Phono preamp in old receiver problem
 

Hi all,

I have an old Sharp AM/FM receiver with an 8-track player. Made
in Japan ca. 1975 or something. It had a BSR turntable which was
broken. I removed the seized turntable, cleaned the whole unit,
sprayed all the pots, replaced the three little 6V bulbs behind
the black/green tuner window, and it is fabulous. It's built
like a tank and weighs a ton. The pots feel like military grade
stuff. The function switches are simply unbelievable. The front
panel is white (OK, bone now) with black controls, the box is
all wood with the then-standard "vinyl wood veneer".

I have a spare turntable which works perfectly. I intended to
connect it to the phono preamp of this receiver. I did, but I am
not getting sound. I am getting low-frequency pink noise, but no
audio signal. What is even stranger is that I hear one of the
channels "pop" when I dis/connect ONE of the two RCA audio
cables going into the phono preamp of the receiver. I tested all
the cables after extending them, and they are OK (see below).

I tried connecting the turntable signal to the line input, and
it DOES work. Of course, the signal is VERY low, but you CAN
hear the LP playing with the volume full up. So either I DID
somehow **** up the audio cable assembly (it tests OK though!)
or the phono preamp is partially or totally NG, in which case
there is probably nothing that can be done.

The line inputs can be used for a CD/DVD player, the receiver
works as a 4-speaker unit or 2 main/2 remote speakers, and it
sounds great. AM and line in are loud as hell, FM volume is
about 30% of that, but still usable.

Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

(The phonograph audio cables were only long enough to reach the
bottom of the turntable, which was 3 inches above the main
circuit board, now they have to reach to the back and out of the
unit, so I had to add about 8 inches of cable - but I tested the
cables, both channels, live /and/ ground, and I made NO mistakes
- everything was connected/soldered correctly.

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us. I have yet to find an 8-track cartridge, but the mechanism
and all the belts seem fine. Plus I don't think anyone needs an
8-track deck, while /quite/ a few people might enjoy having a
receiver with a phono preamp. Unless the phono preamp IS dead,
of course. But maybe someone can help me determine if it
actually IS dead...

I /tried/ to make this short, really!

Any advice will be greatly appreciated.

--
Any mental activity is easy if it need not be subjected to
reality.

Phono preamp in old receiver problem
 

On 9/8/2010 4:12 PM thanatoid spake thus:

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us. I have yet to find an 8-track cartridge, but the mechanism
and all the belts seem fine. Plus I don't think anyone needs an
8-track deck, while /quite/ a few people might enjoy having a
receiver with a phono preamp. Unless the phono preamp IS dead,
of course. But maybe someone can help me determine if it
actually IS dead...

One question is whether this unit uses a ceramic or magnetic phono
cartridge. Most units of its vintage used magnetic, and that's my guess,
but if it has a ceramic cartridge, you're not going to be able to use a
magentic cartridge with its preamp.

Another possibility is to get a small standalone phone preamp and plug
it into the line input. Not what you want, but it would work.


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)

Phono preamp in old receiver problem
 

do you have an iPod, or other mp3 player or any other audio device that you
can hook up to the preamp, just to see if you get a better result ? If so,
you should of course keep the output level of the mp3 player very low at
least to begin with, and gradually increase the volume. Because it will be
a line level signal to the preamp, it will overpower it quickly, but it may
give you a hint as to what is going on..... could possibly eliminate
defects in your turntable or the cable that you made, as all of that would
be bypassed for the experiment...

just an idea... report back please...

James

Phono preamp in old receiver problem
 

In article ,
thanatoid wrote:
Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

Well, I'd say that one of the two standard approaches would work.
Which one you would use, depends on what sort of test equipment you
have available.

Probably the easiest approach is "work backwards". You'd use some
sort of low-level signal injector (something which can create a few
millivolts of audio), starting at the input selector switch (probably)
and working backwards towards the turntable, and see how far back
along this signal chain you can go before you stop getting audio
output through the amplifier.

