Schematic error? Dynatron HFC 105

[Emibell]

Hi, There is a complementary pair of transistors in the output stage that I believe need replacing.
TR17 and TR14 on the attached diagram, which are (Obsolete) C1179 and C1180 respectively.
From other threads I see BC557 and BC547 suggested as replacements.
My query is that the only reference I can find on the net says TR14/C1180 and it’s equivalents are NPN but the schematic shows it outlined in yellow as a PNP.
(Also on the board I have it had already been replaced by somebody with a PNP.)
……..
Thanks for reading, I know it’s easy to get things mixed up reading these diagrams and hope I haven’t made some silly mistake interpreting the information I have found.
……….
Can anyone confirm what type TR14 should be?

[orbanp1]

There is no error in the schematics.
The bottom pair of transistors constitute a Sziklai-pair: https://en.wikipedia.org/wiki/Sziklai_pair.
So the transistor in question is indeed a PNP device.
The schematics you presented is not too legible, so the supply voltage, or the half voltage, is not readable, and you did not give the power rating of the amp either...
That PNP driver transistor receives the full supply voltage, you need about 20% - 30% higher rating in that transistor.
If it is a TO-39 or TO-5 cased transistor then a BC303 (90V, 1A), or 2N2905 (60V, 0.6A) transistor should do.
A BD140 or similar could be used as well. It has TO-126 case, and has 80V and 1A max ratings.
The BC557 has lesser capabilities (50V, 0.2A), though it might last for a while in the amp, depending how hard is the amp driven.

Regards, Peter

[jamesperrett]

Originally Posted by orbanp1

There is no error in the schematics.
The schematics you presented is not too legible, so the supply voltage, or the half voltage, is not readable, and you did not give the power rating of the amp either...

The amp appears identical to the one used in the HFC101 (and other HFC100 series units). The service data is available up top. Unfortunately the circuit diagram isn't that clear but it certainly appears to show a part number of C1180 next to that transistor. However, I wouldn't assume that there should be a 2S in front of that number as the 2SC1180 looks to be a very different beast to the transistor actually used. They use a very unusual package which I don't remember seeing anywhere else.

The output is specified as 45+45W into 8 ohms though no distortion value is specified. The single sided power supply is 72V according to the service data and so the output is at 36V.