Working on this for a friend & have gotten kind of stumped.
The schematic for the suspected area is here:
Symptom: Most of the time when in play/rec the takeup reel will stop for maybe 1/4 second. it will do this three times and then stop. Sometimes it has no problems. It seems to get more stable the longer it runs. Interestingly, the transport buttons do not function during the failure mode so I have to wait for it to glitch a few times and then stop itself.
I did all the normal stuff like resolder suspect joints, check connections, etc. Didn't find anything. Pulled caps that seemed to be related to the motor controller & checked them. They all tested good.
Checked the Hall sensors & am getting what look like good pulses all the way back to the CPU.
Checked the motor controller (IC0006 on board MIX3/7). When the unit is working normally I measure <1V on pin 6 but when things are going poorly I measure 9V.
Does anyone know if this is a known failure mode of the unit or have any other advice? I'm kind of wondering if either Q014 or the motor controller is bad. The periodic "glitching" of the transport makes me think that it's some kind of capacitative issue but I haven't found it if it is so that makes me lean more toward the motor controller since I suppose that kind of thing could happen inside the chip.
I'm trying not to shotgun parts in so thanks for any advice on this.
dave
Yamaha MT8X dropping out of play/rec
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- audio school
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- Location: Corinth, TX
Yamaha MT8X dropping out of play/rec
Dave Randolph
Proprietor, Starr Sound
Proprietor, Starr Sound
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- audio school
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- Joined: Thu Feb 07, 2013 12:34 pm
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Same Problem Here
Dave,
Did you ever figure out the problem with your MT8X? We have one here in for repair with the same exact problem. Please reply if you know how to repair it.
Thank you.
Hank
Providence Music Service
Pawtucket, RI
Did you ever figure out the problem with your MT8X? We have one here in for repair with the same exact problem. Please reply if you know how to repair it.
Thank you.
Hank
Providence Music Service
Pawtucket, RI
-
- audio school
- Posts: 1
- Joined: Wed Mar 27, 2013 1:49 pm
- Location: new york
same problem!
I just traded an otherwise perfectly-working MT8X and I get the exact same problem. The tape will kind of briefly stop of a few times during playback and it's impossible to use any of the other transport buttons during that time.. I have to wait until the tape stops itself and the tape icon lights up. Everything else--FFW, REW, etc--works..
I'm using Maxwell normal bias 60 min tapes, I thought that might have been the problem? will keep trying new things..
Would be really interested to know if you guys ever find a solution..!
I'm using Maxwell normal bias 60 min tapes, I thought that might have been the problem? will keep trying new things..
Would be really interested to know if you guys ever find a solution..!
I solved the problem. It's the reel motor, the one on the center. There are three motors: capstan, reel and a special motor to rise the heads when playing. The reel and the special motor are the same. If you didn't have a spare motor, you can solve the problem simply by swapping the two motors, like i did. Now my mt8x works perfectly!
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