Re: [M]: RA Runaway
| Subject: | Re: [M]: RA Runaway |
| From: | Larry Owens |
| Date: | Wed Aug 15 03:28:07 2001 |
Youre reading my mind. I have a roll of clear milar from some project
years ago, and decided to cut out a piece to fit the bottom plate of my
LX200. This is probably a good permanent solution if you cant locate the
specific component. Electrical tape will deteriorate over time but not the
milar.
If anybody is interested I could cut a few of these and mail them out.
Its somewhat tedious so Id want to charge a modest fee in addition to the
cost.
E-mail me personally if youre interested.
Thanks...
At 01:12 PM 8/14/01 -0700, you wrote:
>>>>
The problem is that the bottom plate is recessed inside the base. Id have
to have something cut out the same size as the plate to fit the recessed
ledge.
The only thing I can see that doesnt look good is a resistor between the
two heat sinked ICs (U17 and U18). This resistor is pushing up tight
against the transparent orange tape going across the heat sink. Im not
sure what this tape is for, but this resistor is clearly bring stressed
when the bottom plate pushes against the heat sink. Hard to see what this
resistor is without a layout drawing.
I guess Ill just wait until the electronics upgrade arrives from Meade.
-Matt
"LaGuardia, Kristofer S." wrote:
Couldnt you just press a piece of paper taught against the base and see
what component is touching? Or better yet, wrap a piece of cardboard with
aluminum foil and press it flush with the base, and see if anything pokes a
hole in the foil. It should be obvious then what component is pressing
against it. If its no clear what component is the intruding one, then try
plastic wrap, itll snag on anything too far down...
> -----Original Message-----
> From: Matt Thomas [mailto:m-e-thomas@home.com]
> Sent: Tuesday, August 14, 2001 12:08 PM
> To: mapug@shore.net
> Subject: Re: [M]: RA Runaway
>
>
> Larry,
>
> Good suggestion. Removing the bottom plate fixes the
> problem. Looking at the
> mother board I cannot see any obvious contacts with the
> plate. I reattached
> the plate and the problem returned, so there is definitely
> something contacting
> it...
>
> Covering the base plate with electrical tape sounds like a
> good idea, of course
> I guess Ill want to leave the heat sink contact exposed...
> Im going to try
> looking closer for the part that might be contacting the plate.
>
> -Matt
>
> Larry Owens wrote:
>
> > Does this problem occur with the RA bottom plate off? If
> you havent
> > powered up without it, its worth a try. A number of
> people have reported
> > problems caused by vertically mounted mother board
> components touching the
> > metal bottom plate. I didnt have a problem, but several components
> > definitely were in contact with the plate. The anodizing
> insulates to a
> > certain extent, but sooner or later those components will
> scratch through
> > and cause a problem. I would predict a problem just like
> yours. Works
> > great, travel with it, vibration causes those components to
> finially short,
> > and your night of viewing is spoiled by an intermittent scope.
> >
> > Pull that bottom plate off, bend down any vertically
> mounted components,
> > and cover the inside of the plate with electrical tape.
> >
> > Even if this isnt your current problem, its a good idea.
> >
> > At 01:46 PM 8/13/01 -0700, you wrote:
> > >I have a two month old 10" LX200. The scope was working
> just fine until
> > >last week. I went on a trip up to Lake Huntington in the
> Sierra Nevada
> > >mountains (7000 elevation) and brought my scope with me
> (packed in the
> > >original shipping foam with the Meade soft carrying case). When I
> > >unpacked the scope and powered it up, the RA drive took off at high
> > >speed to the east. Cycling the power only caused the scope to do
> > >nothing (with "Meade" showing on the hand controller) or
> the RA drive to
> > >take off again.
> > >
> > >Ive read the archives and there is mention of the ribbon
> cable having a
> > >short in it, but Im not sure that is my problem given my
> two months of
> > >good operation.
> > >
> > >Does anyone have any ideas on what to check?
