Indetifying an Electronic Component - Help Pls.

[C152Heavy]

I have a 1991 vintage PC board with a component on it which looks like a diode and I'm trying to identify it.

On the PCB it'd labeled D5 so it'd make sense if it were a diode.

It is axial through hole, 0.1" dia x 0.115" long and is black plastic with a typical diode like polarity ring/stripe at one end. It has markings 16K3.

The 1 & 6 are oriented one above the other as you roll the component around (with the diode axis being horizontal), like the numerals in an old mechanical odometer while the K & 3 are side by side, at 90 degrees to the 1 & 6. You'd read them upright if you turn the diode axis vertical and turn it counter clockwise.

Have Googled with no luck.

Any component experts out there that know what this thing is?

Thanks

D

[jiroy]

Re: Indetifying an Electronic Component - Help Pls.

Any picture of the diode ? , the Mainboard model ? .

For the time being , you can treat it like a regular diode , meaning , on a Multimeter Diode's scale , if it is a regular diode , it should give around 6-7 kohms one way , and if it is a Schottky diode , it will give around 1,5-2 kohms , and if it was Zener it should give around 8-9 kohms . Of course , those measurements should be taken with one leg removed at least .

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

Any picture of the diode ? , the Mainboard model ? .

For the time being , you can treat it like a regular diode , meaning , on a Multimeter Diode's scale , if it is a regular diode , it should give around 6-7 kohms one way , and if it is a Schottky diode , it will give around 1,5-2 kohms , and if it was Zener it should give around 8-9 kohms . Of course , those measurements should be taken with one leg removed at least .

OK, I'll have a look at those measurements, thanks. Once the type is determined, any hints on selecting an appropriate "sizing" or P/N?

FWIW, it's a "logic board" from an Apple Stylewriter, photos attached. The diode is D5 on the through hole component side.

You can see that the electrolytics leaked so that's the starting point. I asked about the diode because I have a second board that had that part fail visibly.

I've had these tucked away thinking that I might learn something to help repair them, that was before I became aware of the badcap phenomon so it's time to have another look.

Thanks,

D

[budm]

Re: Indetifying an Electronic Component - Help Pls.

It is connected to the Base of the Transistor, that Transistor looks to be for the Linear regulator circuit so more likely to be Zener diode.
You can check DCV between the two legs of the Diode to see what you get.

[eccerr0r]

Re: Indetifying an Electronic Component - Help Pls.

Staring at it, it looks more like a buck SMPS holder diode, where L4 is the primary inductor, so it needs to be

- high speed diode (Fast or Schottky)
- probably no more than 2 amperes
- probably no more than 50 volts

I'd guess a FR102 or 1N5822 will do.

Now I can't read R101 - the SMT resistor on the back - to get a good guess how much current it should pass, but it probably isn't way too critical, just don't stick in a 1N4001.

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

Thanks for the replies so far.

BudM, I was planning on cleaning & re-capping before putting power to the board(s) so the voltage measurement will have to wait until then. I'm thinking that that reduces any risk of further damage.

eccerr0r, I read R101 to be labeled 1R2 so unless I'm mistaken that's 1.2 Ohm.

I've uploaded more photos but I'm disappointed that I can't seem to get enough resolution to read the SMT resistors.

Looking ahead, is there a likelihood that failure of the electrolytics would cause collateral damage? Where would one look for that? If there are components at risk I might as well put them on the Digikey shopping list rather than doing two orders.

BTW, the power adapter which connects to CNP is rated 9.5 VDC @ 1.5A.

Thanks!

D
I continue to be a knowledge seeker!

[budm]

Re: Indetifying an Electronic Component - Help Pls.

https://www.badcaps.net/forum/attach...2&d=1487088527
Looking real close at the board, the Anoe is not connected to GND plane, but it looks like it goes to IC2: MC34063 which is Boost/Buck IC, it more likely to have more then one Voltage converter circuits on that board.
So the 9V input probably gets converted to many different Voltages.
https://cdn.badcaps-static.com/pdfs/...88bb560e37.pdf

[eccerr0r]

Re: Indetifying an Electronic Component - Help Pls.

Now I see the anode connected to an inductor to GND (which is a bit weird). The cathode still looks like it's connected to the inductor and IC2.

