Re: Bench PS Problem (Volteq HY3010D)
This is a different model (Hy3020)but might help, I found this one also (HY3010D)
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Re: Bench PS Problem (Volteq HY3010D)
Perhaps while varying the adjustment pot, testing the voltage across it and voltage at the base of the transistor(s) would be some first order tests even without schematics.Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
The 2N3055 is one of those ancient parts that is too good for the price for it to be obsoleted. I'd guess it was designed in the late 1960s.
That 14-pin IC may be a uA723, another ancient part. the linear regulator IC. Basically, it has a precision reference, an error amplifier (with the output pin accessible for compensation purposes), and an output transistor that could be used to drive higher current transistors.
If the output transistor leads are accessible, testing for shorts should be easy, though discerning which one would require removal. There may also be a high current rectifier across the transistors' CE, with the anode at the collector, and the cathode at the emitter. This would provide some protection to the transistors against a higher voltage being externally applied at the output. This could short instead of one of the output transistors shorting CE.
Finding a schematic - dead-tree or online - could be valuable. I'm just working from memory of typical linear power supplies.Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
I suppose the problem is not actually current limit but dissipation limit. I think 4 is actually about right for a single stage series dissipative design with the specs of this psu...
I know my homemade 1.2-15V 2A does exceed the power dissipation of the single series pass transistor... at least the heatsinking is not great. I've fried it a few times already :o However due to the circuit topology I'm not sure if any learnings from its failure can be applied to the OP's supply.Last edited by eccerr0r; 05-18-2017, 07:16 PM.Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
yes, but you probably dont need to desolder them unless they meter bad to begin with.
i'm impressed that it has 4, they can manage 7A or more each!Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
They seem to be 2N3055
Here's the photos: http://imgur.com/a/r0P2z
Forgive me, how do I test the transistors? Solder them out and test for resistance?Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
If the output transistor is a 2N3055 (very common) it's $2 or $3. It could also be a bad potentiometer.
Open it up, clean out the dust, and post some pix!Leave a comment:
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Re: Bench PS Problem (Volteq HY3010D)
probably has a shorted output transistor.Leave a comment:
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Bench PS Problem (Volteq HY3010D)
Bought this bench power supply a few years ago, recently when I start it up, the output voltage is about 25V and I cannot knob it down to zero.
How can I tell if it's a problem with the knobs? Or is it something else?
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This power supply is 30v 5amp. Problem is when turned on after about 3 minutes voltage starting to decrease slowly. (like - 5.8 > 5.7 > 5.6 > 5.5) can't see any damaged component or dry solder joints. Checked main 2 transistors with multimeter. Reading seems ok. Tried changing potentiometers(both coarse and fine) still the same situation. Can any one help me to troubleshoot? What voltages to check? Any ideas helps to fix this. thank you.!
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I have an LG Plasma TV 60PM6700 for the past ~12 years.
In the last ~3-4 months I have been having some issues.- Problem: It started with random picture disappearing (sound still worked).
Frequency: Happened about once a week.
Solution: Had to turn off TV wait a few seconds before turning it on again. - Problem: Then it got worse and the TV started to shut down and when turning on the no picture just sound.
Frequency: Happened about once a week.
Solution: Had to turn off TV wait about 10-20 seconds and turn it on again to solve. - Problem: TV shuts down
- Problem: It started with random picture disappearing (sound still worked).
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Hello Everyone,
I am seeking to repair a knob on an old (circa 1971) Panasonic clock radio (a model RC-6900). The good news is that I have the small, easily lost knob. The bad news is that the knob has come off a slotted post and I need to re-attach it in such a way that I won't have to worry about it coming loose again.
Here is a picture of the bare slotted post (if I have the term right) the knob should be attached to:
As you can see, this is an Old School selector switch, which means it's pretty stiff. Put another way: the knob has to fit... -
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The laptop was turned off because the MOSFET was not transmitting voltage. After checking it turned out that the gate pin on the MOSFET was the problem, because it was producing an inappropriate voltage. and it was discovered that the problem was with the Think engine, so I decided to reprint each pin, and finally the mosfet could work properly. However, there is another problem, even though the voltage has been supplied to the laptop, it still won't turn on, there isn't even an LED indicator. After double... -
PC Specs:- CPU: Ryzen 5 1600
- GPU: GTX 1080 Palit JetStream
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- RAM: Crucial Ballistix Sport 2x8GB 3000MHz (XMP 2.0)
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- OS SSD: ADATA SP920
- OS: Windows 10 21H2
Problem description:
Hi. I have a problem that has been going on for some time (2-3 years). It's hard to explain what it really is. Sometimes, my computer stops playing music, stops videos (starts buffering on youtube), there is no sound in games and when I minimize the game window and return to the game there is a black screen with window borders...
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