The other way is "work forwards"... from the cartridge towards the
preamp and amp, using an oscilliscope to see how far along the chain
you can detect audio when you stimulate the cartridge (e.g. playing an
LP, or touching the stylus gently with a brush).

Take all of the appropriate safety precautions, of course!

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us.

In a component of that type and age, I'd suspect one of two things as
the most likely culprit:

- A bad switch in the signal path (maybe in the preamp, or maybe at
the turntable itself - if I recall correctly, some turntables have
anti-thump muting switches which short the signal from the
cartridge until the stylus is playing the groove), or

- Dried out and "open" electrolytic capacitors, coupling one stage
of the preamp to the next.

There could also be a power supply problem affecting the phono preamp
stage.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Phono preamp in old receiver problem
 

Well, it is most unlikely that both the channels wood go down together now
I'd imagine.
Firstly, if you do not get a buzz when you touch the live of these
connections, then something is not as expected.
Sharp did tend to do stuff in funny ways though, and as has been said
elsewhere you need to find out what the turntable actually did. Was there,
for example, as I found on an old Teleton unit of similar vintage, a little
extra cable from the turntable to the circuit board? This little line
appeared to mute the pick up input in some way, presumably via a switch on
the pick up bearing or similar. I got the impression it used an optical
switch, but as the unit blew a power amp module shortly afterwards, I never
investigated further..

As for 8 track carts, most have seized up by now I'd imagine as the tape was
lubricated. Akai used to make an 8 track recorder which sounded quite good,
but the recording time per track was rubbish and the mechanics were designed
to wear out by the looks of it.

Quite how you cleaned things is hard to see.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"thanatoid" wrote in message
...
Hi all,

I have an old Sharp AM/FM receiver with an 8-track player. Made
in Japan ca. 1975 or something. It had a BSR turntable which was
broken. I removed the seized turntable, cleaned the whole unit,
sprayed all the pots, replaced the three little 6V bulbs behind
the black/green tuner window, and it is fabulous. It's built
like a tank and weighs a ton. The pots feel like military grade
stuff. The function switches are simply unbelievable. The front
panel is white (OK, bone now) with black controls, the box is
all wood with the then-standard "vinyl wood veneer".

I have a spare turntable which works perfectly. I intended to
connect it to the phono preamp of this receiver. I did, but I am
not getting sound. I am getting low-frequency pink noise, but no
audio signal. What is even stranger is that I hear one of the
channels "pop" when I dis/connect ONE of the two RCA audio
cables going into the phono preamp of the receiver. I tested all
the cables after extending them, and they are OK (see below).

I tried connecting the turntable signal to the line input, and
it DOES work. Of course, the signal is VERY low, but you CAN
hear the LP playing with the volume full up. So either I DID
somehow **** up the audio cable assembly (it tests OK though!)
or the phono preamp is partially or totally NG, in which case
there is probably nothing that can be done.

The line inputs can be used for a CD/DVD player, the receiver
works as a 4-speaker unit or 2 main/2 remote speakers, and it
sounds great. AM and line in are loud as hell, FM volume is
about 30% of that, but still usable.

Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

(The phonograph audio cables were only long enough to reach the
bottom of the turntable, which was 3 inches above the main
circuit board, now they have to reach to the back and out of the
unit, so I had to add about 8 inches of cable - but I tested the
cables, both channels, live /and/ ground, and I made NO mistakes
- everything was connected/soldered correctly.

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us. I have yet to find an 8-track cartridge, but the mechanism
and all the belts seem fine. Plus I don't think anyone needs an
8-track deck, while /quite/ a few people might enjoy having a
receiver with a phono preamp. Unless the phono preamp IS dead,
of course. But maybe someone can help me determine if it
actually IS dead...

I /tried/ to make this short, really!

Any advice will be greatly appreciated.

