Where is the fuse that controls the VU meter lights on a JH24?
- Thread starter seankerns
- Start date
sweetbeats
Reel deep thoughts...
You have the manual, yes? Is there an index? If so, look up fuses. Or look in the schematics for a schematic to the power supply and post a hi-res PDF of the power supply schematic.
Bottom line: you really need to knuckle down and read the manual a couple times...at least get familiar with the sections and what is contained in each section. You have to do this in order to help the people that can help you. Not trying to be a hard a$$ here, but that's sort of apropos "your end of the bargain" to get free help...there's only so much us weirdos interested in this stuff can do, especially when you've got the reference document in your hands and we, or at least I don't...I don't recall any other JH-24 owners posting on this forum since I've been a member here for the last decade, so that's part of the issue...just not a lot of user community support or traffic about your machine so we need help from you in ordeer to help you.
[EDIT]
What do you mean by "red and blue lights"?
Bottom line: you really need to knuckle down and read the manual a couple times...at least get familiar with the sections and what is contained in each section. You have to do this in order to help the people that can help you. Not trying to be a hard a$$ here, but that's sort of apropos "your end of the bargain" to get free help...there's only so much us weirdos interested in this stuff can do, especially when you've got the reference document in your hands and we, or at least I don't...I don't recall any other JH-24 owners posting on this forum since I've been a member here for the last decade, so that's part of the issue...just not a lot of user community support or traffic about your machine so we need help from you in ordeer to help you.
[EDIT]
What do you mean by "red and blue lights"?
I do have the manual yes. It is a hardcopy three ring binder, and I also have a PDF print out of it. I have looked through both of those things three times so far without finding anything that shows the meter bridge at all. I have also looked the machine up and down physically without finding any fuses other than a couple of them in line with the reel motors, which were a real pain to take apart, and then the unscrewable ones on the rear of the power supplies all of which so far have tested good, by which I mean they had continuity from one into the other. I am not an electronics technician, so I’m just basically hoping to find something I recognize in those drawings that point me to a fuse. I appreciate your offer to help, and I’m not trying to sound like I don’t want to do the work. I am also conscientious of the fact that it is a 35-year-old machine, and trying not to pull out anything that I can’t figure out where it goes back to. Especially since these machines are apparently notorious for developing bad connections if messed with.
Buy red and blue lights, I mean the blue and red lamps above each VU meter the blue ones generally light up in one of the modes on the transport I think it’s cue mode, and the red ones go on when you hit record and play if the tracks of been recorded in abled via the left buttons on the auto locate.
I was in the process of replacing burned out meter back lamps the little pushy and ones. I had already gotten all of the red and blue lights replaced and working and was working my way through the meter back lights when something caused them all to go out. I’m assuming I touch something and blew a fuse because it was immediate, so I’m just trying to find which fuse that is so that I can replace it and never do that again with the power on. Sorry for the worry reply , Thanks for the help.
Buy red and blue lights, I mean the blue and red lamps above each VU meter the blue ones generally light up in one of the modes on the transport I think it’s cue mode, and the red ones go on when you hit record and play if the tracks of been recorded in abled via the left buttons on the auto locate.
I was in the process of replacing burned out meter back lamps the little pushy and ones. I had already gotten all of the red and blue lights replaced and working and was working my way through the meter back lights when something caused them all to go out. I’m assuming I touch something and blew a fuse because it was immediate, so I’m just trying to find which fuse that is so that I can replace it and never do that again with the power on. Sorry for the worry reply , Thanks for the help.
I started looking in the manual’s for things related to the auto locater, because I noticed that all the lights would go out if I disconnect the connectors from the auto locater to the meter bridge.
So I made the assumption that the meter bridge lights must get their power from those big connectors somewhere, which may not be correct. But again, I have been unable to find anything in the book that shows where they do get their power. I was unable to find anything like fuses in the auto locater itself. I have also traced all of the cables that go from the auto locater to the meter bridges and to the power supplies on the main deck, and don’t see any fuses in line with those either. There has to be one big fuse I’m missing somewhere.
