Help, No Power! (power mode, that is)

[SURTEESS]

here is a copy as if looking through the pcb - easier to trace from component side.

[oab_au]

Originally Posted by SURTEESS

here is a copy as if looking through the pcb - easier to trace from component side.

There are 4 connections .to the unit. As far as I can tell they are counting from the left;
Ground to dim all the lights.
From the Time Control unit.
Positive.
Negitive.



Harvey.

[SURTEESS]

what are the transistor numbers (upright TO92 type - round with flat side)


Suspect that the main power diode - big round one is there for reverse voltage protection (it'll be something like a MR751).

Could you by any chance have swapped over the + / - wires at any stage (either at the connector or at the other end of the wires?).

Wil know more when I get the transistor numbers.

[SVX8588]

Originally Posted by SURTEESS

what are the transistor numbers (upright TO92 type - round with flat side)


Suspect that the main power diode - big round one is there for reverse voltage protection (it'll be something like a MR751).

Could you by any chance have swapped over the + / - wires at any stage (either at the connector or at the other end of the wires?).

Wil know more when I get the transistor numbers.

The one closer to the big diode reads:
C945
P214A

The one closer to the big green transistor reads:
C1213
AKC
1K3

The big diode says S5225 1K on it.

The way this board attaches to the instrument cluster makes it impossible to reverse the connections.



I suppose it's possible that when someone installed the remote starter that some wires got crossed somewhere. I was real careful to make sure that I completely insulated the stripped wires when I removed it. They had not actually cut any wires when it was installed, just stripped a small section and soldered onto the wire. I used shrink wrap and electrical tape when I took it out. Although, I don't think that any of the wires used in the remote starter were directly connected to this.

I'll check that diode tomorrow after work.

[SVX8588]

Turns out that is a T S5225 zener diode. I couldn't read all of it until I removed it from the board. I tested it with my DMM and it tests bad! There is no resistance either direction. So I'm hoping that's the only problem.
Now I just have to find a replacement...

[oab_au]

Originally Posted by SVX8588

Turns out that is a T S5225 zener diode. I couldn't read all of it until I removed it from the board. I tested it with my DMM and it tests bad! There is no resistance either direction. So I'm hoping that's the only problem.
Now I just have to find a replacement...

Yes it is the only thing big enough to blow that track out.

Harvey.

[SVX8588]

I think I found a replacement:

http://www.mouser.com/ProductDetail/...WcTtboKYmJ0%3d

Here's another close up of the diode.



Can anyone confirm that this will work for me?
Thanks

[oab_au]

No that is only 3V 0.5 watt. You need a 7.2V 10 watt.
It has to dissapate the voltage that is dropped from dimming the lights.

Harvey.

[oab_au]

These are closer.
IN2970 6.8v 10watt
IN2973B 9.1 10Watt

The voltage difference will only change the amount of the dimming.

Harvey.

[icingdeath88]

Originally Posted by oab_au

These are closer.
IN2970 6.8v 10watt
IN2973B 9.1 10Watt

The voltage difference will only change the amount of the dimming.

Which would be brighter and which would be dimmer? The 9.1V one would be brighter, right?

Also, you guys are awesome. This is how more of us should go about fixing failed modules and electrical bits. I would have just replaced the whole board or gauge cluster. I am somewhat competent when it comes to soldering things, but my electrical components knowledge is limited. Next time something electrical fails, I'll see if it can be fixed instead of tossing it.

[oab_au]

Originally Posted by icingdeath88

Which would be brighter and which would be dimmer? The 9.1V one would be brighter, right?

Also, you guys are awesome. This is how more of us should go about fixing failed modules and electrical bits. I would have just replaced the whole board or gauge cluster. I am somewhat competent when it comes to soldering things, but my electrical components knowledge is limited. Next time something electrical fails, I'll see if it can be fixed instead of tossing it.

No mate, the 9.1 would be brighter. The 9.1 V is the voltage that the zener brakes down at, so all the voltage over that is dissapated. The lights would run on 9.1Volts.

Harvey.

[icingdeath88]

Originally Posted by oab_au

Yesmate, the 9.1 would be brighter. The 9.1 V is the voltage that the zener brakes down at, so all the voltage over that is dissapated. The lights would run on 9.1Volts.

FTFY ......

[SVX8588]

Originally Posted by oab_au

These are closer.
IN2970 6.8v 10watt
IN2973B 9.1 10Watt

The voltage difference will only change the amount of the dimming.

Harvey.

Hmm, I did a quick search for the 2970 and I found a data sheet that shows it as a huge bolt-type thing (I guess it's called stud-mount). The 2973 looks similar. Are you sure those are the right ones?
There are several good sized resistors on the board, so maybe it's designed so some of those dissipate some of the energy?

Besides they cost $19 a piece and the minimum order from DigiKey is 175

[SURTEESS]

ok - here is "rough" circuit diagram. I am still of the opinion that the supply rails have been swapped over - & the thinnest track is the part that has blown.

Swapping +VE & GND means that D4 is now working a reverse protection mode - hence the blown track ......

As a side issue what sort of signal is from the TCU connection - as it goes through (I presume a high voltage diode before the lower zener?).

U1 is just an oscillator with C2/R4 creating a triangle wave & R3 doing a pseudo PWM - still unsure how this varies to give the various dimmer settings, hence question abouve about TCU.

Let me know if you want me to correct the schematic (give me details as ref-designators Vs values).

[oab_au]

Originally Posted by SURTEESS

ok - here is "rough" circuit diagram. I am still of the opinion that the supply rails have been swapped over - & the thinnest track is the part that has blown.

Swapping +VE & GND means that D4 is now working a reverse protection mode - hence the blown track ......

As a side issue what sort of signal is from the TCU connection - as it goes through (I presume a high voltage diode before the lower zener?).

U1 is just an oscillator with C2/R4 creating a triangle wave & R3 doing a pseudo PWM - still unsure how this varies to give the various dimmer settings, hence question abouve about TCU.

Let me know if you want me to correct the schematic (give me details as ref-designators Vs values).

Thanks for that Steve, makes things a lot better.
The TCU signal is the Time Control Unit, sorry for the confusion.

Harvey.