LX90 not working with internal power.

[S.A.M]

Hello SGL,

Recently I managed to catch the external power lead on the tripod leg while slewing the scope, this resulted in the scope not working and one broken lead.  After checking at home that internal batteries had enough power, it would not work with them yet applying external power (after repairing the broken lead) it works okay?  Could it be a change of the control power panel to get internal power working again or should I leave everything alone while it works on external power?  Any ideas/suggestions with by most grateful.

Peter

[misterp]

Might there be fuse that has blown.

A while ago my LX200 stopped working the it was an internal fuse

Ian

[barkis]

There is a connection internally on the power input plug. That connection breaks when you
insert an external supply. when you remove the external connector, the supply reverts to internal.
That Mechanism may have been fouled up when the strain was put on to the external lead.
You will need to examine that Input connector to be sure.

 

[symmetal]

The reply I gave to your previous post with the wiring of the panel should give you the information you need.

meade-lx-90-power-supply-lead-broken

A multimeter is a cheap and very useful tool for sorting such problems.

With the external power plug removed check for the battery volts (I assume they're 12V) on pins 2 and 3 of the power socket J1. If yes, check if they are also present on pins 1 and 3. Almost certainly they won't be. This means the internal connection on the power socket has failed. Whether it's worth getting the socket replaced or replacing the board just to enable working on batteries is up to you. Adding another switch to replace the actions of the power socket is another option though requires some wiring experience.

Alan

[S.A.M]

Thank you for all the replies.  I do not know if there is an internal fuse within my scope or not?  Alan, you info sounds good, I have a multi meter so if I go down that route I will have an idea of what to expect?

Peter

[symmetal]

Peter, I was just wondering as to whether you had used it with batteries in the past before your mishap, or was that the first time you tried it with batteries and it didn't work. The wires from the batteries go to connector JP6 initially so first confirm that the connector is plugged in and that you can measure the battery volts on connector JP6. If there is no visible fuse accessible from the outside it would have been on this board. There isn't one on the board so I would say there is no fuse in the battery supply.

Alan

[S.A.M]

Alan, I had batteries installed when I had the mishap.  I did not realise I had the batteries in at the time as I had been using external power for a very long time with this scope.  Is connector JP6 on the power circuit or is it nearby as I cannot locate a JP6 on the above diagram?

Peter

[symmetal]

Peter, JP6 is the 2 pin connector at the bottom left of the diagram just above the label 'Batteries'. Another thought is if you've had batteries in there for a long time not being used they may possibly have leaked and caused some corrosion of the battery contacts and leading to a bad connection. Take the batteries out and inspect the battery contacts on the holder in the scope to check they're still clean bare metal before you go to the trouble of getting access to the rear of the power panel.

Alan

[S.A.M]

Hi Alan,

All of the batteries were clean, so no leaks from that area?  Another thing I have noticed when I got a replacement power jack (2.5 mm diameter jack (L49AY product code) from Maplin's) to repair the broken cable it does not sit very snug when attached to the jack on the computer control panel (just below LED light), sought of a lose fit that can stop the power supply to the scope when slewing?  I thought this should be a reasonable push fit , otherwise it could become lose and stop?

Peter

[symmetal]

Hi Peter, the plug you got from Maplins is the wrong size.  It has a pin diameter of 2.5mm and outside barrel diameter of 5.0mm. The correct size is a barrel diameter of 5.5mm. 5.5mm is much more common than 5.0mm. Assuming this LX90 pinouts diagram is correct.

The right part from Maplin would then be HH62S for the short barrel plug or HH63T for the long barrel plug.

The 5.0mm barrel plug you have will fit in the power socket but will be a loose fit and cause an intermittent connection. It is also the short barrel length version. If you still have the the original broken plug you can compare the length to see which is the best match. Or stick something non-metallic down the socket hole like a toothpick to gauge its depth and match it that way. Long or short barrel will both work but a long barrel in a short socket will stick out a bit and not look so neat. A short barrel in a long socket looks good and will work though may not have a good area of contact. 

Alan

[S.A.M]

Hi Alan, that answer my question brilliantly, thank you for that.  I could get a replacement lead from Meade, assuming it had correct end for about £22?  Making my own for a couple of quid makes more sense to me, I will have a look at the Maplin's site and order one.  Will try and see how long the power pin is tonight and order the best fit tomorrow from local store and re make the end piece of power cable.

Peter

[S.A.M]

Hi Alan, I now have the bigger power pin and it is not such a sloppy fit as the previous one, thank you for that.  I used the shorter length of the two.

Peter