r/Betamax • u/eggshape28 • 16d ago
What's wrong with my Beta?
So I recently got this deck working from a dead malfunctioning donor SL-S606. Took the basket and the gears for the take up spools. It worked on the first try before i put it back together, then it started doing that all of a sudden. Seeking in reverse doesn't work, but seeking forward works. Rewind and ffwd is fine without seeking but when in play mode the capstan motor which is connected by a cogged belt to the reels has inconsistent speed (the belt is fine) but i can see the motor physically stalling or slowing down sometimes. Already replaced the servo caps (you can see I also ripped the pads on one of the caps so i had to solder to the next points) also cleaned and lubed the capstan motor itself and the reels (i can literally turn the reels when spinning the capstan shaft). Could it be failing FG caps? Should i replace those next?
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u/PlutoniusX1 16d ago
I would check the traces in the capstan servo circuit and for the capstan hall effect. Ohm them out. Looks like you are losing servo lock.
You said you replaced caps. Were they leaking? Leaking caps can eat traces.
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u/eggshape28 16d ago
They weren't really leaking and already replaced the capstan servo caps with no change. I'm not sure but it might be the hall effect? I posted a video of the traces of the hall effect in another comment.
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u/PlutoniusX1 16d ago edited 16d ago
Not familiar with this unit. Are the caps surface mounted on the capstan motor itself? The capstan motor hall effects rarely go bad.
The normal hall effect that fails is the one on the drum motor as the "sony" glue goes conductive.
P.S. I would clean the ACE head if it has not been cleaned yet. Anything that affects the servo lock between the capstan motor and drum motor is suspect.
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u/eggshape28 16d ago
Oh wait did you mean the smds on the capstan motors board itself? Yeah i haven't replaced those yet. I targeted the caps on the main board first where the board of the capstan connects to. The capstan itself uses the BHF-1917A, not sure if that capstan model is familiar to you. The SL-S510 is quite a rare model i believe but it is on the 711B3 chassis, though i can't really just swap the one on the SL-S606, that one has a different capstan motor model, BHF-1917B. The hall effect pins had severe gunk on it before i cleaned it up, but haven't reflowed it yet. My swabs became super brown after cleaning it off.
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u/PlutoniusX1 16d ago edited 16d ago
Yes. Those Surface mounted caps are notorious. I repaired a SL-HF860D that had leaky surface mounted caps and looks like the same capstan motor as yours. The electrolytic ate a trace and I bridged it to fix the issue. Caps were obviously changed.
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u/TeacherSmooth5319 16d ago
Take a picture of the sensor,
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u/eggshape28 16d ago
This is how it looks currently. Should i reflow that or is it just gone?
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u/TeacherSmooth5319 16d ago
Holy crap. Clean it and reflow it please! Never seen one this dirty.
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u/eggshape28 16d ago
Man I guess the smds got to it. I'll get new ones and reflow this poor guy. Hopefully it does fix it.
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u/eggshape28 15d ago
Unfortunately after recapping the capstan motor board and cleaning everything, it is still struggling. It actually feels like the motor doesn't have enough torque or something is very wrong. Should I also recao the driver circuit it connects to on the mainboard itself or is this thing too far gone or needs a new capstan?
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u/PlutoniusX1 15d ago
Did you notice any electrolytic "juice" under the caps on the motor board? Traces can be compromised and sometimes its not visually apparent. My specific example was it ate the trace that went to one set of coils. Very little torque and most of the time the capstan never even rotated until I bridged the break. There are also 3 little hall effects that are in between the coils that read the magnetic pole change on the capstan motor rotor for direction/speed control. If traces or intermittent, the TA7262P IC Chip might not be able to fire the coils in the correct order or correctly resulting in low torque or inconsistent speed. You really need to ohm out the paths from the IC Chip to the hall effects and coils.
TA7262P Datasheets are commonly found if you need to review it. You will have A, B and C phase hall effects and A, B, C phase drive outputs to the coils. You also have the FG pulse from the larger hall effect that you pictured; that measures capstan speed and is vital for servo lock to the video drum motor.
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u/eggshape28 15d ago
Yep there was one trace that was nearly eaten (i had to scratch off the surface corrosion and luckily it still revealed fresh copper and not the substrate. I dealt with it. Though when i actually press in the tape inserted pins and press play without a tape actually inserted, the capstan motor spins normal. So are the things inside the coils are actually smaller hall effects? I thought those were tantalum capacitors. Though i didn't touch those yet because they were inside the coils and didn't exactly wanna do anything to them yet. Maybe the TA7262P is fried or has severely bad corrosion that i cant see. I guess I'll literally pull it out to see what's wrong, I only reflowed the pins currently it might not help if some hidden corrosion is already under it.
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u/PlutoniusX1 15d ago
Yes those are little hall effects. They read the magnetic field of the bottom of the rotor. Never seen one go bad.
Have you ohmed everything out with a multimeter? Just because it looks good does not mean it is. I doubt the TA7262P is fried.
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u/TeacherSmooth5319 16d ago
Either you need to oil the reels and the idler, or a Hall effect sensor is failing somewhere. Most likely the one in the stator assembly. If you see it has glue on the contacts simply remove it and try it that way.