Organ Power Supply Problems

[Brian Molnar]

I recently bought an old Lowrey TLO organ from the 1960s. When I got it home
and fired up, it worked fine and sounded decent, but then when I turned on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that Reverb
switch turned off.

At this point i figured that something in the switch was messing it up, so i
took off the plate around it and examined it. Thw way the switches work is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other, and
apparently the spring had come out and was laying across both conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing, came
up for a half second (this is indicated by the light on the power switch)
and died.

I'm wondering if the spring coming out and shorting a path between the two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could venture a
guess at to what the problem could be. I'm open to any suggestions. Also, I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Brian Molnar

 

[Ian Gowen]

I had the same type of problem with a subwoofer once. Someone gave
me the subwoofer/speaker set, saying that they didn't work. Heh... all it
needed was a fuse. I thought I knew the voltage rating of the fuse, got a
new one, and installed it. It immediately blew when I turned the power on.
Reason was, the fuse was a fast-acting type, not slow-blow, which it needed.
So if you're using a fast-acting fuse, try a slow-blow and see if that
works.

I think the reason for the slow-blow fuse(on the sub anyway) was that the
speaker is built to take a fairly big signal-- but not for extended periods
of
time. When you have a fast-acting fuse, it receives a base note and
immediately blows.

Hope this helps

Ian

"Brian Molnar" <molnab@rpi.edu> wrote in message
news:c4c21e$oke$1@newsfeeds.rpi.edu...

I recently bought an old Lowrey TLO organ from the 1960s. When I got it
home
and fired up, it worked fine and sounded decent, but then when I turned on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that Reverb
switch turned off.

At this point i figured that something in the switch was messing it up, so
i
took off the plate around it and examined it. Thw way the switches work is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other,
and
apparently the spring had come out and was laying across both conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing,
came
up for a half second (this is indicated by the light on the power switch)
and died.

I'm wondering if the spring coming out and shorting a path between the two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could venture
a
guess at to what the problem could be. I'm open to any suggestions. Also,
I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this
organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Brian Molnar

 

[Hotspur]

On Tue, 30 Mar 2004 09:59:01 -0500, Brian Molnar <molnab@rpi.edu>
wrote:

I recently bought an old Lowrey TLO organ from the 1960s. When I got it home
and fired up, it worked fine and sounded decent, but then when I turned on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that Reverb
switch turned off.

At this point i figured that something in the switch was messing it up, so i
took off the plate around it and examined it. Thw way the switches work is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other, and
apparently the spring had come out and was laying across both conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing, came
up for a half second (this is indicated by the light on the power switch)
and died.

I'm wondering if the spring coming out and shorting a path between the two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could venture a
guess at to what the problem could be. I'm open to any suggestions. Also, I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Brian Molnar
The first thing is to check the fuse holder with a meter/Scope see if

power is surging and check current flow.
There really is no other way of checking except to trace the power
from the wall socket pin all the way through,verify the Transformer
outputs are correct etc.Are you sure the fuse in there is the correct
rating for the organ?
As well as a TV engineer I am a Pro organist but I'm not familier with
Lowry[I play Technics and Wersi]
There are plenty of organ shops in the UK that may have old power
supplys around,same must be said for other countries.
I'll ask around for you but if you live in the USA you have no hope of
getting electronic parts sent there[And I don't blame them] hope your
lucky but any engineer will trace the power for you.Regards Frank

 

[Allen]

Brian Molnar <molnab@rpi.edu> wrote in message news:<c4c21e$oke$1@newsfeeds.rpi.edu>...

I recently bought an old Lowrey TLO organ from the 1960s. When I got it home
and fired up, it worked fine and sounded decent, but then when I turned on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that Reverb
switch turned off.

What is the rating of the fuse? May be someone has changed it with
one under rating. For an organ made in the 60s, I presume it is fully
transistorised without any IC chips. So I guess some of the
transistors were getting old and leaky, and some of the capacitors
might get leaky too. Check if there is any capacitor oil leakage near
to the ON/OFF switch with a torch light. This is quite common in an
old Yamaha Organ like A55. It has a 47nF 600V capacitor accross the
switch and some capacitors directly across the AC mains.

At this point i figured that something in the switch was messing it up, so i
took off the plate around it and examined it. Thw way the switches work is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other, and
apparently the spring had come out and was laying across both conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing, came
up for a half second (this is indicated by the light on the power switch)
and died.

If you suspect the switch is shorted, it is very to confirm with an
ohm meter. Just connect the 2 mains wire from your organ to the ohm
meter and switch to X 1 range. If the resistance drops very low say
below 10 ohms on OFF condition, then the switch is probably faulty.

I'm wondering if the spring coming out and shorting a path between the two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could venture a
guess at to what the problem could be. I'm open to any suggestions. Also, I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Is there a big transformer in the power supply? I dont think it is
very hard to fix the PS but it would be very tough to fix the other
functions of the organ made in the 1960s even with the schematics. As
there are so many transistors, PCBs, and bundles of messy wires.

