Topics

PS2520 aka GW Instek PPT-3615

Siggi
 

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently - multiple
problems. So far I've been unable to turn up a service manual or schematics
for the thing. It does look, however, like this is perhaps a re-branded GS
Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280 schematics are
available. Unfortunately the PS2520 is very different in design, there's a
central digital display/control board, which communicates to the analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies, and
while conceptually similar, those are also quite different in detail.
It looks like the PS2520 has a single AD7541, which is a parallel input
12-bit DAC, per channel, and then a bunch of multiplexing and support logic
around it. Presumably there's a discrete successive approximation ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there was a
broken 74LS244 shorting the 5VD supply. This seems to have taken out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi

Siggi
 

Hey y'all,

TL;DR; need advice on opto-coupler replacement for 4-pin DIP opto-coupler
marked 5H P521.

I'm drilling into this dang thing. OMG the front panel user interface on
this thing is a dog - I didn't get it working yet, and I already know I'm
going to hate it!

The analog design is very conventional for a linear PSU. There's a
darlington follower output, with all the control circuitry driven from a
separate +-15V supply referenced to the output.

I've started to figure out the digital design of the thing and the protocol
between the digial board and the analog channels.
There are 4 analog-board inbound opto-coupled signals, and one outbound.
The inbound signals comprise a clock, a data line and two strobes.
Each analog board has two inbound shift registers, made from CD4094s. A
pair of those makes a 16 bit shift register that's used to control the DAC,
and the other one controls the readback channel.
The readback channel is routed through an 8-1 digital mux, controlled
through the other shift register. I assume the read-back is wired to allow
reading various comparator outputs, to allow software SAR and perhaps
reading back various other bits of data.
The leftover bits are used for relay control and such, but I haven't taken
the time to map them out yet.

The analog-inbound channels are routed through a CD4093 4-way
schmitt-trigger to square up the edges. One of those had failed, but even
after changing it out, the input signal doesn't make muster. The
opto-couplers are tagged 5H P521, and they're driven by a 74HC374 through a
100Ohm resistor. At the other end they have a 180Ohm load and go to a
CD4093 schmitt trigger. Some of them are not making the logic threshold,
and so all the serial comms are borked.

Now, perhaps the 74HC is getting tired - it's managing ~4V drive to the top
of those resistors.
If not that, then the optos are tired, and a few of them. I measured the
current transfer ratio in the worst affected one of them, and it seemed to
be at around 50%.
Maybe I should change both the driver and the optos, be done with it. The
problem is I'm not finding a datasheet for those optos, so I'm not quite
shore what to order for replacements.
These things are marked 5H P521, are driven off 5V HC logic through 100Ohm,
and loaded with 180Ohm on the receiving end. They're 4 pin DIPs.
Y'all have any advice for replacements? There's 15 of those dang things,
all told, so less expensive is probably better :).

Siggi

On Mon, Jun 29, 2015 at 9:56 AM, Sigurður Ásgeirsson <siggi@...> wrote:

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently - multiple
problems. So far I've been unable to turn up a service manual or schematics
for the thing. It does look, however, like this is perhaps a re-branded GS
Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280 schematics are
available. Unfortunately the PS2520 is very different in design, there's a
central digital display/control board, which communicates to the analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies, and
while conceptually similar, those are also quite different in detail.
It looks like the PS2520 has a single AD7541, which is a parallel input
12-bit DAC, per channel, and then a bunch of multiplexing and support logic
around it. Presumably there's a discrete successive approximation ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there was a
broken 74LS244 shorting the 5VD supply. This seems to have taken out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi

[Non-text portions of this message have been removed]

Siggi
 

Re-hi y'all,

looks to me like TLP781(GR,F) is a reasonable replacement. As near as I can
make it, this is the original part <
http://pdf.datasheetcatalog.com/datasheet/toshiba/2233.pdf>. The salient
specs are 2/3us rise/fall time and 50% minimum current transfer ratio, or
100% for the GR rank.
TLP781 is a similar headline timing spec and min 100% current transfer
ratio.

Objections, anyone, anyone, Bueller?

