Fixing motor driver for Rollo

Discussion in 'The Projects Forum' started by opxy, Jan 2, 2013.

  1. opxy

    Thread Starter New Member

    Jan 2, 2013
    Hi all electronics freaks out there,

    I have broken motor driven rollo winder. It is exactly this one:
    (It is in German language but you can get an idea what it is)

    As fixing things is my hobby and quite a lot of fun, I'm trying to fix it and also learn something from it :)

    I started with drawing circuit schematic in Eagle (please take a look at the attachment) and trying to figure out how does it work. Spent almost full day doing that :)

    Before continue let me start with few facts:

    1. SV1 is connector that is connected to microcontroller board
    2. Line 12 on SV1 is PIC Vref
    3. Line 8 and 9 are PIC output for controlling motor motion

    I asume motor motion is controlled this way:

    L8 | L9 | Motor motion
    1 | 1 | Stop
    1 | 0 | Forward
    0 | 1 | Backwards
    0 | 0 | Stop

    4. SV2 is connector for light (sun) sensor - unused as I don't have it

    5. VT06 and VT07 are power Mosfets P & N

    6. U3 is quad OP-AMP

    7. Output (drain) of the VT06 and VT07 is connected to the motor (not drawn on attached schematic)
    It is 24V motor Model FS-398PH-18110 (

    Now my questions!:)

    1. Take a look at the OP-AMP 1IN+, 1OUT and SV1 line 4.

    I don't understand for what this is used. SV1 line 4 is probably INPUT, but why transistor (and circuit around it) VI02 and VT01 are there? Do you think it may be some kind of "current sensor" ? If so how does it work?

    2. I also don't understand why VT02 is there? It looks as it doesn't have any function.

    3. I think there must be some kind of protection if motor (rollo) is stucked, but I just can't find it.

    If anyone could help me explain this two parts of the circuit or at least give me some hint, I would be very thankful.

    If you need any additional details please let me know. If needed I can also draw second bord with PIC and measure all resistors values.


    P.S: Happy new year 2013 !:)
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    To understand the functions I need to see the PIC circuit.

    How about you measure the DC voltages and post it.

    What are the symptoms?

    Can you confirm that the MOSFET/S are not shorted.

    An in circuit diode check on them MOSFET's are needed after disconnecting the Motor completely.
    opxy likes this.
  3. opxy

    Thread Starter New Member

    Jan 2, 2013

    Thank you for the reply.
    I'm at work right now so I can't draw the schematics for microprocessor board. But I will do it when I get home.

    For now I'm only adding photo of the board as attachment (SV1 line one is first line on the left)

    About the symptoms:
    - Motor doesn't turn at all
    - Microcontroller is probably working as the control LED is responding
    - I measured DC voltage on SV1 line 8 & 9:

    On line 9 I get 3,7V when button in pressed
    On line 8 it is always 0V no metter what button I press.

    From this I may assume that there is something wrong with MOSFET VT07.
    Do you know some easy way how to test it? Should I take it out of the circuit.

    - I also measured voltage on 12V and 5V voltage regulators (with out motor connected)

    12V regulator:
    Input: 24V
    Output: 11,77V

    5V regulator:
    Input: 11,77V
    Output: 3,7V

    But they both get VERY hot: cca 80°C.

    As I know they have some protection integrated if they are too hot they shutdown. I need to measure if this actually happens.

    That is all I can say for now. I need to do more measurements when I get home.

    As I said I would be very glad if you could describe me how to measure P & N MOSFETS.

  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    Since the regs get hot you have a shorted component.

    See the droop in 5V. This output is loaded too much and this loading is causing the 12V reg to heat up.

    The input of 5V Reg is from the out put of 12V one.

    By the way u mislabeled the out puts of the Regs in diagram. 12V should be 5V & vice versa.

    You have a shorted component in the 5V line or the Regulator is giving you trouble. (7805).

    I can show you how t deal with it if you could show me the PCB of the control Assy. Nice ones, close up. I need to see it to show you how to deal with it.

    U need a Digital Meter with a Diode check function. If you know hot to check diodes first try to check those Zener diodes for dead short. Then go for the diodes and then the Transistors. Leave them Mosfet for now.
    opxy likes this.
  5. opxy

    Thread Starter New Member

    Jan 2, 2013
    Hi R!f@@,

    Again, thank you for your answer.

    I actually took MOSFET VT07 out yesterday before I saw your post. I tested it and it looks ok.

    Also thank you for warning me about mislabeled reg. In next version of drawing I will change it.

    In attachment is close-up of the circuit. VT07 is missing as it is desoldered. Also RED cable from motor fail off and I didn't solder it back yet.

    If there is shortened element on 5V line I asume it may be
    Transistor VT05, VT04, VT02, VI02 or diodes VD11 and VD09.

    I actually don't know if VD11 & VD09 they are zener or normal diodes. I asume they are just normal diodes.

    If I look to diodes I would say VD18 and VD11 could not couse short circuit or?

    I will not try to measure all diodes and let you know for the results.
  6. opxy

    Thread Starter New Member

    Jan 2, 2013
    Ok I measured all diodes and transistors (in circuit)
    There is no short dead diod (all have inf resistance in one direction).