If R101 = 1.2 ohms, then the current passed through isn't that high, and the FR102 / 1N5822 will work fine as a substitute.

What is the problem that it's exhibiting that you're trying to fix?

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

Now I see the anode connected to an inductor to GND (which is a bit weird). The cathode still looks like it's connected to the inductor and IC2.

If R101 = 1.2 ohms, then the current passed through isn't that high, and the FR102 / 1N5822 will work fine as a substitute.

What is the problem that it's exhibiting that you're trying to fix?

UPDATE: I measured the diode (out of circuit) using a Fluke 77.

Ohms scale: (auto ranging), value is 38.4k Ohm with +V applied to the anode, +V applied to the cathode, not stable (cycling).

Diode scale/setting: V+ applied to the cathode gives 0.209 V, and with +V applied to the anode, V=0

I think this would indicate the diode is behaving normally, please correct me if I'm wrong.

WRT replacement options, the 1N5882 is not an option because its leads are too large in diameter. We're replacing a component with 0.022" diameter leads, I believe that's either a DO-41 package or something similar. The FR102 is also a concern because it seems to be more difficult to obtain, not stock at Mouser and min Qty 40,000 at Digikey.

Any more common options? I'm a little out of my expertise but comparing data sheets, the Digikey P/N SB1H100-E3/73GICT-ND (Vishay SB1H100-E3/73) seems similar except the Vf Max is about 3X the FR102.

To note, I'm looking for the diode equivalent as a replacement on one of my 2 boards which was damaged but let's not go into that right now and get side tracked. I'd rather do the re-cap on both boards first then see where we are at that time.

To answer your question eccerr0r, it's been years but if I recall the problem was the printer would not turn on (momentary push button on). After I get the re-capping done, the status at that time will be a good starting point.

BudM, I expect you're right about the multiple voltages. There would be logic level things but perhaps the drive motors and ink jet heads are higher voltage to reduce current.

Thanks,

D

[eccerr0r]

Re: Indetifying an Electronic Component - Help Pls.

This will probably work.

http://www.digikey.com/product-detai...1CT-ND/4572543

Having that 1.2 ohm resistor there will cause a fairly large voltage drop at 1A so it definitely is not a high current switcher... The 1N5822 is overkill as it will pass 3A safely. This EK-04V1 is only 1A and will have thinner leads.

[Agent24]

Re: Indetifying an Electronic Component - Help Pls.

Looking ahead, is there a likelihood that failure of the electrolytics would cause collateral damage?

Looks like they've caused some corrosion to the board and other components nearby. I would start by removing the capacitors (note down their positions\values etc first) and then giving the board a real good clean and dry.

Note that the traces near the capacitors etc if they have been attacked by electrolyte may well be weaker and easier to damage.

Replace any components with corroded leads, give it a test.

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

This will probably work.

http://www.digikey.com/product-detai...1CT-ND/4572543

Having that 1.2 ohm resistor there will cause a fairly large voltage drop at 1A so it definitely is not a high current switcher... The 1N5822 is overkill as it will pass 3A safely. This EK-04V1 is only 1A and will have thinner leads.

Thanks, eccerr0r that'll fill out my Digikey shopping list.


Agent24, I see you're a Kiwi. I visited your neck of the woods about a year ago, North Island anyhow. So much unspoiled nature & easy going, friendly people, I'd feel right at home there.

All of the electrolytics are scheduled for change and a thorough cleaning & inspection will be part of the process. The other collateral damage I had in mind was to the electrical properties of any other component caused by the changed/degraded properties of the caps. My strengths are not in electronic theory although as the profile tag line says, I'm a knowledge seeker so I'm asking advice from the more knowledgeable members of the forum. When the board(s) was(were) last run the capacitor failure was in its very early stages. As I discovered, they leaked visibly while they were stored away.


Thanks,

D

[Agent24]

Re: Indetifying an Electronic Component - Help Pls.

Cheers Glad you enjoyed it!

Sure, if there are switching converters on here (seems there are) it's possible the switching transistors\ICs may have shorted, if the capacitors went open-circuit. If you haven't checked those already, it would be advisable. Though the thing looks quite low-power so it might be OK.

I'd be more worried about corrosion going up into the components through the legs and causing connection failures, which is why I'd advise replacing anything where corrosion goes up to the plastic.