Siggi

On Wed, Jul 1, 2015 at 4:47 PM, Sigurður Ásgeirsson <siggi@...> wrote:

Hey y'all,

TL;DR; need advice on opto-coupler replacement for 4-pin DIP opto-coupler
marked 5H P521.

I'm drilling into this dang thing. OMG the front panel user interface on
this thing is a dog - I didn't get it working yet, and I already know I'm
going to hate it!

The analog design is very conventional for a linear PSU. There's a
darlington follower output, with all the control circuitry driven from a
separate +-15V supply referenced to the output.

I've started to figure out the digital design of the thing and the
protocol between the digial board and the analog channels.
There are 4 analog-board inbound opto-coupled signals, and one outbound.
The inbound signals comprise a clock, a data line and two strobes.
Each analog board has two inbound shift registers, made from CD4094s. A
pair of those makes a 16 bit shift register that's used to control the DAC,
and the other one controls the readback channel.
The readback channel is routed through an 8-1 digital mux, controlled
through the other shift register. I assume the read-back is wired to allow
reading various comparator outputs, to allow software SAR and perhaps
reading back various other bits of data.
The leftover bits are used for relay control and such, but I haven't taken
the time to map them out yet.

The analog-inbound channels are routed through a CD4093 4-way
schmitt-trigger to square up the edges. One of those had failed, but even
after changing it out, the input signal doesn't make muster. The
opto-couplers are tagged 5H P521, and they're driven by a 74HC374 through a
100Ohm resistor. At the other end they have a 180Ohm load and go to a
CD4093 schmitt trigger. Some of them are not making the logic threshold,
and so all the serial comms are borked.

Now, perhaps the 74HC is getting tired - it's managing ~4V drive to the
top of those resistors.
If not that, then the optos are tired, and a few of them. I measured the
current transfer ratio in the worst affected one of them, and it seemed to
be at around 50%.
Maybe I should change both the driver and the optos, be done with it. The
problem is I'm not finding a datasheet for those optos, so I'm not quite
shore what to order for replacements.
These things are marked 5H P521, are driven off 5V HC logic through
100Ohm, and loaded with 180Ohm on the receiving end. They're 4 pin DIPs.
Y'all have any advice for replacements? There's 15 of those dang things,
all told, so less expensive is probably better :).

Siggi

On Mon, Jun 29, 2015 at 9:56 AM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently - multiple
problems. So far I've been unable to turn up a service manual or schematics
for the thing. It does look, however, like this is perhaps a re-branded GS
Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280 schematics are
available. Unfortunately the PS2520 is very different in design, there's a
central digital display/control board, which communicates to the analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies, and
while conceptually similar, those are also quite different in detail.
It looks like the PS2520 has a single AD7541, which is a parallel input
12-bit DAC, per channel, and then a bunch of multiplexing and support logic
around it. Presumably there's a discrete successive approximation ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there was a
broken 74LS244 shorting the 5VD supply. This seems to have taken out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi

[Non-text portions of this message have been removed]

Siggi
 

Hey y'all,

this thing is starting to get on my nerves. I replaced all the optos, still
get Error -5, no outputs etc.
Looking at the DACs' inputs and outputs it didn't look right. The output
didn't seem to follow setting changes, or at least there were bits (most
bits) missing. The voltages on the inputs also didn't look like any sane
logic I'm familiar with - low highs and high lows and crosstalk between
bits.
I switched the DAC on one of the channels and tested it with a jig to
inject a serial stream to the channel, the DAC now works like a champ. The
serial protocol is LSB first, and the DAC takes the top 12 bits of 16.
Still no output - drilling commences.

So this thing has three opto-isolated channels, and a digital board which
is isolated from all three channels. The digital board has ground at mains
earth, but everything else floats.
What gets me is that all channels and the digital board seem to have all
suffered some sort of trauma - presumably all at once.

By first order of approximation (diode test) the output and driver devices
seem to be fine on CH1/2 at least. The voltage references and the op-amps
I've looked at seem to be fine, but logic is fried here and there.

So far I found a 74LS244 shorted across the rail on the digital board, a
CD4093 effectively shorted from one input to the 5V rail on one channel and
the AD7541 DACs seem to be shorted gate-to-source on most of the inputs on
at least two channels.

