Welcome, Guest. Please login or register.
October 15, 2019, 01:00:53 AM
Home Help Login Register
News: Please post general conversations, videos, music, and similar stuff in the "Tips, Tricks and General MCI conversations" section, use the Misc section for any product not listed in the categories, parts or custom projects. Thanks!

+  MCI Console and Tape Machine Forum
|-+  MCI Tape Machines
| |-+  JH-16 and JH-24 (Moderator: Westrek)
| | |-+  My JH16, a life-journey...
« previous next »
Pages: [1] Print
Author Topic: My JH16, a life-journey...  (Read 2873 times)
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« on: June 05, 2017, 10:51:08 PM »

Disclaimer: I am posting in this thread simply because I heard this message board wasn't going away so quickly - since I can still log in, I can only assume the rest of you still can as well!
But alas, a lot of knowledge that was once here has potentially been flushed into oblivion for eternity - then again, I figure what better way to get that info we all need to share regarding the upkeep of these old machines (especially for a young schmuck like myself) than to spit it all back out there. I would also like to say that over the 4 years I've been a part of this message board I've learned so much reading through the posts of the plentiful experts who (used to?) lurk around here.

So as for my JH16

Well, I'll tell ya ppl she wasn't my first...

No, in fact; the JH16 that currently sits unassumingly in the middle of my living room is my second. I used to own the earlier "widebody" model (i think a 74") which is, would you believe it, in the basement of my house! (where the friend I sold it to keeps it)

My current machine is the 78" model with QUIOR, purchased from a fellow member of this forum. It had the audio cards recapped at some point in its recent history, but as I've poked around in the machine (and believe me, over the last year I've done a lot of poking... poking and prodding and accidentally breaking the... anyways  Lips sealed) I've found several old, original, dried-out capacitors, and a spattering of that who's cursed name shall not be spoken (red IC sockets), lots of grime, lots of dirt and dust... The devils advocate known as the many molex that plague these machines are brown, or grey with caked on dust and age (she's got a little bit of intermittence problems you know.) I've cleaned whichever I've come across a good scrubbing with q tips and isopropyl, and a little bit of contact spray in the fem-molex.

Suffice to say it's a bit of a wreck, but I feel like it does have the potential to be a great machine. It's failed on me for various reasons in the past, but I want to help usher my machine out of the darkness and into the light. I want to take it to all new heights. I figure at this point in my owning this (and my former) MCI machine(s) and having become much more confident in my electronics skills (although not too much more knowledgeable about the science of it) I'm ready to face the music - because as all of you older cats know (and have doom-sayed to the younger generation for at least a generation by now,) that is that analog is not a walk in the park. It's a devotion, and if I want this JH16 to be as good as it could be it needs that type of care.

Also, I would like to thank forum member Brian Roth for helping me out via email over the last couple of years. He's always been able to lead me on the right path towards being able to keep the machine afloat in times of need. Thanks Bri! This thread is an attempt to spread the request for knowledge around the MCI hivemind a little more, although Brian may feel free to add more to this convo should he so desire.  Grin

Without further ado, my MCI has the following issues:
  • VU's won't register on several tracks. I've tried checking the connections mounted on the meters themselves but for my channels 3, 14, and 15 I cant get anything (edit: since making this post i've lost VU16 as well. Dropping like flies here!)
  • windy audio on several tracks, this can result in slow drawn out movements in the meter, sometimes it will drift down completely off scale and then return (intermittent much?)
  • Godawful tape jitters, I'd tried some of michael blackmer's "mods" to fix these jitters, but ultimately those mods ended up rendering my machine catatonic for a while. They've been removed - fine modifications indeed. The Autolocator has been narrowed down as the source of the jitters (as it does not when set to the internal oscillator), the timer chip in the ALIII has been swapped, but the jitters continue
  • lmy rewind has seemed very sluggish in comparison to what it used to be, does the supply reel tension have anything to do with this? It's beyond slow, actually
  • Track 11 wont latch  into Rec mode and stay there without holding your finger on the record button. Swapping relays doesn't work. Perhaps cold solder on the Audio card motherboard is the culprit? this issue is very intermittent. It will latch on for periods of time (seemly random, though, I wanted to believe the problem was localized at the relay istelf), while latched it mayfall out of record moment at random, if that helps to give any indication
  • track  10 makes loud clicking thump when engaging and disengaging in record mode

The list goes on...

