MCI JH110

Beneficial · Post by **Beneficial** » Mon Nov 19, 2007 1:10 pm

I bought an mci jh110c off of ebay... delivered for $300 total. It worked but needed to be calibrated and it would rewind really fast and stop really slow etc. Got a tech to come out to go over it... he laid on his back under the machine for 7 hours (didn't realize it opened up top) and by the time he was done it no longer worked. He didn't charge me but I was stuck with a non working deck. I opened up the top and cleaned all of the molex connectors. That got everything running well but I still wanted it professionally gone over. Had another tech come out... he went through everything fixing small problems here and there... resoldered a couple of the things.. got the tension right and started on the repro calibration. Then the levels dropped drastically and now I just get crazy loud white noise when cranking up the repro gain on both channels as well as one channel when the cue button is pushed in. We had to call it a day at that point. Now I owe the tech $800 for his work but the deck isn't usable. I'm going to have to call him back for some more work at $75/hour to try to track down this (hopefully final) problem. I had this same problem about 7 months ago but it went away on it's own... now it's not going away. Since it's affecting both repro channels I'm assuming it has to be something with the circuitry leading to the heads (maybe more connectors that need to be resoldered). I'd really appreciate any suggestions because this is getting to be really expensive.

airloom · Post by **airloom** » Mon Nov 19, 2007 2:56 pm

Anyone have a pdf of the manual?
That'd help a hell of a lot.
Maybe I'll start a blog about how my buddy and I are restoring this deck and a soundcraft 200B desk.
It'd make the ladies scream.

sonicmook56 · Post by **sonicmook56** » Mon Nov 19, 2007 7:14 pm

First off, you have to replace the red chip sockets if it has them installed. Also check the pins of the DIP packages for any corossion. Mine were coverd with black stuff and I had to scrape it off with a greenie. If you don't do this, forget about having a reliable machine. Mine did crazy things out of the blue.

When I borrowed the manual from a pal, I made a PDF scan of chapters 7 and 8, Maintance and troubleshooting.
Check here
My server is painfully slow, so you might want to download it at night time and it should be done in the morning.

Jim Williams
Posted: Sun 18.11.07, 10:42 am Post subject: Re: MCI JH110
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

I'll have to try that. I've had a bottle of that stuff kicking around the back of the shop for a few years now and never used it. Does it ever harden, or evaporate?[/quote]

brianroth · Post by **brianroth** » Tue Nov 20, 2007 12:44 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.

That assumes that the "wave soldered" pin problems were already solved! <g>

Of course, by now, I guess that is an Ancient History issue....

Bri

brianroth · Post by **brianroth** » Tue Nov 20, 2007 12:54 am

Beneficial

I was gonna say somthing about the techs involved, but I won't...since I wasn't there, and I always assume the best about everyone (but hmmmm...flipping the transport "up" is a commonly known thing...oh well).

If several things all went "goofy" in the same way at the same time, look for a commonality, such as the power supply, which in case no one realizes, is at the bottom of the "pedestal" which holds the deck. Measure the DC voltages inside of the audio drawer(s).

Bri

airloom · Post by **airloom** » Tue Nov 20, 2007 6:49 am

sonicmook56 wrote:First off, you have to replace the red chip sockets if it has them installed. Also check the pins of the DIP packages for any corossion. Mine were coverd with black stuff and I had to scrape it off with a greenie. If you don't do this, forget about having a reliable machine. Mine did crazy things out of the blue.

When I borrowed the manual from a pal, I made a PDF scan of chapters 7 and 8, Maintance and troubleshooting.
Check here
My server is painfully slow, so you might want to download it at night time and it should be done in the morning.

Jim Williams
Posted: Sun 18.11.07, 10:42 am Post subject: Re: MCI JH110
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
I'll have to try that. I've had a bottle of that stuff kicking around the back of the shop for a few years now and never used it. Does it ever harden, or evaporate?

[/quote]

Thanks for the scans!

airloom · Post by **airloom** » Thu Nov 22, 2007 3:42 pm

Ok, I'm about ready to deal with the molex sockets.
What's the best way to do it?
Pull them out, clean them and then re-solder them to the board?
Shit.
I wish I could find one of those logic annunciator boards.
That'd help me a lot.
Fill me in.

brianroth · Post by **brianroth** » Thu Nov 22, 2007 9:38 pm

airloom wrote:Ok, I'm about ready to deal with the molex sockets.
What's the best way to do it?
Pull them out, clean them and then re-solder them to the board?
Shit.
I wish I could find one of those logic annunciator boards.
That'd help me a lot.
Fill me in.

