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JH24...any tips on how to troubleshoot the transport
Old 24th November 2009
  #1
Here for the gear
 
🎧 10 years
JH24...any tips on how to troubleshoot the transport

Hi everyone,

I've visited the forum a number of times in the past, however, this is my first posting.

When I recently bought my 24 track as-is, the transport was not working although I was informed at the time of purchase that the machine had been working properly up to the time it was put into storage [for several years].

Aside from the collected dust, the machine has little apparent wear and appears to have relatively low hours...[built in April 88]

I had heard that contact oxidation and other problems associated with sitting for that long may be the culprits. Rewind, Fast Forward and MVC work fine. Play, record, edit and shield buttons don't light up and don't work.

Stop functions partially...when in FF RW or MVC mode, pressing stop will attempt to stop the tape but only succeeds in slowing it down...

Regardless, I was hoping that someone could suggest some possible "miracle" quick fixes. I have already cleaned the dust out of the machine and checked all connections. Also have read sections of the manual and am preparing to work my way through troubleshooting the various boards and logic circuits.

I would initially like to try my hand at repairing the machine without hiring a tech to do the work. It will be a labour of love. Any suggestions would be welcomed.

And...does anyone have/use the "annunciator" board for troubleshooting

thanks,
Greg
Old 24th November 2009
  #2
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
Pay close attention now <g>...

Many JH machine problems are due to the multiple Molex connectors.

On the underside of the transport are multiple circuit cards that plug onto the transport motherboard via "beds of nails" of Molex pins.

CLOSELY EXAMINE the positioning of the cards onto the motherboard before proceeding.

Then, CAREFULLY pull off each card, at least "part way", then re-seat each card. IF a card is accidentally pulled too far (and detaches from the "bed of nails"), be DAMNED SURE you reseat it onto the same position.

Many times that will correct the intermittents.

Bri
Old 24th November 2009 | Show parent
  #3
Here for the gear
 
🎧 10 years
Bri,

Thank you very much...I am listening!

Prior to my first post I had a good look at those boards and found one of them partially lifted off it's "nails" and pushed it back in place.

At the time I thought I would like to lift them all off and burnish the contacts. I guess I was heading in the right direction...however, I stopped when I realized how tight they were secured and didn't want to snap or crack the boards.

Would you be able to suggest any lubricant that might help ease the boards off their bed of nails and clean the contacts at the same time? Is this a good idea or should I simply wiggle them til they come loose?

Also, the daughter board on the top right with the three red led's [I think that's the analog torque board] appears to have a small plastic shim on several of the pins holding one side of the board slightly higher than the other side...what's that all about. Is that normal?

Greg
Old 24th November 2009 | Show parent
  #4
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
Hello Greg...

Once Upon A Year, resoldering every Molex pin was a typical "point of entry" for MCI decks...but said your machine is 1988 vintage???? MCI was out of business then....

Bri
Old 24th November 2009 | Show parent
  #5
member no 666
 
Fletcher's Avatar
 
🎧 15 years
MCI was not out of business in 1988, they made machines into 1989 [have one]. The molex connector thing is spot on [also, pull the drawers, remove the back panel to the electronics cages, pull the Molex connectors and solder directly to the pins!! audio much better that way].

The other thing I would recommend checking is the two power supplies in the bottom of the back of the machine. For a general failure as you've described I'll bet you probably lost one of the main transistors on at least one of the supplies.

Any way you look at it, you REALLY need to have a tech who knows tape machines take a look at the beast. Even if you get it running you'll need a transport alignment [which requires weights and tools to get the tensions right, and knowledge and skill to get the tape path proper].

Hire a professional!! Do not try this at home.

Peace.
Old 24th November 2009 | Show parent
  #6
Here for the gear
 
🎧 10 years
Bri,

So...if I read you right, you're suggesting that there may be some broken solder joints or damaged pins etc. on some of those boards.

Regarding the age: Out of business...bought by Sony in what was it '82...

Here's why I say '88:
The logo on the front right panel says MCI.
inside the transport door/tray on the left is a metal tag with the manufacture SONY, model JH-24, serial #2153, and date 88A. [1988 April is what I read for that]. The same numbers are hand etched on another tag on the removable back panel.

Me thinks that was very near the end of production...

History: from what I've been able to glean, a local studio bought the machine, owned by a member of Loverboy [West Coast, suburb of Vancouver BC], went to a Radar system in the 90's and phased out analog recording except upon request up until the early 2000's when storage took place.

