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Thread: Boom refresh

  1. #1
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    Boom refresh

    I had one of my Boom which decided to have a farting speaker, and as it was also becoming pretty sticky, I did a full cleanup

    - 2 re-foamed speakers
    - new display
    - front panel cleanup (@JoeMuc2009's method of 15 min in 65░C water + @chill's idea of spray coating)
    - button full scrub + re-paint

    Result is not perfect, but it's not bad. The screen seems to still have some brightness differences between columns, I don't know why (although it looks much worse on picture than it is in reality). This is a Boom where I applied Joe's diode repair, but I took references of the 2 transistors underneath, I'll see if they can be found.

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    Last edited by philippe_44; 2020-04-06 at 01:40.
    LMS 7.9 on Pi 3B+ & Odroid-C2 - SqueezeAMP!, 5xRadio, 3xBoom, 4xDuet, 1xTouch, 1 SB3. Sonos PLAY:3, PLAY:5, Marantz NR1603, Foobar2000, ShairPortW, JRiver 21, 2xChromecast Audio, Chromecast v1 and v2, Squeezelite on Pi, Yamaha WX-010, AppleTV 4, Airport Express, GGMM E5, Riva 1 & 3

  2. #2
    Senior Member JoeMuc2009's Avatar
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    Does anybody about these transistors Q1 and Q7? They are marked W1P (83) and 2F (E). The dot under the F of the latter might be a clue about the manufacturer but so far it's unclear. W1P appears in three places, Q7 is behind the display, Q9 is on the backside of the HV circuitry (also behind the display, near the speaker connector), and Q10 is near the center of the board. 2F (E) has its only appearance as shown in the photo.

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    PN me if your Boom / Classic / Transporter display has issues!

    Blog: https://www.blogger.com/blogger.g?ri...50753#allposts

  3. #3
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    One thing about refreshing front panel: Joe's method of cleaning it in 65░ water for 10-15 mins works very well, but you have to spray the protective coat just immediately after you dried it otherwise it seems to attrack dust very quickly. But if you do that, and wait for 24h to cure, the panel is like new!
    LMS 7.9 on Pi 3B+ & Odroid-C2 - SqueezeAMP!, 5xRadio, 3xBoom, 4xDuet, 1xTouch, 1 SB3. Sonos PLAY:3, PLAY:5, Marantz NR1603, Foobar2000, ShairPortW, JRiver 21, 2xChromecast Audio, Chromecast v1 and v2, Squeezelite on Pi, Yamaha WX-010, AppleTV 4, Airport Express, GGMM E5, Riva 1 & 3

  4. #4
    Senior Member KeBul's Avatar
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    [QUOTE=JoeMuc2009;970544]Does anybody about these transistors Q1 and Q7? They are marked W1P (83) and 2F (E). The dot under the F of the latter might be a clue about the manufacturer but so far it's unclear. W1P appears in three places, Q7 is behind the display, Q9 is on the backside of the HV circuitry (also behind the display, near the speaker connector), and Q10 is near the center of the board. 2F (E) has its only appearance as shown in the photo.
    /QUOTE]

    Joe,

    Did you manage to ID these transistors?

    I'm sure you know much more about this stuff than me but I found these with a bit of searching...

    W1P - https://www.el-component.com/bipolar...tors/pmbt2222a

    The 83 seems to indicate an MMBT4400 which is a slightly lower spec than the MMBT4401 equivalent listed in the above link

    2F - https://www.el-component.com/bipolar...tors/mmbt2907a

    But perhaps it's 2FW (not 2F (E)) which seems to come up as either an SOT23 BC850B or SOT-323, BC850BW

    The dot perhaps indicates a lead free package.

    Kev
    Last edited by KeBul; 2020-04-12 at 14:22.

  5. #5
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    Nice job!

    Looks good Phillipe, I used my boom in the garden at the weekend and the lack of display brightness became really apparent - I have to run at 5 indoors to see it.

    I've been wondering for a while about trying to expand on the information on Joe's site so we can do a 'proper' fix for the display control issue, but that board isn't easy to trace as there's no contrast between tracks and PCB!

    I agree with Kev, the W1P is most likely a PMBT2222A, that ties up with the SMD codebook (http://www.marsport.org.uk/smd/mainframe.htm), 1P is a generally a x2222A device. The Nexperia data sheet page 2 shows the W as a fab. site code (https://assets.nexperia.com/document..._PMBT2222A.pdf

    2F is likely its complement, an x2907A. In the OnSemi version (https://www.onsemi.com/pub/Collateral/PZT2907A-D.PDF) page 1 shows the marking for MMBT2907A as 2F.

    Noritake's site isn't the easiest to navigate, but this Futaba document gives a very detailed explanation of VFD technology: http://www.vwlowen.co.uk/arduino/vfd...ation-Note.pdf, section 5.1 is particularly interesting. Filament voltage should be maintained at a fixed, optimal level, not used to control brightness, so I do wonder what the circuit in the Boom looks like, I'm not convinced it can be the current of 2A that Joe suggests, that seems excessively high based on the Futaba data and outside of the Ic of the transistors above.

    Andy.

  6. #6
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    I’ll get these part but I think we should also look for part with higher current rating just in case. And yes, black PCB might look cool but following traces is a really pain with these. I never use black for my own...

    I’ve refreshed now 3 of my Booms and with the combination of ‘cooking’ the front panel, hair drying it right after and then coating it immediately, results are spectacular. I cure the coating at ~40C for 10 hours and it seems to make it really strong. I also really like that this coating, when you miss, can be peeled off really easy. I’ll have to see how it behaves with time, but at least theses booms look like new now
    Last edited by philippe_44; 2020-04-20 at 18:20.
    LMS 7.9 on Pi 3B+ & Odroid-C2 - SqueezeAMP!, 5xRadio, 3xBoom, 4xDuet, 1xTouch, 1 SB3. Sonos PLAY:3, PLAY:5, Marantz NR1603, Foobar2000, ShairPortW, JRiver 21, 2xChromecast Audio, Chromecast v1 and v2, Squeezelite on Pi, Yamaha WX-010, AppleTV 4, Airport Express, GGMM E5, Riva 1 & 3

  7. #7
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    Quote Originally Posted by ALW View Post
    I agree with Kev, the W1P is most likely a PMBT2222A, that ties up with the SMD codebook (http://www.marsport.org.uk/smd/mainframe.htm), 1P is a generally a x2222A device. The Nexperia data sheet page 2 shows the W as a fab. site code (https://assets.nexperia.com/document..._PMBT2222A.pdf

    2F is likely its complement, an x2907A. In the OnSemi version (https://www.onsemi.com/pub/Collateral/PZT2907A-D.PDF) page 1 shows the marking for MMBT2907A as 2F.
    Andy.
    So I've bought these 2 + a NPN/PNP pair from Diode Inc that are much higher power (still in SOT23, similar beta and characteristic - the exact ones probably don't matter much as you said) but need to check if they fit underneath)
    Last edited by philippe_44; 2020-04-20 at 21:24.
    LMS 7.9 on Pi 3B+ & Odroid-C2 - SqueezeAMP!, 5xRadio, 3xBoom, 4xDuet, 1xTouch, 1 SB3. Sonos PLAY:3, PLAY:5, Marantz NR1603, Foobar2000, ShairPortW, JRiver 21, 2xChromecast Audio, Chromecast v1 and v2, Squeezelite on Pi, Yamaha WX-010, AppleTV 4, Airport Express, GGMM E5, Riva 1 & 3

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