Unobtanium IC for JVC DD-9

[scan80269]

I have struck out three times trying to acquire an Oki MSL9348RS quartz lock motor control IC to repair my DD-9. I placed orders with Encompassparts, Andrews Electronics and Union Electronic Distributors for this part, and each time, the response came back as "no longer available".

Without the quartz lock, the unit plays about 1.5% fast, and the "Quartz Lock" indicator in the counter display is never lit.

Unless someone can help me locate this part, I will have to resort to cannibalizing from a DD-9 or DD-7 parts deck, that is, if I can even find one.

[Pacific Stereo]

Shoot. I have a 9350, but not a 9348.

How can you be sure that the IC is defective?

[jdurbin1]

Well, if you are in the San Diego area and want to sort thru 5 large boxes of NOS JVC IC's... might get lucky *reelspin*

John

[scan80269]

Shoot. I have a 9350, but not a 9348.

How can you be sure that the IC is defective?

I swapped 9348 ICs between my DD-9 and my brother's DD-9, and the problem went over to the other unit.

[Pacific Stereo]

Good enough for me.

[Nakdoc]

I did some research. The IC is the oscillator, divider, phase comparator, and quartz lock led driver for the motor. If the speed is steady at 1.5% fast, then it is the divider section that is not working properly. By doing some measuring and math, changing the crystal frequency might get you back in business. The service manuals do not give the crystal frequency or the ultimate divided-down frequency. What are your service skills? Are you able to measure frequencies with a meter or 'scope?

The whole motor is part # MC951BS, which is nla. When you could get it it was $202. It has a 240 pole rotor and looks like a heck of a nice motor.

[scan80269]

Thanks for the good information, Nakdoc!

The crystal frequency is 5.0496MHz. I currently don't have access to a scope, but checking with my Fluke 289 multimeter showed no waveform output at IC pin 13. The frequency on pin 9 is about 625Hz which jibes with the 1.6ms period square wave indicated in the schematic.

Before I attempt to change the crystal frequency to correct the speed, I'll need a more accurate speed measurement. I previously used a 3KHz W&F tape to get a quick estimate of the speed error, and I'll probably use a 10KHz azimuth tape for a more precise reading. I also did not check for speed difference between beginning and end of tape.

Do you have the datasheet for MSL9348RS? I've had no luck locating this either.

[Nakdoc]

Use the 3kHz tape. Speed is modulated by wow and flutter, so 10kHz would never "settle down" . A proper W&F meter has weighting that makes adjustment a bit easier. No spec sheet so far. It would be nice to find out how the chip is dividing the clock. I checked and Sony did not use this IC. I have a few more references to research.

[Pacific Stereo]

If it's just a matter of 1.5%, you might be able to "bend" that crystal by loading it with some capacitance.

[A.N.T.]

If it's just a matter of 1.5%, you might be able to "bend" that crystal by loading it with some capacitance.

That is impossible - the maximum frequency change for a crystal oscillator by external components is well below 1000 ppm, or 0.1%.

Alex

[Pacific Stereo]

You're correct, I don't know what I was (not) thinking. Waiter, more coffee!! Now that I actually think about it, you are of course correct. In addition to it not working, the divide-down will make any error at the xtal smaller, so that fundamental is going to have to be changed significantly.

[Web Police]

Are there any other JVC DD decks that would have used this part? *scratchchin* JVC Made quite a few different DD Decks in the 80's

[Skywavebe]

I did a web search for that part number and a few places still came up with availability. If when you check the regular places and they are out then it is time to check the old equipment vendors to see what they can come up with. Kind of like finding a LED display for a Studer PR99. They can be found if you look far enough.

[Web Police]

I have a thrift store JVC DD-VR77 here. I don't know if this used a similar IC or not.

[390FE]

Could either of these be used to fix his problem? Either build an adapter circuit to be able to use the Toshiba PLL Motor Controler IC (see attached pic) OR modify the motor controler kit (see attached pic) to work for his application?

From what I can see it looks like that Toshiba PLL Motor Control IC has some of the functions that the faulty IC that needs to be replace has & may be able to be put into a small adapter circuit to replace the NLA JVC part.

Anyone have any thoughts on this?

[Skywavebe]

These items in the last post are certainly not for the repair of such an expensive Direct drive motor. The last item is a hobby kit item that would control a standard DC motor. The first item the Toshiba IC would need to be compared to the original IC to see what the difference are. Somehow I think if a replacement was that easy that someone would have already brought it up as a direct replacement. I can not really say without some technical data.

[Skywavebe]

I have found the S/M for the unit and it looks like the DD motor control is nicely diagrammed in the figure 36 on page 28. Have you guys looked at that as a solution. I would try a different crystal and see what happens.

[scan80269]

I did a web search for that part number and a few places still came up with availability. If when you check the regular places and they are out then it is time to check the old equipment vendors to see what they can come up with. Kind of like finding a LED display for a Studer PR99. They can be found if you look far enough.

Hi Sam, would you mind pointing me to a site that still has the MSL9348RS chip available? Between two DD-9 decks I have only one good chip, so looking for a source to replace the defective chip.

Many thanks and Happy New Year!

[Skywavebe]

I am doing the same thing you should be doing which is an exhaustive search and some of the replies have been negative already.