JVC M90 Tape deck brakes don't disengage, fwd/rwd/play all don't work

Hey people,

After spending a whole bunch of time on getting this deck to work properly and testing it (see other topic), and fixing various other things, I finally put the box back together. After checking everything, I finally went to give it a last test run and...deck's malfunctioning all of a sudden!

Symptoms are: In play mode, the heads move up but immediately go back down. It's not auto-stop. That kicks in 2 seconds later by moving the solenoid. In fwd mode, without a tape, the take up reel will spin but it's struggling. The brakes are engaged (took me a while to figure that one out). In rwd mode, without a tape, same thing, except other direction. It didn't originally do this, I had to loosen up the reel motor a bit with a separate voltage supply. I think this is irrelevant though, just a slightly tired reel motor.

So the one thing they have in common is that in neither mode, the brakes ever disengage. I can disengage them manually by pushing down the spring-loaded brake assembly. I also suspect that the heads not staying engaged might be due to the fact that the assembly that moves up is supposed to be caught by a moving plastic pin on the left side. I can manually push the assembly up and push this plastic pin in place, and then it will stay up.

Sensor-wise everything seems to work as expected. Hall sensor, the optical sensor with the disc, solenoid is operated fine I think (does the expected reset at startup without a tape).

Anyone had anything like this before? Looks like some mechanical linkage problem somewhere in the harder to access guts that I've so far managed to avoid. This deck's really giving me grief.. I lack the ability to just let go though!

i have exactly the same fault on my victor m90 and it was working fine, im actually using her now....im puzzled to feck....sometimes it plays fine and others not

I will say this, it was working 100% before i lubed the deck so im hoping once she settles down she will be ok, did you lube you're deck etc??? im not sure why but this may have caused you're issues too

ok my last reply on this...it's something to do with the eject system, the heads do what you described and it wont rew ff as the brakes are on but if you put a tape in and hammer the eject a few dozen times it will play normally and rew ff until you take the tape out, that's about all i can add to this.....hopefully somebody can solve our issues, good luck

ok issue SOLVED....i squirted some wd40 quite a bit on the eject button and on the eject latch inside the door....now it works perfect....that is you're issue 100%...im not saying use wd40 but that's all i had....good luck

also clean the little micro switches at the top left hand side of deck with servisol, all should be sorted

as much as I love JVC , I have lasonic decks that are more reliable lol.

After all these years iv never had a lasonic lad lol....im quite proud of fixing my victor this time because of all the ones iv had, none have had this issue

it'x strange though as this issue came out of the blue lol but but now she is as good as new

I messed mine up once because I used to turn it off with the tape deck still running I don't do that anymore make sure you press stop on the cassette deck before you turn off the power.

Been there done that lol.....it kept blowing the psu fuse but i sorted it....i remember now what started my drama with the victor though, the head was not raising smoothly and the heads kept jamming in play so i had spin the flywheel to reset....fixed that and then all hell broke loose lol....is you're m90 working now buddy ehh???

stereomads m90 after the long rebuild by my engineer hasn't put a foot wrong lol.....famous last words haha

MY original M90 has been professionally serviced also been vacuume sealed in a space bag and put away in storage
.

you flipping nutter, use it lol

Hey Rimmer (is that a Red Dwarf reference?), you might be on to something here. I hadn't actually paid much attention to the eject mechanism. I haven't fully figured it out yet, it looks as all the bits there do is prevent you from ejecting it while it is playing. But I moved it around a little and then the little plastic pin on the left actually held the head assembly in place as I manually pushed it up. Repeatedly. So now I put in a tape and turned it on again and...nothing, same result Same plastic pin now *doesn't* catch the head assembly any more unless I manually push it into place. Wish there were pictures of the inside mechanism that are so hard to reach so I could maybe figure it out...

Picture of the plastic pin:

Yea love red dwarf haha....perhaps send a pm to caution he knows these decks very well...i can't advise you any further as i just don't have the knowledge but as iv stated i had exactly the same issues with my deck and now it's 100%, wish i could help you further...all i can suggest is try lubing the whole eject mech as that's what i did son

Thanks man, appreciate it. I removed the head assembly with the sliding plate and cleaned up the grease and applied super lube. Moves smoother now. The pin that holds the assembly in place only sticks when the solenoid is engaged I found out. I tried holding the solenoid in place when pressing play to see if that would help, but there's active resistance that wants to push the solenoid back which makes the heads disengage. That's all for tonight.

