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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 17th Jul 2020, 11:47 pm   #1
Techman
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Default Icom IC-PS15 power supply.

I was given this heavy old lump yesterday for helping a chap with his radio and antenna. It had been in his garden shed for a very long time and he said that he sold the radio that used to go with it, but kept the power supply back. He told me that it was faulty in that it would pack up after a while of running. He has had (and still does by the smell) vermin in this shed and the unit stinks to the point that I made the mistake of bringing it in the house and in the morning the house smelt like his shed, so it's gone out into the garage for the time being!

I haven't opened it up yet, but I did plug it in and measured around 13.7 volts at several of the 'outputs' - note the additional output cable tied to the main power cable. The fan on top is just floating around unattached and it's wiring goes in through one of the grill slots on the top of the unit - it doesn't run on switch on, so guess there's a temperature sensor somewhere.

The chap that gave me the unit pointed out the thick layer of nocotine all over it, particularly the power cable and plug, which was on it from when he bought it from it's original owner and not from while it had been in his possession. It can stay out in the garage for a while to air out before I open it up to see what horrors could lurk within - it'll make a good door stop to hold the shed door open on a windy day if nothing else!
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Old 18th Jul 2020, 1:37 am   #2
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Default Re: Icom IC-PS15 power supply.

Yuk!

If we're going to be honest, the big three Japanese manufacturers all made traditional linear power supplies in this era. ALL of their circuits are a bit oddball and ALL of them have been known to fail with the series pass transistors short-circuit, putting the full unregulated voltage (about 22v on receive) straight into the poor transceiver connected to them. Most of these supplies have no crowbar protection. They may have Icom, Trio or Yaesu written on them and a large price premium over the UK manufacturers of the era (BNOS, DRAE etc) but they were a nice quality case filled with fairly poor quality electronics.

(While I'm at it, even posh American setups were decidedly iffy. If you bought a ten-tec corsair, with its matching power supply, they routed mains live up a ribbon cable to the on/off switch in the transceiver, and back again to the transformer in the power supply. Who would have expected 240v on the loose inside a 13.8v powered transceiver running on an external power supply? OK, it was a heavy gauge ribbon cable, but only single-insulated.)

As this one has been around the block a few times, it's likely to have been visited by the phantom twiddler's DC-loving brother. View it as a cabinet, a transformer and a heatsink!

David
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Old 18th Jul 2020, 7:53 pm   #3
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Default Re: Icom IC-PS15 power supply.

You've pretty much summed it up, David.

I had one go to full DC voltage while I was actually sat watching the radio. The 'S' meter light suddenly went a lot brighter coinciding with a strange noise on receive which broke the squelch. I instantly knew what had happened and cut the power!

I used to be very much against switch mode power supplies but, in reality, they're generally a lot safer in use than these 'old school' linear types, and RF noise supposedly generated by them isn't really a problem with them these days - BTW, I'm talking about the ones designed for powering radio equipment and not all the other noise generators that everyone has to contend with! (If I want to leave radios unattended, I've got a big old 12 volt smoothed, but unregulated unit that can never realistically go 'over voltage').

I've opened it up and it's as vile inside as it is on the outside and it still stinks like a poultry shed. In the pictures below you can see the 'add-on' board for the fan sensor, with an 'old school' thermistor, which looks of a type that's nicely familiar and has broken away from its bonding compound sticking it to the heatsink. There's also the remains of glue where the fan would have been stuck to the top of the grill cover The skeleton preset seen down in the depths looks to be the 'set voltage' adjustment of the main unit. There's a good hefty transformer with a double 117 volt primary. The unit is rated at 20 amps, so it could be useful if the smell ever leaves it. There's also still the possible fault of it cutting out after a while - perhaps that fan sensor 'add-on' circuit board incorporates some sort of cut-out? I'll have to stick a good load on it and leave it for a while to see what happens!
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Old 18th Jul 2020, 8:15 pm   #4
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Default Re: Icom IC-PS15 power supply.

Truly gruesome!

I can get the smell just by looking at the photos... maybe those folk using TV ads to flog perfume aren't completely barmy?

Well, it looks like you have a reasonable transformer...

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Old 18th Jul 2020, 8:20 pm   #5
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Default Re: Icom IC-PS15 power supply.