and aside from these quirks, I've just been overall pondering what could be done to overall improve the machine - I feel like I'm married to this particular machine in a way, and I'd like to try and "make it work" so to speak. It sure ain't perfect, but If I can't make it work then I don't think any analog multitrack would be right for me to swap this one with. I've been considering what It would take to redo all the molex connectors. I was reading through some old GS threads where Brian and Larry, and others, we're BS'ing about MCI machines - it was mentioned in there that someone they knew "did a hardware bypass" on every molex in their JH16, and although it could no longer be worked on it never needed work! The joke was a sham, though, as the aformentioned person who had done this mod eventually chimed in, stating that they replaced all the molex with gold (I'm assuming they are talking about a higher quality variety of molex connector). Is this a known modification? It sounds very involved, but a worthy side-step around the known intermittence issues.

And audio. This is a discrete, Xformered machine, loaded with tons of that analog tape mojo yadda yadda. None of that mojo is going away - I really want to get the audio path as clean as it can be in terms of headroom, and unwanted circuit related distortion. It would be amazing to hear some of the methods any of you might have used or even considered in an attempt to clean up the audio path on these units.

And where do you get lightbulbs for this damn thing? Is there a modern, more energy efficient counterpart I could swap in place?

(also thinking about taking this thing apart entierly so that it could have a custom paint job, but now im getting to ahead of myself - did i mention that this machine is cosmetically ugly as hell?)

I'll leave it at that for now,

THANKS Y'ALL
« Last Edit: June 09, 2017, 01:07:48 PM by rennywilson » Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #1 on: June 08, 2017, 12:12:22 PM »

What's more responsive: a JH16 that just blew all its power transistors or this thread?

LOL, just trying to grease the gears here.

PS I'm going to start adding problems to the list above as they come up.

BUMP
« Last Edit: June 08, 2017, 02:25:17 PM by rennywilson » Logged
stageleft
MCI Member
*
Offline Offline

Posts: 9


« Reply #2 on: June 12, 2017, 11:51:58 AM »

Happy to see this site hanging in there. Here's a Dropbox link to my collection of MCI info

https://www.dropbox.com/sh/dlsmqzt7tcq9e64/AACzMglGEQ1SZksuLzyNGzEoa?dl=0

Most valuable are hi res copies of the original JH416(A) schematics with the discrete modules.

Enjoy ...

Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #3 on: June 12, 2017, 01:23:56 PM »

Happy to see this site hanging in there. Here's a Dropbox link to my collection of MCI info

https://www.dropbox.com/sh/dlsmqzt7tcq9e64/AACzMglGEQ1SZksuLzyNGzEoa?dl=0

Most valuable are hi res copies of the original JH416(A) schematics with the discrete modules.

Enjoy ...

Thanks for this!

You get them from Corey, sweetbeats? Well if so they came from me! (I fedex'd my originals to him a few years back.)

FTR I own one of the Discreet 416a boards, very cool specimen.

UPDATE:

Through all my poking around in the machine this last week, I was able to get it working on 14 out of 16 tracks! this is a higher number than this tank has ever been able to manage. Not to mention, every  single  vu  meter WORKS all of a sudden, I cant tell what caused this but I feel like there's something to do with the red bias amp push buttons that are shorting the input signal from hitting the VUs. I am very happy about this, as this deck has never had a full compliment of working meters. Rewind tension is still a bit off, but the session ran without a hitch! I did notice some other issues of which I will add to my list, though.

But 3 cheers for my JH (which didn't transport tape/ sound very good a week ago)

 Grin
Logged
Harrison
MCI Master
MCI Member
*****
Offline Offline

Posts: 305


« Reply #4 on: June 14, 2017, 08:54:09 AM »

re: AL3 jitters

I've put a reply back in yhe original thread
PC
Logged
Harrison
MCI Master
MCI Member
*****
Offline Offline

Posts: 305


« Reply #5 on: June 14, 2017, 09:15:05 AM »

"My rewind has seemed very sluggish in comparison to what it used to be, does the supply reel tension have anything to do with this? It's beyond slow, actually."

Is it supply reel tension? No.

Have you ever resoldered the molex pins on the transport mother board? This is a known problem and requires the removal of the board and closely checking the pins vs pads on both sides. Pins crappy tin plating, joint with pad breaks down
Check that all power trannys in transport chimney are good.
Tensions are adjusted for play only; they have no bearing on any other mode.
How are the idles?