The optos are specced to provide 5KV of isolation - so I wonder what kind
of an event might cause such a thing across 4 isolated domains?

Siggi

On Wed, Jul 1, 2015 at 6:09 PM, Sigurður Ásgeirsson <siggi@...> wrote:

Re-hi y'all,

looks to me like TLP781(GR,F) is a reasonable replacement. As near as I
can make it, this is the original part <
http://pdf.datasheetcatalog.com/datasheet/toshiba/2233.pdf>. The salient
specs are 2/3us rise/fall time and 50% minimum current transfer ratio, or
100% for the GR rank.
TLP781 is a similar headline timing spec and min 100% current transfer
ratio.

Objections, anyone, anyone, Bueller?

Siggi

On Wed, Jul 1, 2015 at 4:47 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

TL;DR; need advice on opto-coupler replacement for 4-pin DIP opto-coupler
marked 5H P521.

I'm drilling into this dang thing. OMG the front panel user interface on
this thing is a dog - I didn't get it working yet, and I already know I'm
going to hate it!

The analog design is very conventional for a linear PSU. There's a
darlington follower output, with all the control circuitry driven from a
separate +-15V supply referenced to the output.

I've started to figure out the digital design of the thing and the
protocol between the digial board and the analog channels.
There are 4 analog-board inbound opto-coupled signals, and one outbound.
The inbound signals comprise a clock, a data line and two strobes.
Each analog board has two inbound shift registers, made from CD4094s. A
pair of those makes a 16 bit shift register that's used to control the DAC,
and the other one controls the readback channel.
The readback channel is routed through an 8-1 digital mux, controlled
through the other shift register. I assume the read-back is wired to allow
reading various comparator outputs, to allow software SAR and perhaps
reading back various other bits of data.
The leftover bits are used for relay control and such, but I haven't
taken the time to map them out yet.

The analog-inbound channels are routed through a CD4093 4-way
schmitt-trigger to square up the edges. One of those had failed, but even
after changing it out, the input signal doesn't make muster. The
opto-couplers are tagged 5H P521, and they're driven by a 74HC374 through a
100Ohm resistor. At the other end they have a 180Ohm load and go to a
CD4093 schmitt trigger. Some of them are not making the logic threshold,
and so all the serial comms are borked.

Now, perhaps the 74HC is getting tired - it's managing ~4V drive to the
top of those resistors.
If not that, then the optos are tired, and a few of them. I measured the
current transfer ratio in the worst affected one of them, and it seemed to
be at around 50%.
Maybe I should change both the driver and the optos, be done with it. The
problem is I'm not finding a datasheet for those optos, so I'm not quite
shore what to order for replacements.
These things are marked 5H P521, are driven off 5V HC logic through
100Ohm, and loaded with 180Ohm on the receiving end. They're 4 pin DIPs.
Y'all have any advice for replacements? There's 15 of those dang things,
all told, so less expensive is probably better :).

Siggi

On Mon, Jun 29, 2015 at 9:56 AM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently - multiple
problems. So far I've been unable to turn up a service manual or schematics
for the thing. It does look, however, like this is perhaps a re-branded GS
Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280 schematics are
available. Unfortunately the PS2520 is very different in design, there's a
central digital display/control board, which communicates to the analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies,
and while conceptually similar, those are also quite different in detail.
It looks like the PS2520 has a single AD7541, which is a parallel input
12-bit DAC, per channel, and then a bunch of multiplexing and support logic
around it. Presumably there's a discrete successive approximation ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there was a
broken 74LS244 shorting the 5VD supply. This seems to have taken out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi

[Non-text portions of this message have been removed]

Siggi
 

Hey y'all,

maybe this is slightly OT as PS2520 is neither a scope nor classic. It's a
nice PSU, though.

Just a note that I finished repairing mine. Turns out all three AD7541 DACs
were gonsky in addition to the carnage I'd recited before.
I also found this YouTube video <https://www.youtube.com/watch?v=q3bn7r77yDY>,
where one of those DACs had failed in the same mode as two of mine. I guess
they must've been a weak point.
In any case, after calibration I can set it to a voltage with 10mV
resolution, and the current read-back is accurate to a mA, which is nice.