Regards,

Allen

Brian Molnar

 

[Al]

In article <f91a20cb.0404021750.69baaf8f@posting.google.com>,
sfbong@tm.net.my (Allen) wrote:

Brian Molnar <molnab@rpi.edu> wrote in message
news:<c4c21e$oke$1@newsfeeds.rpi.edu>...
I recently bought an old Lowrey TLO organ from the 1960s. When I got it
home
and fired up, it worked fine and sounded decent, but then when I turned on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that Reverb
switch turned off.

What is the rating of the fuse? May be someone has changed it with
one under rating. For an organ made in the 60s, I presume it is fully
transistorised without any IC chips. So I guess some of the
transistors were getting old and leaky, and some of the capacitors
might get leaky too. Check if there is any capacitor oil leakage near
to the ON/OFF switch with a torch light. This is quite common in an
old Yamaha Organ like A55. It has a 47nF 600V capacitor accross the
switch and some capacitors directly across the AC mains.


At this point i figured that something in the switch was messing it up, so
i
took off the plate around it and examined it. Thw way the switches work is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other, and
apparently the spring had come out and was laying across both conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing, came
up for a half second (this is indicated by the light on the power switch)
and died.

If you suspect the switch is shorted, it is very to confirm with an
ohm meter. Just connect the 2 mains wire from your organ to the ohm
meter and switch to X 1 range. If the resistance drops very low say
below 10 ohms on OFF condition, then the switch is probably faulty.


I'm wondering if the spring coming out and shorting a path between the two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could venture a
guess at to what the problem could be. I'm open to any suggestions. Also, I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Is there a big transformer in the power supply? I dont think it is
very hard to fix the PS but it would be very tough to fix the other
functions of the organ made in the 1960s even with the schematics. As
there are so many transistors, PCBs, and bundles of messy wires.

Regards,

Allen



Brian Molnar

My son repaired an old organ by replacing the filter capacitors with
close equivalents. The old ones had dried out. Only the ones in the main
power supply had to be replaced.

Al

--
There's never enough time to do it right the first time.......

 

[Mr TUBEAMPS]

is the organ a old valve type.

john

"Allen" <sfbong@tm.net.my> wrote in message
news:f91a20cb.0404021750.69baaf8f@posting.google.com...

Brian Molnar <molnab@rpi.edu> wrote in message
news:<c4c21e$oke$1@newsfeeds.rpi.edu>...
I recently bought an old Lowrey TLO organ from the 1960s. When I got it
home
and fired up, it worked fine and sounded decent, but then when I turned
on
the Main Chorus Reverb it quickly died. So the first place i checked was
the fuse to the power supply / amp unit and sure enough it blew, so i
replaced it with another fuse of the same ratings, the same make / model
even. I turned it on and it came up for about a half a second then died
again. I checked and it blew that fuse too. This was even with that
Reverb
switch turned off.

What is the rating of the fuse? May be someone has changed it with
one under rating. For an organ made in the 60s, I presume it is fully
transistorised without any IC chips. So I guess some of the
transistors were getting old and leaky, and some of the capacitors
might get leaky too. Check if there is any capacitor oil leakage near
to the ON/OFF switch with a torch light. This is quite common in an
old Yamaha Organ like A55. It has a 47nF 600V capacitor accross the
switch and some capacitors directly across the AC mains.


At this point i figured that something in the switch was messing it up,
so i
took off the plate around it and examined it. Thw way the switches work
is
that there are are these plastic rockers that have a spring connected to
them and on each side of the spring are two conductors (SPDT). So the
rocker moves the spring between contacting one condcutor and the other,
and
apparently the spring had come out and was laying across both
conductors,
obviously the problem that caused it to die in the first place. So I
managed to reposition the spring back in the rocker the way it should be
and gave it a few test rocks, without the electricity on, and it looked
like it was doing it's job alright. So I plugged the organ back in and
turned it back on with yet another fuse in, but it did the same thing,
came
up for a half second (this is indicated by the light on the power
switch)
and died.

If you suspect the switch is shorted, it is very to confirm with an
ohm meter. Just connect the 2 mains wire from your organ to the ohm
meter and switch to X 1 range. If the resistance drops very low say
below 10 ohms on OFF condition, then the switch is probably faulty.


I'm wondering if the spring coming out and shorting a path between the
two
conductors may have done damage to some components of the power supply
before the fuse had time to kill it. I was wondering anyone could
venture a
guess at to what the problem could be. I'm open to any suggestions.
Also, I
may be taking a shot in the dark with this one, but I was wondering if
anyone knew where i could possibly get another power supply for this
organ.
It's a Lowrey TLO from, I think, 1968. Any help would greatly be
appreciated.

Is there a big transformer in the power supply? I dont think it is
very hard to fix the PS but it would be very tough to fix the other
functions of the organ made in the 1960s even with the schematics. As
there are so many transistors, PCBs, and bundles of messy wires.

Regards,

Allen



Brian Molnar