Akai GX 630D

[longfade]

Lucked into a GX630D recently and I've noticed a slight dulling of the highs on playback when a/b'd against the source material. I'd like to try adjusting the bias, but don't know where the bias adjust is. I understand that it's inside the unit somewhere. Is there anyone who can tell me where it is?

Thanks!

[cbrworm]

You should get a service manual (paper).

You will find it very helpful through the life of the deck.

Before you change the bias I would clean the heads well - make sure there isn't something holding the tape away from the playback head. Also try a new tape. I am not sure if the GX heads need to be demagnetized - but if they do - missing highs is a sure sign.

For the bias - there should be two pots side by side near the wires that run up to the record head. I usually use an oscilloscope on the leads going to the record head to at least record the starting position in case I want to put them back.

[longfade]

Yes, great advice. My Han-D-Mag is on the way so I'll give the demag a whirl when it arrives. I'm looking around for a service manual, too. They're not that hard to find but being the inveterate bargain hunter that I am I have to find the best deal, don't you know. The machine seems very sound (no pun intended) and doesn't appear to need much of anything as far as I can tell. Calibration and some de-oxit here and there should do it!

Thanks very much.

[Fred Longworth]

In the past, I've seen many cases where the heads were worn and that compromised high-frequency response. The owner of the machine -- or a "junior technician" -- then reduced the bias to crank up the high-frequency response.

Don't do that.

In exchange for increased high-frequency response, you sacrifice dynamic range, in other words, the ceiling beyond which you get rounding or clipping with attendant harmonics will be substantially lowered.

Fred

[thesuau]

All lights work and the fast forward and reverse switch respond, but I do not get a proper response when I hit play or record. It will click and then nothing happens. Any thoughts?

Thanks

[cfan]

My GX-630D seems to have some problems in logic control. When turned on, it run rewinding automatically. I have to stop it in order to command other functions. When pressed FWD, it will run a few turns fast forward and then starts to rewind again. If I press and hold the FWD it will run forwarding until the FWD released (and then run rewinding again ...). Any suggestion? Thanks.