Akai 4000DS. R2R record mechanism not functioning.

[DMcMahon]

Originally Posted by DMcMahon

I think the 2 different cam configurations being discussed is the difference between the Akai 4000DS models (and other similar models) and the Akai GX-4000 models.

David

After checking one of my GX-4000s I see that my conclusion above was erroneous.

Basically the GX-4000 is the same as the 4000DS (at least when comparing to 4000DS Mk.II), each with the 4 cams etc. On the GX-4000X the Record cam, again called Amp switch cam (B), actuates the PB/Record switch SW2 on the Amp PCB.

David

[DMcMahon]

Originally Posted by DMcMahon

After checking one of my GX-4000Ds I see that my conclusion above was erroneous.

Basically the GX-4000D is the same as the 4000DS (at least when comparing to 4000DS Mk.II), each with the 4 cams etc. On the GX-4000D the Record cam, again called Amp switch cam (B), actuates the PB/Record switch SW2 on the Amp PCB.

David

Update edits in bold above.

David

[DMcMahon]

Originally Posted by DMcMahon

If erase is functional then the existing recording should be totally erased when you play back the tape.

David

For clarification only the section of the existing recording will be erased when you record over it, not the complete existing recording on the tape.

David

[petechunnie]

Hi Dave and all.

Ok I've tested the erase function on the tape and it's functioning correctly, therefore the bias most likely is OK you say. Where to from here gents?

[DMcMahon]

Do you see any signal on the VU meters when you playback a recording ?

Note - some recorders will only display the record signal on the VU meters, i.e. not the playback signal.

Have you checked Playback of a recording with headphones connected to the 4000 ?

If the erase signal is working correctly then pretty unlikely that the record bias is bad but the only practical way to confirm 100% would be to monitor the bias signal and make sure it is reaching the heads and that there is some record signal modulation present on the bias signal. This is best done using an oscilloscope.

If there is no playback signal on the VU meters when a recording is played back then once again scope monitoring is really required to see where the signal is being lost.

Not necessarily easy.

David