hdd interference in my h120 line-in recordings

[whatboutbob]

Recording line-in on my h120 I've recently started getting some odd interference in my recordings that corresponds exactly to disk writes.

Here's a sample (2.2meg wav) - snipped from about the 2:40 mark of a recording (first disk write): http://download.yousendit.com/3A030A084707A986 - you'll likely need to crank the volume to hear it.

I'm pretty confident this is a hardware issue (so pls feel free to move this post - i did check the 'posting in this forum' post tho).  Why hardware?

1) No similar issue on my h140
2) It is easily reproducable with current and older versions of rockbox - and it hasn't been an issue in the past with the exact same builds.
3) This h120's had a bit of work done - battery replaced, hdd replaced, usb daughterboard resoldered - so its entirely possible i've screwed something up.

So was just wondering if anyone else has experienced this and could perhaps provide some pointers for a potential fix?

(and yes...i'm definitely going line-in...I'm not getting confused and hearing hdd noise recording with the internal mic)

[petur]

this could be a case of a bad ground connection.

My gues is to inspect the daughterboard as (IIRC) this also contains the HDD connection. A bad connection there could cause current/voltage fluctuations on other connections there.

My 0.02 euro

[whatboutbob]

hrmm...some of the points are a bit oxidised...i'll have to track down some deoxit and see if that has an effect.