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AN640 IC for Technics DD TT unobtainium

Arkless Electronics

Arkless Electronics

Trade: Amp design and repairs.
Yesterday I decided to bite the bullet and do something about fixing my Technics SL-150 MkII TT which has had a speed stability fault for, well, all the time I've had it... (I paid £50 for it with an SME 3009 S3 fitted!) but for a few years switching it on and off a few time would cure it for months at a go... It eventually became faulty no matter what you do. I had it on the bench in about 1999 and worked out it was almost certainly the AN640 motor drive IC but a googleing on the matter has shown them to be no longer available.
I could only find one advertiser that both listed it AND claimed to have it in stock but it is in Mexico and they want $378 for one! I would baulk at £37.80!

It is looking like this lovely DD deck is skip material and all for the sake of one IC.

I'm clutching at straws here really but just wondering if anyone has such a part available or knows any get around, such as a motor drive from another Technics model that is an equivalent? The same part is used on the MkII versions of SL-1300, 1400, 1500, 151 SL15 etc but not the SL1200.

If I had sufficient info I would design a board to carry out the functions of the IC but I can't get any information on it. No datasheet available and not enough info in the service manual.
 
The SP10Mk2 has a discrete version of the same circuit in it, but it has a lot of transistors. Do you know which area has failed? Because if (unlikely I guess) the 50kHz generator is dead that would be easily substituted.

(That IC and associated circuitry essentially gives the motor DC control. That DC is generated by a PLL in the speed control using a signal from the platter and the reference clock. There are complications like braking by running the motor 'backwards' until the platter stops. Not stuff necessary to the average user. You obviously know all this.)

If you decide to scrap it I'll pay for shipping.
 
Paul R said:
The SP10Mk2 has a discrete version of the same circuit in it, but it has a lot of transistors. Do you know which area has failed? Because if (unlikely I guess) the 50kHz generator is dead that would be easily substituted.

(That IC and associated circuitry essentially gives the motor DC control. That DC is generated by a PLL in the speed control using a signal from the platter and the reference clock. There are complications like braking by running the motor 'backwards' until the platter stops. Not stuff necessary to the average user. You obviously know all this.)

If you decide to scrap it I'll pay for shipping.
Click to expand...

Yeah I know all that and it's not the 50KHz generator. Symptoms are a flutter at, I'll guesstimate, 5Hz ish which is both audible and you see the strobe markings jumping backwards and forwards at the same rate. It either does this or works perfectly, nothing in between. Switching between "Start" and "Stop" a few times and/or from 33 to 45 used to get it going OK and it could then work fine for as long as a few months or as short as an hour or so...

I'll have to look up the SP10Mk2 circuitry...
 
How different is the motor to that in the 1200? I wonder if you could botch-in the complete electronics from one of those in an external box with a bit of tweaking/fine-tuning? If it has the same number of poles or whatever it might just be feasible and I’d expect 1200 MkII boards to be widely available for peanuts given how many battered ex-DJ decks get asset-stripped.
 
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337alant said:
Maybe some of these will be OK
https://www.saec-mshop.com/product.php~idx~~~882~~AN640+IC~.html
Says Russian Equivalent
http://rover.ebay.com/rover/1/711-5...0001&campid=5338728743&icep_item=183758995363

https://www.aliexpress.com/item/Ady-ic-5PCS-LOT-AN640-DIP/32769533980.html
http://www.globalmarket.com/product...40-am29f002nbb-90jc-ic-in-stock-11215455.html
Click to expand...

Thanks Alan.
The first one could be a possible but I can't seriously believe that there was a Russian made equivalent to the part...
3rd one down is "no longer available" and the last is a completely different SMD part.
 
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Tony L said:
How different is the motor to that in the 1200? I wonder if you could botch-in the complete electronics from one of those in an external box with a bit of tweaking/fine-tuning? If it has the same number of poles or whatever it might just be feasible and I’d expect 1200 MkII boards to be widely available for peanuts given how many battered ex-DJ decks get asset-stripped.
Click to expand...

It's just about a possible yes and had occurred to me...
 
For $US 15.40 shipping inclusive BIN price, I'd be tempted to try the Russian knock-off.

Seller has a 30-day return policy, and 99.7%/1882 eBay rating.
 
Craig B said:
For $US 15.40 shipping inclusive BIN price, I'd be tempted to try the Russian knock-off.

Seller has a 30-day return policy, and 99.7%/1882 eBay rating.
Click to expand...

I just can't believe that there would be such a demand for Technics DD TT's in Soviet era Russai for them to be making OEM generic copies of a specific motor drive IC!
 
Arkless Electronics said:
I just can't believe that there would be such a demand for Technics DD TT's in Soviet era Russai for them to be making OEM generic copies of a specific motor drive IC!
Click to expand...

USSR-era Russia made countless close copies/reverse-engineered clones of many, many things, so it wouldn’t surprise me if there wasn’t a direct drive turntable or two for the party elites! As a somewhat bizarre example they successfully reverse-engineered and built Sinclair ZX Spectrum computer clones in all manner of odd guises, compatible to the extent they’d actually run Spectrum software. I bet the clone Technics chip is what it says it is! If they could clone a Spectrum ULA something like that is child’s play!
 
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