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Author Topic: IC-745 will not power up.  (Read 4411 times)
N4NYY
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Posts: 4745




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« Reply #15 on: July 22, 2012, 07:17:59 AM »

If you need a ram unit Piexx also sells them

http://www.piexx.com/index.php?main_page=product_info&cPath=8&products_id=26

Support the USA mfg's.

Clif

Wouldn't he have the same reprogramming problem once that battery dies again on the new ram?

Wait, this one has programing in non-volatile ram? I guess I should have read everything first.
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KE3WD
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Posts: 5694




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« Reply #16 on: July 22, 2012, 07:42:23 AM »

If you need a ram unit Piexx also sells them

http://www.piexx.com/index.php?main_page=product_info&cPath=8&products_id=26

Support the USA mfg's.

Clif

Wouldn't he have the same reprogramming problem once that battery dies again on the new ram?


No. 

The aftermarket units are designed just like their more modern counterpart radios, the memory cell can go dead or be removed without losing the basic functions that tell the thing what it is and how to boot up when switched on. 

Which is the whole point of obtaining and installing the aftermarket memory boards. 


73
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KA4POL
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Posts: 1959




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« Reply #17 on: July 22, 2012, 07:57:04 AM »

This is exactly what makes the difference between a volatile and a non volatile memory.
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N4NYY
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Posts: 4745




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« Reply #18 on: July 22, 2012, 08:19:59 AM »

If you need a ram unit Piexx also sells them

http://www.piexx.com/index.php?main_page=product_info&cPath=8&products_id=26

Support the USA mfg's.

Clif

Wouldn't he have the same reprogramming problem once that battery dies again on the new ram?


No. 

The aftermarket units are designed just like their more modern counterpart radios, the memory cell can go dead or be removed without losing the basic functions that tell the thing what it is and how to boot up when switched on. 

Which is the whole point of obtaining and installing the aftermarket memory boards. 


73


Oh hell, he is better off with this one then. It is cheaper and as Clif said, USA made.
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AC5UP
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Posts: 3834




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« Reply #19 on: July 22, 2012, 08:40:01 AM »

Remember that a processor driven radio relies on two levels of RAM........ The firmware that includes all functions needed to allow the radio be a radio (the operating system or 'personality' code) and the user selected setup like menu options and stored frequencies. Have you ever wondered why newer rigs have two reset options? Like reset the radio without blowing out the frequency memories - or - reset everything back to factory default? Now you know...
 
In a modern rig the box-stock function code is stored in non volatile Flash RAM that's immune to a dead battery but can still be upgraded in the field via software that knows the unlock code. The radio actually operates from a working copy stored in RAM. Should this copy become corrupted the CPU will fail to find a valid setup and (usually) flash a cryptic error code. The astute user will then do a keyboard reset which takes the radio back to factory virginity. The operating system should be protected because without it the radio will impersonate a broken radio.

Where ICOM screwed up was in putting everything in volatile battery-backed RAM. As long as the code doesn't become corrupted that's not a problem and I have no doubt the brand new units rolling off the line with fresh batteries never missed a beat. For those of you thinking that was stupid... Yeah... But remember that if the finals blow out, or a Nichicon electrolytic blows chemical cheese-whiz all over the PLL board, the radio will have problems. It just takes a little longer for some parts to fail and the evolution of technology & marketing does have some interesting moments..... Like the SONY Betamax, Apple Lisa, MS-DOS 4.0, Windows Vista, the Ford Pinto, Chevy Vega, Hummer, New Coke, etc.     Cool
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N4NYY
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« Reply #20 on: July 22, 2012, 08:40:34 AM »

My FT-950 has one reset, but can be saved to several programs to PC, and restored later. But as you say, non of the OS lost.

It does not surprise me that Icom did this, and I am not a fan of their stuff. They seem almost arrogant and defiant in their design flaws. I will never buy one of their radios.
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KA4POL
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« Reply #21 on: July 22, 2012, 10:21:18 AM »

Keep in mind that the 745 came out in 1983 and the FT-950 was sold from 2007 on. Technology changed a bit in these 24 years.
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N4NYY
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« Reply #22 on: July 22, 2012, 11:39:16 AM »

Keep in mind that the 745 came out in 1983 and the FT-950 was sold from 2007 on. Technology changed a bit in these 24 years.

I do not think there is any reason that in 1983, they could not have stored system functions on an EEPROM. I mean, Atari games where going for about $30 retail at the time, and I am sure the EEPOM did not cost more than a few bucks.
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W5DXP
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« Reply #23 on: July 22, 2012, 03:31:51 PM »

I do not think there is any reason that in 1983, they could not have stored system functions on an EEPROM. I mean, Atari games where going for about $30 retail at the time, and I am sure the EEPOM did not cost more than a few bucks.

The Atari game cartridges were masked ROMs. The first one cost an arm and a leg but the rest of them were pretty cheap. But masked ROMs cannot be changed so the program in them has to be perfectly acceptable. ICOM probably could not afford to put a masked ROM in their IC-745 because (unlike Atari) of limited sales and engineering changes that would no doubt occur. EEPROMs were still pretty expensive in 1981 and probably didn't fit into the design budget when they started designing the IC-745. P.S. I was in Applications Engineering at Intel at the time and remember those kinds of tradeoffs well in meetings with customers wanting to use EPROMs but not being able to afford them on the specified budgets.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
N4NYY
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Posts: 4745




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« Reply #24 on: July 22, 2012, 04:28:17 PM »

But you are talking 1983. Ham radios were high end cost, vs Atari which was a consumer item. Still, several years later they did not address it when they could have.

Thanks for the good info. 
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AC5UP
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« Reply #25 on: July 22, 2012, 06:51:29 PM »

On a similar note, I started poking at the Mighty Motorola 6X12U six tube AM table radio this evening and was struck by the duality of the good / bad concept when it comes to electronic apparatus. How so? This particular radio is old enough to have waxed paper tubular condensers which are in fact parts from Hell and should be replaced on sight, yet Fabulous 50's enough to employ an early example of a ceramic circuit module.

Remember those? Rectangular dipped ceramic jobbie with something like eight wires protruding from one end. Inside (in this case) is a network of resistors and condensers used to couple a 12AV6 detector / 1st audio tube to the 35C5 audio output. Instead of repeatedly building the same circuit from discrete parts on every chassis, Rosin Core Roberta could solder in one module and be done with it. From what I can tell the time saving wasn't extreme as assemblers tend to get pretty quick when doing the same operation hundreds of times a day, but from a parts count / assembly line efficiency standpoint the module probably made sense.

So what's the duality thing?

The module is a good idea for new construction, but what if one part goes bad inside the dipped coating? Can't exactly get a set of probes in there and the chance of scoring an exact replacement today is very close to zero, so the module is probably a bad idea from a repair standpoint. However... The schizmatic does tell me exactly what's inside the module and how it's wired so I can build a duplicate if needed.

I plan to shotgun the chassis and will replace the module. Not as a modular part, but with traditional point to point wiring in keeping with the vintage.

BTW: Whoever soldered this one back in 1950 was either in a hurry or had no appreciation of Feng Shui under a radio chassis. Overall I'd rate it as sloppy since the filament lines aren't dressed away from the signal paths and some of the soldering is blob-tastic. But... At 62 years old it still plays despite resistors that have no tolerance band and Satan's waxed paper condensers.

Duality.

Worth a second thought....................  Roll Eyes
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