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Strand 300 Help (Repair)

Discussion in 'Lighting and Electrics' started by sborder, Feb 1, 2017.

  1. sborder

    sborder Member

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    Hello Everyone,
    I haven't posted here in quite a while, but I have a question about a Strand 300 that I own that needs some repair.
    The 300 has just been sitting in my storage closet for the past several years and I figure it could be a good project for me to repair it, and maybe use it as a backup console.
    The issue with it is that one of the power regulators failed and exploded, taking with it another component (Motorola 835?) and a few capacitors. Unfortunately, I have since lost the broken parts, so I do not know off hand what they are. Does anyone know what there part numbers are, or have another 300 they could look at to find the parts, and if anything else downstream may have failed? It looks like only the regulator, other chip, and the caps failed, nothing else looks burnt or damaged. I do also need to replace the Varta battery. Anyone know where I might be able to get a replacement battery? I have attached several pictures of the motherboard showing where the damage is. I am fairly good at soldering, and I'm willing to try buying a few parts to get this fixed (I don't have much to loose with it).

    0131171440.jpg 0131171440b.jpg 0131171443.jpg 0131171918a.jpg

    Thanks,
    Sam
     
    Last edited: Feb 1, 2017
  2. FMEng

    FMEng Well-Known Member Fight Leukemia

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  3. sborder

    sborder Member

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    Hi FMEng,
    Thanks for the link! I did meter the battery on the board, it was completely dead, and had corroded.
     
  4. icewolf08

    icewolf08 CBMod CB Mods

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    Why not just find an old DOS compatible mother board and replace the whole thing? The Strand 300/500 series desks were basically built with off-the-shelf parts.
     
  5. sborder

    sborder Member

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    I actually have quite a few old DOS motherboards from the same era, but I couldn't find any one that had a similar power supply setup. The 300 I have is powered by a 24V PSU (which still functions), and the motherboard itself apparently did all the voltage drop-down and regulation.
     
  6. JD

    JD Well-Known Member

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    Yea, the second picture looks like a blown PWM regulator that produced the lower voltage buses. Looks like there are two of them. Could be one for 5V and another for 12V. Some systems run the processor at 3.2 volts. In any case, the multipin pack looks to be a combo regulator/driver and the part with chunks missing looks to be a SMD diode and may be identical to the one next to it. The LM2678 looks like a universal regulator chip, so the missing one is also probably the same. (the voltage levels are set by external components.) Here is the data on that chip - http://www.ti.com/product/LM2678
    The Diode appears to be this guy - http://www.onsemi.com/pub_link/Collateral/MBRD835L-D.PDF
     
  7. sborder

    sborder Member

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    Update,

    Thanks for all the information! I also called Vincent Lighting, and they were able to tell me the rest of the parts I need to repair the board. I think the VARTA battery is what caused the whole incident, since it is wired straight to the output of the 3.3V regulator. I will update you guys further on the results of my repairs.
    Is there anything else I should look out for while attempting the repair of this unit?

    Here is a list of the parts that have died
    LM2676 S-3.3
    835L Barrier Rectifier
    686C Capacitor (C64)
    227A Capacitor (C67)

    Thanks,
    Sam
     
  8. JD

    JD Well-Known Member

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    Beware hidden trace damage under other components near the battery. Flush and inspect. Not sure the battery was the cause as the diode is used in a "buck regulator" design. As such, it's job is to discharge the collapsing inductor field between pulses. A straight overload wouldn't blow it since it is in reverse polarity. However, exceeding the PIV would as the diode would then start conducting to ground. Still, the LM2676 contains limiting which should have caused it to go into overload protection.
    Here is a good description of how the circuit around the regulator works. (see page 25) http://www.ti.com/lit/gpn/lm2678
     
  9. sborder

    sborder Member

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    I will try and look for any trace damage and check continuity of the traces. I have attached a picture of some of the damage done by the leaked battery. Is all hope lost with this, or is it repairable? The damage looks like it is confined to the ground plane only, and not the actual traces.
    0203171158a.jpg
    Sam
     
  10. JD

    JD Well-Known Member

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    Many G10 boards used in computers are actually 4 layers thick, so you may have traces between the two sides. It is pretty disconcerning that the acid made it's way through the plated holes. Since the replacement parts are cheap enough, it is probably worth the risk, but make sure you flush off all the acid and try to see if any of the traces or plated holes are eaten first.
     