So I made the assumption that the meter bridge lights must get their power from those big connectors somewhere, which may not be correct. But again, I have been unable to find anything in the book that shows where they do get their power. I was unable to find anything like fuses in the auto locater itself. I have also traced all of the cables that go from the auto locater to the meter bridges and to the power supplies on the main deck, and don’t see any fuses in line with those either. There has to be one big fuse I’m missing somewhere.
sweetbeats
Reel deep thoughts...
My concern is its not a fuse, because if there is low voltage stuff involved (the mode status lamps...LEDs?) and the meter lamps are 24V powered that's usually the transport supply too...hrmmmm...
Wish I had the manual.
Sean, the most important thing to do right now is to stop, don't start taking stabs at things. There needs to be some stepping back and starting at a root level to sort out what's going on.
There may be a blown fuse, or a problem with one of the supplies.
A typical first step is to ensure all the power supplies are producing clean power of the right voltage. That may be what needs to happen here for starters.
Wish I had the manual.
Sean, the most important thing to do right now is to stop, don't start taking stabs at things. There needs to be some stepping back and starting at a root level to sort out what's going on.
There may be a blown fuse, or a problem with one of the supplies.
A typical first step is to ensure all the power supplies are producing clean power of the right voltage. That may be what needs to happen here for starters.
sweetbeats
Reel deep thoughts...
Then stab away, but 100% of the time I do that I
A. don't solve the problem, and
B. usually create new problems, and
C. always become more confused
I downloaded the JH-24 manual from analogrules.com, but its a mess.
A. don't solve the problem, and
B. usually create new problems, and
C. always become more confused
I downloaded the JH-24 manual from analogrules.com, but its a mess.
And just to support point B above, my intuition as regards the fact that some of the lights work some of the time, as opposed to total failure, is that I probably cooked an IC when I touched that bulb to the wrong thing. Though honestly, I'm a little disappointed if there wasn't a fuse to protect that circuit in case of a short.
sweetbeats
Reel deep thoughts...
Old ICs can be more sensitive to limits, and often the fuses have to be slow-blow anyway or they'll blow every time you power the unit on because of the initial in-rush current...or they'd have to be higher amperage rated...its a double-edged sword.
Wanted to follow up, since I hate it when people pop onto a forum, post for help, go back and forth for a day or two, then disappear.
First off, I learned a very... no, I already knew better, I had reinforced for me a very important lesson about about unplugging or plugging things in which carry voltage, when the power to the machine is on*. I work on tube amps a lot. I know better. Almost always, I get hurried or cocky or both, and make a mistake. Sometimes, there isn't any consequence except a momentary scare, and sometimes a shock to remind me. Other times, like this one, there are consequences. Potentially very bad ones.
Second, Steve Sadler is. The. Man. There may be nobody on the planet who knows as much about MCI machines as Steve does. And he is very, very patient. In a half hour Skype session, he was able to walk me through several troubleshooting steps, which ultimately resulted in finding, and fixing, for the cost of a 3A fuse (and Steve's time, which was totally worth it), the problem that had:
- made all of my VU meter lights inoperative,
- as well as all of the input lights on the meter, bridge,
- the record ready LEDs on my Autolocator III stop lighting, and,
- as it turned out, the VU meters weren't even registering signal in input mode.**
I also, in the course of that 30 minutes, learned a f7ck of a lot about how these machines work, what the power supplies and connectors are supposed to be doing, and a lot about my specific machine. If you are, like me, a DIY wannabe tech, the proverbial "knows enough to get myself into trouble, but not out" guy, working on a machine which is way beyond your depth, someone like Steve is a god-send. I can not recommend his service enough. If you're lucky enough to be such a skilled guy yourself, or have one locally upon whom you can call - on a Sunday, no less, consider yourself blessed. If the above is not true, someone like Steve is indispensable.
