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Posted: 4/17/2021 2:58:23 PM EDT
I have a brand new Astron RS-35A-AP power supply and a brand new Yeasu FTM-7250DR radio. My power cable is the factory one that I have added Powerpole connectors to.
I measure 13.8V at each of the following: 1. At the Powerpole connections on front of power supply 2. At the threaded studs at the rear of the power supply. 3. At the radio end of the power cable without radio attached. I attach the radio to the cable and it won't power on. Voltage drops to 0.80V on all three locations mentioned above. Unplugging the radio and turning the power supply off then back on returns the voltage to 13.8V again -- until I plug the radio in. Please don't tell me that my brand new radio is a brick right out of the box. 
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Posted: 4/17/2021 3:07:05 PM EDT
[#1]
Just to be clear, are you saying that the voltage drops to near zero when you plug in the radio while the radio’s power switch is off, or can you plug in the radio OK but when you attempt to turn on the radio power switch the voltage drops to near zero?
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Posted: 4/17/2021 3:09:45 PM EDT
[#2]
You either have a power supply problem or a radio problem and need to determine where that problem is.
You are getting 13.8 VDC without the radio because there is no load on the power supply. When not transmitting you'll probably see about a 1 to 2 amp load from the radio so I'd hook a 25 to 50 watt 12 volt automotive lamp to the power supply and see what happens. If that works OK then it's probably your radio, if the power supply shuts down with the lamp connected then it's probably the power supply. |
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Posted: 4/17/2021 3:26:15 PM EDT
[#3]
Okay, I just carted the radio outside and constructed a quick test with my Jeep's battery, two pairs of vice grips, and two lengths of wire. THE RADIO TURNS ON JUST FINE WHEN SITTING ON TOP OF MY JEEP'S ENGINE. That means I have a power supply issue. It is brand new. I only plugged it in once to hook up my brand new IC-7300 to install a firmware update, then returned both radio and power supply to their respective boxes.
Any suggestions? |
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Posted: 4/17/2021 3:42:31 PM EDT
[#4]
Are your powerpole connections correctly installed for polarity?
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Posted: 4/17/2021 3:47:34 PM EDT
[#5]
Quote HistoryQuoted: Are your powerpole connections correctly installed for polarity? This. If the radio has a reverse polarity protection diode and you connect it reversed, the power supply will sense the short and shut down. |
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Posted: 4/17/2021 4:04:58 PM EDT
[#6]
Quote HistoryQuoted: Are your powerpole connections correctly installed for polarity? I connected red powerpole to positive on battery and black powerpole to negative on battery and the radio powered up. |
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Posted: 4/17/2021 4:50:22 PM EDT
[#7]
PS is bad, return it.
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Posted: 4/17/2021 4:58:02 PM EDT
[#8]
Nevermind...
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Posted: 4/17/2021 5:06:25 PM EDT
[#9]
Try using the screw terminals on the power supply as opposed to the power poles. Should not make a difference but it could if the problem is in those connectors. Other than that the power supply won't maintain voltage under load and it needs to go in for repair.
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Posted: 4/17/2021 5:28:29 PM EDT
[#10]
As the previous poster suggested, try connecting a 12V lamp DIRECTLY to the power supply terminals. If that works, try connecting it to the end of the radio cable. I would guess the first test works, the second one fails.
I suspect you have a bad connection in the cable, i.e. it's just barely making contact. It's enough to get a reading with your DVM when there's no load, but it's high resistance so when you connect the load the voltage at the radio end drops drastically. The problem would most likely be at the power supply end of the cable. . |
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Posted: 4/17/2021 5:40:46 PM EDT
[#11]
I just left Walmart after buying a halogen headlight. Do you guys know how hard it is to find a headlight for a 1996 Jeep XJ? I've been driving it to work for almost 18 years now, and figured if I'm buying a headlight, I might as well get one I may have a future use for.
