Hakko 808 too hot!

[4tified]

Recently replaced my Hakko 808 heating element and wasn't paying attention to what I was doing.... shorted the leads coming from the heating element, which in turn blew a resistor. Based on the color bands, I replaced it with an equivalent 1ohm, 2 Watt Resistor with 5% tolerance. (Brown, Black, Gold, Gold). Problem is now, the Hakko desoldering tip glows red after it has heated up, indicating that the temperature is way too high. Turned down voltage as far as it would go and decresed the calibration pot as well, but to no avail.

Is is possible that the because the resistor is 2 watts versus 1 watt that too much power is going to the heating element or could having the resistor in backwards be an issue? The voltage adjuster is nothing but a potentiameter, so is it possible that the resistor blowing could have harmed that component? No other components look damaged.

Thanks for the help guys!

[Krankshaft]

Re: Hakko 808 too hot!

You installed the wrong value resistor the resistance is wrong. It's very easy when a resistor gets charred for the color bands to be misinterpreted.

Resistor wattage has nothing to do with your issue. Resistor wattage is like cap voltage as long as it's equal or higher than the original value you're fine. If wattage is too low the resistor will overheat and self destruct that's all.

[4tified]

Re: Hakko 808 too hot!

You installed the wrong value resistor the resistance is wrong. It's very easy when a resistor gets charred for the color bands to be misinterpreted.

Resistor wattage has nothing to do with your issue. Resistor wattage is like cap voltage as long as it's equal or higher than the original value you're fine. If wattage is too low the resistor will overheat and self destruct that's all.

I could've sworn I had the right one!

Do you reckon the 1ohm resistor is too high or too low? I had a feeling the wattage didn't matter, but I just needed to verify.

[stj]

Re: Hakko 808 too hot!

got a foto of the old one?

btw, all the irons i'v seen with a ballast resistor use 5w ceramic box type ones - 2w seems a bit low to me.
i can imagine a 2w one getting hot enough to desolder itself!

[4tified]

Re: Hakko 808 too hot!

got a foto of the old one?

btw, all the irons i'v seen with a ballast resistor use 5w ceramic box type ones - 2w seems a bit low to me.
i can imagine a 2w one getting hot enough to desolder itself!

Unfortunately I don't have the old resistor nor a picture of it. I do know that the resistor is replaced was no more than 2 watts (based on the size and shape), but I am not 100% sure of the resistance. There are no schematics of the 808 that I know of, I've looked everywhere. The two things I know of are the tolerance level and the max wattage. Should I try a higher resistance?

[Quasar]

Re: Hakko 808 too hot!

Sounds like you blew a MOSFET on the temp control board. Need a pic of board or a schematic or component ID's. If the MOSFET that cycles the heater shorted, it would do what you've described.

Q

EDIT: Your resistor value is correct. There is an 8 pin IC on the board. Please lookup the part number to see what it does. The whole board (p/n B1738) is around $60.

Image attached

[Krankshaft]

Re: Hakko 808 too hot!

Oh man what was I thinking. My brain must have really been fried last night. Nice catch Quasar!

Your FET is shorted connecting line voltage to the heating element constantly. Temperature is regulated by switching a FET on and off rapidly via a PWM controller. It's feedback is the tips temperature via a thermistor.

That 8 pin IC is probably a PWM / FET combo. Check underneath the board if there is no SMD transistor on it I'm right. If there is a transistor that IC is a PWM controller and you may luck out and be able to repair this board.

The IC is made by NEC part number UPC1701C.

[Quasar]

Re: Hakko 808 too hot!

Here: http://www.bdent.com/UPC1701C-p/upc1701c.htm

Attached ENGLISH datasheet... lol

Q

[Krankshaft]

Re: Hakko 808 too hot!

A triac instead of a FET talking about bare bones technology. Saved them the price of a bridge rectifier I guess .

Thanks to Q's ENGLISH translation it's a specialty temperature control IC for heating elements.

All the brains of your temperature regulator are in this IC.

[PCBONEZ]

Re: Hakko 808 too hot!

I think this is it. - Doesn't appear to use PWM.
Haven't found it in English yet though...
.

[Krankshaft]

Re: Hakko 808 too hot!

Yeah the IC is MUCH older I was thinking too modern.

It's a circuit that pulses the triac at the zero voltage point of the AC wave.

Here's the datasheet thanks to Quasar's link:



It says in the datasheet triac controller so there should be a triac somewhere that's shorted out.

The triac will be connected across one side of the load. So trace out the two power wires going to the heating element (the other thinner wires go to the temperature sensor) it will be connected inline with one of those wires. It's going to be a dead short.

Don't forget to put the old POT back in the board. Depending on what POT you adjusted the temperature may be out of spec after the repair.

[PCBONEZ]

Re: Hakko 808 too hot!

Here Yar...

http://cgi.ebay.com/ANALOG-INTEGRATE...item3a4fe2d69d

http://cgi.ebay.com/UPC1701C-Integra...item255dd90bcc

.

[4tified]

Re: Hakko 808 too hot!

You guys are awesome! I will take a look when I get home. Thanks for the links!

[japlytic]

Re: Hakko 808 too hot!

You installed the wrong value resistor the resistance is wrong. It's very easy when a resistor gets charred for the color bands to be misinterpreted.

I misinterpreted a resistor which became discoloured as 10 ohms, where it was actually 22 ohms (I actually measured it, and it was within an E12 value). Fortunately, this resistor was used as part of an RC snubber network across an output rectifier on a power supply board.

[Quasar]

Re: Hakko 808 too hot!

@4tified - Would you post some pics of this board hooked up to the gun?
Especially the underside. I think the triac must be on that side, as it's not shown in the exploded parts diagram.

Q

[Quasar]

Re: Hakko 808 too hot!

-bump-

Hello ?

[4tified]

Re: Hakko 808 too hot!

Sorry guys, I've been really busy lately. Here are the pics.

[Krankshaft]

Re: Hakko 808 too hot!

It's the component designated as T1 (T for Triac) measure it it's probably shorted.

Measure between the input and output pins (they would be referred to as A1 and A2 in the datasheet) one side of the triac will be connected to line voltage the other to the heating element. This is where your short should be.

Ignore the gate lead which is fed from the temperature control IC.

[stj]

Re: Hakko 808 too hot!

dont ignore the gate lead, it could be leaky to one of the other pins - then it would self-bias and latch on.
i'v seen that happen.

[Toasty]

Re: Hakko 808 too hot!

I attached the pics so we don't lose them (like the last 12 hours did.)

Please upload direct to forums. Use the Advanced Editor and Manage Attachments.

Toast