Quantcast

High voltage value for a Sequel II

MartinLogan Owners (MLO)

Help Support MartinLogan Owners (MLO):

L

lucm

Guest
Hi all
My best friend own sequel II since many years now. It was on of the most clear sound I have ever heard.
UNfortunatly these speakers now have loose their dynamic. After ready this forum we did a good vacuum cleaning and connexion cleaning, it is better but still not meet our expectation.
I use a HV probe to check the voltage on the stator anf found only 1090 volts on both of them. I was expecting more voltage.
1-Is there someone who can tel me what is the reference voltage on the stator ( between red and blue wires) and the commun fault.
2-a other question; on the HV bd there is a switch with 2 position marked 0 and 1. These swith seem to close a diodes rectifier. Their are set to 0. Did someon know what are they switch use for ?
I am thinking about replacing my own speaker and would like to use his martin logan as a reference.. so I need them to work..
thanks for any help an good listening.
Luc
 

enilsen

Well-known member
Joined
Apr 7, 2005
Messages
102
Reaction score
0
Location
Central Sweden
Did you check to see if the static charge is even across the Mylar membrane?
The stators voltage will actively change when music is played so this measurement might not reveal anything except that there is plenty of HV.

The Mylar membrane on the other hand is an active component subject to loss of static charge. When dust and other containments are attracted to this, they can create small bridges which the static charge can escapes through. The design of ML speakers have bands across the stators to hold the Mylar membrane in place so it doesn’t rest on the HV stators. These bands are not conductive, but should enough containments collect on the band itself they could discharge sufficient amounts of static charge to make a difference in sound quality.

Hence there are 2 popular methods for addressing this problem. The most common method is vacuuming the panels which normally addresses loose containments resting in and on the stators and membrane (which you have tried). The second method is washing the panels with warm water. This will remove containments that the vacuumed method did not address and presumably freshen up the Mylar surface.

I have written another post on how to determine if the Mylar membrane is suffering from loss of static charge, but still can hold a static charge.

http://www.martinloganowners.com/~tdacquis/forum/showthread.php?t=631

As you are familiar with HV measurements it shouldn’t be problem for you to determine if there are areas that could be improved in sound by using this technique and focusing your cleaning efforts if needed.
 
L

lucm

Guest
Thanks for your answer. It seems after cleaning that all panels was working. I took note of your procedure to test after a cleaning.
About HV i did made mesurement with and without the stator connected with the same value of 1090 voltes, that mean at least that there is no escape of hv on the stator. But I was expecting the value to be around 4000 volts or more. Actually the sound level is very low and do think we have HV pb. Any idea of the static voltage without signal ?
thanks for you precious help.
luc
 
L

lucm

Guest
Thanks for the Email adress of Mister Power ( is it a nike name ?).
I already subit this question through the service request of the official martin logan site, so I will wiat a while before asking again there.
thanks
Luc
 

enilsen

Well-known member
Joined
Apr 7, 2005
Messages
102
Reaction score
0
Location
Central Sweden
Personally I have never had an urge to research the voltage of the stators. Instead I have always done swap between panels and HV boxes to identify problems with either the boxes or the panels. If there is a problem with the voltage on the HV box, then I suspect you would have very little sound if any.

Right now I’m assuming both left and right stators have 1090 volts at idle so why assume there is a problem with the boxes.

Assuming both panels are equally weak, you could try a little experiment to see if the connection between the bias strip at the bottom of the Mylar membrane is loosing its charge (connectivity). Hidden behind the lower area of the stator which is not perforated there is an aluminum strip that is stretched across the Mylar membrane. This in turn is sandwiched in place by an insulating foam band and the front stator. You can not see this, but trust me its there and the third center wire is the one that powers it.

Take a small eye dropper or a thin tube filled with regular tap water and place it against the membrane just above the lower perforated edge of the front stator. Allow a small amount of water to run down the membrane into the foam insulator. Hopefully this will assist the bias aluminum strip to re-establish a better connection and yield a better charge to the membrane.

If this does help then there is a more permanent fix on this posting below.

http://www.martinloganowners.com/~tdacquis/forum/showthread.php?t=606
 

Peter Hogan

Well-known member
Joined
Dec 31, 2004
Messages
295
Reaction score
1
Location
Fitchburg, MA
lucm said:
I use a HV probe to check the voltage on the stator anf found only 1090 volts on both of them. I was expecting more voltage.

Luc
Hi,
That does sound low. Where are you measuring the high voltage? There is 30-75 megohms of resistors in series with the high voltage supply and the panels. If you are measuring on the panel side of the resistors, you are going to get a low reading, from the resistors dropping the voltage when the HV probe is present. You want to measure the voltage BEFORE the resistors on the PCB.

Peter
 
L

lucm

Guest
hi,
effectively i did mesurement on connector to stator so after the resistor. Your are probably writh as my HV probe si consuming current, and there is a current limitator (this resistor) I need mesure before it. Any idea of HV I must found ? My probe is only 5 kv ...
regards
Luc
 
L

lucm

Guest
hi Enilsen,
you are write, I got the same HV on both on the but with low ready. Peter just post that there is a resistor in charge of current limitation. So I need to redo the mesure before it. If HV is upper I will look on the milar connection like you explain. May be some carbon into water can creeate a new connection? Never try to put some fine scrath of a pencil into water ? It can be an alternative to your soap that I am not sure to find in france.
regards
Luc
 

Peter Hogan

Well-known member
Joined
Dec 31, 2004
Messages
295
Reaction score
1
Location
Fitchburg, MA
lucm said:
hi,
effectively i did mesurement on connector to stator so after the resistor. Your are probably writh as my HV probe si consuming current, and there is a current limitator (this resistor) I need mesure before it. Any idea of HV I must found ? My probe is only 5 kv ...
regards
Luc
Hi,
I believe most ML's run 3-4KV, so you should be fine with a 5KV probe.

Peter
 

enilsen

Well-known member
Joined
Apr 7, 2005
Messages
102
Reaction score
0
Location
Central Sweden
I wouldn't put anything into the water like carbon from a pencil. You are only testing to see if the bias strip is loosing its connection to the Mylar membrane. The special soap solution is only needed if you determine that the connection can be improved by this simple test. If you need this particular soap in France then a drug store should carry it as it is a quite common product worldwide.
 
L

lucm

Guest
Hi peter.
Thanks
I am planning to redoo the mesure when I will go to see my friend.
I will let you know
Luc
 
L

lucm

Guest
Hi Enilsen.
I will stay on your advice and test first with water after the checking of HV before the current limitator resistor. Thanks for all these precious advices.
Luc
 
Top