[sdiy] My Fancy Paperweight, the ESQ

[Scott Nordlund]

Something (like a bad IC..) may be drawing too much current and causing the 7812's voltage to drop, in which case it will probably get quite warm.  It shouldn't be hard to check that before you swap it.  Check the voltage on the input side too.

----------------------------------------
> Date: Thu, 13 Aug 2009 14:35:30 -0700
> From: lightburnx at yahoo.com
> Subject: Re: [sdiy] My Fancy Paperweight, the ESQ
> To: synth-diy at dropmix.xs4all.nl
>
> Ok, I did some readings...
>
> These are voltages from the regulators I could get at (I forget if there's any beneath the keyboard assembly, but I think no).
>
> Q1 MC7812CT - 6.25V (not a good sign)
> Q2 MC7812CT - 12.12V (ok)
> Q3 UA7805C - 4.93V (ok)
> Q4 UA7805C - 5.0V (ok!)
>
> Q? AN7905F - 7.1V (um...)
>
> The battery is at full voltage. As in, it's a 3 volt battery, and it reads at 3.01V - untouched.
>
>
> Doing a system reset by holding down soft button #1 when powering on made the screen flicker briefly (I think it may do that anyway when you boot it up), but it just gives me the low battery warning, and same old name/make/os screen.
>
> Try and swap the bad regulators?
>
>
> _Kyle
>
> --- On Thu, 8/13/09, Rainer Buchty  wrote:
>
>> From: Rainer Buchty 
>> Subject: Re: [sdiy] My Fancy Paperweight, the ESQ
>> To: "Kyle Stephens" 
>> Cc: synth-diy at dropmix.xs4all.nl
>> Date: Thursday, August 13, 2009, 1:03 PM
>> On Thu, 13 Aug 2009, Kyle Stephens
>> wrote:
>>
>>> It was suggested that given my problems with it (after
>> replacing the memory battery, it still stays stuck on a
>> screen telling the make, model, and OS)(MIDI doesn't work
>> either btw), there was liable to be some something wrong
>> with one of the logic ICs.
>>
>> So it's not even leaving the reset routine, otherwise it
>> would die in the sound selection menu.
>>
>> The question is indeed, why. Does it boot without the
>> battery?
>>
>>> Well, how ought I go about testing that sort of
>> thing?
>>
>> A logic analyzer might come in handy as you could directly
>> see on which address it's getting stuck.
>>
>> Otherwise you need to track down, why it freezes, e.g.
>> getting stuck in the interrupt service routine, not
>> acknowledging anything from the keyboard processor, etc.
>>
>> Rainer
>>
>>
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy

_________________________________________________________________
Get free photo software from Windows Live
http://www.windowslive.com/online/photos?ocid=PID23393::T:WLMTAGL:ON:WL:en-US:SI_PH_software:082009