Can you identify this component? - Page 1
Forum section: electronics / repair

author: Tommy44
author_rank: Newbie
timestamp: November 17, 2017, 02:42:20 pm
content: Hi! Can anyone help me identify the 4 orangish diodes (what I believe them to be) on this board? It is a Brett Aqualine hot tub touchpad board circa 1997. I can't find a schematic and there are no text markings on the components, but I believe them to be a signal diode. I appreciate any help you can provide. Thanks!

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 17, 2017, 02:51:04 pm
content: They look like 4148 . You need to check how they are wired, being four of them it looks like it is probably a bridge rectifier, that is easily proven with a meter and if it is a bridge then provided they have a normal volt drop I would think just about any silicon diode will do.

author: purp
author_rank: Newbie
timestamp: November 17, 2017, 02:52:00 pm
content: Lift one and get your eyes on.

author: flynwill
author_rank: Regular Contributor
timestamp: November 17, 2017, 02:52:49 pm
content: They certainly look like small signal diodes, 1N914, 1N4148, or similar. But I've also seen Zeners in the same glass package. There do appear to be marked, you may need to unsolder one and see what it says, or keep tracing the circuit to determine the function.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 17, 2017, 02:58:10 pm
content: Can I have another guess?Protection diodes for some inputs or outputs. A meter will tell you which. I reckon each diode will have one end connected to each of the four capacitors and the other end all tied together, maybe grounded.Insufficient data for meaningful conclusion, get stuck in there.

author: Tommy44
author_rank: Newbie
timestamp: November 17, 2017, 03:00:38 pm
content: Wow, you guys are fast!Seeing 4 of them I too thought it was a bridge rectifier, however I believe the input into the board is a DC signal (probably 12V) since the only external connection to this board is the 26 pin "J1" head. That would connect to a control board with the relays to turn on and off motors. Unfortunately I don't have access to that based on its location.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 17, 2017, 03:07:20 pm
content: It is not a power rectifier so won't be concerned with the supply. It is likely to be to maybe some external switches if it is protection so that when you are holding the electric fire while wet, being electrocuted you won't damage your next of kins hottub

author: Tommy44
author_rank: Newbie
timestamp: November 17, 2017, 03:09:05 pm
content: Quote from: Mjolinor on November 17, 2017, 03:07:20 pmLOL that is comforting!

author: SeanB
author_rank: Super Contributor
timestamp: November 17, 2017, 03:19:49 pm
content: You can make out most of the markings, showing 1N4148 on the diodes. There as input protection, clamping the voltages on the input to the 5V rail after they pass through RP5, which looks like a SIL resistor array, probably something in the range of 1k to 4k7. Then C5 to C8 provide some EMI filtering and low pass with the resistors, and the diodes clamp the voltage to the positive rail. The resistor array above the diodes likely is a commoned block, providing a 22k to 100k pull up for the inputs, so the switches pull them to ground to activate the input.

author: Tommy44
author_rank: Newbie
timestamp: November 17, 2017, 03:24:25 pm
content: Quote from: SeanB on November 17, 2017, 03:19:49 pmThank you sir. Could you kindly explain how you got 1N4148 from the markings?

author: Armadillo
author_rank: Super Contributor
timestamp: November 17, 2017, 04:04:59 pm
content: Quote from: Tommy44 on November 17, 2017, 03:24:25 pmAnyway, it's a "German Diode"..... Goggle for Germanium Diode and see which one come closer. 1N is clearly written there. Could be 1N and followed by some number like 34 and etc....You may need magnifying glass.

author: glarsson
author_rank: Frequent Contributor
timestamp: November 17, 2017, 06:05:25 pm
content: Quote from: Armadillo on November 17, 2017, 04:04:59 pmThe 1N4148 is a ordinary silicon diode, not a germanium diode.

author: Armadillo
author_rank: Super Contributor
timestamp: November 17, 2017, 06:25:53 pm
content: Quote from: glarsson on November 17, 2017, 06:05:25 pmFor that longer slender body, I didn't say its a 1N4148. Can you read the "34" in my text?From the picture, I think a number "3" is printed in there.....obviously the picture quality isn't that great...

author: martinator
author_rank: Contributor
timestamp: November 17, 2017, 06:47:10 pm
content: Did this circuit board used to belong to Ron Jeremy?

author: glarsson
author_rank: Frequent Contributor
timestamp: November 17, 2017, 06:57:12 pm
content: Quote from: Armadillo on November 17, 2017, 06:25:53 pmThe internal structure as seen through the glass is clearly not a 1N34A germanium diode (in a DO-7 package). It does, however, match what a small signal silicon diode looks like (in a DO-35 package).

author: Armadillo
author_rank: Super Contributor
timestamp: November 17, 2017, 07:08:32 pm
content: Quote from: glarsson on November 17, 2017, 06:57:12 pmNah!... seriously you need to be affirmative in your intention to guide others and not leaving wild cards like DO35 package. So you saying that its a 1N4148?

author: glarsson
author_rank: Frequent Contributor
timestamp: November 17, 2017, 07:22:59 pm
content: I am saying that it is not a germanium diode. It is easy to see by looking through the clear glass.

author: Armadillo
author_rank: Super Contributor
timestamp: November 17, 2017, 07:27:31 pm
content: Quote from: glarsson on November 17, 2017, 07:22:59 pmYou are saying D035 package. It's easy.DO35 = 4mm longDO7 = 7mm longNo need to pretend bionic eyes to see through the glass.