Re: How to Recondition (Reform) Electrolytic Capacitors and Why
Sorry for the late reply. Picture attached.
Thank you momaka....
maxbarjr
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Last Activity: 01-08-2021, 07:50 PM
Joined: 03-25-2016
Location: Baguio City
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Re: How to Recondition (Reform) Electrolytic Capacitors and Why
Yes, the vents are open and as I said, some signs of liquid discharge. But even though there were signs of some fluid release, I still tried to reform these caps. I was able to get a 48V power supply that can be adjusted from 36 to 48 volts. I used a 1.2K 10w resistor in series with the + terminal of the cap and monitored the voltage after the resistor (+ terminal) with a 40v input. It took about 5 minutes to get to 40v on the meter. I kept it connected for about 15min after it reached 40vdc then disconnected...Last edited by maxbarjr; 07-12-2018, 06:03 AM.Leave a comment:
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Re: How to Recondition (Reform) Electrolytic Capacitors and Why
Thank you momaka. Yes, they have a vent and some have signs of some fluid release....Leave a comment:
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Re: Need schematic diagram of this...
redwire, thank you for the link. I will have a look if any similarity....Leave a comment:
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Re: Need schematic diagram of this...
Attached photos as requested. Although may not be a high resolution but that's the best I can get....Leave a comment:
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Re: How to Recondition (Reform) Electrolytic Capacitors and Why
I just found this thread and I have a question. I have some old 32,000uF 40V capacitors by Sangamo. I only have 30VDC bench adjustable power supply. Can I use it to reform this caps or I need to have 40VDC psu?Leave a comment:
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Need schematic diagram of this Super-MITE 11, SM11-2/230A
Anybody know where I can get a schematic diagram of this power supply? It is rated 12VDC@84A switching power supply. The unit is not working and have some dark marks on the pcb, a sign of overheating in that area.
Thank you in advance.... -
Re: Linear PSU Pass Transistor Question.
Thank you....Leave a comment:
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Re: Linear PSU Pass Transistor Question.
Both the heatsink and the transistor. Measured the temps on them and almost the same....Leave a comment:
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Re: Linear PSU Pass Transistor Question.
Thank you for sharing those documents. Very interesting. Thinking of adding 6 more 2N3055 on another heatsink mounted on the other side of the case. Will that reduce the heat on the heatsink and will it increase the power handing of the psu? Any improvement suggestions are welcome....Last edited by maxbarjr; 07-01-2018, 04:58 PM.Leave a comment:
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Re: Linear PSU Pass Transistor Question.
You must be referring the the single transistor at the back just above the output terminals. It warms up a bit but not much. This transistor is the Q100 that drives the base of the pass transistors. It is not part of the 6 pass transistors. The heatsink and pass transistors has almost the same temps when measued. The rectifiers are just warm being fitted on those copper bus bars.
Oh yes, I have been repairing computers before and have seen a cpu really smoking without the heatsink and fan....Last edited by maxbarjr; 06-29-2018, 09:51 PM.Leave a comment:
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Re: Linear PSU Pass Transistor Question.
I used a Kenwood TM-281A at H power output of 65W into a dummy load. Here are some results of the measurements.
Between C and E: 10.2V with radio keyed, 12.5V unkeyed
Across the 0.1 Ohm resistor: 0.15 with radio keyed.
Temperature taken with a Fluke 287 meter and a Fluke 80BK-A probe: 140F 1min keyed.
Pictures of my homebrew power supply attached....Leave a comment:
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Re: Linear PSU Pass Transistor Question.
Not really very small transformer. It's very heavy. Maybe about 10kg. It's 4.5 inches tall x 5.5 inches wide x 3 inches thick....Leave a comment:
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Re: Linear PSU Pass Transistor Question.
Thank you for your comments. Yes, it's a 100W RF transmitter. I should have added, intermittent transmit of 5sec on, 5sec off for 60secs to a 150W dummy load. Yes it goes to 2 diode for a fullwave rectification and filtered with a 64,000uF 40V capacitor. You are correct, on the peak voltage of 25.4V at no load. The regulator board is powered by a 1.5A separate transformer with 21-0-21 secondary to provide a 29V to the regulator circuit. Output so far is 13.85V without load, 13.80vdc with load (100W RF). Transistor get a bit...Last edited by maxbarjr; 06-28-2018, 02:34 AM.Leave a comment:
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Linear PSU Pass Transistor Question.
I made a linear power supply for HAM Radio use. The transformer has a secondary voltage of 18-0-18 at 240VAC input. Transformer has no labels or markings except for the primary and secondary voltages. The secondary wire size is 3.5mm. The transformer core dimentions are 11mm(h)x 8mm(d)x13.5mm(w). So no idea how many amperes the transformer was. Anyway, I made a 13.8vdc psu base on an Astron RM-50M schematics. The only difference are the pass transistors as I can't source the 2n3771 so I used the 2N3055x6 with 0.1 5W emitter resistor. Power supply works ok except that the pass transistors gets... -
Re: Question: Pure sine wave inverter.
Wow, I have not noticed those 0 ohms resistors there. Good point. I will leave it from there for now. I will check that up next time.
Thank you budm for your inputs. Really appreciate it....Leave a comment:
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Re: Rectifier Datasheet
Yes it is a DO-5 package. I measured it as 17.4mm. I also attach another pix showing the symbol like letter T before 702.
Thank you....Leave a comment:
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Re: Question: Pure sine wave inverter.
I have to remove the board to be able to get a better view of the front and back. So here is is. I don't see any pads that you can short or open to change any functionality. What I think is since this is a PIC, could it be in the program that tells which frequency (50 or 60) it should work?
I am new to microcontrollers so I can't say much what I am seeing.
Thanks....Leave a comment:
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Rectifier Datasheet
I have 4 rectifiers that I can't find any datasheet for it. I believe these are power rectifiers. It is marked TR 50 (then the sign of a diode then looks like a T then) 702. Please see attached pix.
Can anyone identify these and provide a link to where I can download the datasheet?
Many thanks.... -
Re: Question: Pure sine wave inverter.
Hi budm. Thank you for those attachments. This is interesting. I am out of town now. I will take a picture of the backside of the board when I get home by next week. I will also check if there is a similarity on the schematic you send and the board pwm board on the inverter.
I have electronics background and been repairing boards up to component level. I can draw schematics.
Again, thank you....Leave a comment:
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