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Having trouble identifying a diode needed for a repair.

AgTech4020

Sep 22, 2016
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I am working on repairing a baler monitor and I have two dammaged diodes but have been unable to identify them. They are clearly labeled G1504 9924C however the numbers are not leading me anywhere. I believe it is a TVS, approximately 9mm long and 4mm diameter. It is used in a 12 volt circuit. Picture is attached. I would welcome any advice.

Thanks
 

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Where is it used in the circuit?
 

AgTech4020

Sep 22, 2016
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It is used in conjunction with a selector switch.
 

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Excellent. Is one end connected to the "signal"? If so, where is the other end connected?

There are two, are they connected in parallel, inverse parallel, or perhaps in series?

Out of interest, if they are undamaged, why the question?
 

dorke

Jun 20, 2015
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They could be 1N5404 rectifier diodes
Are those "3 black thick wires" coming from a line transformer ?
 

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Yeah, especially if that is a voltage selector switch. Those wires might even come from the incoming mains.
 

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That chip is a serial input latched driver, so unlikely to be mains voltage, but low voltage rectifier or input protection are a definite possibility
 

73's de Edd

Aug 21, 2015
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Agree . . . . .
The two diodes of a line frequency Full wave rectifier circuit
Researches out as
1N5804 400V 3A diode.. . . . family
and the units solder connections shows some heat stress in the past.
ALSO doesn't that TVS diode sitting beside them also seem to look cracked all across its very center?
Between the set of power diodes and the TVS there is a burn out in the PCB foil path.

73's de Edd
 
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AgTech4020

Sep 22, 2016
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Ok so they say a picture is worth a thousand words so I attached three more pictures.

The two diodes in question are cracked down the side and the third which is a 1N6282AG split in two. The black leads go to a three position selection switch. This is a 12 volt 30amp input agricultural baler control box.

Hope this helps.
 

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Those diodes are all in parallel across two of the spade terminals. They could be reverse voltage protection.

Did anything get connected incorrectly, even for just an instant?
 

dorke

Jun 20, 2015
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You have 2 wires(red in the drawing) destroyed by over current (a short?)in the 2 diodes.
The diodes look to be connected in a rectification arrangement.
The 3rd diode 1N6282AG(yellow) is a 30V transient suppressor .
The fact it is cracked means high voltage(>41V) was probably connected or generated momentarily and a high current probably flowed through it(>36A).
If this was indeed the case,other parts on the board may be damaged.

Anything written on the "switch"?
Do you have a DMM to check resistance?

BTW,
You didn't do a very nice job removing the 3 diodes.
The board is now full of solder debris, you have to remove them all to prevent shorts in the circuit.

IMG_1170.JPG
 

73's de Edd

Aug 21, 2015
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Sir AgTech4020 . . . . . . .

Sooooo . . . .this 'pears to be late 1990'sh---- early 2000 vintage piece of equipment.
And any 30 amp association would have to be specifically related to the HEAVY heatsinked area.

With the three black wires from this units transformer carrying in the reduced AC line voltage to
that full wave rectifier set of diodes, and possibly having had to OOOOOOmph out enough short circuited
current to have vaporized the dual foil path up to the diode pairs anodes.
The diode pairs cathodes then alternately generate the DC supply voltage, to be initially be held in
check . . .spike amplitude wise . . .by that adjunct shunt TVS diode that just couldn't handle its
severe overload condition that it had been subjected to.

(VERY-VERY-VERY , rarely do I see that degree of severity of overload ! . . . . . ONLY UNLESS you was WHITE LIGHTNING WHACKED ! )

NOW that you have the defunct parts out of circuit do you NOW, possibly, find yourself with a dead short when
testing across that BLUE main storage electrolytic . . . . then the top two foil vias that I see branching away from it . . .
OR possibly more vias , if the bottom side of the board ALSO has some like foil paths involved .

Is I correct in reading your units BLUE electrolytic capacitor as being a Nichicon 220 or 330 microfarad at a 50 VDC rating ?

I can't positively read to confirm the "prefix" numbering of this TVS . . .with the center possibly reading as 282A . . . and the units suffix marking , being the usual distinct gibberish numbering stream typically as is encountered on TVS units markings
If the above number validates . . . that would then cross into a 1N6282A TVS unit.

If it's still putting out, can you give us the raw AC across the 3 black wires from the power transformer . . . it assuredly being arranged as . . . AC Voltage---Center-tap--- AC Voltage.



73's de Edd
 
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AgTech4020

Sep 22, 2016
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I am admittedly a novice at this. I was somewhat disappointed with the way the diodes came off the board so I completely agree about the Solder mess. Solder sucker didn't work very well and I fought with solder wick to remove what I could. I have some cleanup to do before I proceed with the repair. This is going to be my first attempt at repairing traces so I have ordered trace material and epoxy.

OK so I've attached a photo of the switch label and yes I do have a nice digital fluke meter. I agree based on the amount of damage it is likely that I will find more issues elsewhere. The harness going to the Baler had been crushed and shorted but why it didn't just blow the fuse I'm really not sure.

73's de Edd you are correct on the capacitor as it is a Nichicon 220 50v. There is however no AC input to this as it has a direct 12 V input so no transformer at the end of the black wires just the three position switch it in the attached picture.
 

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dorke

Jun 20, 2015
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You can repair the traces with a simple wire,no need for trace material.
By "What is written on the switch" I meant the "functionality label"-what is it switching.
This equipment is probably operated by a 12V or 24V truck battery,isn't it?
The voltage suppressor diode is probably protection against voltage ignition/alternator surges.

Could you please trace what feeds the switch?

Locate a GND trace on the board ,and please measure resistance with the Fluke to it from the blue arrow point.

IMG_1170.JPG
 

73's de Edd

Aug 21, 2015
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Okay, I have got it now, we ARE in Kansas along with Toto and we are strictly Battery powered (12 dc) NO overhead AC lines to be seen anywhere !
What was being meant by the labeling on the switch was actually being the markings on the panel that it is mounted onto, just above and below the switch. E.g. . . .what different action is activated when temporarily engaging into those positions ?
From the VAST supply of switches that OTTO offers, I believe that this one researches out as being a single pole double throw rocker switch with momentary action from the center normal position to the spring loaded return of its upper or lower . . .temporary positions.

Hypothetical . . . Guesstimated . . . Mode of operation :

The top START position is activated by the switch
That activates a baler cycle and the mechanism failsafe engages to remove 12 dc from one supply route to the system so that the START button position is no longer functional .
Should a baling problem be seen, one could stop that mechanism in its cycle by engaging the switches bottom HALT position and then correct the problem with a pitchfork and elbow grease.


73's de Edd

.
 
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AgTech4020

Sep 22, 2016
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Sorry about the delayed response, busy weekend.

I have no continuity between the ground circuit and the circuit in your previous picture response. It looks to me like the three position switch is supplied with the ground circuit. The other side of the diodes all go to the control side of push in automotive relays.

Thoughts?
 

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