MCI JH110

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Brad McGowan
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A new problem...

Post by Brad McGowan » Thu Nov 06, 2008 8:34 am

I've been making some progress on the erase issue. Having the oscilloscope has definitely helped. And using the hum shield too. Duh.

Now I seem to have developed a rather annoying problem. If I rewind tape such that it spools off the take-up reel, neither motor stops, but instead the reel of tape spins faster and faster and won't slow down unless I turn off the machine. I know that's not normal. I also noticed that if there is no tape on the machine and I power it up that both reels will spin. Is this normal?

What might cause this runaway motor problem? Where should I troublshoot first? Is it an optical sensor issue?

thanks,
Brad

cjmnash
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Re: A new problem...

Post by cjmnash » Thu Nov 06, 2008 10:17 am

Brad McGowan wrote: Now I seem to have developed a rather annoying problem. If I rewind tape such that it spools off the take-up reel, neither motor stops, but instead the reel of tape spins faster and faster and won't slow down unless I turn off the machine. I know that's not normal. I also noticed that if there is no tape on the machine and I power it up that both reels will spin. Is this normal?

What might cause this runaway motor problem? Where should I troublshoot first? Is it an optical sensor issue?

thanks,
Brad
hey brad-

that's not normal!
sounds like a tape brake sensor gone bad or out of adjustment. (the black thing to the right of the capstan motor) depending on what version of 110 you have it might have an adjustment pot which will be located on a small pc board underneath the deck plate directly below the sensor.

about half the time it's out of adjustment, the other half of the time it's a bad tape sensor.

later,

chris mara
www.welcometo1979.com
www.nobraineraudio.com
Owner: Welcome To 1979 Studio & Mara Machines

Brad McGowan
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Post by Brad McGowan » Thu Nov 06, 2008 7:18 pm

Hey Chris,

I have the 18V "A" revision. I'm going to see if I can figure out what's going on with it tonight and report back. The darn thing was working just fine a couple days ago too. Bummer.

Brad

Brad McGowan
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Post by Brad McGowan » Sun Mar 01, 2009 5:41 pm

Aren't tape decks fun...it turns out the hum I've been living with the last few months is due to a bad capstan motor. Does anyone here have an extra JH110 8-track capstan motor they could part with?

thanks,
Brad

CurtZHP
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Post by CurtZHP » Sun Mar 01, 2009 6:55 pm

I don't mean to suggest that you wouldn't be smart enough to check this yourself, but make sure there isn't a piece of debris or flaky tape stuck in the sensor, fooling it into thinking there's tape threaded on the machine.
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Brad McGowan
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Post by Brad McGowan » Mon Mar 02, 2009 6:02 am

I think I may have figured out my problems with the tape break sensor if that is what you are referring to. I think there's just not enough light in my control room. If I shine a flashlight at the thing it seems to work fine.

Still need a capstan motor though....

Brad

CurtZHP
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Post by CurtZHP » Mon Mar 02, 2009 11:55 am

Try giving it a good cleaning. I don't have a lot of bright light in my studio and mine works fine.
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Brad McGowan
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Post by Brad McGowan » Thu Mar 19, 2009 7:43 am

Do any of you guys have any spare repro cards. I'm specifically looking for 18V "A" revisions cards.

thanks,
Brad

Al_Huero
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Post by Al_Huero » Thu Mar 19, 2009 12:32 pm

Brad McGowan wrote:Aren't tape decks fun...it turns out the hum I've been living with the last few months is due to a bad capstan motor. Does anyone here have an extra JH110 8-track capstan motor they could part with?

thanks,
Brad
I had mine rebuilt by Amp Services in Florida. Check them out if you still need it.

Al_Huero
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Post by Al_Huero » Thu Mar 19, 2009 12:33 pm

Brad McGowan wrote:Do any of you guys have any spare repro cards. I'm specifically looking for 18V "A" revisions cards.

thanks,
Brad
I may, I have some old JH-110 cards that came with a 2-track machine I've got. Send me a picture of your card and I'll see if it mathes.

airloom
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Damn right.

Post by airloom » Sat Apr 25, 2009 4:57 pm

A year and a half after acquiring our 8 track, we got it working today.
It sat in the studio for over a year untouched.
Steve Sadler's service was invaluable.
I love you.

