Hey all ... I am reconstructing Uniflite 'electronic modules' (aka 'E.M.'s - these are simply 3 different 6-circuit wiring loom nylon connector blocks (red, green & blue) ... 2 [red & green] with 5 diodes tied together and 1 [blue] with 4 diodes; 2 pairs of diodes tied together independantly) that form part of a twin screw boat's '7 POINT W DUAL HELM' alarm panel circuitry ... to allow a test function of 7 12VDC incandescent lights (on each of 2 panels [these 'lights' are AMP Incandescent Panel Indicator light capsules and supposedly use a 2162 (or equivalent) bulb that draws 0.1A, each, at 14VDC] that are normally never tested at the same time), and, a selectable acoustic alarm function (<1" compact all-weather enunciator [amperage draw unknown] on upper helm flybridge station and a bell [amperage draw unknown] for lower helm salon / interior station). For those inclined to help me out and who prefer schematics to descriptions in order to properly assess current demands, I can upload those as required.
The way Uniflite mounted the E.M.'s to a multiple wiring loom termination base with a clear plastic cover (latter probably meant to prevent errant physical contact and/or act as a dust cover) inside the flybridge fibreglass cowling (typically dry-ish compartment) right below a potential water entry point (forward masthead light that has evidently seen servicing and poor wire entry re-sealing) resulted in the inevitable ... water dripped down onto the E.M. assembly, and, over time, collected in the bottom of the clear cover (great design eh?), immersing the lowest E.M. (blue) and resulting in severe corrosion damage.
In sourcing replacement diodes for the SYLVANIA ECG 125's that had been used by Uniflite back in 1978, I was provided with generic 1N4007's, however, now that I'm ready to recontsruct the E.M.'s, I have found cause for concern over the amperage ratings of the two similar part numbers ... it seems the ECG 125's were rated for 2.5A @ 25° C whereas a cross-over part like NTE 125's are rated at 1A @ 75° C ... as are the 1N4007's.
So, the ECG 125 / NTE 125 'Average Rectified Output Current @ TA' amperage values are seemingly test temperature dependant ... could this also be said for the 1N4007's as well?
The 1N4007 will work the same as the ECG 125's. The difference in rating has to do with the "conditions" of the rating. The ECG 125 is rated with the leads at 25 °C. The leads are the main path for heat to leave the diode. Naturally if you kept the leads "cold" you can safely pump more current through without damage from overheating.
BTW I am not a fan of NTE parts. I recommend you stick with 1N4007's from a well known mfg.
Thanks to all who stepped up to educate me on the 1N4007 ... I would have responded sooner but this forum didn't notify me of any of your Replies (unless I missed an option box when I posted [or registered] 1459PDT 05NOV21 Edit: I figured out the Nofifications banner thing in my Profile Preferences and have enabled them) ... at any rate, I think I will go with the 1N4007's, as the 1N5408's, even though rated for 3A and providing a greater heat tolerance margin, will not physically fit Uniflite's design for the electronic module base and cover arrangement.
Back in the day (1978/9), Uniflite used SYLVANIA ECG 125's and their size / form factor appears nearly identical to the 1N4007's, so, there's that reassurance. BTW, I cannot tell who made the 1N4007's I bought from R.P. Electronics in Burnaby (Vancouver), B.C., Canada, so, cannot comment on their supposed quality or lack thereof ... I will say that at least NTE had a tech that responded to Q.'s about the thermal effects on amperage carrying capacity of diodes in general and the ECG 125's vs. their own NTE 125's specifically, so, there's that in their favour, even if their product sourcing is sketchy.
That's no surprising, its more reliable not to inform you.
You are best, if you have started a thread to look at least daily, much more often if you can, although it says the first replies were posted 11days ago, they wer probably posted within 1 to 4 hours from when you started the thread.
I think you are over thinking the situation, 1A diode to conduct 0.1A is a suitable application, more so for the physical build of the diode, it is quite rugged and is epoxy and has decent gauge leads to make an installation easy and stable.
One difference in the current/heat handling of the diodes is the metal of the leads. All of the 1n4000 series use steel leads. The other diodes may be using a copper alloy.
Paul