From prior work on corroded boards, I would say, be prepared to hunt down parts\tracks which have gone open-circuit without visible signs, too.

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

Cheers Glad you enjoyed it!

Sure, if there are switching converters on here (seems there are) it's possible the switching transistors\ICs may have shorted, if the capacitors went open-circuit. If you haven't checked those already, it would be advisable. Though the thing looks quite low-power so it might be OK.

I'd be more worried about corrosion going up into the components through the legs and causing connection failures, which is why I'd advise replacing anything where corrosion goes up to the plastic.

From prior work on corroded boards, I would say, be prepared to hunt down parts\tracks which have gone open-circuit without visible signs, too.

Thanks, that gives me some things to keep an eye out for as I move ahead.

Cheers,

D

[C152Heavy]

UPDATE: Progress Report, Re: Indetifying an Electronic Component - Help Pls.

Reporting back after the initial round of repair.

I have 2 boards and started with the one appearing to be in better shape and having less of a damage history. I re-capped it, including repairing a few damaged tracks.

A word or two on the tracks; there was one track where a plated through hole just happened to be under one of the larger caps and this had failed on both boards many years ago prompting the jumper you see in the photos. Not knowing about leaking caps (this was 20 years ago...) I assumed it was a voltage arc over from the cap shell and isolated the track with a mylar shield under the cap. and the board worked for a short time again.

The other track issue was damage to plated through holes (PTH) at the caps which I attribute to very narrow pads around some of the holes (like about .020"), the effects of leaked electrolyte (corrosion delaminating the PTH from the substrate) and component leads which were crimped/bent hard over in the PTHs so they were well lodged in the PTHs mechanically so not easy to extract. I ended up cutting some of the leads I could get access to and taking them out one at a time which helped. I notice too that the PCB was not tinned where it wasn't solder masked so the tracks didn't have that protection either.

In any case there were two caps where at least one of the PTHs came out with the lead and required jumpering. My skills/experience with the circumstances probably didn't help either. It is the most difficult board I have tried to remove components from though. In the end the results were not especially pretty but functional.

So, this first board seems to have recovered partial function, it responds to the activate signal (on button) and tries to do the print head initialization but draws too much current and either does a soft shut down or blows the wall wart fuse. After looking around a bit I decided to set it aside to think about it and re-cap the second board which showed more signs of electrolyte damage/corrosion.

I didn't give the second board as great a chance of easy revival because of the corrosion and because it had a finger trouble event 20 years ago the last time I looked into this. Fessing up, I accidentally shorted something when I set the board down while troubleshooting and damaged the D5 I inquired about. After replacing it I had no luck with the board so this is when I set the works aside until I was better prepared to trouble shoot it.

Fast forward to today I found I had also blown the fuse in the wall wart which kept me from making more of a mess with it LOL!

So, now that I have fessed up, I re-capped the board and the wall wart (including a new through hole fuse....) and......nothing! A little more poking around and measuring to see where the power seemed to stop and I heard something arcing when I wiggled the power plug which was a bit strange. At that point I found the massive solder joints of the power plug on the PC board had cracked.

Re-flowed the joints and shazam!, I now have a working printer.


Next up is look at the detachable paper handler to see why it doesn't (probably dusty!) then clean up the print head/cartridge or replace it and try to figure out why the other board doesn't work. This is all about it being a learning exercise after all.

So, toward that end I have made some initial measurements and the only anomaly I have found so far is that the voltage drop across D5 (Thanks for the replacement recommendation, eccerr0r) is about 5V for the unit not working right and 0.68V for the one that is.

I haven't dug much deeper but perhaps it's something to do with IC2, the TI-MC33063A which is the basis of that DC-DC convertor and is associated with L5.

If anyone has any further suggestions to troubleshoot this I'd certainly appreciate any advice.

Thanks,

D

[Agent24]

Re: Indetifying an Electronic Component - Help Pls.

Having the full 5v across the diode implies something after the diode (or diode itself) is open-circuit.

[C152Heavy]

Re: Indetifying an Electronic Component - Help Pls.

Having the full 5v across the diode implies something after the diode (or diode itself) is open-circuit.

Thanks, I'll follow that lead. When you say after the diode, you mean on the cathode side, correct?

I don't think the diode is open however, given that it is new and the replaced unit seemed to check OK.

Thanks,

D