller board with ( only 12 volts not 18 volts that it normally works at ) with out the Desoldiering Gun hook to the controller board and measure the current of the board it should not be more than 30 or 40 milliamperes if it higher than check the surface mount capacitors on that board for any of them are getting real warm it has happened to me before

Also check the fan controller board and see if it has resistors in it or has an ic chip in it there are two versions of this unit the earlier version and the later version

One note about this switching power supply it claims to able to put out 15 amps me personally it would be lucky on a good day to put out maybe 10 amp with out straining

Thanks! I'll do those things and post back. The fan box has two resistors inside and the fan is labelled 24v

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

Ok it’s working now but i’m not super confident that it’s actually fixed. I reflowed the vref chip, pwm chip, and mosfets, then put it back onto the heat sink with some breakout wires to put a load on it. It worked fine straight away. I did hear a buzzing sound from the transformer for a short while though which was odd..

[stj]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

maybe it needs soldering or the windings/core are loose.

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

maybe it needs soldering or the windings/core are loose.

Yeah maybe I'll reflow that too then just see how it goes

[sam_sam_sam]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

Yeah maybe I'll reflow that too then just see how it goes

I have a question for you when you use this Desoldiering Gun unit how many hours do you have it on in one session

Because when I use mine it might be on for hours

[petehall347]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

wondering why the soldering gave up so soon ? lead free i guess .

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

I have a question for you when you use this Desoldiering Gun unit how many hours do you have it on in one session

Because when I use mine it might be on for hours

Usually an hour or so at a time, sometimes more, sometimes less.


The solder failed because it's badly soldered in the first place

[sam_sam_sam]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

It probably would not hurt to resolder all of solder joints on the power supply board just for good measure yeah I know it a pain in the a** but you might not have any more problems with for a while

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

It probably would not hurt to resolder all of solder joints on the power supply board just for good measure yeah I know it a pain in the a** but you might not have any more problems with for a while

Probably not a terrible idea

[stj]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

wondering why the soldering gave up so soon ? lead free i guess .

lead-free is stronger,
these units vibrate when the pump is on, and the soldering may not be great to begin with.

my experience with chinese boards, SMD are great but throughhole can be questionable.
probably because SMD boards are machine-assembled and not stuffed & soldered by lines of bored women.

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

lead-free is stronger,
these units vibrate when the pump is on, and the soldering may not be great to begin with.

my experience with chinese boards, SMD are great but throughhole can be questionable.
probably because SMD boards are machine-assembled and not stuffed & soldered by lines of bored women.

Stronger yes but more susceptible to cracking with repeated expansion and contraction.

[stj]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

there is no expansion and contraction in these - they are fan cooled.

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

there is no expansion and contraction in these - they are fan cooled.

These are just built poorly.

[phreak97]

Re: 18VDC PSU has dropped to 10v - ZD-915 desoldering station

I have 6 of these unit

Try this first hook up two 12 volt MR16 50 watt bulbs or (two 1157 automotive light ) in series and see if the power supply is shutting down and restarting

I had one of them that the mosfet had issues with it and was pulling the power supply down
This is reason for having you check the power supply by it self do not run this power supply with out the heat sink installed you will fry the switching power supply regulator ic chip if you do with a load on it

If it is do the following

The first you need to do is is replace the switching regulator ic chip this is the ic chip that has 5 or 6 pins to it and replace of the capacitors on this board ( I have had to change a few of them before on these units


Look at the switching power supply regulator ic chip it hard to tell in that picture if it has a crack at the top of it or not

as mentioned earlier about the optic sensor ic chip and the voltage reference ic chip it would not hurt to maybe replace that as well or at least check it to make sure it is working correctly or not

The next thing is if you have a lab power supply power the temperature controller board with ( only 12 volts not 18 volts that it normally works at ) with out the Desoldiering Gun hook to the controller board and measure the current of the board it should not be more than 30 or 40 milliamperes if it higher than check the surface mount capacitors on that board for any of them are getting real warm it has happened to me before

Also check the fan controller board and see if it has resistors in it or has an ic chip in it there are two versions of this unit the earlier version and the later version

One note about this switching power supply it claims to able to put out 15 amps me personally it would be lucky on a good day to put out maybe 10 amp with out straining

Ok as it is now it works after maybe 10-20 seconds of flashing error/heat and beeping at about 4Hz, seems to be overloading, shutting off, coming back on. Doesn't do it with the gun unplugged. It's making a high pitched noise for a while too, the psu is still not happy. Annoyingly I reassembled it. Do you know the part numbers of the chips and mosfets? If theyre cheap enough I might just shotgun the lot and be done with it. All caps had low esr.