Siggi

On Sun, Jul 5, 2015 at 5:32 PM, Sigurður Ásgeirsson <siggi@...> wrote:

Hey y'all,

this thing is starting to get on my nerves. I replaced all the optos,
still get Error -5, no outputs etc.
Looking at the DACs' inputs and outputs it didn't look right. The output
didn't seem to follow setting changes, or at least there were bits (most
bits) missing. The voltages on the inputs also didn't look like any sane
logic I'm familiar with - low highs and high lows and crosstalk between
bits.
I switched the DAC on one of the channels and tested it with a jig to
inject a serial stream to the channel, the DAC now works like a champ. The
serial protocol is LSB first, and the DAC takes the top 12 bits of 16.
Still no output - drilling commences.

So this thing has three opto-isolated channels, and a digital board which
is isolated from all three channels. The digital board has ground at mains
earth, but everything else floats.
What gets me is that all channels and the digital board seem to have all
suffered some sort of trauma - presumably all at once.

By first order of approximation (diode test) the output and driver devices
seem to be fine on CH1/2 at least. The voltage references and the op-amps
I've looked at seem to be fine, but logic is fried here and there.

So far I found a 74LS244 shorted across the rail on the digital board, a
CD4093 effectively shorted from one input to the 5V rail on one channel and
the AD7541 DACs seem to be shorted gate-to-source on most of the inputs on
at least two channels.

The optos are specced to provide 5KV of isolation - so I wonder what kind
of an event might cause such a thing across 4 isolated domains?

Siggi

On Wed, Jul 1, 2015 at 6:09 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Re-hi y'all,

looks to me like TLP781(GR,F) is a reasonable replacement. As near as I
can make it, this is the original part <
http://pdf.datasheetcatalog.com/datasheet/toshiba/2233.pdf>. The salient
specs are 2/3us rise/fall time and 50% minimum current transfer ratio, or
100% for the GR rank.
TLP781 is a similar headline timing spec and min 100% current transfer
ratio.

Objections, anyone, anyone, Bueller?

Siggi

On Wed, Jul 1, 2015 at 4:47 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

TL;DR; need advice on opto-coupler replacement for 4-pin DIP
opto-coupler marked 5H P521.

I'm drilling into this dang thing. OMG the front panel user interface on
this thing is a dog - I didn't get it working yet, and I already know I'm
going to hate it!

The analog design is very conventional for a linear PSU. There's a
darlington follower output, with all the control circuitry driven from a
separate +-15V supply referenced to the output.

I've started to figure out the digital design of the thing and the
protocol between the digial board and the analog channels.
There are 4 analog-board inbound opto-coupled signals, and one outbound.
The inbound signals comprise a clock, a data line and two strobes.
Each analog board has two inbound shift registers, made from CD4094s. A
pair of those makes a 16 bit shift register that's used to control the DAC,
and the other one controls the readback channel.
The readback channel is routed through an 8-1 digital mux, controlled
through the other shift register. I assume the read-back is wired to allow
reading various comparator outputs, to allow software SAR and perhaps
reading back various other bits of data.
The leftover bits are used for relay control and such, but I haven't
taken the time to map them out yet.

The analog-inbound channels are routed through a CD4093 4-way
schmitt-trigger to square up the edges. One of those had failed, but even
after changing it out, the input signal doesn't make muster. The
opto-couplers are tagged 5H P521, and they're driven by a 74HC374 through a
100Ohm resistor. At the other end they have a 180Ohm load and go to a
CD4093 schmitt trigger. Some of them are not making the logic threshold,
and so all the serial comms are borked.

Now, perhaps the 74HC is getting tired - it's managing ~4V drive to the
top of those resistors.
If not that, then the optos are tired, and a few of them. I measured the
current transfer ratio in the worst affected one of them, and it seemed to
be at around 50%.
Maybe I should change both the driver and the optos, be done with it.
The problem is I'm not finding a datasheet for those optos, so I'm not
quite shore what to order for replacements.
These things are marked 5H P521, are driven off 5V HC logic through
100Ohm, and loaded with 180Ohm on the receiving end. They're 4 pin DIPs.
Y'all have any advice for replacements? There's 15 of those dang things,
all told, so less expensive is probably better :).

