Diagnose Inverter motor dirve - aircon unit

[Mr Sandman]

Hi all,

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at the
three large electrolytic caps which show 43vdc, but oddly 85v ac. The
expected voltage at the capacitors should be 180-380vac.

I am a low level electronics experience chap, so need some advice on how
these caps would typically be charged.

They are used, as i understand it, to smooth the supply to the variable
speed fan and compressor in the aircon unit.

Looking at the other test points on main pcb, everything else checks out ok.

Here is a link to the (large) manual for the aircon unit if any one fancies
helping me out.

http://www.manualslib.com/download/896742/Sinclair-Ash-18aie.html

Id apreciate any help/guidance,

Many thanks,

Steve

 

[Phil Allison]

Mr Sandman wrote:

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at the
three large electrolytic caps which show 43vdc, but oddly 85v ac. The
expected voltage at the capacitors should be 180-380vac.

** Gobbledgook.

Large electros acquire *DC voltage* after being charged.

What sort of multimeter / voltmeter are you using ??

An old moving coil one by any chance - many of the latter read double voltage on the AC ranges compared to the DC ranges if mistakenly used for DC.

Reverse the probes and the reading drops to zero.



.... Phil

 

[Rheilly Phoull]

On 23/07/2016 3:18 PM, Mr Sandman wrote:

Hi all,

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at
the three large electrolytic caps which show 43vdc, but oddly 85v ac.
The expected voltage at the capacitors should be 180-380vac.

I am a low level electronics experience chap, so need some advice on how
these caps would typically be charged.

They are used, as i understand it, to smooth the supply to the variable
speed fan and compressor in the aircon unit.

Looking at the other test points on main pcb, everything else checks out
ok.

Here is a link to the (large) manual for the aircon unit if any one
fancies helping me out.

http://www.manualslib.com/download/896742/Sinclair-Ash-18aie.html

Id apreciate any help/guidance,

Many thanks,

Steve

You have worked through the logic of the trouble shooting guide for the
charge failure ??

 

[Mr Sandman]

"Rheilly Phoull" wrote in message
news:d7GdnaRHmZ7dvg7KnZ2dnUU7-L3NnZ2d@westnet.com.au...

On 23/07/2016 3:18 PM, Mr Sandman wrote:

Hi all,

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at
the three large electrolytic caps which show 43vdc, but oddly 85v ac.
The expected voltage at the capacitors should be 180-380vac.

I am a low level electronics experience chap, so need some advice on how
these caps would typically be charged.

They are used, as i understand it, to smooth the supply to the variable
speed fan and compressor in the aircon unit.

Looking at the other test points on main pcb, everything else checks out
ok.

Here is a link to the (large) manual for the aircon unit if any one
fancies helping me out.

http://www.manualslib.com/download/896742/Sinclair-Ash-18aie.html

Id apreciate any help/guidance,

Many thanks,

Steve

You have worked through the logic of the trouble shooting guide for the
charge failure ??

yes i have, i went through the tests for main board, the only test that was
wrong was test three, giving readings i mentioned.

There is no further troubleshooting that would identify the component that
is faulty as i could see in the manual.

cheers

steve

 

[Mr Sandman]

"Phil Allison" wrote in message
news:f3fd34de-e385-4ca6-bb90-aedc4018f777@googlegroups.com...

Mr Sandman wrote:

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at the
three large electrolytic caps which show 43vdc, but oddly 85v ac. The
expected voltage at the capacitors should be 180-380vac.

** Gobbledgook.

Large electros acquire *DC voltage* after being charged.

What sort of multimeter / voltmeter are you using ??

An old moving coil one by any chance - many of the latter read double
voltage on the AC ranges compared to the DC ranges if mistakenly used for
DC.

Reverse the probes and the reading drops to zero.

---------

I am using a digital multimeter, a fairly decent one. Probing the caps
directly i get the voltages i mentioned. is this showing ripple indication a
bad capacitor rather than a bad charging component? the caps show no signs
of leakage or expansion externally.

thanks for the help, sorry im a newbie, and dyslexic so may sound muddled.

cheers

steve

 

[Rheilly Phoull]

On 23/07/2016 10:18 PM, Mr Sandman wrote:

"Rheilly Phoull" wrote in message
news:d7GdnaRHmZ7dvg7KnZ2dnUU7-L3NnZ2d@westnet.com.au...

On 23/07/2016 3:18 PM, Mr Sandman wrote:
Hi all,

I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at
the three large electrolytic caps which show 43vdc, but oddly 85v ac.
The expected voltage at the capacitors should be 180-380vac.

I am a low level electronics experience chap, so need some advice on how
these caps would typically be charged.

They are used, as i understand it, to smooth the supply to the variable
speed fan and compressor in the aircon unit.

Looking at the other test points on main pcb, everything else checks out
ok.

Here is a link to the (large) manual for the aircon unit if any one
fancies helping me out.

http://www.manualslib.com/download/896742/Sinclair-Ash-18aie.html

Id apreciate any help/guidance,

Many thanks,

Steve

You have worked through the logic of the trouble shooting guide for the
charge failure ??

yes i have, i went through the tests for main board, the only test that
was wrong was test three, giving readings i mentioned.

There is no further troubleshooting that would identify the component
that is faulty as i could see in the manual.

cheers

steve

So as Phil says, you should be checking for DC at the caps and if that
is only 43vdc then the fault is in the charging board. Are you intending
to repair the board or replace it?

 

[Phil Allison]

Mr Sandman wrote:

Mr Sandman wrote:


I have an aircon unit that failed. Fault code 'PU' says the capacitor
charging circuit failed, this is confirmed by checking the voltage at the
three large electrolytic caps which show 43vdc, but oddly 85v ac. The
expected voltage at the capacitors should be 180-380vac.


** Gobbledgook.

Large electros acquire *DC voltage* after being charged.

What sort of multimeter / voltmeter are you using ??

An old moving coil one by any chance - many of the latter read double
voltage on the AC ranges compared to the DC ranges if mistakenly used for
DC.

Reverse the probes and the reading drops to zero.

---------

I am using a digital multimeter, a fairly decent one.

** Make and model - please !

Probing the caps
directly i get the voltages i mentioned.

** What about when you reverse the leads?

FYI:

There has got to be at least one DMM maker who uses a half wave rectifier directly coupled to the DC meter circuit - mimicking how an moving coil multi-meter does the same job.



.... Phil