So, what turned out to be the problem? Steve led me through a series of steps, in a very specific order, then had me slide out the channel 1-8 drawer, and measure the fuses at the bottom, both of which are 3A fuses intended to supply 24VDC each. One of them was blown. (By the way, never discount something stupid and simple like a bad alligator clip lead screwing you up. Suspect every piece of gear if something doesn't make sense). By the way, I had previously "checked" that fuse by seeing if there was continuity across it. There was. What there wasn't, was 24V at both ends like there was supposed to be.
So, I'm back to where I was before I started swapping lamps out live. And I will never, ever do that again.
*Unless someone like Steve tells you to do it. And make sure you listen and understand instructions before you act. One of the first things Steve asked me to do was to unplug the Tuchel connectors from the meter bridge. With the power on. At other points, like when he had me pull the three connectors from the top of the power supply, and when I plugged them back in, he had me power the machine off.
**I had missed this detail until I was in the process of getting things ready to talk to Steve today. The meters showed when something was playing back, and they registered incoming and outgoing signal when recording, but not when the machine was sitting idle in Input mode.
After getting that all working again, I very carefully put back every cover I had removed, rolled the machine very gingerly back into place, and backed away, slowly.
BTW, on a personal note, speaking to Steve reminded me a lot of my grandfather, who taught me how to do a lot of things when I was kid. Very patient, and very literal. He had, at various points in his career, trained machinists and technicians at John Deere in the 50's and 60's, and pilots during WWII. He understood the value of teaching a man to fish, rather than catching them for him, but some days, it's okay to clue them in on what the fish are biting on that day. And he was very much of the philosophy of letting people learn from mistakes, as long as they didn't get themselves or someone else killed. One of his favorite tricks, when training anyone, was to give them a set of instructions, and tell them to read the entire thing, beginning to end, before starting. I'm sure most of you know where this is going. When a student would come to him, stuck on a problem, and say they had followed the directions and still screwed up, his first question was whether they had actually read _all of the instructions first_. Invariably, the last instruction would be something along the lines of, "Do not perform step 6."
First off, I learned a very... no, I already knew better, I had reinforced for me a very important lesson about about unplugging or plugging things in which carry voltage, when the power to the machine is on*. I work on tube amps a lot. I know better. Almost always, I get hurried or cocky or both, and make a mistake. Sometimes, there isn't any consequence except a momentary scare, and sometimes a shock to remind me. Other times, like this one, there are consequences. Potentially very bad ones.
Second, Steve Sadler is. The. Man. There may be nobody on the planet who knows as much about MCI machines as Steve does. And he is very, very patient. In a half hour Skype session, he was able to walk me through several troubleshooting steps, which ultimately resulted in finding, and fixing, for the cost of a 3A fuse (and Steve's time, which was totally worth it), the problem that had:
- made all of my VU meter lights inoperative,
- as well as all of the input lights on the meter, bridge,
- the record ready LEDs on my Autolocator III stop lighting, and,
- as it turned out, the VU meters weren't even registering signal in input mode.**
I also, in the course of that 30 minutes, learned a f7ck of a lot about how these machines work, what the power supplies and connectors are supposed to be doing, and a lot about my specific machine. If you are, like me, a DIY wannabe tech, the proverbial "knows enough to get myself into trouble, but not out" guy, working on a machine which is way beyond your depth, someone like Steve is a god-send. I can not recommend his service enough. If you're lucky enough to be such a skilled guy yourself, or have one locally upon whom you can call - on a Sunday, no less, consider yourself blessed. If the above is not true, someone like Steve is indispensable.
So, what turned out to be the problem? Steve led me through a series of steps, in a very specific order, then had me slide out the channel 1-8 drawer, and measure the fuses at the bottom, both of which are 3A fuses intended to supply 24VDC each. One of them was blown. (By the way, never discount something stupid and simple like a bad alligator clip lead screwing you up. Suspect every piece of gear if something doesn't make sense). By the way, I had previously "checked" that fuse by seeing if there was continuity across it. There was. What there wasn't, was 24V at both ends like there was supposed to be.
