Identifying old amplifier.

Thread Starter

hitu26787

Joined Nov 14, 2022
14
Hi friends I want to know whether this circuit is complet amplifier or something else. I took out from old music system.

It has 1 x 3 pin input slot in down side left corner.
4 output slot for speaker.
2x2 pin slot on top side connected with trnsformer wire connected to bord.
And 2 other slot which were directly joined with sound recorder.
Can anyone help to identify whether it is amplifier or not.
 

Dodgydave

Joined Jun 22, 2012
10,583
I would say it's a power supply and an input/ output sockets for signal or speakers.
Can you take pictures of the black chip on the heatsink..
 

Thread Starter

hitu26787

Joined Nov 14, 2022
14
I would say it's a power supply and an input/ output sockets for signal or speakers.
Can you take pictures of the black chip on the heatsink..
Yes I ll send photo of it. Input in this circuit was coming from another board which was getting input signal from fm, cassatte and power supply from this circuit board.
 

Dodgydave

Joined Jun 22, 2012
10,583
Yes looks like a full amplifier, the picture of the 9 pin amp chip on the heatsink we can't see it..( behind the large capacitor)IMG_20221114_144218.jpg
 
Last edited:

Audioguru again

Joined Oct 21, 2019
5,406
The amplifier IC has 9 pins and is bolted on each side so it is not in a TO-220 case.
There is a TO-220 transistor or voltage regulator bolted to the heatsink near the orange capacitors.
 

MisterBill2

Joined Jan 23, 2018
13,688
What We are seeing is an amplifier with a power supply. That is obvious by the power transformer with the power diodes. The 9 pin device is a stereo power amplifier IC. There is indeed quite a bit of additional circuitry, probably amplifiers to boost the signal up to what the power amp requires. To learn more the TS will need to see the type number on that 9 pin IC.

What is confusing is the repeated references to "slots". I see quite a few RCA jacks, also correctly identified as "phono jacks" because that was the original application. It took about 35 years to cone up with a cheaper connector that was as widely accepted.
 

Thread Starter

hitu26787

Joined Nov 14, 2022
14
What We are seeing is an amplifier with a power supply. That is obvious by the power transformer with the power diodes. The 9 pin device is a stereo power amplifier IC. There is indeed quite a bit of additional circuitry, probably amplifiers to boost the signal up to what the power amp requires. To learn more the TS will need to see the type number on that 9 pin IC.

What is confusing is the repeated references to "slots". I see quite a few RCA jacks, also correctly identified as "phono jacks" because that was the original application. It took about 35 years to cone up with a cheaper connector that was as widely accepted.
Thanx for ur reply. I am not much knowledgeable in this line so I call them slots..
That 9 pin ic is TDA 1523. Does it work as amplifier an if so how many watt of speaker it can run. This music system had 2 x 3 inch magnate speakers with cone size around 10-12 inches. Watts or ohm were not written on it.
 

MisterBill2

Joined Jan 23, 2018
13,688
In the era when that amplifier was common the concept of "subwoofer" had not yet been developed. It was just a single stereo amplifier for an all-in-one low-end home entertainment package. Good but not great.
 

MisterBill2

Joined Jan 23, 2018
13,688
Certainly there were bass speakers, but the subwoofer for that thumping bass was not part of most music systems at the time. My Marantz system has 8 inch woofers, and produced very nice rock, back in 1985. But there were no sub-base sounds.
That came mostly with the "RAP" sound, which I do not put in the same realm as any actual music.

TDA 1521, 23807, HSH9210 4 I am guessing that the HSH is the plant code for the IC, 92 is the year,10 is for October, and 4 is the day. Most larger semiconductor devices do have a date code that is for quality control purposes. This is my interpretation. That would have the amp being close to30years old, since all of the parts would be a bit older than the assembly.
 
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