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GM digital dash

B

BOB URZ

Jan 1, 1970
0
Has anyone here attempted to repair a 90's GM digital dash unit?
From what i can research, they have a small power inverter board
as well as the typical bad solder joints in them. My brother in law
is bringing his over and i am trying to prepare. Anybody been inside
one?

Bob
 
A

Art

Jan 1, 1970
0
Pull the dash assembly, call the local GMC Service Facility, ask what the
exchange price is for the item, and bite the bullet. Most of these
invertors, etc are priority parts available only from the supplier to the
manufacturer of the vehicle.
 
J

Jerry G.

Jan 1, 1970
0
Most of the parts are priority type parts in these. You will not be able to
buy most of the parts on these boards. If it built up on a flex board, even
fixing a cold solder connection will be difficult. The only fix is to pull
it out, take it to a GM parts dealer, and pay the exchange for a new one.
This is the same for all of these cars.

--

Jerry G.
======


Has anyone here attempted to repair a 90's GM digital dash unit?
From what i can research, they have a small power inverter board
as well as the typical bad solder joints in them. My brother in law
is bringing his over and i am trying to prepare. Anybody been inside
one?

Bob


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B

Bob Urz

Jan 1, 1970
0
Jerry said:
Most of the parts are priority type parts in these. You will not be able to
buy most of the parts on these boards. If it built up on a flex board, even
fixing a cold solder connection will be difficult. The only fix is to pull
it out, take it to a GM parts dealer, and pay the exchange for a new one.
This is the same for all of these cars.
Come on guys, someone has tried to do this somewhere. There are a number
of internet sites advertising dash repair. And since GM does NOT sell
parts to do this, they have figured out how. Basically, these dashes
have a step up power supply to run the display tubes. Not brain
surgery, just a switcher and some parts. And i am guessing Jerry that
your right and there house numbered parts. But that does NOT mean
there not fixable. Once you know what the circuit does and the case
style of the output device, one can probably make some assumptions
and go to a parts catalog and try a few devices. Hell, it might just
be caps with bad ESR or solder joints. Other people are doing this.
Granted, customized CPU chips or ASIC would be a problem. But i believe
in the older dashes its just solder joints and power supply problems
for the most part.


So no, i am an not going to tell my Brother in law to junk a car that's
probably not worth much more than a $800 digital dash (if its even still
available). Its worth a shot to figure it out. And maybe if i do,
i will offer that service too along with my other repair services.

So i ask again, any other braves soles actually dig into one?
Once i get it and dig into it, i will report back.

Bob
 
W

William R. Walsh

Jan 1, 1970
0
Hi!
Come on guys, someone has tried to do this somewhere.

I'm sure somebody has, but around here these things exist only in the print
of the manuals for the car. Other than in very new cars where such a thing
might be standard issue, I have never seen one.

Maybe such dashes in older cars are rare enough that the few people who know
how to fix them or have bothered to take them out and have a look are either
keeping to themselves or doing the repair for profit.
There are a number
of internet sites advertising dash repair. And since GM does NOT sell
parts to do this, they have figured out how. Basically, these dashes
have a step up power supply to run the display tubes. Not brain
surgery, just a switcher and some parts.

Well, you're never going to know unless you take it out of there and have a
look at it. Worst case you find that it's somehow potted or uses really
oddball parts.

I suppose locating a working example of the same or a similar dash would
also be a good way to learn. You could make measurements and see what the
circuitry is doing where.
So i ask again, any other braves soles actually dig into one?
Once i get it and dig into it, i will report back.

No, but if I ever happen to see one in an older car (and preferably in the
junkyard) I will take it out and look at it. I'm looking forward to hearing
your report on these.

William
 
J

James Sweet

Jan 1, 1970
0
Bob Urz said:
Come on guys, someone has tried to do this somewhere. There are a number
of internet sites advertising dash repair. And since GM does NOT sell
parts to do this, they have figured out how. Basically, these dashes
have a step up power supply to run the display tubes. Not brain
surgery, just a switcher and some parts. And i am guessing Jerry that
your right and there house numbered parts. But that does NOT mean
there not fixable. Once you know what the circuit does and the case
style of the output device, one can probably make some assumptions
and go to a parts catalog and try a few devices. Hell, it might just
be caps with bad ESR or solder joints. Other people are doing this.
Granted, customized CPU chips or ASIC would be a problem. But i believe
in the older dashes its just solder joints and power supply problems
for the most part.


What sort of tubes does the inverter run? If you have an idea of what sort
of voltage they require it shouldn't be too hard to put something together,
I've built DC-DC coverters based on the MAX771, as well as small self
oscillating converters.
 
A

Art

Jan 1, 1970
0
It will be very interesting indeed to see the reverse engineering repair for
these infernal items. I would also presume that GM Technician Centre in
Warren, Michigan may be of some interest if an inexpensive, after market,
viable repair can actually be preformed without involving any parts from one
of their suppliers. Please, Do keep us posted. Dying to see your specific
results.
 
T

Tony Marsillo

Jan 1, 1970
0
Bob,
I used to own an '86 Cadillac Seville with the digital dash. I had a problem
with the dash being out. My problrm was in the Delso Central Power Supply
(16058596). It was located under the dash, and feed power to the display.
From my notes (4/1996):

CR2, Power diode, marked 9145B T8533, shorted, replaced with 1N4725 3A/1000V

Also found bad solder connection at 8 and 16 pin DIP IC.

I don't have any more info. Hope this helps.
 
P

Phil Bowser

Jan 1, 1970
0
I have no exp. on the GM, but let me know how you fare, and I am
currently working on my 1990 Dodge Ramcharger "Electro-mechanical"
speedometer unit... It has a 20-tooth cheap plastic gear that is so brittle
the teeth are breaking off (happened in cold weather) for the odometer. I
would much rather repair it than buy an exchange hard-too-find, and equally
unreliable replacement part... whatever happened to brass (or even teflon)
gears?? I cannot believe something was made this cheaply for an automotive
application... I've seen microcassette decks, VCR decks, etc. with much
better gears in them (unfortunately for me, not the right SIZE).

This particlular speedo unit uses +12V, GND, and a 5Vp-p square wave
pulse from the distance sensor on the xmission...

A coworker has a GM digital dash that the speedo fails to
illuminate/display anything... I will be looking into it within the month...

BOB URZ said:
Has anyone here attempted to repair a 90's GM digital dash unit?
From what i can research, they have a small power inverter board
as well as the typical bad solder joints in them. My brother in law
is bringing his over and i am trying to prepare. Anybody been inside
one?

Bob
=----
 
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