So, I'm back to where I was before I started swapping lamps out live. And I will never, ever do that again.
*Unless someone like Steve tells you to do it. And make sure you listen and understand instructions before you act. One of the first things Steve asked me to do was to unplug the Tuchel connectors from the meter bridge. With the power on. At other points, like when he had me pull the three connectors from the top of the power supply, and when I plugged them back in, he had me power the machine off.
**I had missed this detail until I was in the process of getting things ready to talk to Steve today. The meters showed when something was playing back, and they registered incoming and outgoing signal when recording, but not when the machine was sitting idle in Input mode.
After getting that all working again, I very carefully put back every cover I had removed, rolled the machine very gingerly back into place, and backed away, slowly.
BTW, on a personal note, speaking to Steve reminded me a lot of my grandfather, who taught me how to do a lot of things when I was kid. Very patient, and very literal. He had, at various points in his career, trained machinists and technicians at John Deere in the 50's and 60's, and pilots during WWII. He understood the value of teaching a man to fish, rather than catching them for him, but some days, it's okay to clue them in on what the fish are biting on that day. And he was very much of the philosophy of letting people learn from mistakes, as long as they didn't get themselves or someone else killed. One of his favorite tricks, when training anyone, was to give them a set of instructions, and tell them to read the entire thing, beginning to end, before starting. I'm sure most of you know where this is going. When a student would come to him, stuck on a problem, and say they had followed the directions and still screwed up, his first question was whether they had actually read _all of the instructions first_. Invariably, the last instruction would be something along the lines of, "Do not perform step 6."
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sweetbeats
Reel deep thoughts...
I enjoyed your last post for a number of reasons. Thanks for sharing, Sean. Very great to read if your contact with a subject matter expert on your machine as well as your increase in knowledge and successful repairs. Good stuff. Thanks and congrats.
Nice little "morality play!
The idea of "jump in it will be the chatsbychansenpipe, always is on these things" approach to repair is one that should be reserved to very experienced techs.
If you are fixing a dozen different things a day as an itinerant service tech you WILL perforce go for the quickest 'educated guess'. You have to if you are 1) going to get through the worklist, 2)make any money!
For the noob or when faced with unfamiliar gear K.I.S.Sir! Go back to basics. Often the best start is to study the schematic and do 'cold checks' with a mmeter. If that does not throw up any anomalies, next check DC conditions. E.g. OP amps must have both inputs at the same potential (offset will be mV) and if they are, output must be the same (+or- offset+DC gain) .
We all fly by trouser arse at times but the logical, systematic approach almost always wins.
Dave.
The idea of "jump in it will be the chatsbychansenpipe, always is on these things" approach to repair is one that should be reserved to very experienced techs.
If you are fixing a dozen different things a day as an itinerant service tech you WILL perforce go for the quickest 'educated guess'. You have to if you are 1) going to get through the worklist, 2)make any money!
For the noob or when faced with unfamiliar gear K.I.S.Sir! Go back to basics. Often the best start is to study the schematic and do 'cold checks' with a mmeter. If that does not throw up any anomalies, next check DC conditions. E.g. OP amps must have both inputs at the same potential (offset will be mV) and if they are, output must be the same (+or- offset+DC gain) .
We all fly by trouser arse at times but the logical, systematic approach almost always wins.
Dave.
Well, to be pedantic, it was _a_ 24V fuse, just not F3 or F4 on the power supply. I had been going around testing fuses generally, but as I said, this one had "tested" good previously. I might never have found it, the way I was testing it. And I'm glad it was just a fuse this time, too.
miroslav
Cosmic Cowboy
Did you get any info from him on your "PLAY" problem?
Didn't go there yet, for a couple of reasons.
First, it appears that the machine benefits greatly from staying on, as far as how all of the transport works.
Second, there are some things in the manual I can check myself first. I am paying for Steve's support, and I know he would be happy to go through it with me, but I do want to have looked over the procedure forst myself.
With all that drama going on around the input situation, I felt that was enough to deal with in one day. And he had another call coming in.