Siggi

On Mon, Jun 29, 2015 at 9:56 AM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently -
multiple problems. So far I've been unable to turn up a service manual or
schematics for the thing. It does look, however, like this is perhaps a
re-branded GS Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280 schematics are
available. Unfortunately the PS2520 is very different in design, there's a
central digital display/control board, which communicates to the analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies,
and while conceptually similar, those are also quite different in detail.
It looks like the PS2520 has a single AD7541, which is a parallel input
12-bit DAC, per channel, and then a bunch of multiplexing and support logic
around it. Presumably there's a discrete successive approximation ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there was a
broken 74LS244 shorting the 5VD supply. This seems to have taken out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi

ArtekManuals
 

Siggi

While the name if the group is TEKSCOPES ..it is generally accepted that
discussion about ANY piece of Tektronix gear is acceptable for
discussion and on topic

Dave

On 8/16/2015 5:24 PM, Sigurður Ásgeirsson siggi@... [TekScopes] wrote:

Hey y'all,

maybe this is slightly OT as PS2520 is neither a scope nor classic. It's a
nice PSU, though.

Just a note that I finished repairing mine. Turns out all three AD7541
DACs
were gonsky in addition to the carnage I'd recited before.
I also found this YouTube video
<https://www.youtube.com/watch?v=q3bn7r77yDY>,
where one of those DACs had failed in the same mode as two of mine. I
guess
they must've been a weak point.
In any case, after calibration I can set it to a voltage with 10mV
resolution, and the current read-back is accurate to a mA, which is nice.

Siggi

On Sun, Jul 5, 2015 at 5:32 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

this thing is starting to get on my nerves. I replaced all the optos,
still get Error -5, no outputs etc.
Looking at the DACs' inputs and outputs it didn't look right. The output
didn't seem to follow setting changes, or at least there were bits (most
bits) missing. The voltages on the inputs also didn't look like any sane
logic I'm familiar with - low highs and high lows and crosstalk between
bits.
I switched the DAC on one of the channels and tested it with a jig to
inject a serial stream to the channel, the DAC now works like a
champ. The
serial protocol is LSB first, and the DAC takes the top 12 bits of 16.
Still no output - drilling commences.

So this thing has three opto-isolated channels, and a digital board
which
is isolated from all three channels. The digital board has ground at
mains
earth, but everything else floats.
What gets me is that all channels and the digital board seem to have all
suffered some sort of trauma - presumably all at once.

By first order of approximation (diode test) the output and driver
devices
seem to be fine on CH1/2 at least. The voltage references and the
op-amps
I've looked at seem to be fine, but logic is fried here and there.

So far I found a 74LS244 shorted across the rail on the digital board, a
CD4093 effectively shorted from one input to the 5V rail on one
channel and
the AD7541 DACs seem to be shorted gate-to-source on most of the
inputs on
at least two channels.

The optos are specced to provide 5KV of isolation - so I wonder what
kind
of an event might cause such a thing across 4 isolated domains?

Siggi

On Wed, Jul 1, 2015 at 6:09 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Re-hi y'all,

looks to me like TLP781(GR,F) is a reasonable replacement. As near as I
can make it, this is the original part <
http://pdf.datasheetcatalog.com/datasheet/toshiba/2233.pdf>. The
salient
specs are 2/3us rise/fall time and 50% minimum current transfer
ratio, or
100% for the GR rank.
TLP781 is a similar headline timing spec and min 100% current transfer
ratio.

Objections, anyone, anyone, Bueller?

Siggi

On Wed, Jul 1, 2015 at 4:47 PM, Sigurður Ásgeirsson <siggi@...>
wrote:

Hey y'all,

TL;DR; need advice on opto-coupler replacement for 4-pin DIP
opto-coupler marked 5H P521.

I'm drilling into this dang thing. OMG the front panel user
interface on
this thing is a dog - I didn't get it working yet, and I already
know I'm
going to hate it!

The analog design is very conventional for a linear PSU. There's a
darlington follower output, with all the control circuitry driven
from a
separate +-15V supply referenced to the output.

