Akai 1721 L Recording Problem
 

Hello!
I have run into a small problem with my Akai 1721 L (again). It seems that whenever I use my new tapes on this machine the right channel seems to go dull intermittently, almost like a head clog but whenever I use tapes that have been previously recorded on another machine it records absolutely fine.
I noticed that the erase head seems to be covered in a substance that no amount of cleaning seems to get off and the lower part of that head is the worse than the upper. I'm not sure if this is corrosion or something else but the fact that it is an intermittent problem and it works fine with other tapes is very odd. The record/playback head has been well and truly cleaned.
This is the replacement head that I ordered and it came from an Akai 1722 L but the erase head still seemed to be dirty looking and impossible to clean.

Any idea what this might be?

-Daniel

Re: Akai 1721 L Recording Problem
 

Hello, if this is a really stubborn mark, try a small amount of acetone free nail varnish remover. I've always found this to work, although it doesn't say anything about it on the forum. TBH alcohol isn't much of a cleaner, although that is all they'll tell you to use, or meths. I've also found a small amount of Brasso on a cotton bud to remove stubborn stains or corrosion. Hope this helps. Dave.

Re: Akai 1721 L Recording Problem
 

Thanks! havent heard of these methods before but i will look into it. I have a junk head block that I can try this one before doing it on the real machine. I'm pretty sure I can get a hold of those materials

Re: Akai 1721 L Recording Problem
 

I have a 1721 and the erase head looks just as you describe (like surface rust) . It doesn't seem to affect performance do I've not bothered about it. The fault you describe doesn't appear to be related to the erase head anyway?

Re: Akai 1721 L Recording Problem
 

Yeah at this point im not too sure. It seems to work fine with older tape though, so I think i'll just use that for the moment :)

Re: Akai 1721 L Recording Problem
 

Okay I have got hold of some more (old) tape and it still has the same problem. Anybody know why this may be? I'm all out of ideas at the moment other than to clean up the erase head. Not really sure what's going on.

Re: Akai 1721 L Recording Problem
 

If you say recordings made on other tape recorders play back correctly (your first post did not quite make that clear) but recordings made on the Akai occasionally sound dull on only the right hand track then it is possible that either your Akai has a RHS recording bias-level problem or that there is intermittent problem in the RHS replay stage of your Akai. Does the intermittent dullness happen at the same places on the tape when replaying?

By the Way: can you try playing a recording made on your Akai on another machine? If you can then does it sound alright at points where the Akai sounds dull?

Re: Akai 1721 L Recording Problem
 

Hello.
Unfortunately I do not have another working machine to try it on. The intermittent dullness does happen at the same point when replaying so it's most probably to do with the recording stage.

I cant say I have come across a machine with a problem like this. Would you say this is a simple fix?

Re: Akai 1721 L Recording Problem
 

I'm not familiar with this machine but do you have a circuit diagram for it?

If so then I would be looking for how the recording bias level is set.

Failing that, if you record the same content on the same tape a second time does the dullness happen in the same physical place on the tape? Perhaps not from your earlier use of the machine??

I assume that it is not a bad contact on the recording switch?

Re: Akai 1721 L Recording Problem
 

I dont think it would be a bad contact.
It's hard to tell but the dullness seems to be at the same points when I record the same content over the previous recording. What puzzles me is that it records fine on some tapes that have been used in some of the machines I used to own.

There is a service manual here if that helps. It explains how to make adjustments to the record playback and erase bias/voltage

http://www.hifiengine.com/manual_lib...ai/1721l.shtml

Re: Akai 1721 L Recording Problem
 

As far as I understand there's an extra amplifier stage to feed the record heads used for recording only. Ie the playback amp may work but the output to the speakers during playback is fwd into an extra stage on record (tr5) So it could be a fault anywhere in this stage. By coincidence I have a 1721 that has just developed a similar fault and I've checked voltages round this stage which are ok and am about to feed an audio signal in record mode and see where it disappears. I'll let you know if I solve mine before you do!