> > >
> > >Thanks,
> > >Matt Thomas
> > >
> > >
> > >
> > >
> > ------------------------------------------------
> > Larry Owens ccd@astrophotographer.net
> > ------------------------------------------------
>
>
<<<<
------------------------------------------------
Larry Owens ccd@astrophotographer.net
------------------------------------------------
years ago, and decided to cut out a piece to fit the bottom plate of my
LX200. This is probably a good permanent solution if you cant locate the
specific component. Electrical tape will deteriorate over time but not the
milar.
If anybody is interested I could cut a few of these and mail them out.
Its somewhat tedious so Id want to charge a modest fee in addition to the
cost.
E-mail me personally if youre interested.
Thanks...
At 01:12 PM 8/14/01 -0700, you wrote:
>>>>
The problem is that the bottom plate is recessed inside the base. Id have
to have something cut out the same size as the plate to fit the recessed
ledge.
The only thing I can see that doesnt look good is a resistor between the
two heat sinked ICs (U17 and U18). This resistor is pushing up tight
against the transparent orange tape going across the heat sink. Im not
sure what this tape is for, but this resistor is clearly bring stressed
when the bottom plate pushes against the heat sink. Hard to see what this
resistor is without a layout drawing.
I guess Ill just wait until the electronics upgrade arrives from Meade.
-Matt
"LaGuardia, Kristofer S." wrote:
Couldnt you just press a piece of paper taught against the base and see
what component is touching? Or better yet, wrap a piece of cardboard with
aluminum foil and press it flush with the base, and see if anything pokes a
hole in the foil. It should be obvious then what component is pressing
against it. If its no clear what component is the intruding one, then try
plastic wrap, itll snag on anything too far down...
> -----Original Message-----
> From: Matt Thomas [
> Sent: Tuesday, August 14, 2001 12:08 PM
> To: mapug@shore.net
> Subject: Re: [M]: RA Runaway
>
>
> Larry,
>
> Good suggestion. Removing the bottom plate fixes the
> problem. Looking at the
> mother board I cannot see any obvious contacts with the
> plate. I reattached
> the plate and the problem returned, so there is definitely
> something contacting
> it...
>
> Covering the base plate with electrical tape sounds like a
> good idea, of course
> I guess Ill want to leave the heat sink contact exposed...
> Im going to try
> looking closer for the part that might be contacting the plate.
>
> -Matt
>
> Larry Owens wrote:
>
> > Does this problem occur with the RA bottom plate off? If
> you havent
> > powered up without it, its worth a try. A number of
> people have reported
> > problems caused by vertically mounted mother board
> components touching the
> > metal bottom plate. I didnt have a problem, but several components
> > definitely were in contact with the plate. The anodizing
> insulates to a
> > certain extent, but sooner or later those components will
> scratch through
> > and cause a problem. I would predict a problem just like
> yours. Works
> > great, travel with it, vibration causes those components to
> finially short,
> > and your night of viewing is spoiled by an intermittent scope.
> >
> > Pull that bottom plate off, bend down any vertically
> mounted components,
> > and cover the inside of the plate with electrical tape.
> >
> > Even if this isnt your current problem, its a good idea.
> >
> > At 01:46 PM 8/13/01 -0700, you wrote:
> > >I have a two month old 10" LX200. The scope was working
> just fine until
> > >last week. I went on a trip up to Lake Huntington in the
> Sierra Nevada
> > >mountains (7000 elevation) and brought my scope with me
> (packed in the
> > >original shipping foam with the Meade soft carrying case). When I
> > >unpacked the scope and powered it up, the RA drive took off at high
> > >speed to the east. Cycling the power only caused the scope to do
> > >nothing (with "Meade" showing on the hand controller) or
> the RA drive to
> > >take off again.
> > >
> > >Ive read the archives and there is mention of the ribbon
> cable having a
> > >short in it, but Im not sure that is my problem given my
> two months of
> > >good operation.
> > >
> > >Does anyone have any ideas on what to check?
> > >
> > >Thanks,
> > >Matt Thomas
> > >
> > >
> > >
> > >
> > ------------------------------------------------
> > Larry Owens ccd@astrophotographer.net
> > ------------------------------------------------
>
>
<<<<
------------------------------------------------
Larry Owens ccd@astrophotographer.net
------------------------------------------------
