On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for >>smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for >smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com> >wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for >>smoothing purposes. My question is: how much ripple should I expect to >>see across that cap if all's working well? I have to say I'm seeing a >>*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have checked the frequeny of the ripple whilst I was at it.
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap in a Marconi RF signal generator and it's
finding its way to the RF output, which of course should ideally have
zero ripple on it. The aforementioned cap tests fine WRT ESR and
capacitance in-circuit, I should add.
Thanks,
CD.
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap in a Marconi RF signal generator and it's
finding its way to the RF output, which of course should ideally have
zero ripple on it. The aforementioned cap tests fine WRT ESR and
capacitance in-circuit, I should add.
Thanks,
CD.
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for
smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have
checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of
the diodes haas gone open circuit. Another possibility is a fault in
some other part of the circuit that is drawing too much current - you
might smell something getting hot.
On Sun, 25 Feb 2024 19:16:24 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for
smoothing purposes. My question is: how much ripple should I expect to >> >>see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have
checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of
the diodes haas gone open circuit. Another possibility is a fault in
some other part of the circuit that is drawing too much current - you
might smell something getting hot.
There's nothing getting hot, but the ripple had a definite saw-tooth
shape to it, which could be indicative of abnormal operation.
Shame there are no schematics available anywhere on the net; always
makes troubleshooting much harder.
On Mon, 26 Feb 2024 09:59:12 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:16:24 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com> >>>>>> wrote:
So - in the case of a linear power supply - the rectified output of >>>>>>> the transformer typically goes straight to a big old storage cap for >>>>>>> smoothing purposes. My question is: how much ripple should I expect to >>>>>>> see across that cap if all's working well? I have to say I'm seeing a >>>>>>> *lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have >>>>> checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of >>>> the diodes haas gone open circuit. Another possibility is a fault in
some other part of the circuit that is drawing too much current - you
might smell something getting hot.
There's nothing getting hot, but the ripple had a definite saw-tooth
shape to it, which could be indicative of abnormal operation.
Shame there are no schematics available anywhere on the net; always
makes troubleshooting much harder.
Is the rectifier circuit half-wave or full-wave? If the latter, is the
ripple also full wave?
Marconi have used these things (not these exact components of course,
but the same footprint/pinout:
http://tinyurl.com/5ab3fd7h
So full wave. Is the ripple full wave? Well, I did mean to check the frequency of it, but other stuff got in the way. I'm going to have to re-investigate a bit more thoroughly later in the week.
Some designers allowed a larger amount of ripple on the first capacitor
to reduce the heating of the mains transformer (the copper losses are
proportional to I squared, so by allowing a longer charging time per
cycle at a lower current, they achieved lower overall resistance
losses). As long as the lowest part of the ripple was sufficiently far
above the stabilised output, a series stabiliser could cope with it.
Is the 'stabilised' line actually stable or is there ripple on it in the
form of a series of little notches?
Not sure what you mean by stabilised line. There are two secondary
windings on the mains transformer which go into separate bridge
rectifiiers of the type linked to above and then on downstream to the
first tank caps. One line has a ton of ripple on it, the other very
little indeed. Again, I'll need to go back and pay more attention to
what's going on here. I've missed out too many important details.
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:16:24 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for
smoothing purposes. My question is: how much ripple should I expect to >> >> >>see across that cap if all's working well? I have to say I'm seeing a >> >> >>*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have
checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of
the diodes haas gone open circuit. Another possibility is a fault in
some other part of the circuit that is drawing too much current - you
might smell something getting hot.
There's nothing getting hot, but the ripple had a definite saw-tooth
shape to it, which could be indicative of abnormal operation.
Shame there are no schematics available anywhere on the net; always
makes troubleshooting much harder.
Is the rectifier circuit half-wave or full-wave? If the latter, is the >ripple also full wave?
Some designers allowed a larger amount of ripple on the first capacitor
to reduce the heating of the mains transformer (the copper losses are >proportional to I squared, so by allowing a longer charging time per
cycle at a lower current, they achieved lower overall resistance
losses). As long as the lowest part of the ripple was sufficiently far
above the stabilised output, a series stabiliser could cope with it.
Is the 'stabilised' line actually stable or is there ripple on it in the
form of a series of little notches?
On 26 Feb 2024 at 10:16:41 GMT, "Cursitor Doom" <cd@notformail.com> wrote:
On Mon, 26 Feb 2024 09:59:12 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:16:24 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com> >>>>>>> wrote:
So - in the case of a linear power supply - the rectified output of >>>>>>>> the transformer typically goes straight to a big old storage cap for >>>>>>>> smoothing purposes. My question is: how much ripple should I expect to >>>>>>>> see across that cap if all's working well? I have to say I'm seeing a >>>>>>>> *lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have >>>>>> checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of >>>>> the diodes haas gone open circuit. Another possibility is a fault in >>>>> some other part of the circuit that is drawing too much current - you >>>>> might smell something getting hot.
There's nothing getting hot, but the ripple had a definite saw-tooth
shape to it, which could be indicative of abnormal operation.
Shame there are no schematics available anywhere on the net; always
makes troubleshooting much harder.
Is the rectifier circuit half-wave or full-wave? If the latter, is the
ripple also full wave?