 I'll try it when I get home and update.The funny thing is that after I'd hook the radio up to the power supply's powerpoles, both the powerpoles and the rear studs would read 0.79V. I used my radio cable when I tested with my Jeep battery. I hooked two 12-gauge wires to the battery and stuffed their ends into the powerpoles on my radio cable, and it powered right up. |
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Posted: 4/17/2021 5:49:12 PM EDT
[#12]
This power supply has a foldback current limiting feature that protects from excessive current and continuous shorted output. It is acting like it is going into foldback. The most obvious reason, which has already been proposed, is reversed polarity. But you are certain that is not the case. It will be very interesting to read about the results from the headlight test.
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Posted: 4/17/2021 6:11:25 PM EDT
[#13]
Okay, the headlight works if I stick the positive lead in the red powerpole and the negative lead in the black powerpole on the power supply. It also works if I plug the radio cable into the powerpoles on the power supply and then touch the headlight leads to the blades in the factory radio plug end of the cable.
I'm at a loss. |
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Posted: 4/17/2021 6:24:24 PM EDT
[#14]
 Now it gets even more weird. If I connect wires to the rear power supply studs and precariously stick the other ends in my radio's short pigtail plug, the dang radio powers up.  |
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Posted: 4/17/2021 6:28:40 PM EDT
[#15]
Quote HistoryQuoted: Okay, the headlight works if I stick the positive lead in the red powerpole and the negative lead in the black powerpole on the power supply. It also works if I plug the radio cable into the powerpoles on the power supply and then touch the headlight leads to the blades in the factory radio plug end of the cable. I'm at a loss. It sounds like the radio is drawing an excessive amount of current to just be in receive mode. You would get no indication of that using the battery but for whatever reason it is causing the power supply to fold back. I don't know what wattage headlight you got but if it's 50 watts that's 3.6 amps @ 13.8 volts which should exceed the receive current of the radio. There is certainly no reason for a 35 amp power supply to fold back even if the radio was in transmit mode. What amp fuses are in the power cord? |
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Posted: 4/17/2021 6:28:43 PM EDT
[#16]
You don't need me to tell you that something is not right. From what you have said, it seems as though both the radio and PS may be ok. Maybe.
Why don't you take the power wires and examine them with a meter? Check the resistance for each. Are they identical or nearly so, or is one very different from the other? Do the power wires have inline fuses? Try swapping them out for new fuses. |
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Posted: 4/17/2021 6:34:34 PM EDT
[#17]
Quote HistoryQuoted: https://i.imgur.com/cBpsrUZ.jpg Now it gets even more weird. If I connect wires to the rear power supply studs and precariously stick the other ends in my radio's short pigtail plug, the dang radio powers up. Short in the other side of the connector? Can you check continuity? |
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Posted: 4/17/2021 6:34:39 PM EDT
[#18]
 I also checked continuity on my factory radio cable that I added powerpoles to, just for peace of mind, since the wires are in corrugated tubing and aren't visible -- black powerpole end matches black lead blade that connects to radio's black pigtail lead. Therefore, polarity is correct. The fuses in the cable are whatever the radio came with, and both are good. I'm getting continuity through both wires, and the headlight lit up when powered through the cable. All I did to the factory cable was shorten it and add a powerpole plug that I bought that had 12" of wire already attached. I want to use this radio in both my truck and home. Hence I am installing a powerpole panel in place of my truck's cigarette lighter (new wiring, of course).  