Just heat the Molex pins at the printed circuit board connection point and add a TINY amount of fresh solder to ensure the Molex pins are properly soldered to the board. The ONLY thing that completes the electrical connection is that small "cone" of solder.

Bri

dirtdog · Post by **dirtdog** » Thu Nov 22, 2007 11:41 pm

When replacing the red sockets is there a different socket type that should be used or should the chips be soldered directly to the board?

Jim Williams · Post by **Jim Williams** » Fri Nov 23, 2007 7:08 am

Use a good machine socket like Millimax or Amp. Get 'um from DigiKey or Mouser. Do not solder the IC to the pcb as that will likely end the ability to remove a defective one cleanly without pcb damage.

sonicmook56 · Post by **sonicmook56** » Sat Nov 24, 2007 2:51 pm

Ok, so now that I have replaced the red sockets, re soldered the molexes, replaced a few bad amps, cleaned relay sockets, cleaned more molex pins, re tensioned spring contacts, exc, I'm now just starting to get audio onto tape and back somewhat OK.

Problem is low frequencies are not at the same phase as higher frequencies on the repro head. In order to get low frequency phase closer (but not right) I have to adjust the azimuth all the way to the end of it's travel.

I think I have the stack visually aligned well enough.

If I record tones, it's off, and if I use my test tape, it's off too.

Everything is OK when monitoring off the cue.

Could the repro head be bad?

~B

ladewd · Post by **ladewd** » Sat Nov 24, 2007 4:53 pm

One channel of your heads may be wired out of phase. Do an experiment, get both channels 180 degrees out, put the scope in regular 2 channel view and press the invert switch on the scope on channel 2. Both channels should appear in phase at this point. Does it track all frequencies in phase then? More importantly, does the head look aligned at this point?

Remember I mentioned that if you torque that little head mounting screw too tight, it will distort the head? What this really does is screw up the phase relationship between channel 1 and channel 2. So that they never will track properly. Is this what you're observing?

It doesn't appear so from the description you gave. You CAN get it in phase when the azimuth is clearly tilted to the max on the repro head, correct?

Note: If you set the phase on the rec and repro head referencing the repro tape, then you'll always need to make minor adjustments to the heads when in record. Like I mentioned in a previous post, in that case adjust the rec head and use the repro head as your reference.

Another issue: on JH machines, the low freq adjust comes before the level control on the repro card. Excessive lo freq EQ will mess with your phase at lo freqs (as well as making it difficult to align levels and frequencies correctly). Before starting any repro alignment on a previously unaligned JH machine, always turn the low freq pots down all the way and then count 5 to 6 revolutions in the clockwise direction to set the pot close to the middle of its travel. (They're 18 turn pots).

Ensure you aligned phase at 1K before looking at the high freqs. After that gradually go up th freqs and tweak a bit at each frequency. If you get 1k and 10k in phase, the low freqs should be fine. If not, you may have an electronic problem somewhere.

Cary

airloom · Post by **airloom** » Sat Dec 08, 2007 4:00 pm

For those of you with the manual for this, I have a question about a replacement IC.
They're on the Analog Torque board
They're ICs # 3 + 7
They say 532 above them
I'm wondering if the acceptable replacement is the Analog Devices 532 Internally Trimmed Circuit Multiplier:

www.analog.com/productSelection/pdf/AD532_c.pdf

I just can't find anything stating that they are for sure the correct part.
Thanks.

ladewd · Post by **ladewd** » Sun Dec 09, 2007 10:45 am

AD532 is what you're looking for (analog multiplier). You found the spec sheet, and I hope you're able to find the devices. BTW, I've never seen one fail, but stranger things have happened. I would imagine not plugging in the Analog Torque Board properly would result in the possible incineration of these chips. I've fixed dozens of these boards which were cross-plugged onto the motherboard and still never had one fail.

They were not cheap IC's. We used to pay close to a $100 a piece for them and we bought in quantitiy (and that was while they were still being manufactured on a regular basis). IMHO, I'd suspect anything else on the board other than those chips, unless it appears that it burned up (or is missing?). That's an awful lot of money to spend to shotgun a problem. Good luck with it. Maybe, since they're not in great demand anymore, you can get a pair significantly cheaper. I believe the "J" suffix part was used in the JH110.

Cary

airloom · Post by **airloom** » Sun Dec 09, 2007 12:08 pm

We're just replacing all of the ICs that came out of the red sockets because we can't seem to clean them. They're pretty nasty.
Ugh.
What a pain.
Who invented those damn red sockets.

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MCI JH110

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