Issues with Tape Deck

[jordancolburn]

I recently picked up an old akai quad 1/4" deck because it was cheap and I like to tinker. I'm not expecting great results other than tracking basic stuff for a lo-fi sound and maybe some tape-delay.

I'm having a few issues and was hoping people with tape experience might be able to help troubleshoot.

My main issue is some noise. Monitoring the inputs sounds fine, but on playback, the rear channels have significant amounts of noise that comes in and goes out periodically (like 1/2 second of noise coming in, then back out, then in, but it's not periodic on a set schedule and happens even with no signal on the tape, but only when the tape is playing back).

The other weird issue is recording in quad (all four tracks in one direction) , but only playing signals on the first two results into some pretty significant bleed into the other tracks that should be silent.

To me it seems like some kind of alignment issue between the playback and record heads, but I don't know enough to tell. My other thought would be somewhere in the circuit between where I monitor the signal and it going to the record head or coming off the playback head to the outputs could have a bad cap/amp/solder connection.

[Drone]

Are you using new or used tape?

I've seen some weird issues with old tape that's been improperly stored, but that's more a phasing sound where one segment of the real the tape has been damaged in some way (not an expert).

[Teacher's Pet]

Does anyone else picture the subject line of this thread on their tombstone?

[jordancolburn]

Does anyone else picture the subject line of this thread on their tombstone?

I've just been messing with it for a week or two and it already feels that way. I can only imagine...

Are you using new or used tape?

I've tried it with used and with some NOS tape and get the same issues. The issues do not appear on tape recorded on other machines, so I assume the Playback portion is fine.

Since monitoring the input doesn't have this noise, and playback of other material is fine, I assume the problem is somewhere between the input and the rec heads (also potentially the erase heads doing a poor job?).

I took most of the thing apart and didn't find anything obvious like poor solder joints or leaky caps. Cleaned it inside and reseated all the boards and still get the issues. Even swapped the input and playback boards for front/rear channels and still have the same issues on the rear channels which has me leaning toward some issue with the OSC board or the tape heads.