I've started to figure out the digital design of the thing and the
protocol between the digial board and the analog channels.
There are 4 analog-board inbound opto-coupled signals, and one
outbound.
The inbound signals comprise a clock, a data line and two strobes.
Each analog board has two inbound shift registers, made from
CD4094s. A
pair of those makes a 16 bit shift register that's used to control
the DAC,
and the other one controls the readback channel.
The readback channel is routed through an 8-1 digital mux, controlled
through the other shift register. I assume the read-back is wired
to allow
reading various comparator outputs, to allow software SAR and perhaps
reading back various other bits of data.
The leftover bits are used for relay control and such, but I haven't
taken the time to map them out yet.

The analog-inbound channels are routed through a CD4093 4-way
schmitt-trigger to square up the edges. One of those had failed,
but even
after changing it out, the input signal doesn't make muster. The
opto-couplers are tagged 5H P521, and they're driven by a 74HC374
through a
100Ohm resistor. At the other end they have a 180Ohm load and go to a
CD4093 schmitt trigger. Some of them are not making the logic
threshold,
and so all the serial comms are borked.

Now, perhaps the 74HC is getting tired - it's managing ~4V drive
to the
top of those resistors.
If not that, then the optos are tired, and a few of them. I
measured the
current transfer ratio in the worst affected one of them, and it
seemed to
be at around 50%.
Maybe I should change both the driver and the optos, be done with it.
The problem is I'm not finding a datasheet for those optos, so I'm not
quite shore what to order for replacements.
These things are marked 5H P521, are driven off 5V HC logic through
100Ohm, and loaded with 180Ohm on the receiving end. They're 4 pin
DIPs.
Y'all have any advice for replacements? There's 15 of those dang
things,
all told, so less expensive is probably better :).

Siggi

On Mon, Jun 29, 2015 at 9:56 AM, Sigurður Ásgeirsson
<siggi@...>
wrote:

Hey y'all,

I'm sorting through a PS2520 that came to me with - evidently -
multiple problems. So far I've been unable to turn up a service
manual or
schematics for the thing. It does look, however, like this is
perhaps a
re-branded GS Instek PPT-3615.
I don't suppose anyone here has that service manual?

There's been mention in previous threads that the PS280
schematics are
available. Unfortunately the PS2520 is very different in design,
there's a
central digital display/control board, which communicates to the
analog
boards through opto-isolated serial comms.
I've found a service manual for more recent GW Instek power supplies,
and while conceptually similar, those are also quite different in
detail.
It looks like the PS2520 has a single AD7541, which is a parallel
input
12-bit DAC, per channel, and then a bunch of multiplexing and
support logic
around it. Presumably there's a discrete successive approximation
ADC built
around the DAC to do the read-back.

So far the problems I've sorted through are pretty mundane, there
was a
broken 74LS244 shorting the 5VD supply. This seems to have taken
out the
bridge rectifier for same.
Now I'm sorting through problems on the CH1 analog board, where for
starters there's a 4093 schmitt trigger shorting one of the
optical inputs
to the 5V rail.
I'll get through this eventually, but it sure would be nice to have
schematics :).

Siggi



--
Dave
Manuals@...
www.ArtekManuals.com

Ken Eckert
 

Hi;

I know this is an old thread, I have just uploaded the schematics, calibration procedure and op/prog manuals for the PS2520G and PS2521G aka GW Instek PPT-3615 and PPS-1830 (and possibly PPE-3323) to KO44b and the Boat Anchor Manual Archive sites.
Ken

Siggi
 

Hey Ken,

Thanks for digging those up. Do you happen to remember where these
surfaced? Just curious...

Now that I’ve seen the calibration procedure, I wonder if perhaps over
zealous hi-pot testing was the cause for mine suffering damage in three
galvanically isolated domains.

Siggi

On Tue, Jul 16, 2019 at 16:32 Ken Eckert <eckertkp@...> wrote:

Hi;

I know this is an old thread, I have just uploaded the schematics,
calibration procedure and op/prog manuals for the PS2520G and PS2521G aka
GW Instek PPT-3615 and PPS-1830 (and possibly PPE-3323) to KO44b and the
Boat Anchor Manual Archive sites.
Ken