  11. sborder

    sborder Member

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    Update,

    The parts were installed, and nothing blew up. The power button on the panels works, but I get nothing when powered on. The main panel display has "Jun 15 2000 Panel ID: 1A-01-90-09" very dimly barely visible on it. There is nothing showing on the VGA ports, it doesn't even turn the monitor on. I'm going to leave it 'on' for a while to let the new battery charge up a bit.
    Any ideas what is going on with the console?
    0208171450c.jpg
     
  12. FMEng

    FMEng Well-Known Member Fight Leukemia

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    BIOS and firmware might be erased.
     
  13. JD

    JD Well-Known Member

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    Could also have open traces or hidden damage preventing a boot. Did you check the voltages coming from those supplies? Make sure one of those TP's has 5 volts on it.
     
  14. sborder

    sborder Member

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    So, I checked to see if there was 5V and 3.3V on the board, both voltages are showing within spec. How would I know if the BIOS / Firmware is erased VS a lost trace? Is there a way to re-flash the firmware? The floppy drive doesn't see that a floppy is inserted if I insert one. If it is a broken trace, is it fixable? Does anyone have a schematic for this board?

    Thanks,
    Sam
     
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  15. JD

    JD Well-Known Member

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    The only thing I can offer is the sequence of what happens when you apply power to a computer, which this basically is. There is a lot that goes on before the floppy or display can work.
    1) As the busses first power up, small "reset" chips send a pulse that resets the processors to their "0" state.
    2) The processor begins to read the BIOS and "learns" what it is connected to. (no display)
    3) The processor executes a POST (power on self test) which includes initializing connected display adapters and disk drives.
    4) At the completion of the test, it will sound a beeper with one beep, or beep a failure code. (It is possible that a beeper was never installed as this is a light board.)
    5) The processor will begin to load the Operating System out of ROM or off the floppy drive.
    So, from your description, it's failing before step 3. Modern display adapters often have their own processor (even if part of the motherboard), so it may be before step 2 even begins. This is what I'm thinking about a damaged trace.
     
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  16. FMEng

    FMEng Well-Known Member Fight Leukemia

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    This is a long shot, but you might be able to take a strong flashlight and shine it through the board where the battery leaked to see if internal-layer traces were damaged.

    I would also check the plated through holes for continuity with an ohmmeter. If any are open, insert 30 gauge wire-wrap wire and solder both sides. Wire-wrap wire is also good for repairing damaged point to point traces.
     
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  17. AAMorgan

    AAMorgan Member

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    Did you ever get this Strand 300 going? I have one with the same dim message on the display.
     
  18. Mac Hosehead

    Mac Hosehead Active Member

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    It would seem the green rechargeable battery, shown in a picture above, is a common failure in these consoles. I believe a bad battery can cause it to not boot. A while ago, someone gave me a Strand 300 with a bad battery. I replaced it with another battery that had the same specs. It lasted about 3 months.

    The battery is a 3.6v 150mA NiMh. After replacing it once, I decided to use a 3.6v NiCd battery from a cordless phone. The battery is bigger so I mounted it on the case and ran wires from the motherboard. So far, it is still working.

    To replace the battery, I had to remove the motherboard. On the underside of the motherboard at the battery, there was a circuit trace cut and a diode added. I would assume that this was done by the factory before it was purchased.

    If you wish to try and replace the battery, I would remove the top and examine the motherboard. If there are other components that look damaged then I would call it a loss.
     
  19. AAMorgan

    AAMorgan Member

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    Same issues going on here. Leaky VARTA battery. I desoldered the battery and found this underneath. Is it dead?
    IMG_0732.jpg
     
  20. Mac Hosehead

    Mac Hosehead Active Member

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    I would try to clean the board up as much as you can. I first replaced it with a battery from ebay. It didn't last long but you could know if the console is going to work.
     
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