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Old 07-18-2019, 05:13 PM   #41
captainKKK
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

UPDATE: Originally, I ordered 1N5408 from aliexpress and since that was taking too long, I paid twice the price for half the quantity from a USA seller on eBay, for delivery in a week. In the pics herein, you can see the eBay sellers product is on the RIGHT and the Chinese seller on Aliexpress is on the left. If SIZE MATTERS, then the Chinese Aliexpress product is superior. Also note, not only is the chinese diode itself large in diameter and length, the diameter of the cathode and anode wires on the chinese product is larger. Remember, herein the USA sold eBay product blew out 3 times before I placed the heatsink. Just FYI. Opinions?
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Last edited by captainKKK; 07-18-2019 at 05:15 PM..
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Old 07-18-2019, 06:01 PM   #42
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

lots of good stuff is produced in china under licence . and lots are produced on the cheap that anyone can sell on .
one on the left looks better markings to me .
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Old 07-18-2019, 07:51 PM   #43
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

The 1N5408 must be bigger than the typical 1N4007s I hope people have seen before... Need a scale to really tell how big they are, but yes they should be larger to dissipate more heat and hence support more amperes.

Some diodes, from left to right:

(15 amp stud rectifier)
1N1614 (1969)

(6 amps plastic)
P600M

(3 amps)
MR851 Motorola (1983)
SMR750

(1 amp)
1N4007 Motorola (1981)
1N4007 (??)

1N1379 240A
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Old 07-19-2019, 01:46 AM   #44
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

Quote:
Originally Posted by captainKKK View Post
UPDATE: Originally, I ordered 1N5408 from aliexpress and since that was taking too long, I paid twice the price for half the quantity from a USA seller on eBay, for delivery in a week. In the pics herein, you can see the eBay sellers product is on the RIGHT and the Chinese seller on Aliexpress is on the left. If SIZE MATTERS, then the Chinese Aliexpress product is superior. Also note, not only is the chinese diode itself large in diameter and length, the diameter of the cathode and anode wires on the chinese product is larger. Remember, herein the USA sold eBay product blew out 3 times before I placed the heatsink. Just FYI. Opinions?
the one on the left is new and has lead-free solder coated wires, the one on the right looks very old.
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Old 07-19-2019, 06:26 AM   #45
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

I could have sworn I had a 1N5408 somewhere, and I finally found it... same size as the MR851/SMR750. And yeah I've noticed a lot of my old diodes have "shitty paint jobs" that scratch off very easily. However the size difference of the two you have is probably inconsequential, though if they are both the size of a "tiny" 1N4007, that's a problem...

And it could very well that the "USA seller" bought a boatload (literally) of counterfeit 1N5408's to resell...
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Old 07-19-2019, 07:03 AM   #46
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

those p600's bring back memories!

i used to fix boards that had an early type on them, the package had pads with soldered on leads.
when the voltage regulator shorted they used to get so hot they desolderd themselves and fell into the casing, leaving the wires on the board!!!
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Old 07-19-2019, 09:53 AM   #47
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

Yeah I've heard a bunch of horror stories about the P600's as well. Though rated for 6A, that thing must get HOT, how could plastic deal with that much heat!!! IIRC the P600's seem to be readily available and probably the highest current plastic tubular diodes available and people readily use it reverse voltage protection, including things that require many more than 6A.

I'd imagine at that much current, one needs to look into heat sinking, and should be using TO-220 diodes instead... or some other solution...
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Old 07-19-2019, 11:00 AM   #48
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

it used to be common to loop the leads before going on the pcb so the heat would disipate before it reached the board!
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Old 07-20-2019, 07:12 AM   #49
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Default Re: Harbor Freight Tools Heat Gun Item 96289 JSRF-601C Repair

And now they keep leads short to use foil as heat sinking
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