Marconi have used these things (not these exact components of course,
but the same footprint/pinout:
http://tinyurl.com/5ab3fd7h
So full wave. Is the ripple full wave? Well, I did mean to check the
frequency of it, but other stuff got in the way. I'm going to have to
re-investigate a bit more thoroughly later in the week.
Some designers allowed a larger amount of ripple on the first capacitor
to reduce the heating of the mains transformer (the copper losses are
proportional to I squared, so by allowing a longer charging time per
cycle at a lower current, they achieved lower overall resistance
losses). As long as the lowest part of the ripple was sufficiently far
above the stabilised output, a series stabiliser could cope with it.
Is the 'stabilised' line actually stable or is there ripple on it in the >>> form of a series of little notches?
Not sure what you mean by stabilised line. There are two secondary
windings on the mains transformer which go into separate bridge
rectifiiers of the type linked to above and then on downstream to the
first tank caps. One line has a ton of ripple on it, the other very
little indeed. Again, I'll need to go back and pay more attention to
what's going on here. I've missed out too many important details.
Older practice, when active devices were expensive and bulky was to have an >active stabiliser circuit (which also got rid of the ripple) directly after >the power supply. Nowadays they tend to have voltage regulators for each >module or circuit, local to that module. If you have the latter arrangement I >would be looking for ripple on the output of each local regulator rather than >the main power supply. Or the high ripple could be due to excessive current >being drawn from one power supply. Anything getting excessively hot?
On Mon, 26 Feb 2024 09:59:12 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:16:24 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Sun, 25 Feb 2024 19:40:48 +0100, HW <none@no.no> wrote:
On Sun, 25 Feb 2024 18:01:19 +0000, Cursitor Doom <cd@notformail.com> >> >> >wrote:
So - in the case of a linear power supply - the rectified output of >> >> >>the transformer typically goes straight to a big old storage cap for >> >> >>smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a >> >> >>*lot* of ripple on this cap
Check if a diode in the bridge rectifier has failed.
Good idea! I must admit I'd overlooked that possibility. I should have >> >> checked the frequeny of the ripple whilst I was at it.
The shape of the ripple will tell you if that has happened or if one of >> >the diodes haas gone open circuit. Another possibility is a fault in
some other part of the circuit that is drawing too much current - you
might smell something getting hot.
There's nothing getting hot, but the ripple had a definite saw-tooth
shape to it, which could be indicative of abnormal operation.
Shame there are no schematics available anywhere on the net; always
makes troubleshooting much harder.
Is the rectifier circuit half-wave or full-wave? If the latter, is the >ripple also full wave?
Marconi have used these things (not these exact components of course,
but the same footprint/pinout:
http://tinyurl.com/5ab3fd7h
So full wave. Is the ripple full wave? Well, I did mean to check the frequency of it, but other stuff got in the way. I'm going to have to re-investigate a bit more thoroughly later in the week.
Some designers allowed a larger amount of ripple on the first capacitor
to reduce the heating of the mains transformer (the copper losses are >proportional to I squared, so by allowing a longer charging time per
cycle at a lower current, they achieved lower overall resistance
losses). As long as the lowest part of the ripple was sufficiently far >above the stabilised output, a series stabiliser could cope with it.
Is the 'stabilised' line actually stable or is there ripple on it in the >form of a series of little notches?
Not sure what you mean by stabilised line. There are two secondary
windings on the mains transformer which go into separate bridge
rectifiiers of the type linked to above and then on downstream to the
first tank caps. One line has a ton of ripple on it, the other very
little indeed. Again, I'll need to go back and pay more attention to
what's going on here. I've missed out too many important details.
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap in a Marconi RF signal generator and it's
finding its way to the RF output, which of course should ideally have
zero ripple on it. The aforementioned cap tests fine WRT ESR and
capacitance in-circuit, I should add.
Thanks,
CD.
On 2/25/2024 1:01 PM, Cursitor Doom wrote:
So - in the case of a linear power supply - the rectified output of
the transformer typically goes straight to a big old storage cap for
smoothing purposes. My question is: how much ripple should I expect to
see across that cap if all's working well? I have to say I'm seeing a
*lot* of ripple on this cap in a Marconi RF signal generator and it's
finding its way to the RF output, which of course should ideally have
zero ripple on it. The aforementioned cap tests fine WRT ESR and
capacitance in-circuit, I should add.
Thanks,
CD.
Prior to the regulator circuit, the ripple voltage
depends upon current drawn for a given supply at a
given frequency. The higher the current drawn, the
greater the ripple for your supply. So one possibility
in your generator is that too much current is being
drawn i.e. a defect in some circuit "downstream" of
the bridge/cap.
Depending on what follows the diode/capacitor supply you
may have a regulator failure. Regulators hold the voltage
at some specific value, thus they remove ripple. Voltage
measurements usually reveal which regulator is failing to
provide the proper output voltage. Again a defect downstream
may pull the voltage down. Without a manual/schematic its
harder to diagnose - but it is still possible. And I read
somewhere that manuals are available. See the url posted
below - it may help.
Next - perhaps the ripple really isn't excessive. By that
I mean it may be within spec for your generator. You may
find this site helpful:
https://groups.io/g/Marconi-Test-Instruments
Good luck. Let us know whe you fix it!
Ed
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