Akai GX-M50 3 head adjustments.

P

pishta

Active Member
I have the service manual but I dont have an O-scope, or the meters needed to calibrate..or the know how. My rig is record challenged big time. 3 head unit has a head skew issue. I can get pretty good playback but the record is terrible. It wanders in and out in sound and on the VU meter, and when I play side B I can hear side A backwards ! The head block has 3 adjustment screws: 2 allen screws top and bottom to adjust the head tilt and tape path "depth" by turning them both at the same time. The azimuth screw on the left side just rocks the head on the 2 allen screws against a spring on the right side. So PB/R azimuth is a ballet of azimuth adjustment as well as tape path depth adjustment to get the record head back on track once you tweak the PB head as they rock in different directions. I guess the price we pay for a 3 head deck. Add to that is the fact that this deck needs to have the front face removed to access the lower allen screw (?) and that takes the cassette door out of the adjustment. Does the tape door pin the cassette back against the "wall" on the drive heads, or does it float in the door mechanism because you need to play a tape in order to adjust the azimuth Whats the going price to get a deck back to par? Im in So. Cal.
 
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You have to fix the tape skewing problem. Likely there is nothing wrong with head alignment. It is the tape that is out of alignment (not the head). To fix skewing, a new erase head pressure pad and a new pinch roller are needed.

Don't touch any head alignment screws.

A qualified shop would charge about $300 to $400 to get everything 100%. New belts, pressure pad, pinch roller, new idler tires. full TP alignment, full electronics alignment.
 
well, I have completely turned about every adjustment screw sans the height adjustment on that head block so that is out the window. I can get it to play great, its just recording that is not working and I bet its not all the alignment but the other pots in there, ie bias. I touch those with a screwdeiver and the meters go crazy. Im probably in way over my head trying to get the recording back to snuff on this deck. I do have a decent Aiwa that is untouched, that has B and C for recording. I dont see the erase head pressure pad....They are just so cheap these days on the bay that its not worth the 3-400 estimated to get this up and running when I can pick up a much more modern deck for that price. Thanks.
 
Any deck you buy off eBay will need servicing because all tape decks are quite old by now. And if the eBay seller says "everything works fine" or " just serviced", don't believe it. The cost of the deck plus servicing will end up costing you $300 to $400 total.
 
Thanks, I got nothing to lose by messing with it now, it was cheap anyway so Im not out big money. Im reading the schematic and I can find some reference voltages so Im starting to probe and the first one I test is out of spec DC wise. Ill start at the power supply. There are 5 transistors and an AC coil associated with the erase head and the first one is supposed to be at .1V and its at .3 and the rest are as bad +- 20%. time to hit the schematics with a VOM.
 
You have to fix the tape skewing first. As I said before, the erase head pressure pad is missing and you need a new pinch roller. That is causing your defects.

Doubt you will be able to correctly re-align the heads that you messed with. Need test tapes and jigs and test equipment to do that.
 
i would set the head adjusters back where there was in the first place ... they should have been locked in place with a dab of paint or something ...
if you did things properly you would have recorded what you did and be able to put back where things were .
 
Boy, you guys are all heart! Ill plod through and report what I can without any dedicated test tools. I fabbed a part that was actually snapped off, its a plastic pin that the erase head comes up against, the missing "pressure pad"? . It was broken off and took a pic of someone else's to compare to mine to realize it. I was able to check the service manuals assembly diagram and see the part graphically. Although there is no compressible 'pad' per se on that part, it does capture the tape against the erase head more than the unassisted change of the tape plane alone does. When I looked at the alignment adjusters, the paint dabs were clean off the block, obviously the PO had already tampered with them and probably got the thing so far out of adjustment that he gave up and sold it off. That is when I came into possession of it. So all the hindsight errors that were made were not all on me.
 
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