Does anyone knows about these machine ?
The speed of my machine is not acurate it's always going up down and I notice that I can stop the capstan with my finger when it's in play mode and also the tachmeter doesn't work most of the time. I think both parts has the same electronic cards I don't have the manual with me right now.
The machine as been used for a movie back in the 80s and that was it. I'm the second owner and when I bought it everything has been clean up and looked over to make sure that nothing was wrong and it worked for a month but then it broke up and now everything sounds like somebody has put some acid in my coffee.

Any help or theory about it would be appreciated

99% of the problems you'll have with these machines are related to the molex connectors used to connect all the boards to the mother board. If you lift the deck up and look to the right you will see a board with three LEDs on it. This is the Phase Lock Loop board. Pull it off and carefully put it back on being certain that you don't cross any of the molex pins. See if that corrects your speed problem. There are several tachs in the machine, one for each reel motor and one in the capstan motor. Also there is one for the tape counter. Which one isn't working?

CA

"If you lift the deck up and look to the right you will see a board with three LEDs on it. This is the Phase Lock Loop board. Pull it off and carefully put it back on being certain that you don't cross any of the molex pins."

i use deoxit and a tooth brush on my MCI...clean every point that a connection exist, and try reseating all ic's...cleaning the ic sockets with deoxit is also a good idea...a good site on the web: http://www.analogrules.com/index.html
www.atrservice.com

good luck!

p.s.
the capstan maybe pooped out,
http://www.precisionmotorworks.com/
find a service manual, see it's trouble shooting sheet and be persistent.

I realized that something in the power suply on the regulator access pannel the bottom right LM 320 is always cold and the three other are a bit hot so yeah I'm not an expert in electronics but I'm trying to learn I made a bit of repair before when someone told me solder this or that but I never troubleshooted something yet. If You guys can give me more clues I'd really appreciate 'cause I'm going to bring it to a real technician but I'm probably going to do all the soldering and repair myself even though he's going to do the diagnostic and i'd like to understand what I'm doing because I live in montreal and most of the guys that knows about tape machine are working for the CBC and they don't give a fuck about poor indie studio and this tech that I know is really busy doing the job for every other music lover studio so if I can spare him some time by having some more ideas it be realy nice.
I know it's not the tape tension
it's the the idle setting or the offsetnull it has nothing to do with the analog torque board and the phase lockloop bd is fine too
could it be something in that board that inside the capstan motor ????
Anyway if these info gives you any idea please let me know
and I really appreciate what you said already

Thanks a lot

and sorry for my french canadian spelling mistake !!!!!!!!

also thanks hiredgeek for letting me know that someone is doing tape again or will do it.
You know I grew up with digital my parents didn't really have a sound system at home and I only had a cd player but when I heard vinyl later I've got a life time booooooner !!!!!! No women ever made that much horny or felt that way (ok maybe I'm pushing it too far but.... close to it!!)

It could be a dead photocell inside the capstan motor. There are 2. You can look at the signals with an o-scope. They reside in the bottom part of the motor.

When you're in PLAY, and press TVI, what does the display read?

Are you absolutely certain your Phase Lock is OK? Does the machine work in all speeds? Does Vari-Speed work? How is the pinch roller pressure? Just some other areas to check. There is a pot on the PLL, which adjusts a duty cycle. The manual says 70%-30%. You will need an O-scope for this one as well. If you got one, adjust it for 60%-40%. The details are in the manual. I don't mess with these machines much anymore, but I worked in the service dept at MCI for 10 years. I've forgotten more than I remember, but I hope this helps.

CA

This could be way off base, and my experience is with the JH-114 transport but...

If the brake solenoid doesn't pick up, you'll get the kind of odd speed response you describe. On something like the JH-16, when you block the tape sensor, you should hear a prominent "click" as the brake solenoid picks up and releases the brakes. No "click" means the brakes are dragging and your speed control gets all kind of crazy. I had this happen to me.

I know we're talking about a JH-110 here, but there's likely some similarities that are at least worth checking out...

Different brake assemblies than the JH110, but the idea is valid. The 114 deck had one solenoid for both brakes and the 110 had separate ones. He'd be noticing some real sluggish wind speeds as well if it were the brakes.

The whole capstan system can be described easily. You need the both capstan tach photocells to be working. The reference frequency in the Phase Lock board needs to be correct. These two signals are compared and an error signal is generated which corrects the speed of the capstan. There is a network of gates and dividers in the PLL board which supply the correct reference frequencies for the motor at the various tape speeds. If an IC in the PLL is flakey, it could be sending 2 frequencies at the same time. This will confuse the motor and result in the problem described. Also there are gates which control whether the crystal or the VCO (vari-speed) supply the reference. The proper reference is 19.2kHz for 30ips. It is divided in half for 15ips and again for 7.5ips.

There are also a pair of 2N3055's on the back of the deck which power the capstan motor. I very rarely see these fail, so my guess is the capstan tach or PLL board. Certainly don't rule out bad molex connections or fractured solder on the male molex pins on the motherboard.


A note on molex connectors. Spraying them is not enough to fix them in the long term. You have 2 options. One is to replace the pins inside the connector. The other is to remove the connectors, remove the pins from the housings, clean them with a pencil eraser and "re-spring" or stretch them out so they exsert enough pressure on the male pins on the motherboard.
In my experience, 99% of failed Molexes are a result of insufficient contact pressure which results from inserting and removing the boards numerous times. The oxidation of the metal is only part of the equation.

Some more thoughts: Do you see any abnormal movement on the dancer arm? I've heard "chirps" in the audio when the reel motor tachs were intermittent. If the dancer arm is stable, then the problem probably resides in the capstan loop. If not it may be a tension problem. Have you checked the PLL duty cycle adjustment in the manual?

CA

Tanks for all yr advice now I got my manual back home and I started to dismount one of these mci jh 110a that I found in the garbage with the manual acouple of month ago (no shit!!!!) it was standing across the street in front of my appartment in a pile of dirty furniture and a shitload of discusting black bag that smelled like dead bodies but i guess that some of the parts will be usefull for fixing my 8tk because it is the same model.
Now I know what parts I should bring to the tech so that we can make some test
Thanks a lot again and I'll give more news about the repair in 1-2 week

So now the machine is at the Pine studio in mtl and me Craig form there started to checkout PLL board to night
you were right there was something wrong with it
the gain pot was not high enough so I cranked it up and we played a 10khz
At the playback the variation in frequencies were going from 9.99 khz to 10.01 khz but pretty much stable at 10 khz so it's a good news. I also had a problem with the tape sensor but then again it was juste a pot. So we are not done yet but tommorow night we're going to readjuste the tension, the capstan voltage and make sure that the reference frequency for the speed is the good one.
All that to ask if someone has a 1 inche tone tape for sale
I know it's a bad idea to use an old tape but i'm think that if anyone of you has one you probably stored it properly
I'm broke !!!!

Alright more late news tommorow

( I still make mistake but the spellcheck is too slow my old school internet )