I just got 2 Phase Linear 400 Amps and neither has VU meter lamps that work. I would like to put in colored leds instead. What is the voltage and series resistor required to do this replacement?
Thanks
Thanks
Does no reply mean that nobody knows the answer or I just asked a real stupid question.Barnacle said:
Bill
Well
At last a phase linear fan ! I have 2 off 400,s myself
firstly measure the voltage across the lamp then detuct 2.5 volts for the led divide the remainder voltage by 0.02 and that will give you the value of resistor that you require ! this will give about 20 ma per led
You may want to rectify the votage with a bridge rectifier as the drive to the lamp is ac
Regards Trev
At last a phase linear fan ! I have 2 off 400,s myself
firstly measure the voltage across the lamp then detuct 2.5 volts for the led divide the remainder voltage by 0.02 and that will give you the value of resistor that you require ! this will give about 20 ma per led
You may want to rectify the votage with a bridge rectifier as the drive to the lamp is ac
Regards Trev
Phase Linear Forever
Thanks for the lesson
I have 2 PL400s now and a PL4000 preamp on the way--Love the stuff. Also it was built just a few miles from me here in Kirkland Washington. Now I need a McIntosh for pure beauty. Got my Big JBLs with Electrovoice horns a couple weeks ago and with the Phase Linears it blows my video room apart with the sounds of the 60s and 70s. Oh how I missed those old sounds as I progressed through the digital age but finally gained my senses back and went back in time to the good old analog creatures. I want to Bi-amp the phase linears [if possible ? ] for each of the JBLs and use my Quatre 250 for the horns and then set up my Dahlquists with a Tube Dynaco 120 for the easy listening of norah Jones.
latala said:
Thanks for the lesson
I have 2 PL400s now and a PL4000 preamp on the way--Love the stuff. Also it was built just a few miles from me here in Kirkland Washington. Now I need a McIntosh for pure beauty. Got my Big JBLs with Electrovoice horns a couple weeks ago and with the Phase Linears it blows my video room apart with the sounds of the 60s and 70s. Oh how I missed those old sounds as I progressed through the digital age but finally gained my senses back and went back in time to the good old analog creatures. I want to Bi-amp the phase linears [if possible ? ] for each of the JBLs and use my Quatre 250 for the horns and then set up my Dahlquists with a Tube Dynaco 120 for the easy listening of norah Jones.
Wow
That system sounds awsome! Despite some people calling them Flame Linears I have found that with the correct matching equipment they can sound superb.
At the moment I am not using mine but do not intend to get rid of them .
Regards Trev
That system sounds awsome! Despite some people calling them Flame Linears I have found that with the correct matching equipment they can sound superb.
At the moment I am not using mine but do not intend to get rid of them .
Regards Trev
Rectifier
part of the advice.
Thanks again
Get those PLs up and running !
What would be the advantage of the bridge rectifier in LED circuit? or would it just not work without being rectified? You confused me a little with the "you may want to rectify"latala said:
part of the advice.Thanks again
Get those PLs up and running !
As the supply to the lamps is AC youwould only get illumination on 1/2 of ther cycle .Also there is a danger that the led would be damaged by a reverse voltage all though that is unlikely
The brightness would also be affected because of the half cycle operation
Also there could be a flickering effect when you view the light while moving your head because of the speed of the led most lamp filaments are to slow for this effect to show
If you have room you could use 2 leds in reverse parrallel is,e cathode of 1 to anode of 2 and anode of 1 the cathode of 2 this would eliminate all the effects so mentioned without the need for a bridge rectifier
regards Trev
The brightness would also be affected because of the half cycle operation
Also there could be a flickering effect when you view the light while moving your head because of the speed of the led most lamp filaments are to slow for this effect to show
If you have room you could use 2 leds in reverse parrallel is,e cathode of 1 to anode of 2 and anode of 1 the cathode of 2 this would eliminate all the effects so mentioned without the need for a bridge rectifier
regards Trev
4 leds
The 2 PL panel meters have 4 LEDs each so I presume that I could use this reverse setup for each pair of LEDs or use a series / parallel combination for the hookup of all 8 lights and no rectifier. If this would work with 8 LEDs a little circuit diagram or explanation would be appreciated.