Is that really a glass cartridge fuse butt-soldered to a reservoir capacitor tag?! I'd be worried about what else could be lurking inside just waiting to inflict horribleness on its load. I think, as David says, you've got some iron and copper (transformer) and aluminium (heatsink) as a basis to build something decent on. As it stands, I wouldn't risk it with anything more valuable than a second-hand headlamp bulb,

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Old 18th Jul 2020, 8:51 pm   #6
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Default Re: Icom IC-PS15 power supply.

I have seen (here) some grotty photos of nice kit and now perfect photos of grotty kit. As turretslug says, a good basis for a good looking power supply, you have all the expensive bits there, box, transformer and capacitors.
 
Old 19th Jul 2020, 12:30 pm   #7
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Default Re: Icom IC-PS15 power supply.

Quote:
Originally Posted by Radio Wrangler View Post
If you bought a ten-tec corsair, with its matching power supply, they routed mains live up a ribbon cable to the on/off switch in the transceiver, and back again to the transformer in the power supply. Who would have expected 240v on the loose inside a 13.8v powered transceiver running on an external power supply?
This one's like that!

I was wondering what those two extra thinner wires were for in the output cable.

I've not actually looked at it any more and it's still out in the garage, but I did a little bit of research on it last night and was looking at the circuit diagram for the first time. I'm guessing that those wires must be cut off and bypasses somewhere within the unit, as there's nothing to meter on them - lucky I always have the meter set on a higher range when first measuring unknowns and lucky I didn't touch the ends of them if they hadn't been isolated, as the whole lot had just been cut off flush and un-insulated, and it had been in use like that with just one of the outputs plus that 'add-on' socket on the thin wire presumably being used for something. I've stripped the outer sleeving back and separated them all now!

I know what you mean about being able to smell it just by looking at the pictures. I kept imagining I could smell it at various times in the house yesterday, and I've been used to dealing with bad smells in the past, digging out septic tanks and their outflow pipes, working in labs dealing with dead animal parts, working on farms many years ago and I've kept some livestock myself.

The soldered in glass fuse is supposedly rated at 20 amps, and I suppose it could be argued that it's not a user replaceable item and that any proper holder would have to be able to make a very good, and reliable contact at that sort of current (making excuses for them), but the unit is not 20 amps continuous current rated, it's apparently 50% duty cycle. The two pass transistors are 30 amp devices with a max junction temp of 175c.
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Old 19th Jul 2020, 9:39 pm   #8
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Default Re: Icom IC-PS15 power supply.

It's been outside on the old 'pew' for most of the day and been loaded up with a couple of old car headlights at around 10 amps or so (even with voltage drop in the connecting wires) for an hour or two. It doesn't like being plugged in with the load already connected (no output) as it can't detect its reference voltage, so 'on' first and 'load' connected second. I didn't experiment to see what level of load would work on switch on, but it would be whatever the original transceiver would have taken when on receive.

It looked as though that fan had been arranged to 'suck' air from the internals, but once I'd propped it up blowing on the rear heatsink, it cut in and cooled the heatsink from being almost too hot to touch, back down to a normal warm temperature. When it first cut in, I thought it seemed a bit feeble, but I think the speed increased with increasing temperature until the temperature came down and the fan cut off. The fan cut in and out periodically and kept the heatsink temperature stable, even though that thermistor isn't properly bonded to it. I can't quite decide if it's heatsink compound that's dried out or some kind of fire cement that was originally holding it in place. It's not a brilliant idea having it hard against the metal as the ends have wired connections that could possibly short to it, although in reality, this doesn't seem to have been a problem. The control circuit is home built on perf board, so someone's been a busy boy in the distant past, but it certainly does work well, although the fan should have been fitted on the back, blowing directly on the heatsink, and not drawing air from the main innards. A fan and control unit seems to have been an optional extra when these power supplies were new, and that's absolutely ridiculous, as it should have been part of the power unit from manufacture in my opinion - no wonder someone added their own!

It's in the house now and it's lost its farm yard mouse piddle smell, with just that 'smokers' smell if you sniff it. I blew the innards out with the air blower, but not a lot came out of it due to the muck being like stuck on tar - smokers take note, looking particularly at some of the previous pictures, this is what your lungs will look like!
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