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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Jan Mon 22, 2018 2:41 am 
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ok, well, i guess that shoots the 1.6 ohm impedance load idea, perhaps.

steve

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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Jan Mon 22, 2018 7:17 am 
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Wally58 wrote:
The NTE example that I used may have different specs than the Chrysler chip. I just picked the NTE1232 because of the similar pinout, configuration and that it is used in automotive applications.
It suggests an 8 watt output which the Chrysler radio circuit may or may not support.
I have a 1988 NTE catalog that I just used to find a 5-pin AF amplifier IC in a TO-220 case with a similar non-inverted/inverted input, 12 volt Vcc/ground and single output pin.
I doubt that we could find published specs for the 3598445 IC other than its rated output.

Wally,
Pretty good pick! My 1998 NTE cross reference guide lists the NTE1232 as the replacement for 8445(Chrysler). Looking at the NTE PDF of electrical characteristics for NTE1232 I see that the output resistances noted are either 4Ω or 2Ω. My guess is that 4Ω is probably a good match for the Chrysler radio.

By the way, I think Sams dropped the ball on AR-181 (page 35) being a similar radio. Not only is it a two speaker with fader output, the output is a transistor pair, not a chip. It is similar in outward appearance though.

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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Jan Tue 23, 2018 3:31 am 
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excellent, guys

steve

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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Jan Sat 27, 2018 1:29 pm 
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I finally got down to the library and scanned the Chrysler AM radio schematic in Sams AR-181. This Sams edition is from 1974, which is an older design radio than Dutch rabbit's 1978 radio.
The older design would explain the discrete transistor audio output stage rather than the newer audio output IC in his radio. The AM tuner section may be similar to his as that part may not have changed much?
The Sams AR-290 folder may still be the most accurate guide, even if it isn't an exact match for the 4048362 radio.
As ICs became more popular in the 1970's, they replaced discrete transistors in order to simplify circuitry. Modular designs made for easier and less expensive assembly and manufacturing techniques, which the auto (or any) industry is constantly striving for.
The Sams AR-181 also had a Chrysler AM radio with an integral 8-track player and a Chrysler AM/FM (monaural) mechanical SearchTune radio for the more expensive offerings. These were way different in layout than the base AM radio.
I always like to peruse the pictures of the (then brand new) units in the older Photofacts as they bring back a flood of memories.
The Photofact index isn't entirely accurate and I have found errors before. Sometimes the manufacturer will make running changes that Sams can't possibly be held responsible for keeping up with, but Sams did have supplements and addenda updates when they could. Overall the information is helpful, but you have to take them with a grain of salt. An error can be misleading and waste time until you catch it.
Sams sometimes lists other part manufacturers in the parts listings that may be used as 'substitute' replacements. This has been invaluable to me in cases where (e.g.) an IF transformer needed replacement and the original could not be found and I had no idea of a generic or aftermarket substitute.
The reference designators used by Sams is different than the manufacturers, but sometimes the Sams schematic is easier to read. Rider's and Beitman's seem to match the manufacturers schematic and service information more closely.


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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Jan Sat 27, 2018 4:46 pm 
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i got another radio today. i believe it is the Model 4048362. the knobs match up just like the 4048362 pic/docs. also, i was told that it was a Model 4048362, although the sticker is missing.

this 4048362 radio that i just received uses the the 8445 chip just like my 3401640.

since the 4048362 uses the 8445 chip and it says 3.2 ohm in the 4048362 servic data ; my 3401640 radio useds the 8445 chip ; we can do the transitive property of equality and say: "if A = B and B = C, then A = C.

my radio will do a 3.2 ohm speaker.

steve

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 Post subject: Re: 1978 Dodge Radio Schematic Spkr Impedance Needed, Questi
PostPosted: Feb Wed 07, 2018 3:59 am 
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I would like to use a 161 bulb in these radios. they are a bit less lumens and are a bit less wattage. I'm going to presume that the 161 will be a bit cooler than the others.

https://www.ebay.com/itm/2PK-12v-AUTO-B ... 1438.l2649

also, would a LED wedge bulb look to "artificial" when illuminating the dial ?

https://www.ebay.com/itm/JDM-ASTAR-2X-W ... 1438.l2649

I would like to have this illuminated as original as possible. will LED's make it look different than original ?

power supply current load with a 161 or LED bulb is not an issue.

thoughts appreciated,

steve

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