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Volteq HY series bench supply, wrong current display

Started by Joerg October 16, 2021
With a lot of Sherlock Holmes sniffing I could find it but the 
schematics for those things are horrid.

https://www.audio-thai.com/index.php?topic=15325.0

I have the HY3030EX (30V/30A). The problem is that it shows arbitrarily 
high currents that aren't there and they are proportionate to the set 
voltage. Shows 11A at max voltage without any load. Of course, nothing 
becomes hot because those are fake numbers. Once it hits overcurrent it 
locks itself up and the output voltage drops to zero. Has to be 
power-cycled it every time.

The internal connections appear to be ok.

Maybe it ain't worth repairing but maybe one of you had that happen?

-- 
Regards, Joerg

http://www.analogconsultants.com/
On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <news@analogconsultants.com>
wrote:

>HY3030EX
Did you check out the A/D reference? RL
On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <news@analogconsultants.com>
wrote:

>With a lot of Sherlock Holmes sniffing I could find it but the >schematics for those things are horrid. > >https://www.audio-thai.com/index.php?topic=15325.0 > >I have the HY3030EX (30V/30A). The problem is that it shows arbitrarily >high currents that aren't there and they are proportionate to the set >voltage. Shows 11A at max voltage without any load. Of course, nothing >becomes hot because those are fake numbers. Once it hits overcurrent it >locks itself up and the output voltage drops to zero. Has to be >power-cycled it every time. > >The internal connections appear to be ok. > >Maybe it ain't worth repairing but maybe one of you had that happen?
Sounds like a typicall issue for these supplies. We use quite a few of them and have seen this problem too. The schematics are still good enough to at least try and fix them. I can see some design flaws especialy in their output current limiting that can break the output FET if you short the output at high voltage. boB
On 10/16/21 2:49 PM, legg wrote:
> On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <news@analogconsultants.com> > wrote: > >> HY3030EX > > Did you check out the A/D reference? >
Looks ok. The main board is sending a voltage up to the ADC for the current display which varies with the set voltage (but shouldn't). The current signaling runs in the tens of millivolts which was a poor design decision and they had to add a CM toroid, probably to get that quiet. -- Regards, Joerg http://www.analogconsultants.com/
On 10/16/21 3:18 PM, boB wrote:
> On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <news@analogconsultants.com> > wrote: > >> With a lot of Sherlock Holmes sniffing I could find it but the >> schematics for those things are horrid. >> >> https://www.audio-thai.com/index.php?topic=15325.0 >> >> I have the HY3030EX (30V/30A). The problem is that it shows arbitrarily >> high currents that aren't there and they are proportionate to the set >> voltage. Shows 11A at max voltage without any load. Of course, nothing >> becomes hot because those are fake numbers. Once it hits overcurrent it >> locks itself up and the output voltage drops to zero. Has to be >> power-cycled it every time. >> >> The internal connections appear to be ok. >> >> Maybe it ain't worth repairing but maybe one of you had that happen? > > > Sounds like a typicall issue for these supplies. We use quite a few > of them and have seen this problem too. > > The schematics are still good enough to at least try and fix them. >
I could try but got so many projects already. I was hoping someone would say "Oh, that happened to me as well and the fault turned out to be ..."
> I can see some design flaws especialy in their output current limiting > that can break the output FET if you short the output at high voltage. >
Yeah, the design is sub-optimal. Many of the parts are pretty robust though and they gave it a way more massive heat sink than my ham radio SMPS. -- Regards, Joerg http://www.analogconsultants.com/
On Saturday, October 16, 2021 at 10:37:12 PM UTC, Joerg wrote:
> On 10/16/21 3:18 PM, boB wrote: > > On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <ne...@analogconsultants.com> > > wrote: > > > >> With a lot of Sherlock Holmes sniffing I could find it but the > >> schematics for those things are horrid. > >> > >> https://www.audio-thai.com/index.php?topic=15325.0 > >> > >> I have the HY3030EX (30V/30A). The problem is that it shows arbitrarily > >> high currents that aren't there and they are proportionate to the set > >> voltage. Shows 11A at max voltage without any load. Of course, nothing > >> becomes hot because those are fake numbers. Once it hits overcurrent it > >> locks itself up and the output voltage drops to zero. Has to be > >> power-cycled it every time. > >> > >> The internal connections appear to be ok. > >> > >> Maybe it ain't worth repairing but maybe one of you had that happen? > > > > > > Sounds like a typicall issue for these supplies. We use quite a few > > of them and have seen this problem too. > > > > The schematics are still good enough to at least try and fix them. > > > I could try but got so many projects already. I was hoping someone would > say "Oh, that happened to me as well and the fault turned out to be ..." > > I can see some design flaws especialy in their output current limiting > > that can break the output FET if you short the output at high voltage. > > > Yeah, the design is sub-optimal. Many of the parts are pretty robust > though and they gave it a way more massive heat sink than my ham radio SMPS. > -- > Regards, Joerg > > http://www.analogconsultants.com/
Hi Joerg, My first inclination is to check the current-sense resistor "R206". That alone, if raised in resistance, or opened up, would cause such behavior. = RS
 Rich S wrote:
=================
> > >> With a lot of Sherlock Holmes sniffing I could find it but the > > >> schematics for those things are horrid. > > >> > > >> https://www.audio-thai.com/index.php?topic=15325.0 > > >> > > My first inclination is to check the > current-sense resistor "R206".
** Where the heck is that ? The posted schem is illegible.
> That alone, if raised in resistance, > or opened up, > would cause such behavior.
** But no operation either. ..... Phil
17.10.21 01:48, Phil Allison  wrote:
> Rich S wrote: >================= >> > >> With a lot of Sherlock Holmes sniffing I could find it but the >> > >> schematics for those things are horrid. >> > >> >> > >> https://www.audio-thai.com/index.php?topic=15325.0 >> > >> >> >> My first inclination is to check the >> current-sense resistor "R206". > >** Where the heck is that ? > > The posted schem is illegible. >
Click on the PDF link after the schematics images
>> That alone, if raised in resistance, >> or opened up, >> would cause such behavior. > >** But no operation either. > > >..... Phil
-- Klaus
On Sat, 16 Oct 2021 15:32:46 -0700, Joerg <news@analogconsultants.com>
wrote:

>On 10/16/21 2:49 PM, legg wrote: >> On Sat, 16 Oct 2021 13:00:19 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> HY3030EX >> >> Did you check out the A/D reference? >> > >Looks ok. The main board is sending a voltage up to the ADC for the >current display which varies with the set voltage (but shouldn't). The >current signaling runs in the tens of millivolts which was a poor design >decision and they had to add a CM toroid, probably to get that quiet.
In Schematic, it looks like current sensing is completely independent - A jellybean 7107 circuit. No controller influence. Check isolated supply levels for this section. RL
On 10/16/21 1:00 PM, Joerg wrote:
> With a lot of Sherlock Holmes sniffing I could find it but the > schematics for those things are horrid. > > https://www.audio-thai.com/index.php?topic=15325.0 > > I have the HY3030EX (30V/30A). The problem is that it shows arbitrarily > high currents that aren't there and they are proportionate to the set > voltage. Shows 11A at max voltage without any load. Of course, nothing > becomes hot because those are fake numbers. Once it hits overcurrent it > locks itself up and the output voltage drops to zero. Has to be > power-cycled it every time. > > The internal connections appear to be ok. > > Maybe it ain't worth repairing but maybe one of you had that happen? >
Gentlemen, found it. It wasn't just one poor solder joint but three. All in the connection from the big current shunt to the 7107 display board for the current display, plus one on the voltage display board. Not sure how but this also caused the power supply to lock up. If someone else has that happen: Check the blue and black wires going through a toroid towards the back of the unit. They measure sort of ok but give them a tug near the solder joints and the resistance changes. I can't remember when I last saw such a poor solder job. Basically consisting of splats and dull blobs. I'll have to take the whole thing apart and resolder the wires. Considering that they also jammed in lots of the screws because many things didn't line up that won't be fun. -- Regards, Joerg http://www.analogconsultants.com/