--
Any mental activity is easy if it need not be subjected to
reality.

Phono preamp in old receiver problem
 

"thanatoid" wrote in message
...
Hi all,

I have an old Sharp AM/FM receiver with an 8-track player. Made
in Japan ca. 1975 or something. It had a BSR turntable which was
broken. I removed the seized turntable, cleaned the whole unit,
sprayed all the pots, replaced the three little 6V bulbs behind
the black/green tuner window, and it is fabulous. It's built
like a tank and weighs a ton. The pots feel like military grade
stuff. The function switches are simply unbelievable. The front
panel is white (OK, bone now) with black controls, the box is
all wood with the then-standard "vinyl wood veneer".

I have a spare turntable which works perfectly. I intended to
connect it to the phono preamp of this receiver. I did, but I am
not getting sound. I am getting low-frequency pink noise, but no
audio signal. What is even stranger is that I hear one of the
channels "pop" when I dis/connect ONE of the two RCA audio
cables going into the phono preamp of the receiver. I tested all
the cables after extending them, and they are OK (see below).

I tried connecting the turntable signal to the line input, and
it DOES work. Of course, the signal is VERY low, but you CAN
hear the LP playing with the volume full up. So either I DID
somehow **** up the audio cable assembly (it tests OK though!)
or the phono preamp is partially or totally NG, in which case
there is probably nothing that can be done.

The line inputs can be used for a CD/DVD player, the receiver
works as a 4-speaker unit or 2 main/2 remote speakers, and it
sounds great. AM and line in are loud as hell, FM volume is
about 30% of that, but still usable.

Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

(The phonograph audio cables were only long enough to reach the
bottom of the turntable, which was 3 inches above the main
circuit board, now they have to reach to the back and out of the
unit, so I had to add about 8 inches of cable - but I tested the
cables, both channels, live /and/ ground, and I made NO mistakes
- everything was connected/soldered correctly.

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us. I have yet to find an 8-track cartridge, but the mechanism
and all the belts seem fine. Plus I don't think anyone needs an
8-track deck, while /quite/ a few people might enjoy having a
receiver with a phono preamp. Unless the phono preamp IS dead,
of course. But maybe someone can help me determine if it
actually IS dead...

I /tried/ to make this short, really!

Any advice will be greatly appreciated.

--
Any mental activity is easy if it need not be subjected to
reality.


Perhaps the stylus on the replacement turntable is not quite seated
properly. This would produce your symptom. No sound when plugged into the
(ceramic) phono input, hear a pop w/ unplug, hear low sound on another
input.

I'm presuming your original turntable had a ceramic cartridge, but it would
help to know if this is true; also what kind of cartridge is in your
replacement table.

Mark Z.

Mark Z.

Phono preamp in old receiver problem
 

Hello,

while I don't know your specific Sharp receiver (you did not specify
the model number) many 'compact systems' with BSR changers used ceramic
cartridges that give a line level output, so this receiver may not have
a phono preamp at all.

Regards,
Tim Schwartz
Bristol Electronics


On 9/8/2010 7:12 PM, thanatoid wrote:
Hi all,

I have an old Sharp AM/FM receiver with an 8-track player. Made
in Japan ca. 1975 or something. It had a BSR turntable which was
broken. I removed the seized turntable, cleaned the whole unit,
sprayed all the pots, replaced the three little 6V bulbs behind
the black/green tuner window, and it is fabulous. It's built
like a tank and weighs a ton. The pots feel like military grade
stuff. The function switches are simply unbelievable. The front
panel is white (OK, bone now) with black controls, the box is
all wood with the then-standard "vinyl wood veneer".

I have a spare turntable which works perfectly. I intended to
connect it to the phono preamp of this receiver. I did, but I am
not getting sound. I am getting low-frequency pink noise, but no
audio signal. What is even stranger is that I hear one of the
channels "pop" when I dis/connect ONE of the two RCA audio
cables going into the phono preamp of the receiver. I tested all
the cables after extending them, and they are OK (see below).

