QU32 dead?

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This topic contains 6 replies, has 4 voices, and was last updated by Profile photo of Wilts Wilts 3 months, 1 week ago.

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  • #67381
    Profile photo of Wilts
    Wilts
    Participant

    Just before the midnight service last night, our QU32 suddenly started producing what sounded like square waves on all the output channels. I tried the obvious things (cycling the power, disconnecting everything but the mains, hard reset) but it still powers up in that state. The touchscreen does respond though.

    I’m guessing it is a repair centre job but in the off chance it might be something I’ve overlooked I thought I would ask here first if anyone has had this problem and what they did about about.

    Sadly it is out of warranty so I will be will be looking for a UK repairer. Any recommendations? Do any of these have loan items? Failing that, any cost effective hire companies in the UK where I can hire a replacement – a quick look indicated costs of £300 per week!

    Alternatively, I don’t suppose anyone has a service manual do they?

    Thanks

    Paul

    #67387
    Profile photo of ddff_lv
    ddff_lv
    Participant

    Depending on how qualified you are, you might want to open the desk and check all the supply voltages (I’d start with +15 and -15 VDC that are feeding opamp buffers).

    ddff

    #67393
    Profile photo of MarkPAman
    MarkPAman
    Participant

    If it will let you, re-installing the firmware has to be worth a try.

    As to a replacement desk, where in the UK are you?

    #67397
    Profile photo of Wilts
    Wilts
    Participant

    Mark
    Thanks – wiill try a reinstall.

    I’m based near Southampton.

    #67525
    Profile photo of Dick Rees
    Dick Rees
    Participant

    Just to be 100% sure…

    You disconnected everything BUT THE MAINS. Before proceeding, I’d do two things:

    1. Check to make sure the signal generator has not accidentally been engaged.

    2. Disconnect the mains as well and listen to the board on headphones to see if it is “full of noise”. If you get no noise on the headphones, start re-connecting things one at a time until the noise returns.

    Good luck, and remember what Douglas Adams advised: DON’T PANIC.

    #67556
    Profile photo of Wilts
    Wilts
    Participant

    Sadly a reinstall didn’t work. I put a scope on an output and got 50Hz square waves at +10 to -4v, even with the desk shutdown prior to mains off. Sounds like a PSU problem to me……

    #68175
    Profile photo of Wilts
    Wilts
    Participant

    For completeness, it was PSU failure. A capacitor had gone short circuit on the -15v analogue rail. Not exactly a cheap repair……

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