Last month, the studio sold it's assets and I heard about it from a member of faculty at a local college where I teach music production. The college didn't want to buy the JH-24 because it wasn't in running condition but I leaped at the opportunity...I was introduced to recording on Ampex, Scully and Otari multi-tracks back in the 70's and early 80's.

My hope is to carefully restore it to it's original condition, maintain it and use it as an "analog plug-in" for bed tracks. Many of my students and many clients are enamoured with analog but want to mix on their DAW's.

A buddy of mine has a pair of tac scorpions that we are cleaning up and making into one console and installing it as a front end partner for the JH-24 for the time being.

Greg
Old 24th November 2009 | Show parent
  #7
Here for the gear
 
🎧 10 years
thank you Fletcher.

I will definitely want to pull in a pro at some time. Your suggestions for what I might be able to do and not do are exactly what I need at this moment.

I haven't aligned a 2" machine [Otari MX80] in close to 20 years...I almost forgot how to load the tape...but I intuitively performed the virgin flip [read about it at this forum just hours after doing it!]

Greg
Old 8th December 2009 | Show parent
  #8
Here for the gear
 
🎧 10 years
Great tips...especially Brian with a confirmation from Fletcher.

I did exactly what you suggested...carefully removed every daughterboard; also the motherboard, and all harnesses; inspected and cleaned the contacts on all the boards.

Reassembled and all problems are gone. Transport functions normal...running like a top.

Many thanks,
Greg
Old 8th December 2009 | Show parent
  #9
Harmless Wacko
 
🎧 15 years
Quote:
Originally Posted by Coquitlamgreg ➑️
Great tips...especially Brian with a confirmation from Fletcher.

I did exactly what you suggested...carefully removed every daughterboard; also the motherboard, and all harnesses; inspected and cleaned the contacts on all the boards.

Reassembled and all problems are gone. Transport functions normal...running like a top.

Many thanks,
Greg
Great news Greg!!!

Staying after the molex stuff is huge with keeping the JH24's going.

If ya do... it's amazing how little work they can be, all things considered.

Best regards,

SM.
Old 8th December 2009 | Show parent
  #10
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
I guess I may have "slipped a cog" on the exact year that MCI/Sony ceased production. But, hopefully by 1988/89 the OTHER problems with the Molex pins (which was faulty soldering) had been resolved. That was a MCI problem for a number of years, dating even back into the 70's.

Glad to hear that reseating the cards seemed to clear things up!

Bri
Old 8th December 2009 | Show parent
  #11
Lives for gear
 
soupking's Avatar
 
🎧 15 years
We were recording last weekend to a JH24 (circa 1983).

We set everything up and shut it down while going to lunch. Found out that was a bad idea.

Once we got back the tape started rolling off the tape. Turned out a couple of the "_blank_" were just kind of dirty and needed pulling in and out again. I forgot what my friend told me, but after that we were up and rolling.

It's amazing how sensitive those machines are. Dirty connections seem to be our biggest issue. Not sure if they're molex or otherwise.

Best of luck!
-soup
Old 8th December 2009 | Show parent
  #12
Gear Guru
 
drBill's Avatar
 
🎧 15 years
Quote:
Originally Posted by Fletcher ➑️
Any way you look at it, you REALLY need to have a tech who knows tape machines take a look at the beast. Even if you get it running you'll need a transport alignment [which requires weights and tools to get the tensions right, and knowledge and skill to get the tape path proper].

Hire a professional!! Do not try this at home.
I'd have to second that advice. thumbsupthumbsup

Quote:
Originally Posted by soupking ➑️
It's amazing how sensitive those machines are. Dirty connections seem to be our biggest issue. Not sure if they're molex or otherwise.

Best of luck!
-soup
Ditto. Great sounding machines, but can be quite troublesome if the maintainence is not kept up with.
Old 8th December 2009 | Show parent
  #13
Gear Maniac
 
🎧 15 years
Cool tape machines, if a little finicky.

You should also have several of those power supply transistors on hand.

Quote:
Originally Posted by Coquitlamgreg ➑️
...
Here's why I say '88:
The logo on the front right panel says MCI.
inside the transport door/tray on the left is a metal tag with the manufacture SONY, model JH-24, serial #2153, and date 88A. [1988 April is what I read for that]. The same numbers are hand etched on another tag on the removable back panel.
...
I'm only guessing in regards to MCI, but knowing how some other things are date coded I'd guess that 88A indicates January of 1988.

Randy Blevins in Nashville has plenty of MCI parts.
Old 25th February 2010 | Show parent
  #14
Lives for gear
 
🎧 15 years
No... you DON'T have to have any special tools to set up a MCI JH-24 or JH-110.
The transport on both models is called a JH-114.
JH-24s and JH-110s are basically the same except for different sized motors and a few minor component changes.