I tried connecting the turntable signal to the line input, and
it DOES work. Of course, the signal is VERY low, but you CAN
hear the LP playing with the volume full up. So either I DID
somehow **** up the audio cable assembly (it tests OK though!)
or the phono preamp is partially or totally NG, in which case
there is probably nothing that can be done.

The line inputs can be used for a CD/DVD player, the receiver
works as a 4-speaker unit or 2 main/2 remote speakers, and it
sounds great. AM and line in are loud as hell, FM volume is
about 30% of that, but still usable.

Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

(The phonograph audio cables were only long enough to reach the
bottom of the turntable, which was 3 inches above the main
circuit board, now they have to reach to the back and out of the
unit, so I had to add about 8 inches of cable - but I tested the
cables, both channels, live /and/ ground, and I made NO mistakes
- everything was connected/soldered correctly.

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us. I have yet to find an 8-track cartridge, but the mechanism
and all the belts seem fine. Plus I don't think anyone needs an
8-track deck, while /quite/ a few people might enjoy having a
receiver with a phono preamp. Unless the phono preamp IS dead,
of course. But maybe someone can help me determine if it
actually IS dead...

I /tried/ to make this short, really!

Any advice will be greatly appreciated.

Phono preamp in old receiver problem
 

thanatoid wrote:

I /tried/ to make this short, really!

Are you sure the original turntable had a magnetic cartridge? - and if so,
did it contain a preamp for it? - is there a feedback path through a switch
that doesn't work, Sony did stuff like that on their taperecorders causing
the record amp to oscillate if the switch was defective.

Any advice will be greatly appreciated.

Kind regards

Peter Larsen

Phono preamp in old receiver problem
 

David Nebenzahl wrote in
.com:

snip

One question is whether this unit uses a ceramic or
magnetic phono cartridge. Most units of its vintage used
magnetic, and that's my guess, but if it has a ceramic
cartridge, you're not going to be able to use a magentic
cartridge with its preamp.

Another possibility is to get a small standalone phone
preamp and plug it into the line input. Not what you want,
but it would work.

Thanks for the reply.

See below for parts addressing both these suggestion, sort of.

-- Update (very long, I apologize!) --

First of all, many thanks to all who replied. It is very much
appreciated.

Now for the /bad/ part.

Something one person mentioned in his reply made me remember a
rather *crucial* detail which I had forgotten (I am not
completely senile yet, but I have been /incredibly/ busy for the
last few weeks, and my brain is running out of RAM).

It is this: BEFORE I removed the BSR turntable, I DID check to
see whether there was AUDIO SIGNAL coming from it. There was,
loud and clear - when I touched the stylus, it sounded like an
earthquake. Very little "system noise", too.

The turntable itself was "seized" - after I have (with some
violence) managed to take it apart, I saw that the 2 main cog
wheels of the belt-less motor were practically frozen together
at a bizarre angle and would NOT budge. I have NO idea how that
happened - and the 4" screwdriver shaft, 2 children's plastic
letters with magnets, and assorted bits of 30+ year old food I
found inside the receiver could NOT have had anything to do with
it, either, since the BSR motor was fairly well enclosed within
the /incredibly/ complicated mechanical design (a changer).

Now that I have remembered this, it is obvious I screwed
something up. I have never seen a ceramic cartridge, but I am
99.99% positive that BOTH the BSR and the Sony (ca. 1990)
turntable carts are magnetic. So, since I have no signal but
weird pink noise, I must have screwed up the cables. Or do you
think I may have destroyed the preamp?

(This may be a good moment to mention that I am using the term
"phono preamp" in a generic sense. I always thought a phono
preamp might be/would be a small enclosed piece of electronics,
but in this receiver, it appears to be a part of the main
circuit board - the two original (and now extended) cables from
the BSR turntable stylus/arm are soldered right onto the circuit
board, and go who-knows-where - presumably, into components
which make up this receiver's "phone preamp" section.)

