TTi TS3021S Power Supply Calibration Issue

M

MarkB

Guest
Hi

I have a TTi (Thurlby Thandar) TS3021S Bench Power Supply which works fine
but has a slight calibration issue with its voltage display.

According to the specifications, the voltage display should be accurate to
0.2%. Mine always reads low by aboiut 1.5%.

I suspect I can fix this by a simple adjustment of an internal trimmer
resistor. But which one? There are approx. 10 on the main circuit board.

Does anybody have a service manual, circuit diagram, or any other
information that would help me fix this problem?

Thanks in advance for your help.

Mark
 
MarkB <markb@conceptfp.+.com> wrote in message
news:dpednSEJNPr8nJLWnZ2dnUVZ7omdnZ2d@brightview.co.uk...
Hi

I have a TTi (Thurlby Thandar) TS3021S Bench Power Supply which works fine
but has a slight calibration issue with its voltage display.

According to the specifications, the voltage display should be accurate to
0.2%. Mine always reads low by aboiut 1.5%.

I suspect I can fix this by a simple adjustment of an internal trimmer
resistor. But which one? There are approx. 10 on the main circuit board.

Does anybody have a service manual, circuit diagram, or any other
information that would help me fix this problem?

Thanks in advance for your help.

Mark
Click to expand...
Mark each trimmer and also measure whatever the in circuit resistance of
each trimmer is, before speculative adjusting. Perhaps create a WWW repair
brief for others while at it


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
N_Cook <diverse@tcp.co.uk> wrote in message
news:heo24t$qnc$1@news.eternal-september.org...
MarkB <markb@conceptfp.+.com> wrote in message
news:dpednSEJNPr8nJLWnZ2dnUVZ7omdnZ2d@brightview.co.uk...
Hi

I have a TTi (Thurlby Thandar) TS3021S Bench Power Supply which works
fine
but has a slight calibration issue with its voltage display.

According to the specifications, the voltage display should be accurate
to
0.2%. Mine always reads low by aboiut 1.5%.

I suspect I can fix this by a simple adjustment of an internal trimmer
resistor. But which one? There are approx. 10 on the main circuit
board.

Does anybody have a service manual, circuit diagram, or any other
information that would help me fix this problem?

Thanks in advance for your help.

Mark



Mark each trimmer and also measure whatever the in circuit resistance of
each trimmer is, before speculative adjusting. Perhaps create a WWW
repair
brief for others while at it


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Click to expand...
JIC check the "trimmer" ( in circuit) resistance with probes either way
round and note if different

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
I am still hoping someone might be able to tell me which trimmer has the
effect I desire. Experimenting with the trimmers is the final option and if
it comes to that, I might not bother since the unit basically works as is.

But thanks for your advice. The point about measuring the resistance both
ways is a good one - I might not have thought of that.

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:heo392$4aj$1@news.eternal-september.org...
N_Cook <diverse@tcp.co.uk> wrote in message
news:heo24t$qnc$1@news.eternal-september.org...
MarkB <markb@conceptfp.+.com> wrote in message
news:dpednSEJNPr8nJLWnZ2dnUVZ7omdnZ2d@brightview.co.uk...
Hi

I have a TTi (Thurlby Thandar) TS3021S Bench Power Supply which works
fine
but has a slight calibration issue with its voltage display.

According to the specifications, the voltage display should be accurate
to
0.2%. Mine always reads low by aboiut 1.5%.

I suspect I can fix this by a simple adjustment of an internal trimmer
resistor. But which one? There are approx. 10 on the main circuit
board.

Does anybody have a service manual, circuit diagram, or any other
information that would help me fix this problem?

Thanks in advance for your help.

Mark



Mark each trimmer and also measure whatever the in circuit resistance of
each trimmer is, before speculative adjusting. Perhaps create a WWW
repair
brief for others while at it


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




JIC check the "trimmer" ( in circuit) resistance with probes either way
round and note if different

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Click to expand...
 
On Thu, 26 Nov 2009 22:29:53 -0000, "MarkB" <markb@conceptfp.+.com> wrote:

Hi

I have a TTi (Thurlby Thandar) TS3021S Bench Power Supply which works fine
but has a slight calibration issue with its voltage display.

According to the specifications, the voltage display should be accurate to
0.2%. Mine always reads low by aboiut 1.5%.

I suspect I can fix this by a simple adjustment of an internal trimmer
resistor. But which one? There are approx. 10 on the main circuit board.
Click to expand...
Is the meter a complete panel meter (separate item) with only a few connections
or is it just a display with the A-D on the main PCB?
If it is a panel meter then you could look up the model and/or check the voltage
at its input connections.
If it is just a display then see what chip is driving it and look up the pinout
of that to see where the analogue inputs are


--
Geo
 
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