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Posted: 4/17/2021 6:50:59 PM EDT
[#19]
Quote HistoryQuoted: The fuses in the cable are whatever the radio came with, and both are good. I'm getting continuity through both wires, and the headlight lit up when powered through the cable. All I did to the factory cable was shorten it and add a powerpole plug that I bought that had 12" of wire already attached. The reason I asked about the fuses is that if they are 20 amp fuses and the power supply is shutting down without the fuses blowing then it has a problem or there is a problem in the cable somewhere. The radio should be pulling about 2 amps in receive mode and less than the rating of the fuses in transmit mode. |
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Posted: 4/17/2021 6:54:50 PM EDT
[#20]
 This works, too. Leads connected to REAR of power supply and stuck in the powerpole ends of the cable connected to the radio. So, the problem occurs when connecting to the powerpoles on front of the power supply with the radio cable's powerpole ends. Even sticking bare wires in the power supply's powerpoles and connecting to the radio works. |
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Posted: 4/17/2021 7:00:11 PM EDT
[#21]
Quote HistoryQuoted: This works, too. Leads connected to REAR of power supply and stuck in the powerpole ends of the cable connected to the radio. So, the problem occurs when connecting to the powerpoles on front of the power supply with the radio cable's powerpole ends. Even sticking bare wires in the power supply's powerpoles and connecting to the radio works. Problem solved. It's in the cable. |
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Posted: 4/17/2021 7:04:01 PM EDT
[#22]
Quote HistoryQuoted: Problem solved. It's in the cable. Are the tabs in the connectors just not making good contacts? Can I tweak them with a screwdriver to make them contact better? I "think" I damaged the connectors in the cable just now try to preload them. Anyone have a source for a QUALITY powerpole plug with pigtails already attached? The cable works when I stick wires in its powerpoles and connect the other ends to the powerpoles or studs on the power supply. |
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Posted: 4/17/2021 7:48:32 PM EDT
[#23]
Just get the crimpers, you'll be money ahead in the long run.
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Posted: 4/17/2021 8:01:50 PM EDT
[#24]
Quote HistoryQuoted: Are the tabs in the connectors just not making good contacts? Can I tweak them with a screwdriver to make them contact better? I "think" I damaged the connectors in the cable just now try to preload them. Anyone have a source for a QUALITY powerpole plug with pigtails already attached? The cable works when I stick wires in its powerpoles and connect the other ends to the powerpoles or studs on the power supply. I used those connectors years ago when I was racing R/C cars. At the time they were called "Sermos" connectors and the metal part could be removed from the plastic part to adjust the tension. I quit using them because I was having some problems but it's been way too many years for me to remember what that problem was. Did you solder the metal tabs to the wires or just crimp them? I'd strongly recommend soldering any type of power connection, I've had problems with crimped connections before and always solder my connections. |
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Posted: 4/17/2021 8:08:08 PM EDT
[#25]
Easiest explanation, whoever installed the powerpoles in the power supply connected the polarity backwards.
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Posted: 4/17/2021 8:11:11 PM EDT
[#26]
Quote HistoryQuoted: I used those connectors years ago when I was racing R/C cars. At the time they were called "Sermos" connectors and the metal part could be removed from the plastic part to adjust the tension. I quit using them because I was having some problems but it's been way too many years for me to remember what that problem was. Did you solder the metal tabs to the wires or just crimp them? I'd strongly recommend soldering any type of power connection, I've had problems with crimped connections before and always solder my connections. I bought THIS because I didn't own the crimper and figured I'd never need them more than once. I cut that damned plug off my cable and attached the cable leads to the rear of the power supply and it's powered-up just fine. I'll tell you guys right now that RT Systems software is the greatest thing since sliced bread. I used it for my HT and was able to copy and paste 82 repeaters into it with two mouse clicks. Tonight, I opened that HT list, copied them, pasted them into my new software, and had them in my mobile radio in less than a minute! Now both radios' repeater lists are a mirror image of each other. |
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Posted: 4/17/2021 8:14:00 PM EDT
[#27]
Quote HistoryQuoted: Easiest explanation, whoever installed the powerpoles in the power supply connected the polarity backwards. I initially pondered that, but discounted it when I was able to add jumper wires from black powerpole to black powerpole and red powerpole to red powerpole and make the radio work. Something was happening when they were plugged together that didn't happen when I used jumpers. |
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Posted: 4/17/2021 8:31:57 PM EDT
[#28]
Quote HistoryQuoted: I bought THIS because I didn't own the crimper and figured I'd never need them more than once. I cut that damned plug off my cable and attached the cable leads to the rear of the power supply and it's powered-up just fine. We got to the point that we sort of expect a certain level of QC before something goes out. It takes less than a minute to check continuity on both sides and infinite resistance between the leads. Apparently that doesn't get done any longer. I bought a cable adapter a couple of months ago and when I plugged it into the radio it immediately went into transmit mode. I took the cable end apart and there was a solder bridge where there wasn't supposed to be one. You just can't get good help these days. Glad you got it worked out. |
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Posted: 4/17/2021 8:35:15 PM EDT
[#29]
Quote HistoryQuoted: I initially pondered that, but discounted it when I was able to add jumper wires from black powerpole to black powerpole and red powerpole to red powerpole and make the radio work. Something was happening when they were plugged together that didn't happen when I used jumpers. |
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Posted: 4/18/2021 2:13:49 PM EDT
[#30]
So is this correct?