(THIS may /also/ be a good moment to mention that while I have
had some disastrous luck with simple things and astoundingly
good luck with complicated things, I am NOT a technician, and do
not own an oscilloscope - I check connections with two gator
clips connected to a 1.5V battery with a flashlight bulb, and
after over 30 years of "considering it", I finally bought a five
dollar "voltmeter" which /appears/ to work - I found out a cheap
110V/22V AC/DC adapter outputs 25VDC when set to 12V output
[when the input voltage is set to 110V] and 12.5VDC from its 9V
setting [when the input voltage is set to 110V (it is 110V
here)]. The Sony turntable (originally a component of a system,
with a tiny power connector which plugs into the back of the
main system unit and where I found out 12VDC is output) is
running on a supposedly "regulated" fancy Radio Shack AC/DC
adapter which puts out 11.8V DC. (When I reverse the polarity,
the turntable spins backwards.)

If anyone has read this far, please accept my deep thanks for
your patience. I can't write more concisely - I realize it's an
illness.

Anyway - the question now is WHAT did I do to mess things up?
Since I consider the receiver largely indestructible, I do not
think I have *destroyed* anything, not to mention the voltages
involved are totally minuscule and it being a solid state unit -
as the front panel proudly states ;-) - there is little danger
of blowing it up. Plus everything else works.

My plan is as follows:

1. Cut the original "BSR cartridge/turntable to the main circuit
board" cables, strip ends.
2. Attach gator clips to them and connect to the Sony turntable
output cable.
3. Hopefully, hear sound. Extend cables again, making SURE I
don't screw up this time.

If I hear no sound, I will connect the 4 very thin cables from
the original BSR cartridge (I saved the cart assembly and cables
before I saw the turntable was connected to the circuit board
with 2 standard cables with RCA plugs) to the cut cables leading
to the circuit board and see if I hear anything. If I do, I will
post for more advice.

But for now, my question is:

If after doing all this, I still get the /same/ pink noise (NOT
hum - strange, huh?) and get NO audio, WHAT do I do?

Thank you /very much/ for your patience, and my apologies for
having forgotten a crucial part of the puzzle. Further help will
be greatly appreciated. If anyone wants to see pix of the 2
cartridges or the circuit board where the phono audio cables are
soldered into it, I can post them to photobucket or something,
OR a binary group if you have binaries access.

The replies are different in every one of the 5 groups, so I
will post this followup to each group separately. I don't really
understand how crossposting works, since I never do it, and
eternal september /may/ be "funny" about crossposting to boot.


--
Any mental activity is easy if it need not be subjected to
reality.

Phono preamp in old receiver problem
 

"James" wrote in
net:

do you have an iPod, or other mp3 player or any other audio
device that you can hook up to the preamp, just to see if
you get a better result ?

Thanks for the reply.

Not really, also it is VERY tight and dark and weird in there.

If so, you should of course keep
the output level of the mp3 player very low at least to
begin with, and gradually increase the volume. Because it
will be a line level signal to the preamp, it will
overpower it quickly, but it may give you a hint as to what
is going on..... could possibly eliminate defects in your
turntable or the cable that you made, as all of that would
be bypassed for the experiment...

just an idea... report back please...

Here it is... VERY long, sorry!

-- Update (very long, I apologize!) --

First of all, many thanks to all who replied. It is very much
appreciated.

Now for the /bad/ part.

Something one person mentioned in his reply made me remember a
rather *crucial* detail which I had forgotten (I am not
completely senile yet, but I have been /incredibly/ busy for the
last few weeks, and my brain is running out of RAM).

It is this: BEFORE I removed the BSR turntable, I DID check to
see whether there was AUDIO SIGNAL coming from it. There was,
loud and clear - when I touched the stylus, it sounded like an
earthquake. Very little "system noise", too.

