Akai 4000DS sound fault - UK Vintage Radio Repair and Restoration Discussion Forum

Highams · 5th Nov 2020, 5:19 pm

Hi,
I have an Akai 4000DS reel/reel. As soon as it's switched on, there is a sound similar to that of an 'earth' fault, hum with distortion.
Playback is still ok as this is a somewhat background noise.
I get this using both phono and din plugs and have tried 2 other amps.
I just purchased another machine (cheap/spares/repair) and this does the same.
Any advice please?
Thanks.

DMcMahon · 6th Nov 2020, 12:48 am

Are these MK. l or Mk. ll units ?

The Mk. l could sometimes suffer from a variety of noise problems due to noisy 2SC458LG transistors and noisy LD-3141 Op Amp ICs, but more of hiss/clicks type noise. Evidently also hum issues due to screening of the mains transformer. There is a good document about it somewhere on the web.

David

Highams · 6th Nov 2020, 9:25 am

Thanks David,
They are both Mk.1 machines, the second purchased with no faults.
My first machine is due to go to a tech. guy after lockdown, so just experimenting with thoughts before then.
I'm using standard hi-fi phono/Din cables, are there screened versions that might stop this? is it anything to do with incoming cable/tv/internet equipment? (although it's the other side of the room).

DMcMahon · 6th Nov 2020, 12:16 pm

Standard cables should/will be screened. Unlikely I would think related to external interference.

I found the link to one of the 4000DS MK. I noise information sites.

https://electronicaid.webs.com/akai4000dsmki.htm

David

5th Nov 2020, 5:19 pm	#1
Highams Diode Join Date: Nov 2020 Location: Ashford, Kent, UK. Posts: 2	Akai 4000DS sound fault Hi, I have an Akai 4000DS reel/reel. As soon as it's switched on, there is a sound similar to that of an 'earth' fault, hum with distortion. Playback is still ok as this is a somewhat background noise. I get this using both phono and din plugs and have tried 2 other amps. I just purchased another machine (cheap/spares/repair) and this does the same. Any advice please? Thanks.

6th Nov 2020, 12:48 am	#2
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,604	Re: Akai 4000DS sound fault Are these MK. l or Mk. ll units ? The Mk. l could sometimes suffer from a variety of noise problems due to noisy 2SC458LG transistors and noisy LD-3141 Op Amp ICs, but more of hiss/clicks type noise. Evidently also hum issues due to screening of the mains transformer. There is a good document about it somewhere on the web. David

6th Nov 2020, 9:25 am	#3
Highams Diode Join Date: Nov 2020 Location: Ashford, Kent, UK. Posts: 2	Re: Akai 4000DS sound fault Thanks David, They are both Mk.1 machines, the second purchased with no faults. My first machine is due to go to a tech. guy after lockdown, so just experimenting with thoughts before then. I'm using standard hi-fi phono/Din cables, are there screened versions that might stop this? is it anything to do with incoming cable/tv/internet equipment? (although it's the other side of the room).

6th Nov 2020, 12:16 pm	#4
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,604	Re: Akai 4000DS sound fault Standard cables should/will be screened. Unlikely I would think related to external interference. I found the link to one of the 4000DS MK. I noise information sites. https://electronicaid.webs.com/akai4000dsmki.htm David