Justin Foley
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Post by Justin Foley » Fri May 22, 2009 8:42 am

Jim Williams wrote:I've cured Molexia on these by using Stabilant 22 on the molex pins. It's a polymer that becomes conductive in the presence of electric current, in other words, a current dependent liquid solder.
ANALOG NEOPHYTES WHO ARE LEARNING STUFF ON A SECOND/THIRD/EIGHTH HAND MCI, HEED MY WORDS (and I consider myself one of you):

I got around to doing this last night on two channels of my JH-110C 8 track. I bought some Stabilant 22S and figured I'd just do a simple cleaning of the audio on one of the channels. This is pretty clean machine for being a 1/4 of a century old, but I thought "I just bought this stuff and it's expensive as hell so I might as well try it". Here's what I did:

1. Opened up the drawer on Channel 1-2 and unplugged all of the easily unpluggable stuff on Channel 1 (audio cards, molex connectors, those yellow towers in the back (relays?)).

2. Took a foam tipped swab (Qtip like) and dipped an end into my bottle of 99.9% alcohol. Did a quick scrubbing of each Molex pin sticking out of anything - main board or audio board; did the same with the pins on the end of the relays. Ended up going through about 2 double ended swabs for the whole channel (never, of course, redipping the same end back into the alcohol).

3. I gently inserted the end of the smallest Allen wrench I had into the opposite side of each female Molex connector (jesus, that reads like an adult novel) to slightly bend the contact part for a tighter connection. If someone's got a better method to do this, I'm all ears.

4. I had a very, very fine brush (like the stuff you'd find on this page) that I'd gotten with the Stabilant. I applied a drop of the Stabilant (diluted, as per the instructions) onto the head of the brush and rubbed the inside of the female connection of each of the things I'd unplugged. This ended up requiring about 4 or 5 drops for the whole channel.

5. I plugged everything back in.

This whole thing seemed like a pain in the neck and it took between 15 and 20 minutes. I was grumbling about all the other things I'd rather do with my time

Now the tape I had on the machine had a stereo drum kit on channels one and two, recorded right after the last machine alignment. Suddenly, there was a problem with the balance between the channels. Such a big problem that had to check faders, cables leading to the machines, etc. Problem persisted, so I took a deep breath and got ready to do channel 2. Before I did, however, I set the mixing board fader for channel 2 so that playback peaked at 0db.

I did steps 1 - 5 for channel 2, hit play and looked at the meter.

It was peaking solidly at +10db.

I had INSTANTLY gained 10db on the playback of the machine! No other changes, no cleaning to any other connectors, no nothing. Just the 15 minute clean above and the playback that had been peaking at 0db was now peaking at 10db, maybe 12db. And my balance problem between channels was gone - as they were now both treated.

I'm sure I have to do a new alignment on those channels, and now I'm sure I'm going to have to do the same procedure for the whole machine. I realize that this is opening up a can of worms, probably uncovering some barely connecting Molex bottoms that will now require a resolder or something, but HOLY CRAP. What a difference.

I figure, turn on a good ball game, heat up the soldering station and just attack the machine with this stuff. Hopefully a few hours later I'll have a tape deck that is recording and reproducing audio more efficiently and cleanly.

10db!

= Justin

daved
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Post by daved » Fri May 22, 2009 9:21 am

imagine how great it would sound (and how much more reliable it would be) if you replaced all the molex connectors with something more solid-grabbing and air-tight...

-d-
Dave Davis
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amorris
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Post by amorris » Fri May 22, 2009 12:18 pm

imagine how great it would sound (and how much more reliable it would be) if you replaced all the molex connectors with something more solid-grabbing and air-tight...
trifurcon

http://www.molex.com/cmc_upload/0/000/1 ... 4-7674.pdf

ive used these on other machines, but have had zero problems with them.
Studio Technician

hinkasaurus
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Post by hinkasaurus » Thu May 28, 2009 12:42 am

Hello all,

I've got a 110C 8 channel machine. You know the 2 caps that are piggybacked on the audio motherboard as R5? Can someone tell me the value of each cap?

The larger cap on my machine is a 220uf 35v but I cannot decipher the numbers on the smaller one (it's orange). Here is what's on the small cap:
electrolico -- 81000 -- 06.79 and that's it. Where a common cap would have, say, nichicon - 220uf - 35v, this one only has those numbers.

Any ideas? Thanks in advance,

Jim
__jim__

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