The turntable itself was "seized" - after I have (with some
violence) managed to take it apart, I saw that the 2 main cog
wheels of the belt-less motor were practically frozen together
at a bizarre angle and would NOT budge. I have NO idea how that
happened - and the 4" screwdriver shaft, 2 children's plastic
letters with magnets, and assorted bits of 30+ year old food I
found inside the receiver could NOT have had anything to do with
it, either, since the BSR motor was fairly well enclosed within
the /incredibly/ complicated mechanical design (a changer).

Now that I have remembered this, it is obvious I screwed
something up. I have never seen a ceramic cartridge, but I am
99.99% positive that BOTH the BSR and the Sony (ca. 1990)
turntable carts are magnetic. So, since I have no signal but
weird pink noise, I must have screwed up the cables. Or do you
think I may have destroyed the preamp?

(This may be a good moment to mention that I am using the term
"phono preamp" in a generic sense. I always thought a phono
preamp might be/would be a small enclosed piece of electronics,
but in this receiver, it appears to be a part of the main
circuit board - the two original (and now extended) cables from
the BSR turntable stylus/arm are soldered right onto the circuit
board, and go who-knows-where - presumably, into components
which make up this receiver's "phone preamp" section.)

(THIS may /also/ be a good moment to mention that while I have
had some disastrous luck with simple things and astoundingly
good luck with complicated things, I am NOT a technician, and do
not own an oscilloscope - I check connections with two gator
clips connected to a 1.5V battery with a flashlight bulb, and
after over 30 years of "considering it", I finally bought a five
dollar "voltmeter" which /appears/ to work - I found out a cheap
110V/22V AC/DC adapter outputs 25VDC when set to 12V output
[when the input voltage is set to 110V] and 12.5VDC from its 9V
setting [when the input voltage is set to 110V (it is 110V
here)]. The Sony turntable (originally a component of a system,
with a tiny power connector which plugs into the back of the
main system unit and where I found out 12VDC is output) is
running on a supposedly "regulated" fancy Radio Shack AC/DC
adapter which puts out 11.8V DC. (When I reverse the polarity,
the turntable spins backwards.)

If anyone has read this far, please accept my deep thanks for
your patience. I can't write more concisely - I realize it's an
illness.

Anyway - the question now is WHAT did I do to mess things up?
Since I consider the receiver largely indestructible, I do not
think I have *destroyed* anything, not to mention the voltages
involved are totally minuscule and it being a solid state unit -
as the front panel proudly states ;-) - there is little danger
of blowing it up. Plus everything else works.

My plan is as follows:

1. Cut the original "BSR cartridge/turntable to the main circuit
board" cables, strip ends.
2. Attach gator clips to them and connect to the Sony turntable
output cable.
3. Hopefully, hear sound. Extend cables again, making SURE I
don't screw up this time.

If I hear no sound, I will connect the 4 very thin cables from
the original BSR cartridge (I saved the cart assembly and cables
before I saw the turntable was connected to the circuit board
with 2 standard cables with RCA plugs) to the cut cables leading
to the circuit board and see if I hear anything. If I do, I will
post for more advice.

But for now, my question is:

If after doing all this, I still get the /same/ pink noise (NOT
hum - strange, huh?) and get NO audio, WHAT do I do?

Thank you /very much/ for your patience, and my apologies for
having forgotten a crucial part of the puzzle. Further help will
be greatly appreciated. If anyone wants to see pix of the 2
cartridges or the circuit board where the phono audio cables are
soldered into it, I can post them to photobucket or something,
OR a binary group if you have binaries access.

The replies are different in every one of the 5 groups, so I
will post this followup to each group separately. I don't really
understand how crossposting works, since I never do it, and
eternal september /may/ be "funny" about crossposting to boot.


--
Any mental activity is easy if it need not be subjected to
reality.