I just saw this today. I worked at MCI and worked on a shitload of JH-24’s. It’s been 30 years since I’ve even thought about these machines. What’s stuck in my memory, is the machine doesn’t know it’s actually in stop so it won’t go into play until you move the supply reel back a bit to add tension.
Look at the Analog Torque Board alignment. This sets tensions and offsets. All you need is a voltmeter, a manual, a tweaker and follow the alignment procedure in the manual. You may as well get your hands dirty because these machines need constant maintenance and there is a huge shortage of people that work on them and we’re all dying off. Once you align the ATB, Then I’d troubleshoot the other problem. The only thing that sticks in my mind is this problem is related to a “motion sensing” issue. I seem to think it’s related to the tachs which are mounted to the rear of the reel motors. They’re not fun to find or replace. Sony pretty much demolished MCI and their support system.
BTW, I currently work for David Kulka at Studio Electronics, but I gave up on tape machines a few years back. You tend to get married to them, if you get my drift, and since you’re always the last to have worked on it, you’re always responsible to keep them running however old they may be.
I would start getting acquainted with the machine and it’s idiosyncrasies. That’s the best advice I can offer you. Getting a hold of Steve Sadler in Nashville may be a good option for you. He charges for telephone support, but he’s been working on these machines longer than I have and if you can figure out how to use a meter and scope, he can walk you through any repair. We did this at MCI for years since the damn things weren’t exactly portable. You can PM me if you have any questions.
Look at the Analog Torque Board alignment. This sets tensions and offsets. All you need is a voltmeter, a manual, a tweaker and follow the alignment procedure in the manual. You may as well get your hands dirty because these machines need constant maintenance and there is a huge shortage of people that work on them and we’re all dying off. Once you align the ATB, Then I’d troubleshoot the other problem. The only thing that sticks in my mind is this problem is related to a “motion sensing” issue. I seem to think it’s related to the tachs which are mounted to the rear of the reel motors. They’re not fun to find or replace. Sony pretty much demolished MCI and their support system.
BTW, I currently work for David Kulka at Studio Electronics, but I gave up on tape machines a few years back. You tend to get married to them, if you get my drift, and since you’re always the last to have worked on it, you’re always responsible to keep them running however old they may be.
I would start getting acquainted with the machine and it’s idiosyncrasies. That’s the best advice I can offer you. Getting a hold of Steve Sadler in Nashville may be a good option for you. He charges for telephone support, but he’s been working on these machines longer than I have and if you can figure out how to use a meter and scope, he can walk you through any repair. We did this at MCI for years since the damn things weren’t exactly portable. You can PM me if you have any questions.