I have set up too many MCI transports to count WITHOUT anything except a greenie and a full roll of tape.
This is the beauty of the MCI constant tension design.

Set the OFFSET NULL, set the IDLE TENSION, set the TAKE-UP REEL TENSION by looking at the DANCER ARM and then set the SUPPLY REEL TENSION by looking at a 10K tone while switching the PUCK OFF switch on and on.
Although this is a simplified explanation it is still very simple stuff.

You could say that I didn't use a Tentelometer or weights, but if you look in the MCI manual they don't require you to have either.
The Tentelometer can actually be used in-correctly and give you wrong readings.
The weights are just not required for proper hold back tension or anything on a JH-114 transport.
The DANCER ARM and PUCK OFF toggling along with the VU meters will tell you everything you need to know.

You could also say that I was lucky, but NONE of these machines experienced head wear that was out of the ordinary.
Several of the JH-110s were used in dub rooms and ran almost constantly for 8 hour, five days per week.
NONE had head wear that was out of the usual.
I have had three different JH-24s and none had head wear that was out of the ordinary and I'd know BECAUSE I PAID FOR IT WHEN IT WAS DONE!
This means that the tension was pretty darn close to correct.
You can thank Jeep Harned and the MCI design team that invented the system.

Setting up other tape decks can be more tricky.

BTW... the Molex connector issue is important on MCI decks because the transport uses rather low voltages (+5 VDC in places.)
A bad Molex connection (or ANY type of connection) will cause the voltage to drop and if it drops far enough some components will not pass the voltage or will not respond properly or at all to the low voltage.
As a consequence... no action.
Old 25th February 2010 | Show parent
  #15
Gear Addict
 
bassman's Avatar
 
🎧 15 years
Just had to chime in here as I feel like one of the "old guys" now...

I've fixed that damn power supply transistor thing so many times. We had extra parts around always so a weekend session wouldn't get shut down. Great machines. Find a 2" 16-track headstack for it and you'll be in love....

-ashley
Old 19th August 2012 | Show parent
  #16
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Coquitlamgreg ➑️
Great tips...especially Brian with a confirmation from Fletcher.

I did exactly what you suggested...carefully removed every daughterboard; also the motherboard, and all harnesses; inspected and cleaned the contacts on all the boards.

Reassembled and all problems are gone. Transport functions normal...running like a top.

Many thanks,
Greg


this works!
Old 19th August 2012
  #17
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
Keep in mind..the MCI machines are now perhaps 25+ years old...or more!

How many automobiles from, say, 1983 are still in operation???

And folks "diss" MCI's...sheeesh..LOL!

Studers were MUCH more expensive in that same time era..and STUDERS are slowly breaking down as well. Trust me....

Shrug.

Gotta keep up with them, vs. letting them decay.

OR say "screw it..I'll just work in the box.... and buy plug-ins"

Shrug again....

Bri
Old 19th August 2012
  #18
Lives for gear
 
🎧 10 years
Good analogy... the MCI is very much like my old 86 911 Carrera... temperamental, and required constant attention but damn she was beautiful and produced on the road like nothing else. The 911 is gone but the MCI is staying with, its sitting next the DAW in my apartment. Thanks for the help and advice in this thread Brian and everyone else too!
Old 19th August 2012
  #19
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
lol...

http://www.youtube.com/watch?v=qS-7EPDR-PY\

just kidding...!!!

Bri
Old 19th August 2012
  #20
Gear Addict
 
🎧 5 years
How in the world did this thread get re-started?

DB
Old 19th August 2012 | Show parent
  #21
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by fnninns ➑️
How in the world did this thread get re-started?

DB
Because tape...is a good thing...maybe the best of things...and no good thing ever dies.
Old 19th August 2012 | Show parent
  #22
Lives for gear
 
Radardoug's Avatar
 
🎧 10 years
Quote:
Originally Posted by brianroth ➑️
lol...

http://www.youtube.com/watch?v=qS-7EPDR-PY\

just kidding...!!!

Bri
I thought it was going to be a working MCI! So disappointed!
Cheers Bri.
Old 19th August 2012
  #23
Lives for gear
 
brianroth's Avatar
 
🎧 15 years
And vinyl still is ALIVE..IT'S ALIVE! lol

http://www.qualityrecordpressings.com/

Bri
Old 19th August 2012 | Show parent
  #24
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Radardoug ➑️
I thought it was going to be a working MCI! So disappointed!
Cheers Bri.

here you go...this is my machine...apologies for the poor video quality

jh24 - YouTube
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