Thanks
That sounds reasonablelatala said:
The 2 PL panel meters have 4 LEDs each so I presume that I could use this reverse setup for each pair of LEDs or use a series / parallel combination for the hookup of all 8 lights and no rectifier. If this would work with 8 LEDs a little circuit diagram or explanation would be appreciated.
Thanks
Burned Secondary ? 6VAC 
Bill
I went to measure the voltage at the meter lamps and there is none. The supposedly 6v to the lamps come from the transformer and it appears that the transformer secondary is burned out. My next choice is to pick up a dc voltage after the Mains rectifier which is 75VDC and use that for the power to the LEDs with the appropriate resistor. Does that sound reasonable?latala said:
Bill
I would check every thing out as the 6 v sec burning out seams to be unlikly ?
however if I had to go down the route you have mentioned I would wire all leds in series and then use a dropper resistor between the posative supply and ground
remember though that some blue /white leds require about 4 volts each so 8 x 4 = 36 volts 70 volts from supply - 36 = 34 volts
divided by 20 ma = 1.7 k ohm 1.5 k is near enough
power dissipated by the resistor is 0.68 watts
so in this case a 1.5 k resistor rated at 1 watt would be fine
trust this helps
regards trev
however if I had to go down the route you have mentioned I would wire all leds in series and then use a dropper resistor between the posative supply and ground
remember though that some blue /white leds require about 4 volts each so 8 x 4 = 36 volts 70 volts from supply - 36 = 34 volts
divided by 20 ma = 1.7 k ohm 1.5 k is near enough
power dissipated by the resistor is 0.68 watts
so in this case a 1.5 k resistor rated at 1 watt would be fine
trust this helps
regards trev
6v transformer
I totally agree with you on the transformer at fault although there are 2 red leads [6v]out from the transformer that go nowhere except the meter lights and there is 0v between them. The schematic verifys this, I have never had a blown transformer. Just leaves me the option to get the voltage somewhere else.
Thanks for the design help
Bill
I totally agree with you on the transformer at fault although there are 2 red leads [6v]out from the transformer that go nowhere except the meter lights and there is 0v between them. The schematic verifys this, I have never had a blown transformer. Just leaves me the option to get the voltage somewhere else.
Thanks for the design help
Bill
Phase Linear xfmr problem
Use an ohm meter on the xfmr winding. If it's open then the problem is the connection between the winding and the red wire. You would have to remove the xfmr from the chassis and take the cover off that the the rectifier mounts on.
I experimented with LEDs on a 400 a few years back. The problem is that incandescent bulbs disperse light in all directions whereas the LED has a limited pattern from the tip. When inserted Horizontally the LEDs don't light up the panel very well. I found some green ultra high output LEDs that were OK, but I really wanted blue.
I've got some other mods for the 400 in the works. PM me if interested.
Use an ohm meter on the xfmr winding. If it's open then the problem is the connection between the winding and the red wire. You would have to remove the xfmr from the chassis and take the cover off that the the rectifier mounts on.
I experimented with LEDs on a 400 a few years back. The problem is that incandescent bulbs disperse light in all directions whereas the LED has a limited pattern from the tip. When inserted Horizontally the LEDs don't light up the panel very well. I found some green ultra high output LEDs that were OK, but I really wanted blue.
I've got some other mods for the 400 in the works. PM me if interested.
Re: PL400
Bill,
You're user preferences don't allow email through this forum. Mine does. Send a PM.
Barnacle said:
Bill,
You're user preferences don't allow email through this forum. Mine does. Send a PM.
I just recently used some blue 5mm wide (60 degree) dispersion LED's with a 40 ohm resistor for current limiting attached to each LED leg. Like the earlier post mentioned, with just AC supplying them, you may notice a flicker while moving your head, but I really haven't noticed it all that much. Like D3imlay mentioned, LED's are designed to project their light out the end, so you should choose one with the highest dispersion angle, and a neat trick I used was to lightly sand the outside with scotch brite, or some 400 grit sand paper to make it more translucent. That made a huge difference on throwing out more light from the sides. Depending on which meter you have, mine has the Honeywells, I would like to see if it's possible to apply some reflective foil tape at the bottom on the meter to throw some more light up off the bottom. I will take some pictures shortly and get them posted here, but battling a Large bias voltage issue I am having with it right now, so the project is at a stand still.
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