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latigid on

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Posts posted by latigid on

  1. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    What output do you get from MIOS Studio with "set debug on"? The encoders are directly connected to 165 inputs, so IC4 is not involved here. 

    Looks like there are a lot of blobs around IC3?

    Encoder pins connect to Plate J1, pins 8 and 9, if that helps. The encoder shouldn't hit anything below it, but you could try to slip a piece of card in between the boards to rule out unintentional short circuits.

    R13 does go to pin 3 of that IC. But make sure that it doesn't connect anywhere else.

  3. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    10 minutes ago, Smithy said:

    Andy can you confirm that pin 13 in IC5 is linked to Encoder 6 before I order the replacement SN74HC165?
    Thanks!

    That's right! Not sure exactly what your issue is here, but if you've narrowed it down to pin 13, IC5, you could bodge wire it to pin 3 on J5? Pin 1 of the connector has a square pad.

  4. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    12 minutes ago, Smithy said:

    I trusted my cutting of the RJ leads and went ahead and de-soldered all the Mattias switches in the Lemec PCB.
    Turns out there was a short between the bottom leg of T16 and the unused pad to the right of it!

    Thank god for my desoldering station otherwise this would have taken much longer, if i could even do it all with a manual pump!

    IMG_20210526_212922.thumb.jpg.82b6ad3b7c689b3ba5daf37e2481b7e2.jpg


    I owe you an expensive beer when I'm done!

    I'm going to test the superflux leds now with the diode test on my multimeter in case the heat has damaged them.
    I also found an issue in the RH Lemec board earlier.

    Turning Encoder 4 lights up the LEDs in the 3 switches below it. I'll post more detail on that later.

    Clean work, you're doing great! That is a via that brings the SR signal to the transistor. 

     

  5. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    28 minutes ago, Smithy said:

    fixed the image.

    Thanks, it works. Can't see anything obvious. You can check the components I mentioned before. It could also be a too-long resistor leg, also on RJs? Before desoldering all of the switches, you might try to remove those resistors.

  6. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    41 minutes ago, Smithy said:

    I tried soldering a bridge between pin 15 and pin 16 of IC4 and no luck. The 4 leds still light when seq_l is loaded. I presume thats exactly what I was meant to do?

    What I meant was to desolder a potential bridge there. Generally you don't want the output shorted to the power supply. But a constant voltage here would mean that the transistor base was always in the high state and not able to switch as required with the 595 pulses.

     

    41 minutes ago, Smithy said:

    I just have to remove the switch caps and light shields to be able to separate the boards again I presume?

    I guess that's the case... light|shields and keycaps can stay on!

  7. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    I could not see your picture of the soldering

    As the behaviour is common to a column (two columns, but they are only separated by RJ4/8) it is probably caused by

    1. Wrong transistor type or otherwise an error with T16. Yep, that's on the top side of lemec_L!
    2. The pin driving T16, so R16 and IC4, pin 15. With luck you just have a solder bridge to +5V (pin 16).

    Good luck!

  9. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    3 minutes ago, Smithy said:

    Just checked the Erata for that pcb on the wiki and it says:

    The C3 cathode row is missing a PCB trace. Join the two legs of SW19 as shown in pink, preferably on the bottom of the PCB. The LED cathode leg could simply be bent across to the switch pin.
    http://www.midibox.org/dokuwiki/doku.php?id=seqv4plus_le_mec

    Will give this a go!

    Also a good catch, I had forgotten about that! There is not much risk in soldering in the MEC switches. It is only the Matias switches that you really want to be sure about because once they go in you have to desolder all of them to get to the inside of the PCB stacks (BC808s).

  10. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    2021-05-24.thumb.PNG.5593e41c09a91ed1b8f629bb0aaf0981.PNG

    The switches SW17/18/20 won't work in the matrix unless this is bridged, actually done by the switch SW19 itself. Try to insert a MEC switch here. Sometimes it will work without soldering, sometimes you need to solder it in (or otherwise bridge it) to get a signal.

  11. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    The 3M headers seemed to be easy to source and typically had good stock. It is also less effort to keep track of one part series. The 6mm "standard" single-row header might work (see above post) but the extra fractions of a mm help. That is why the 8.08mm part was ordered. Feel free to stick with 8mm. The same TE part on Mouser/Digikey is discontinued.

    Remember that the TE part you found has a plastic base height of 2.8mm, whereas the 3M one is "only" 2.54. So already there is a difference of 1mm.

  12. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

    There are two types of SMT resistor networks in the SEQ v4+. The bussed one on the JA board and two isolated on lemec_R to serve as current limiting for the activity matrix. Just use the product page to make sure you're ordering 8x resistors in a 16-pin package. If there are 15 resistors, that's the bussed one. (Seems like your RS part is good.)

    (There are also bussed THT arrays on lemec boards)

    For the pin headers, even normal length ones could work but they tend not to make good enough contact. Adding up the thicknesses:

    connector 5mm
    PCB 1.6mm
    inter-PCB spacing 3mm

    - plastic thickness 2.8mm

    6.8mm of pin
     

    So I would suggest 826630, or actually 826935 as it matches the tin plating better. The 8mm one that you found would probably still work, just be aware that if it sticks through the header too much, it might contact the case.

     

  15. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted · Edited by latigid on

    You will probably get bad ghosting without the BAT54s. Short of ordering a new board, just "stack" the BAT54s 1:1 on top of the BC818s, so with the text still facing up for both transistor and diode.

    Please stuff R17 (any value up to 10k) or simply bridge it. C6 and the nearby diode can be left unpopulated.

  18. Troubleshooting midiphy SEQ v4+

    in MIDIbox SEQ

    Posted

      

    6 hours ago, Smithy said:

    So I've been getting erratic behavior with the LEDs on the switches of the JA PCB.
    I wonder if i made the same mistake soldering the wrong type resistor network?
    The markings on the IC at RN1 are 4816P LF1-103 C1809
    instead of 4816P-T02-103LF.

    I blame myself for not checking the BOM on midiphy and solely relying on the video!

    Thankfully i have a hot air station, flux and solder paste so should be able to remedy this issue.

     

    Yup, that's a common one! Actually Peter shows you the Mouser part number in the video but of course it is not 100% obvious and the part numbers are fairly similar.

    If you used leaded solder, you should be able to remove it easily. Flux can help but it is not 100% necessary. Normally I try for about 300°C and a relatively high airflow for this. If you need higher temperature it will probably be okay for the RN, but you'll need to take care of the other chips, MEC switches and encoder.

    When removing the chip, you might need to wiggle it to get the solder moving. When I do it, I always try to slide the chip laterally along the leads i.e. towards/along the long sides of the pads. This tends to keep the PCB pads intact and doesn't bend the chip leads, hopefully also the leads don't get too messy with solder blobs.

    When done, if necessary clean up the PCB pads with flux/braid to make the surface flat again. If necessary do the same with the chip. If it's not possible to easily get things flat, you can add flux and use the reflow hot air station again.

    Good luck!

  19. Dummy Plugs

    in Parts Questions

    Posted · Edited by latigid on

    You can get plugs of this form that have solder pins, but maybe you want to hack one together with a normal IDC (ribbon) plug?

    Take an IDC and remove the crimping part, then bridge all of the pins required, except leave the supply voltage (or 0V) floating to avoid shorting the power supply.

    Or take a ribbon cable and do the same? Just leave one conductor free. 

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