MCI JH-636 Story

[briank]

Oh I missed that little proto board at the back of your PSU...huh! I see the two caps, resistor annnnd...is that a little TO-220 IC on there? Can't tell where the wires go/come from. You ask anybody on the MCI forum about that?

Not yet, I'll get some pics and info up and see what they think. On closer inspection, it's got a couple 4.7uf/160v caps, a few resistors, a couple small diodes and what you're seeing is an LM317, and in the pic above you can kind of see where its wires are soldered onto some Molex pins at the top right corner of the large PCB on top of the big trafo. I need to stick my nose in the schem for that board and get a feel for where in the 600's world it actually IS.

*sigh*

I can't wait to hear my JH-416 too...gonna be awhile, but it'll be fun getting there. Focusing on finishing up my Soundtracs cleanup first...16 channels to go...and getting the MM-1000 working reliably and getting it calibrated...getting a working studio basically, and that's all on the back-burner right now with more important projects here at home. All in good time.

For sure! I'll be interested to find out down the line how it compared to the Soundtracs, which is a good board in its own right. I expect they will sound and handle quite a bit differently, for better or worse!

Are those cinch Jones connectors inside your PSU? The one with the proto-board? And I just really like the backplane on the mixer frame. Their mixer design really went through vast changes in refinement from 400 to 500 to 600. So many great little ideas you know?

Yes, there are cinches connecting the regulator boards into the audio PSU since they're mounted on removable "chimneys" that pull out for easier cleaning/servicing. Each PSU also has cinch connections on the PSU side of the the cable looms that connect to the console.

The funny thing is that the 600 series was the replacement for the 400 series. The 500 was built in tandem with both the 400s and 600s for parts of their production runs and was always the flagship. The 600s are certainly a departure from the 400s for being a "replacement," though! It really speaks for how much the industry changed through the mid and late '70s, though I would imagine there are some "family similarities" going between the 400, 500 and 600 particularly when it comes to routing.

 

[briank]

Hehe, don't worry SWEETBEATS, it happens to the best of us. I put in a marathon console re-capping session the last couple days, pile of fader packs and a few channel modules trying to get a section done before an overdub session today.

Got to the session early, stuck everything back in the console, powered up and almost immediately heard a "pop...pop!!!"

Ohhh boy, what is it this time? Just follow your nose....fried resistors smell like roasted dog farts, but this was more of a burnt cotton candy & chocolate stink. Popped caps...but where? A few more sniffs brought me towards the channel modules I'd just done. Pulled them up, and found the culprits on one of 'em.

In my haste, I'd gotten two little 47uf polars backwards on the last channel I did last night. I always check my work when I finish a module, it's pretty easy because they're mostly all oriented the same way, so a quick scan easily reveals if "one of these things is not like the others"...except for these couple of oddball sideways ones.

D'oh! Oh well, 2 out of 2,900 ain't bad.

Here's what a couple of Panasonic FR series caps look like inside out...

As for catharsis, I cleaned up and replaced them in a few minutes and the session didn't get mussed. We flogged a live conga and blues harp overdub summed to one track, Peluso 22 251 tube mic on the conga in the live room and the harp through a bullet mic and a Twin Reverb to an SM57, API preamps then EQ'd and summed to tape with the console. Now there's a spot of good fun!

Sorry I haven't updated this thread in a while friends, been very busy indeed! I'll be posting soon about the re-cap process along with photos and a bit of video.

As of this writing, all I have left to do is one channel, a dozen fader packs, one on each VU meter buffer, and a handful in the automation system. Also need to do the audio PSU caps, but they're a bit pricey and I have some evil ideas there that will take some planning. Muhaa...muhahaha!

 

[Muckelroy]

fried resistors smell like roasted dog farts, but this was more of a burnt cotton candy & chocolate stink.

How does one roast a dog fart?

 

[briank]

Slow, dry heat

 

[sweetbeats]

Pressure cooker or crock pot with a rubber gasket on the lid helps to contain. The TRICK is getting the dog to fart INTO the cooker. It helps if the dog is a frequent farter. Fortunately we have an element of predictability with our dog since she loves eating fresh horse manure and then often gets diarrhea as a result along with some award winning and extended flatulance.

Yep.

Non-stop fun here.

Hey Brian, yah popped caps stink a very odd stink...and the odor LINNNNGERS. Its not like a cooked opamp or resistor...that tends to clear out eventually but it has taken MONTHS for the smell from that blown cap in my MM-1000 supply to clear and my oldest daughter says she can still smell it (she has been dubbed "Radar Nose"). And the mess gets EVERYWHERE! I found more residue recently when doing some cabling repair on the Ampex.

Thanks for sharing your foible. It reminds me that it can happen to anybody...your dedication to recapping that monster is admirable...that's...a lot...of caps.

