Old tape recorder missing part

[Rait]

Hello

Found old russian tape recorder from 1971 and missing loudspeaker. Can someone read attached chematic and tell, can I put 4 ohm loudspeaker. It is connected to output transformer with coil resistant 2 ohm. Is it possible to damage transformer if speaker not matched? Or difference only output loudness?

Thank for help advance.
Rait

 

[lcsaszar]

Hello Rait,

You can't destroy the transformer. It will work fine, and most likely you won't notice the difference. If the original speaker was 8 or 16 ohms, the 4 ohm speaker will draw higher current which can kill the output transistors. On the other hand it will take more power, i. e. it will be louder. So you probably turn down the volume a bit, and it will be safe again.

 

[Rait]

Thanks Icsaszar. Are thare any way to read from this schematic how many ohm was loudspeaker originaly used. I am not good in electronics. Technical data in manual say that audio power is 0,3 watt. I d like to restore recorder as originaly as possible. Thanks.

 

[Cal Weldon]

In tape deck from 1971 I am guessing 8 or 16Ω.

 

[PRR]

If the secondary DC resistance is really 2 Ohms (most ohmmeters are not good with small resistance), then we would expect 10 or 20 Ohm speaker for low loss.

Considering this was a very low-class product, they may have let losses run a little high. So maybe 8 or 16 Ohms.

Use 8 Ohms and don't turn it up into distortion.