It works when you connect to the rear posts of the power supply but does not when you connect to the power pole connections on the front? Is that right? Check the polarity of the voltage on the power pole connections on the front. make sure red is positive. If the polarity is correct, then my guess is that there is a bad connection / cold solder / high resistance connection in the power pole connections on the front of the power supply. Either the power pole connections themselves or the wires at the board connection. If you can take the top off without voiding the warranty, connect the radio to the from power pole connections, turn on the radio and measure the voltage drop across the power pole connection. There should not be any. If there isn't, then work your way back and check across each connection to include where the wires are connected to the power circuit board. If you find a voltage drop then there is resistance in the connection that becomes apparent when current flows through it. It would not be apparent if there is no current. Like it is from your OP. 0.8V is suspiciously the same voltage drop across a forward biased diode / transistor junction. ETA: What does the front voltage and current meters show when connected to the front and the radio in not working? |
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Posted: 4/18/2021 8:29:15 PM EDT
[#31]
What do you use to measure voltage? Do you know how to measure polarity on a DC power source?
I often help local hams when they have problems with radios. The power related problem I see the most is usually cause by voltage drop in power cables. Fuses and fuse holders are often to blame. Some connections develop resistance and cause voltage drop in the cable. When this happens, radios work fine on receive but shut down on transmit. Icom 4 prong plugs on the radio side often fail too. I've seen relatively new radios and cables fail. Reversed polarity can damage a radio, especially if wrong type fuses (time delay) are used. Like several guys mentioned, most radios have protection diodes but I've seen them fail too. Be careful with polarity and ALWAYS check it on the end of the cable (radio side) before plugging it into a radio. |
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Posted: 4/18/2021 8:35:39 PM EDT
[#32]
I'm 99% positive that the problem was in the Powerpole plug that I bought off eBay. I could stick wires into the power supply Powerpoles and the radio would power up just fine. It just wouldn't work with that eBay plug. I installed the radio in my truck today and it works just fine. The power supply worked just fine last night to power my radio during programming.
When I receive the Powerpole components that a very generous member of this forum is sending me, I'll try connecting them to the power supply. Then we'll know once and for all if there is a problem with the power supply's Powerpoles. Thanks, gentlemen, for all the replies. I sincerely appreciate each and every one of them. |
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Posted: 4/19/2021 6:13:22 AM EDT
[#33]
Try measuring the resistance of the power leads and see what kind of readings you get. With protection circuits possibly in play, a simple continuity check is not enough.
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Posted: 4/19/2021 9:50:51 PM EDT
[#34]
If you isolate the Ebay pigtail, and measure resistance between the two conductors, is it open? Long shot: do you have access to a "Hypot" tester(tests insulation between conductors at high voltages)?
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Posted: 4/20/2021 6:07:20 AM EDT
[#35]
Quote HistoryQuoted: If you isolate the Ebay pigtail, and measure resistance between the two conductors, is it open? Long shot: do you have access to a "Hypot" tester(tests insulation between conductors at high voltages)? As a last ditch effort the other day, I stuck tiny screwdriver into each side of the plug in an attempt to tweak the connectors a little bit in order to facilitate a better connection, and broke at least one of the connectors. I then cut it off my power cable and tossed it into the trash. I definitely don't have any specialized electrical testing equipment beyond a cheap digital ohm/ap/volt meter. |
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Posted: 4/20/2021 6:25:07 AM EDT
[#36]
I don't have a Hypot tester myself, not something you would use everyday! A former employer of mine had them, and I was able to borrow one a number of years ago to find an intermittent short in a harness(which, after reading through this thread and thinking about it, sounds like it may have been your problem). They are great for finding shorts using real world voltage, which may reveal a short that the voltage of an Ohmmeter won't cause. I'm glad you got past it.
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