 

[Esrb99]

Read through this entire thread, and registered just to respond! I'm looking at a JH 636 myself for our high school's new audio engineering program. We've been using an allen and heath saber, but with the MIDI mute system failing and it being a split design, we've been looking for an inline. A 636 popped up 90 minutes away, and it's so tempting! Would love to ask the OP some questions now that it's been a while...

 

[sweetbeats]

We’ll see if he responds, but it *has* been 9 years since the last post...

 

[ryebot]

636 Info

Hello,

For what it's worth, I've also scoured this fantastic thread many times, and wondered what happened with that board and Brian, as well as finding other internet sources regarding MCI 600 series; archives of the now defunct mcirecording.com and other lost sites in my search for knowledge. I have restored and still own a JH-618 and also own a JH-636 which I am in the process of restoring. I am quite familiar with them so perhaps I might be able to answer your questions? Many of the members here on this forum I've found are familiar with this era of tech and there are a lot of similarities even though designs are different.

Glad to give back some of what I've learned here and elsewhere on the inter webs, if possible!

Cheers,

ryebot

PS, there is also an MCI JH500 mixing desk fan club group on Facebook, many healthy brains are active there as well!

Read through this entire thread, and registered just to respond! I'm looking at a JH 636 myself for our high school's new audio engineering program. We've been using an allen and heath saber, but with the MIDI mute system failing and it being a split design, we've been looking for an inline. A 636 popped up 90 minutes away, and it's so tempting! Would love to ask the OP some questions now that it's been a while...

 

[Esrb99]

Thanks for the response!

We did end up getting the board; we stood it up on its legs, loaded up the channels and just ran some quick sounds from a mic'd up radio through channels 1-3 so far. Unfortunately I am on quarentine right now, so no access to the board, but would definitely appreciate a brain to bounce thoughts off of as we get her up and running!

We did have a channel that looked like it had a blow-up under the preamp card-heck, the trace was near charred off! I'll get better



photos as soon as I'm back in the classroom-in the meantime, here she is. We're only loading 24 channels right now, and got extra channel blanks coming to make a base for our keyboard and mouse. Plan to use Whirlwind AB-8s to toggle between tape and the Orion 32 AD/DA without using patch cables

 

[ryebot]

Cool! Good news!

That switcher looks like a great plan! I'd read some advice on an older forum suggesting using a DB25 data switch box to flip between tape and converters...

Be prepared for little burnouts here and there, and interesting aromas! Many of my modules have char marks from the past and have been repaired by myself or previous owners/techs and are still making beautiful sound.

I'll be on the lookout to keep this thread going!

-ryebot

Thanks for the response!

We did end up getting the board; we stood it up on its legs, loaded up the channels and just ran some quick sounds from a mic'd up radio through channels 1-3 so far. Unfortunately I am on quarentine right now, so no access to the board, but would definitely appreciate a brain to bounce thoughts off of as we get her up and running!

We did have a channel that looked like it had a blow-up under the preamp card-heck, the trace was near charred off! I'll get better

View attachment 106963

photos as soon as I'm back in the classroom-in the meantime, here she is. We're only loading 24 channels right now, and got extra channel blanks coming to make a base for our keyboard and mouse. Plan to use Whirlwind AB-8s to toggle between tape and the Orion 32 AD/DA without using patch cables

 

[janob75]

Hello everybody I have just acquired this fabulous console which will change a lot of things in my production process. I read this post last year thinking that if I bought an in/line console it would be this one. Already for the budget and then for the real function in / line. I was able to acquire with an apr-24 with the Dolby SR 24 tracks that goes with it. The almost perfect kit. I would have liked a jh-24 but the budget again and again. In short, the console is finally here. She made the vendée globe to reach me. She comes from the assortments in Spain. And bringing it in from abroad was hell for me. 2 months of travel. The blocker console has the entrance to Spain in all the shit that goes with it. But she's finally here

 

[janob75]

I will go into full maintenance for this beautiful lady. Redo everything. I have it for a while. Fortunately I am helped by a high-flying technician. Who works at the Joinville auditorium and at the FEMIS in PARIS. An old friend who maintained SSL 4000E
in studios when I was freelancing. He knows them well.

 

[janob75]

It seems that here several people went through this hell for the best sound. So if I could discuss this experience, I would be more than reassured.

 

[janob75]

Fear in my stomach, I go into maintenance next month now that I have the house to welcome him. Good for you all sound friends.

 

[janob75]

I will continue this fabulous post from @briank (photos and progress of the maintenance that I will start.) which made me dream and which is somewhere at the origin of my purchase for this prestigious console. Given the number of albums made in this format.

 

[janob75]

D'autre photos, je suis tellement heureux: in frensh@the texte

 

[janob75]

 

[janob75]

 

[janob75]

 

[janob75]