    How ever I find VI02 and VT08 (on schematics is VT01 - mistake) problematic - see measurements. I think I will take it from circuit tomorrow and measure it again

    Code ( (Unknown Language)):
    2. [COLOR=Red][B]VI02[/B] (specifications: [URL][/URL])
    3. ------------------------------
    4.  B | C | E | resistance OHM
    5. ------------------------------
    6.  + | - |   |  0,5k
    7.  + |   | - |  1,53k
    8.  - |   | + | inf
    9.    | + |   |  0,5k
    10.    | - | + |  inf
    11.    | + | - |  0,91k
    13. [B]VT01[/B]
    14. ------------------------------
    15.  B | C | E | resistance OHM
    16. ------------------------------
    17.  + | - |   |  1,29k
    18.  + |   | - |  1,3k
    19.  - |   | + |  inf
    20.  - | + |   |  inf
    21.    | - | + |  1,956k
    22.    | + | - |  inf[/COLOR]
    24. [B]VT05[/B]
    25. ------------------------------
    26.  B | C | E | resistance OHM
    27. ------------------------------
    28.  + | - |   |  1,29k
    29.  + |   | - |  1,28k
    30.  - |   | + |  inf
    31.  - | + |   |  inf
    32.    | - | + |  inf
    33.    | + | - |  inf
    35. [B]VT04[/B]
    36. ------------------------------
    37.  B | C | E | resistance OHM
    38. ------------------------------
    39.  + | - |   |  1,28k
    40.  + |   | - |  1,31k
    41.  - |   | + |  inf
    42.  - | + |   |  inf
    43.    | - | + |  inf
    44.    | + | - |  inf
    46. [B]VT08[/B] (on schematics VT02 -mistake)
    47. ------------------------------
    48.  B | C | E | resistance OHM
    49. ------------------------------
    50.  + | - |   |  1,29k
    51.  + |   | - |  1,30k
    52.  - |   | + |  inf
    53.  - | + |   |  inf
    54.    | - | + |  inf
    55.    | + | - |  inf
    Last edited by a moderator: Jan 5, 2013
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    OK. Remove both MOSFET and check for stable 12V and 5V.

    If 5V sags, then remove U3 ans do the test

    PS. Keep the uC board removed if you can
    opxy likes this.
  8. opxy

    Thread Starter New Member

    Jan 2, 2013
    Did you see measurements I sent?

    Unfortunately I can not disconnect uC board as they are permanently connected together.

    I will try to remove VT06 MOSFET as well and hopefully U3 - It will be quite a task since I don't have hot air soldering tool. If I manage to fix this board I will probably invest in one :)

    @bertus: Thanks for correcting "code".
  9. opxy

    Thread Starter New Member

    Jan 2, 2013

    I desoldered both MOSFETs & U3 op-amps. There are still only 3,87V from 5V reg.

    What do you think about my transistors measurements?

  10. opxy

    Thread Starter New Member

    Jan 2, 2013
    Latest update:

    I desoldered following parts:

    U3 4xOP-AMP
    VT06 MOSFET P & N
    VT07 MOSFET P & N

    VT01 Transistor
    VT08 Transistor (on schematics 02 - mistake)
    VI02 Transistor

    Voltage on 5V Reg is still 3,8V.

    I'm thinking to desolder voltage regulator and actually check if it is working correctly by it self. I'm just wondering if should I use condensators in test circuits or voltage regulator alone would be ok?

    Maybe there is mistake on logic bord. I will try to draw schematics today.

  11. envisionelec

    New Member

    Apr 24, 2012
    78L05 is dead.

    When you replace it, put a 1N4001 diode anti-parallel with In and Out to reduce reverse biasing to 0.6V.

    Your schematic has the 12V and 5V Nets listed improperly. Hint: Look at the regulators.
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    Get a 5V reg.

    If you have can a To-220 Package can be installed without a problem. If not get the original package.

    Check for voltage before soldering any other component.
  13. opxy

    Thread Starter New Member

    Jan 2, 2013
    Yesterday I was drawing uC board schematics. It is not finished yet. Today I will continue and will post all together.

    Regarding 5V regulator, I'm thinking to do like that:

    1. Desolder 5V reg and try it on dev-board (with 12V input from lab power supply)
    2. If it will output 5V it is probably ok and something else is broken
    3. If it will output 3.8V I will assume it is broken
    4. I will connect roll circuit 5V rail to my lab power supply and measure Line 8 and 9 voltages with oscilloscope.

    I think I will be able to do this within hour or two.

    Thank you both for suggestions!!

  14. opxy

    Thread Starter New Member

    Jan 2, 2013
    Envisionelec you were right about 78L05.

    I desoldered 78L05 and put it on dev board, connected Input to 12V power supply and measure output with oscilloscope. In test circuit I didn't use any condensator (I hope it didn't affect measurements too much)

    The output was between 3,6 - 3,8V.

    What I'm planning to do now is to solder back all components that were desoldered and try to power 5V rail with lab power supply. Do you think this is good idea?

  15. opxy

    Thread Starter New Member

    Jan 2, 2013
    It is working!!! :))

    Connected to the Lab Power supply (24V & 5V - instead of 78L05).

    I will order new 78L05 tomorrow.

    @Envisionelec: Can you tell me more about "1N4001 diode anti-parallel with In and Out to reduce reverse biasing to 0.6V" ?

    Thank you for help!!

    P.S.: I will still draw full circuit and post it - in case anyone else will need it in future.

  16. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    Reverse bias diode is not typically necessary in this case.

    They are mostly used in LAB PSU to protect them from all sorts of wrong connection at the output.

    Since your board is fixed load as you see, messing with it ain't a good idea.

    If it works, leave it.