Finding an obscure part for the Hakko 936b (NEC uPC1701)

[crispytato]

Hi there, I've been looking into building up a Hakko 936b based on the original design found online, using the original Hakko PCB, because my atten clone has bit the dust, and I was hoping to get slightly better performance out of it since it was running a weird semi-clone board that I wasn't all too impressed with. I've hit a stumbling block in my quest though, as the design requires a specific triac driver, and it's looking like it'll be a real pain to source locally.

The part number is uPC1701 (and its made by NEC). The only datasheet I could find was here, and it's in Japanese unfortunately.

I was wondering if anyone could recommend an alternative that's available on one of the major component suppliers that ship to NZ quickly (Digikey, RS, Element, Mouser, are all good, RS is best). Maybe even if this part is available under a different designation! I've had no luck finding more info on it, I'd appreciate anything about it that anyone could elaborate on. a datasheet would be great! anything else that you know about the part that might lead me in the right direction would be sweet as! They're apparently sold on Ebay, but the price is high for a single dip-8, and I'm very cautious of hard-to-find older parts showing up on Ebay, as I've had fakes while getting replacement mosfets/other obscure parts for repairing old gear.

Many thanks in advance! I hope someone can help me find some useful info.

chris

[dannyf]

it is the controller - the block diagram should give you some sense as to how it works.

Otherwise, replacing it with a mcu is completely doable, particularly a 8pdip one - I did it with a 12F675.

[amyk]

It's a zero-crossing detection circuit.
English datasheet: http://cdn.sonigate.com/product_pdfs/UPC1701C.pdf

All the clones perform an equivalent function using a '324 or similar comparator.

[dannyf]

Yeah. The simplest form here is to compare the reading from the temperature sensor vs. desired setting and then turn on / off the element.

Easily done with a mcu.

[flolic]

I bought it on ebay for a few bucks and it works just fine. IMHO not worth the trouble wasting time searching for alternative...

[dannyf]

It is actually a fairly simple exercise to design a minimalist circuit that can take both / either A1321 and/or A1322 elements. T12 is a little bit harder to deal with circuit wise.

I built a few that runs off a laptop supply and consists of just a few parts in addition to a mcu. It can be built to also drive a LCD with temperature read out.

[wraper]

Putting hakko board into atten will not make it better. Using original hakko heater and tips on atten would make the difference.

[crispytato]

It's a zero-crossing detection circuit.
English datasheet: http://cdn.sonigate.com/product_pdfs/UPC1701C.pdf

All the clones perform an equivalent function using a '324 or similar comparator.

This is perfect! Thank you!

as for people saying that there's no point doing this mod, I intend to buy a proper Hakko iron with the ceramic heating element (that's supposed to heat up much faster/have better thermal capacity), and replace much of the insides. The case and transformer I will keep the same as it saves me buying all new parts, and I'm a poor student

Before I attempt this, I'm going to make further attempts to revive the current circuit, I fried a couple of components (triac, some diodes, lm358 and a couple others) but the replacements that I've used haven't got it working properly. It just sits at full-on all the time now.

Thanks for all the advice given in here, I'll update once I sort out a solution

I think I might just go for a new ic on ebay, and wait out the china-shipping, since I've got a little faith that I'll get a genuine part now. Might try getting one from 2 different vendors, just to hedge my bets (and have a replacement  )

[dannyf]

There actually are people who integrate a mcu-based controller into a laptop power supply, with digital read-out, to drive Hakko handles, all for less than $20.

[beatgr]

Consider using ON Semiconductor UAA2016
Zero Voltage Switch Power Controller
http://www.mouser.com/ds/2/308/UAA2016-D-117189.pdf

The UAA2016 is designed to drive triacs with the Zero Voltage technique which allows RFI free power regulation of resistive loads. Operating directly on the AC power line, its main application is the precision regulation of electrical heating systems such as panel heaters or irons.

Mouser stocks this part.  $1.51 USD
https://www.mouser.com/ProductDetail/ON-Semiconductor/UAA2016PG/?qs=sGAEpiMZZMuzIDJVHEkzuafJYKfGjFR%2fgp3Ngkx6VJA%3d

[Chris56000]

Hi!

Just a quick PS to the above, I've compared the two devices, and it looks like the UAA2016 will drop into a circuit originally designed for the uPC1701 - altho' a comparison of the NEC and ONSemi data suggests the power supply is reversed on the UAA2016 device, this is not so as NEC give voltages as negative on pin 5 with respect to pin 7!

Altho' it looks like NEC have dropped spiders in toner and let 'em scuttle over the paper, I've attached an English uPC1701C sheet to this note in case nobody can find it again!

Chris Williams

[floobydust]

Both IC's operate from a -ve voltage rail in order to provide gate current to the triac.
So Vcc is 0V and VEE is -9V. You would need the same -ve rail when using an MCU with triacs.
It gets pretty confusing.

[KL27x]

as for people saying that there's no point doing this mod, I intend to buy a proper Hakko iron with the ceramic heating element (that's supposed to heat up much faster/have better thermal capacity), and replace much of the insides. The case and transformer I will keep the same as it saves me buying all new parts, and I'm a poor student

The only way to get a genuine Hakko iron is to spend like $70.00. So after you buy your "genuine" hakko iron for $15.00 on ebay/alibaba, shipped from China or Hong Kong, be sure to at least buy the genuine heater from Hakko. Also, notice that the materials in the iron are part of the equation. The hakko plastic has low thermal conductivity and high heat resistance, so more of the power is getting to the tip rather than leaking away to the environment.

Another area to check is the transformer/psu. A genuine hakko 888 sags about 0.01V under load. And that's at a nominal 26V, not 24V.

I agree with others that the circuitry in these 936/888 Hakko stations is completely unremarkable. There's nowhere much for a clone station to cheap out on. Well, except for horrendous sharing of LED resistors in the ones with 7 segment displays. I don't think you're going to improve your performance via the control board. But it is a fun project if you got the time.