Jump to content
Ultimate Subaru Message Board

1984 Subaru digital instrument panel


Recommended Posts

We need to find a working digital instrument panel for our 1984 Subaru 2-door hardtop.  The factory labeled the little car as a "Hardtop".  I don't know which other models might interchange.  This car has turbo with 1800 single cam engine but we could possibly work with any 1984 digital instrument panel and may nont require an instrument panel particularly from a "turbo" car.  Any lead would be appreciated. 

Link to comment
Share on other sites

They made a few that worked.... it seems to be like the clocks in GLs & loyales. Out of about 7, only one worked long term. I came up with a mod that fixes most of them permanently. I don't know if the digital dash had the same kind of silly design compromises that the clocks had, or if whatever fails is more complicated.

Link to comment
Share on other sites

The majority of clock failures is due to the choice of main power regulator. THE clock circuit runs on 5v. THE 3 most practical ways to get 5v from 12 are switching regulator, pass transistor regulator, zener regulator. These are listed by order , highest to lowest. Cost, efficiency, complexity.

 

They chose the cheapest simplest and least efficient one. SO it has to cook away a watt or 2 of heat. In a small enclosed box. THAT is installed in a closed space, dashboard, where the ambient temperature can get over 140 degrees. The resistor that drops most of the voltage as waste heat gets so hot that it causes the solder on its leads to corrode and the connections fail. A linear pass transistor regulator would have to dissipate roughly half the power that the zener regulator does. Even back then, those were cheap and common. Side note, a switcher was not a financially practical choice back then.

 

There is one other feature of the clock design that can be improved also. BY adding a diode and capacitor to the keep alive power feed, the clock doesn't forget the time when starting the car like it did a few times per year, before I added them. They actually had no filter on that line to smooth over momentary voltage dips.

Link to comment
Share on other sites

Interesting analysis DaveT, I'm not an EE by trade, so don't have the knowledge base to triage the failed dashes I've come across.  This may help my friends who are helping me with this project, so thanks!

 

Do you think a similar phenomena is the reason for the EA81-digidash failures?

Link to comment
Share on other sites

It would be the first thing I would try to trace out. I have never run a car with a digital dash, so I don't know what the fail looks like.

 

When I can't get a schematic of something, I just start drawing out the schematic from the actual circuit. As long as it isn't potted, or using custom ICs, it is just patient / puzzle. Then redraw so it makes sense.

Link to comment
Share on other sites

  • 10 months later...

I know this is old but do you still have a working digital cluster?. I have a 83 gl-10 wagon non turbo

Thanks

 

does the dash beep?  if so the dash may not be the issue. 

 

they are very sensitive to input voltage, so a weak alternator or electrical system can cause them to enter a safe mode and not turn on.  id double check your input voltage before replacing.  I don't know exact specifics, I just had to research it once.  the info is here so do some searching.

Link to comment
Share on other sites

http://www.mttechsuba.com/used-subaru-loyale-parts/1985-1994-loyale/2267675 Says for 85-94 loyale but I imagine it would work still. 

 

no it won't

 

needs to be for 83-84 GL-10 Hardtop to be exact. Sedan would be next best.  Wagon works too....but the difference will be in the display for doors ajar and wagon won't have turbo indicator.  

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...