EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: davorin on November 08, 2014, 03:47:23 pm

Title: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 08, 2014, 03:47:23 pm
Good afternoon (o;

I just acquired a Sony DTC-670 which I knew it was defect, but not the ral cause..

Now when I put in a cassette it closes, pulls the tape in, starts rorating the head and soon after stops with a "CLOSE" blinking in the display...
Closing the lid without a tape shows no errors...

Some simple mechanical switch gone wrong?

Title: Re: Sony DAT DTC-670, Close blinks in display
Post by: radhaz on November 09, 2014, 11:07:24 pm
It sounds like a switch problem. Here is a service manual:
http://www.hifiengine.com/manual_library/sony/dtc-670.shtml (http://www.hifiengine.com/manual_library/sony/dtc-670.shtml)
Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 13, 2014, 05:10:44 pm
Well..the service manual I already have...and only some end consumer type fault messages are included....

Got hold of a second one now...and swapped the drive...after few tries the tape starts playing now....also recordong...
though strange with recordings that now and then some milli seconds are missing...just like a bad CD with lots of scratches...


Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 15, 2014, 10:47:59 am
This is really weired....got it now at that point that it records fine from SPDIF in with audio feed from a Wandboard Linux board...

But when I power off the DAT device and switch it on next day to play back...there is no recording anymore..just the 48kHz is blinking...


Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 15, 2014, 04:09:25 pm
Hmm...happens even with frsh recordings....sound is fine for a few minutes, then distorted (not nice to hear through headphone ;o)...and then okay again...
Now suddenly plays back the Pink Floyd Endless River recording from yesterday (o;


Time to throw away the tapes? I already cleaned the drum head....



Hmm..just discovered that the distortion is not as the same spot when I rewind and play it back again....


Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 15, 2014, 06:03:03 pm
Signal on the drum head seems fine during recording....

Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 16, 2014, 10:49:08 am
Swapped the RF preamp board from another 670 and now it palys back a recording...let's see for how long ;-))

Though it doesn't write the Start ID automatically anymore...
Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: davorin on November 16, 2014, 06:37:06 pm
Hmm...no joy....no playback anymore.....

Even replaced the capacitors on the RF amplifier board as suggested on a Youtube video....

No wonder Ebay is full of Sony DAT recorders marked as broken/for repair....Just never bid for one...you will never get it fixed (o;


Title: Re: Sony DAT DTC-670, distorted or no playback
Post by: Cyberdragon on November 17, 2014, 04:59:27 pm
Sounds like it could be a loose coil connection inside the read/write head itself causing intermittent failure. Try finding a replacement.