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ADC Accutrac 4000, looking for manuals

C

ChrisW6ATV

Pack Rat
Hi all-

I just picked up an ADC Accutrac 4000 today, and I remember when these came out, it was the coolest thing in record players.

My Accutrac has these basic problems:
-It does not respond to any of the control buttons (other than the speed buttons; 33 and 45 RPM both work fine).
-Its tone arm moves freely, but the cueing lever/platform is stuck too high to play records.

My first steps will be to replace the tone arm belt and check/replace the electrolytic and tantalum capacitors, and I appreciate any other basic suggestions as well.

I am a highly experienced technician with many types of electronic and electro-mechanical systems, so I have no hesitation to learn and do whatever it takes to get this machine working properly. I see that Vinyl Engine has all of the manuals for these, but they are not accepting new members. (I am a member of Hi-Fi Engine, but that is separate.) Do any of you have copies of the manuals you can share with me, or sources for them? I appreciate your help!

Chris
 
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Thank you, Jeff! I sent you a PM.

I removed the bottom cover and removed the half-rotted belt for replacement, and I also saw that a part has been cut off the circuit board. (The missing part was to the left of the gap between the two ICs.) From another picture of the board I see it was probably a 1/2-watt resistor, I will confirm when I have the manual. This turntable starts spinning as soon as the power is turned on, I suspect that is not normal. Perhaps the bad belt or lubrication problems caused trouble in the logic of the operation and that was a "quick and dirty" way to make the table usable in purely manual mode. At least some of the control system still works since I can change the speed properly.PXL_20240928_183923977small.jpg
 
I don't really know what the problem is on your turntable but here's something easy to try: With the turntable off, move the tonearm in slightly, until it's just barely resting on the edge of tonearm rest without it falling off. Turn on the turntable on and see if it the platter still spins.
 
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Hi, rrres-

I did try that, and also with the arm in other positions, and the platter still spins as soon as I turn the power on. Right now, the belt is not installed, and with the resistor removed that I mentioned above, I think I need to fix those items and start testing other parts and controls next. Thank you for your suggestion.
 
Hi all-

I finally had a chance to start working on this turntable again. First, I found other pictures of the circuit board online, and the removed resistor was also missing from several of those boards too. It is R18, 4.7 megohms. Perhaps it was a production change after some boards were built (mine definitely had the part at one time), or removed from USA models versus UK/European ones?

Now for the good news: I bought a new belt/o-ring, and I checked the cueing platform issue. I turned the idler that the belt goes around; it seemed a bit sticky at first but then turned freely. I found that it raises and lowers the tone arm when turned, so I turned it end-to-end a few times and left it at the "low" end before installing the belt. I reinstalled the platter and put on a 12-inch record, and turned the power on. The first thing I noticed is that the platter did not spin immediately as it had before. So I pressed "all" and "play", and it started turning and moved the arm to the record's beginning and started playing the record, good so far. In further basic tests and an adjustment of the sensor control, I could press "2" and it played the second track, and "reject" returns the arm to the resting post (but about 4-6mm from its cradle point, "almost falling off the end" toward the record) and stops the turntable.

I am massively excited! Based on my tests, this machine is about 95 percent functional already, it seems. I will do things such as lubricating the controls and testing all buttons and functions, and properly setting up the tracking force and anti-skate. I will also check the tone arm landing position to see if it is normal or can/should be adjusted. I also want to get a good look at the stylus to check its condition, and of course play some records to see how this turntable sounds! :) Do any of you recommend pre-emptive cleaning/re-lubrication of the tone arm control assembly or other tasks? Thank you for any further advice or comments.
 
Cool! It really is fun to see these working.

I occasionally do random track numbers just to see the tonearm move back and forth and play the tracks in the order I've inputted...though I've noticed and have to admit that there are occasional hiccups, especially with newer records. I'm ok with it. Since these were released in the mid 70's, I've noticed the sensing really works well with records from around that era or earlier.

There is lubrication instructions in the service manual. There is also a section that talks about adjusting the relationship between tonearm and timing/braking wheel.

Please post when you get the landing position corrected. I have one that is landing slightly short of the tonearm rest...and if I manually force it to land at the correct position, the timing wheel goes out-of-whack and the platter spins continuously. Since it's working well (aside from the tonearm landing short of the rest) I'm afraid to continue tinkering with it and possibly causing more problems.
 
Thank you for your notes, rrres. I did read through some of the adjustment and test information in the service manual. No item that I found seemed to refer to "tone arm rest landing position", but one or more adjustments explicitly mention putting the tone arm "at the edge of the rest", which is about where mine lands, so maybe mine is normal. I do see mention of a limit switch associated with the timing wheel; maybe that is related to the arm landing position.

I will go through a cleaning and full test procedure here before deciding if I have any true problems, and I will post an update.
 
I hope that helps your turntable to last many years of good use. I have not learned enough about these machines to know if excessive internal heat is the main cause of failure of either of the ICs in the Accutrac turntables. But, it certainly cannot hurt. :)
 
rrres, I am also fascinated to see that your controller board has a pair of resistors physically paralleled. (They are just above the point between the two ICs, in your picture.) If you saw my other posts(s), I mentioned a removed resistor on my controller board. The paralleled set on your board is in the same area. I am now thinking that these turntables had more "production changes" or "on-the-fly modifications" (both meaning the same thing :) ) than is commonly mentioned or discussed.
 
Yes, since your original post was about possible missing components, I did notice the differences in your turntable's control board and mine. Are you familiar with the Heathkit version of this turntable?
 
I know that the Heathkit exists, and also that its description said "no soldering required" if I remember right, such that must have included a pre-assembled board. I do not know any other details of it.
 
Following along. I just fire up my Accutrac 4000. And it seems to be working.
Sound is not great. I think I may need a cartridge.IMG_6085.jpeg
 
Kasanay said:
Following along. I just fire up my Accutrac 4000. And it seems to be working.
Sound is not great. I think I may need a cartridge.View attachment 3379528
Click to expand...
If you just need a new stylus, then some online stores have replacement styli. Pricey in my opinion but there's no other choice...I don't think...I rely on ebay for spares and parts.
 
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