PS: love red dwarf! Always been a big fan

Been a while since I was inside mine but I might be able to help. That lever is part of the pause mechanism, there are three odd shaped plastic levers piled on top of each other and that one's on top. They are attached to the drive gear assembly unit. It's possible there's something sticking or out of place there.

That's the pause switch right under your arrow, which disengages (and disables pause transistor Q706) when the head assembly lowers, which I believe it does in pause mode. I think that allows the circuit to ignore auto-stop in play mode but yet paused, since auto-stop normally triggers when the right reel stops spinning (the magnet for the auto-stop sensor is on the tape counter shaft).

You probably noticed there's a plastic pin riding in that spiral groove on the back of the drive gear, to raise/lower the head assembly. The solenoid has to kick in to make that turn through its cycle, so if anything related to that is amiss it could cause the head assembly to misbehave. I had issues with this running smoothly until added some grease. Somehow this pause mechanism ties into that but I don't know exactly how they interact.

The M90 has an eject safety switch. Pressing eject during play will instantly cause the deck to stop to prevent head damage from the chamber opening.

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I no longer think the eject safety is a "switch" but rather a mechanical function. I just spoke from memory and as I haven't worked on an M90 in 5 years, and my memory is virtually useless these days, I guess I was just speaking outta my asss, lol.

Exactly. You can even see how it works in the pic. Those three shafts with all the plastic pieces is the eject safety. The lever on the upper-left shaft rests against the head plate. So when you press play, it turns clockwise a little bit, which makes the lever attached to it, on the upper-right shaft, to turn CCW. That swings its lower part to the right, getting in the way - but not completely - of a tab on the main slider, that you can see just to the right of the lower shaft. That way, if you press eject while playing, it allows the eject button to move the main slider up a tiny bit until it hits this lever.

That's just enough movement to trigger a stop, but not open the door quite yet. A pin on the main slider, left of the lower shaft, pushes up against the upper part of that pointy lever on the lower shaft. That makes it turn clockwise, so the lower part of it pushes the sliding metal plate along the bottom of the deck to the left. That stops the deck and puts the heads down. When it does that, the lever up top that's resting on the head plate turns back, allowing the lever attached to it to get out of the way of the main slider's tab, allowing a full eject.

There's even a lever that gets pushed by the back side of the eject hook, that raises the feelers for tape recordability and presence out of the way.

Superduper said:

The M90 has an eject safety switch. Pressing eject during play will instantly cause the deck to stop to prevent head damage from the chamber opening. Check the switch. If it is bad or sticking, the MPU might sense that the eject button is being depressed and prevent the heads from actuating.

Click to expand...

this makes total sense now....as when it's ejected everything locks up....good call Sir

Not sure this helps but I looked my parts M90 deck. I located the solenoid on the back right (facing the rear). I turned the flywheel by hand in the correct direction and held the solenoid plunger up. When I did this the heads started coming up. During their upward travel I release the solenoid. The heads continued to rise until eventually you could feel the mechanism lock in place and the resistance went away on the flywheel. That plastic pawl you were referring to doesn't hold it when in play mode. The inside cam turned by the flywheel does (although I can't get in there to take a really good shot).

In this shot you can see the heads are up but that plastic pawl doesn't support it in play mode


When pause is pressed that solenoid responds with a quick jump. This causes the pawl to leap over right as cam disengages and the heads start to fall. This pawl catches the mechanism on the way down and you end up with what you were doing. This is pause mode. Notice the gap between the pinch roller and capstan when the pawl is holding it.


Then when Play is pressed again the solenoid energizes and the inside cam lifts the heads from their current posistion upwards taking the tension off the plastic pawl which leaps back to it's neutral position and play is now engaged with the deck holding it internally.

If I press up and hold that solenoid the deck does exactly what you were saying. Heads come up then fall back down. Everything seems to be done by the reaction of the solenoid. That triggers the mechanism to engage. So it could be sticking or is being instructed to operate longer or shorter than needed by the circuit. It looks to me like this deck is one of those decks where everything has to happen at exactly the right time and duration or it goes to hell...lol

I did this all by hand. The solenoid shaft I moved was on the back pictured here. Hard to see but the pin rides in a slot with a larger sized circular hole at the top.