We're trying to troubleshoot an ancient power supply for a high pressure
mercury arc lamp. Theres a SOLA transformer that feeds into a rectifier
stack and then two large filter caps. The output from the filter caps is
only 60 vdc while they are rated for 150 wvdc. Every SOLA I've seen had
a 115 vac regulated output. Theres no specs except for the SOLA part
number "21-877". Do they all output 115 vac or were there lower voltage
models? My guess is that the oil capacitor has gone bad and its no
longer regulating correctly. Any thoughts?


Adam

"Adam Stouffer" wrote in message
...
We're trying to troubleshoot an ancient power supply for a
high pressure mercury arc lamp. Theres a SOLA transformer
that feeds into a rectifier stack and then two large
filter caps. The output from the filter caps is only 60
vdc while they are rated for 150 wvdc. Every SOLA I've
seen had a 115 vac regulated output. Theres no specs
except for the SOLA part number "21-877". Do they all
output 115 vac or were there lower voltage models? My
guess is that the oil capacitor has gone bad and its no
longer regulating correctly. Any thoughts?


Adam
Sola transformers were made for all sorts of output
voltages. The caps do go bad which changes the volage at the
output and can prevent the transformer from regulating. I
also have a couple of old Sola's which do not regulate at
the correct voltage despite new caps of the right value. I
have never been able to find out what causes this.
Note that the capacitors must be non-polarized types.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Adam Stouffer wrote:
We're trying to troubleshoot an ancient power supply for a high pressure
mercury arc lamp. Theres a SOLA transformer that feeds into a rectifier
stack and then two large filter caps. The output from the filter caps is
only 60 vdc while they are rated for 150 wvdc. Every SOLA I've seen had
a 115 vac regulated output. Theres no specs except for the SOLA part
number "21-877". Do they all output 115 vac or were there lower voltage
models? My guess is that the oil capacitor has gone bad and its no
longer regulating correctly. Any thoughts?

Could be, stick it on a bridge and see. Is it leaking?

It may not have a 115vac regulated output. Some of the Sola
transformers were step-up or step-down. A call to Sola should identify
the part number. I have seen some with 24VAC secondaries.

Is the thing rated for 60cycle use? A 50 cycle ferroresonant transformer
will go berserk on 60 cycle power.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Richard Knoppow wrote:
Sola transformers were made for all sorts of output
voltages. The caps do go bad which changes the volage at the
output and can prevent the transformer from regulating. I
also have a couple of old Sola's which do not regulate at
the correct voltage despite new caps of the right value. I
have never been able to find out what causes this.

Most probably load. These things MUST be loaded to half the rated
maximum load for proper regulation.

Note that the capacitors must be non-polarized types.

Film caps are recommended.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:

Could be, stick it on a bridge and see. Is it leaking?

Not physically Tomorrow I'll do some testing.


It may not have a 115vac regulated output. Some of the Sola
transformers were step-up or step-down. A call to Sola should identify
the part number. I have seen some with 24VAC secondaries.

I tried calling them but the guy basically laughed and told me good
luck. My understanding is its the Sola name but owned by a different
company. I tried searching to see if anyone had scans of an old catalog
but no luck.


Is the thing rated for 60cycle use? A 50 cycle ferroresonant transformer
will go berserk on 60 cycle power.
--scott


Its definitely 60 cycle. The supply runs a "super pressure" mercury arc
lamp for an optical comparator. Up until yesterday its had regular use
for years but now the lamp will not sustain an arc. The only problem
that stands out is seeing 60 volts on the caps rated for 150. Thanks for
the quick reply.


Adam

"Scott Dorsey" wrote in message
...
Richard Knoppow wrote:
Sola transformers were made for all sorts of output
voltages. The caps do go bad which changes the volage at
the
output and can prevent the transformer from regulating. I
also have a couple of old Sola's which do not regulate at
the correct voltage despite new caps of the right value. I
have never been able to find out what causes this.

Most probably load. These things MUST be loaded to half
the rated
maximum load for proper regulation.

Note that the capacitors must be non-polarized types.

Film caps are recommended.
--scott

These don't regulate at the correct voltage regardless
of load. My good Sola's have just about the specified
voltage open circuit.


--

--
Richard Knoppow
Los Angeles
WB6KBL

Adam Stouffer wrote:

Its definitely 60 cycle. The supply runs a "super pressure" mercury arc
lamp for an optical comparator. Up until yesterday its had regular use
for years but now the lamp will not sustain an arc. The only problem
that stands out is seeing 60 volts on the caps rated for 150. Thanks for
the quick reply.

Get the data sheet for the arc lamp itself and see what voltages it is
supposed to have for starting and running. Then work back from there.

If I saw a low voltage on the supply filter caps I would check the
rectifiers before anything else.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

(Scott Dorsey) writes:

Adam Stouffer wrote:

Its definitely 60 cycle. The supply runs a "super pressure" mercury arc
lamp for an optical comparator. Up until yesterday its had regular use
for years but now the lamp will not sustain an arc. The only problem
that stands out is seeing 60 volts on the caps rated for 150. Thanks for
the quick reply.

Get the data sheet for the arc lamp itself and see what voltages it is
supposed to have for starting and running. Then work back from there.

If I saw a low voltage on the supply filter caps I would check the
rectifiers before anything else.
--scott

It appears to me that OP seems to think that BECAUSE the caps are rated
for 150WVDC that 60V is "abnormal". 150% over-rate on caps is not even
noteworthy.