PC

Logged
Harrison
MCI Master
MCI Member
*****
Offline Offline

Posts: 305


« Reply #6 on: June 15, 2017, 10:03:16 AM »

Track 11 won't latch  into Rec mode

The fault is on the strip board.  Record completion P7/7 grounds the record relay via the remote ready switch.
Momentary record P12/B puts 24v onto the relay via CR2. The relay is then self held in record via R6 (240R) and lights the record lamp. Q. Does the track record lamp light when you hold the record button down?

So either R6 is blown or solder pad breaking down around this, or the play 24v track from P12/A does not get to the relay socket.

I have seen broken/burnt tracks on these boards
PC
Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #7 on: April 05, 2019, 04:35:56 PM »

Hey all! It's Rene again.

Just popping in here, trying to troubleshoot my JH16, track 10 still produces choked, distorted, and really low-level audio while in repro, trying to figure out what the heck went wrong!

A tech initially delved into the problem, and passed on the findings to me. We isolated it to the channel strip board, as ch 9's identical board was able to properly record and reproduce with ch 10's slotted electronics and molex plugged, buss board etc. I also found very little difference in multimeter readings between the 2 boards.

And at this point ive essentially transformed Card 10 INTO card 9 by swapping their components in an attempt to isolate the issue, ive even given all the Cinch card slot readers a 180 turn, recapped, re-flowed numerous times, and ch 10 still wont record and reproduce quality audio...

All's that's left is diodes and resistors, do i keep swapping and replacing? Reflowing? Should I build up some solder on the elec cards to make a better card connection? Maybe its a tiny short or something to do with the relay sockets? (the tech checked them for continuity, however).

I'm running out of ideas...   Huh What would a great MCI tech do next?
Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #8 on: April 05, 2019, 07:09:20 PM »

Well, It appears I spoke too soon, right after making that last post I swapped the last obvious part, aka, the biggest resistor-looking thing, which may actually be a 5000 Uh inductor, according to my schems (which aren't actually the identical ones for my JH16, unfortunately).

Upon very close examination you can see a bit of discoloration on the bad part, the lesson is: it pays to take an extra long visual scan of this stuff!
Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #9 on: April 06, 2019, 05:07:03 PM »

Onto track 16, which will not latch. Looking at the schem it would seem that P7 is my issue, as I can get the relay on ch 16 to latch if P7 is swapped between a working channel, ruling out the strip board. My bus board voltages also seem very consistent throughout.

 It's not the molex either, where exactly does the other end of this molex lead? the remote? Vus?

I just wanna give a belated thank you to harrison for contributing your knowledge, without a whisp of a response for such a long time (I was on tour so much of last year I didn't have a chance to even think about these repairs!)

Another useful tidbit, the remote led for 16 will illuminate while rec is held, however it is extremely dim by comparison.

Back at it...

EDIT

I seem to have found the issue here also, I traced it to the Rec light itself on the remote itself not quite completing its path. It's dimly lit nature was a clue to success!
« Last Edit: April 06, 2019, 06:05:35 PM by rennywilson » Logged
rennywilson
MCI Member
**
Offline Offline

Posts: 72


« Reply #10 on: April 16, 2019, 03:50:58 PM »

Well,

After more putsin' around, swapping components on a bad record card (bad transistor), I'm now fairly certain that my machine has it's full 16 track compliment!

No, this is not the JH13, or 14 im used to  Tongue

Which is amazing considering this old thing (which came out of a storage shed in the southwest with a fair degree of oxidization) has never been fully operational, today would be its first time under my ownership, that's over 5 years folks.

When you can't afford to pay a real tech for a house call, are too chicken to do it yourself, and too busy recording projects all the time just to cover the studio overhead, hence the life-journey subject line... sheesh!

To electronic confidence and competence, soon I'm gonna redo the lights on this thing and I'll post a pic!

Speaking of which, has anyone put modern low voltage LED's into their JH tape machine (or console vu's for that matter)? I was thinking of skipping out on getting the 24v incandescents which aren't the cheapest in favor of something cheaper, brighter, and that will last longer - what's the smartest way to do this?

*crickets*
Logged
Berwyn636
MCI Member
**
Offline Offline

Posts: 53



« Reply #11 on: May 30, 2019, 01:57:43 PM »

I weaved LED tape through all of my VU meters on my console and it worked great! Pulled the old 24V harness out.
Logged

MCI brown is the new black.
Pages: [1] Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!