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General control line discussion => Open Forum => Topic started by: frank mccune on May 15, 2021, 01:24:34 PM
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My glow driver same make and model, puts out 0-5.5v. I think that it has about 3 plus Ohms.
suggestions/comments?
Stay well,
Frank
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Have you tried Mouser?
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Mouser, Newark and Digikey are the usual places to get things.
But you will need to figure out exactly what it is you are trying to replace.
If it is really 3 ohms then it must be a wire-wound pot for example.
That would narrow it down, but then you need to figure out the mounting style and shaft type.
And then there will be the price - the least expensive 3 ohm single turn wire-wound pot on Digikey is about $60 :o
ebay or aliexpress (i.e. from China on a slow boat) might be a source for something more affordable.
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1 Ohm rheostat RWA-RP103FD1R0 surplussales.com
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Plenty of other ways to drop voltage, you can use the forward voltage loss of a diode and that's a good way if you have an old bridge rectifier hanging around.
Or a coil of insulated wire tapped at certain points is just dandy.
Chris.
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My glow driver same make and model, puts out 0-5.5v. I think that it has about 3 plus Ohms.
Same make and model as what? If this is the Northeast Engineering panel your "friend" has, then, from the schematic posted in the earlier thread, it is a 25K, low-current pot, which should be about $2 at any supply house. The pot is not in the current path to the plug, it is way up front and sets the gain of amplifier A2, nearly no current flows through it. I imagine that it is linear taper, not audio taper.
Brett
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Hello All:
Thanks for the help.
Brett, kindly give me some values to enable to purchase a replacement pot. I guess that I need volts, amps, ohms and wattage. Will pass the information on to my friend.
Tia,
Frank
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Brett, kindly give me some values to enable to purchase a replacement pot. I guess that I need volts, amps, ohms and wattage. Will pass the information on to my friend.
Again - is this the *Northeast engineering power panel* that is the same as the previous thread? I am getting confused because you are jumping between saying this is for your panel, and your friend's panel.
Brett
p.s. presuming my previous guesses were correct, this one should do:
https://www.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/P160KN-0QC15B25K?qs=%252BUYXD5bnyXpu15%2FMUCx5iA%3D%3D
76 cents.
But please confirm the information about the panel, and I am going to have you take apart the panel, remove the pot, and take pictures of it from all sides - particularly where it shows the specifications or part number - before I suggest you buy anything. In point of fact, I probably have something very similar if not identical in my giant box of replacement potentiometers.
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Hello Brett:
To make clear a few points, the two glow drivers are the same. My friend and I each have identical models. Ours do not have an on/off switch.
I was able to lift the pot high enough to see the following information stamped on the side of the pot. It read, NOBLE B25K, sign for omega, ohms,7723 JAPAN. The size matched the description of the pot that you sent me!
If you wish, I will just order one.
The ironic thing about this story is that the owner is retired Neonatologist who spent a large portion of his life teaching in a medical university. He is not confident to take on tasks like this. He trusts an idiot like me.lol. He is a friend and I am happy to help him.
Brett, you never fails to impress me with your knowledge! Now if we were neighbors, ...Lol
Thanks fo all of the help,
Frank
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Hello Brett:
To make clear a few points, the two glow drivers are the same. My friend and I each have identical models. Ours do not have an on/off switch.
I was able to lift the pot high enough to see the following information stamped on the side of the pot. It read, NOBLE B25K, sign for omega, ohms,7723 JAPAN. The size matched the description of the pot that you sent me!
So, it is a 25K pot (as shown on the schematic) , and I *think* B is a linear taper. as I had guessed. What does the shaft look like -serrated, round with a flat, round, etc?
Brett
p.s. in review, I almost certainly DO NOT have 25K linear taper pots. I have 5K audio (Zenith pocket transistor radios) and 50K audio (Channel Master/Sanyo lunchbox and solid state tabletop radios) but not 25K linear. So, when we figure out which shaft you need, you will have to take it from there, or I can add it to my next Mouser order (which may not be for a while since I am on airplanes for the next month and a half) .
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Hi Brett:
The shaft is smooth, sans a flat, has a screw slot on the end. It has a plastic knob that is held in place via a slotted set screw.
Does the pot that you posted fill the bill?
I hope this helps.
Stay well,
Frank
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The shaft is smooth, sans a flat, has a screw slot on the end. It has a plastic knob that is held in place via a slotted set screw.
OK, so that narrows it down to maybe 2,000 possibilities.
Post a picture.
Or look at the pictures in DigiKey, and get the one that looks about right. Don't be surprised if you have to get another one; there's a lot of possibilities and even expert repair folk can get it wrong.
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Hi Brett:
The shaft is smooth, sans a flat, has a screw slot on the end. It has a plastic knob that is held in place via a slotted set screw.
Does the pot that you posted fill the bill?
Try this one (~$7.00):
https://www.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/P230-2EC35BR25K?qs=56eeD6vBg8gsxx8%2F8bSbjA%3D%3D
The picture shows a flat shaft but the data sheet shows the "E" shaft style as round/smooth/slotted.
No guarantees of course, and I am curious how you determined it was the pot, but this appears to meet the specifications.
Brett
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OK, so that narrows it down to maybe 2,000 possibilities.
He's not exaggerating Frank!! You have NO idea how many options and possibilities there are!! You REALLY need to post a picture of some kind. you just can't say "pot" and expect anyone to go by that alone, and even the data off the OEM part is sketchy.
Type at you later,
Dan McEntee
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He's not exaggerating Frank!! You have NO idea how many options and possibilities there are!! You REALLY need to post a picture of some kind. you just can't say "pot" and expect anyone to go by that alone, and even the data off the OEM part is sketchy.
I think it was satisfactory. We already had a fuzzy schematic, that seemed to show 25K, and given the application, it should probably be a linear taper. Given it's position in the negative feedback path of an op amp means it cannot be passing any significant power, so anything with the right resistance should be sufficient (and the available pots are 500 mW, far more than sufficient, and insulated to 300V and it maybe sees 3-4 volts).
His readout off the pot was B25K and what is probably a date code (23 week of 1977, sounds about right). B is linear taper as expected, and its's 25K as expected. The only other important characteristic is the shaft type, Frank can certainly tell whether it is smooth, serrated, or D-shaped (and smooth or d-shaped would probably work OK with his smooth shaft knob with a set screw). I think it is probably too long, but that could be cut off, or just left alone.
The much better question is why the pot is suspected - it's a good guess, the one moving part that might wear out or get dirty. Maybe some contact cleaner would fix it. The original was a Noble pot, known for pretty high quality, and very unlikely to wear out in this application. But getting dirty, that is probably to be expected. But I would also replace the electrolytic capacitors before anything else.
I have worked on a Northeast power panel (with no schematic) before, and I think the problem was the output transistor, which does have to pass a lot of current.
Brett