Sony TC-458 not changing speed .

[NorfolkDaveUK]

I`ve just re-tested the transistor and it IS shot I think . how annoying . lol .

[NorfolkDaveUK]

Can someone help me here please . The 2sc867 transistor here in the UK is £20 and I`m not paying that . So can anyone tell me if the following would be a fair replacement .

2SC867 :

Maximum Collector-Base Voltage |Vcb|: 400 V

Maximum Emitter-Base Voltage |Veb|: 10 V

Maximum Collector Current |Ic max|: 1 A


PHE13005:

Maximum DC Collector Current 4 A

Maximum Collector Emitter Voltage 400 V

Maximum Emitter Base Voltage 9 V

Package Type TO-220AB

Different package and Slightly lower E to B voltage but should be ok shouldnt it . These are £10 for 50 !


David

[Station X]

Originally Posted by NorfolkDaveUK

I`ve just re-tested the transistor and it IS shot I think . how annoying . lol .

Why do you THINK it's faulty?

[julie_m]

Hmm ..... Probably not enough gain. The PHE13005 has a hFE of just 12 - 40 at 1A. The 2SC867 has a hFE of 50 or more.

BD441 might be a better match, but will only withstand 80V at the collector. Of course, that might not be a problem, depending what voltage it has to switch.

The package should not be a problem. TO220 and TO126 packages were designed to be mounted directly in place of a TO66 / TO3 package: the middle pin (collector) is connected to the heatsink tab.

EDIT: Oops -- crossed with Graham. Good advice there, how did the transistor measure up?

[NorfolkDaveUK]

Originally Posted by Station X

Why do you THINK it's faulty?

because base to collector is giving me a much lower reading than base to emitter , and is also giving me the same low reading when i swap the leads around ( out of circuit) , so its shot .

[NorfolkDaveUK]

Originally Posted by julie_m

Hmm ..... Probably not enough gain. The PHE13005 has a hFE of just 12 - 40 at 1A. The 2SC867 has a hFE of 50 or more.

BD441 might be a better match, but will only withstand 80V at the collector. Of course, that might not be a problem, depending what voltage it has to switch.

The package should not be a problem. TO220 and TO126 packages were designed to be mounted directly in place of a TO66 / TO3 package: the middle pin (collector) is connected to the heatsink tab.

EDIT: Oops -- crossed with Graham. Good advice there, how did the transistor measure up?

Thanks Julie , I have ordered some 13005 and will give them a try , the Collector needs 80v so it would be pushing the 441 to its limit . I`ll see how the 13005 holds up and go from there i think.

[Station X]

Originally Posted by NorfolkDaveUK

because base to collector is giving me a much lower reading than base to emitter , and is also giving me the same low reading when i swap the leads around ( out of circuit) , so its shot .

OK. I only queried it because you said you thought it was faulty rather than that it was faulty.

When giving test results it's always useful if you state what you're measuring and what the result is including units. For example Forward Volt Drop Base to Emitter 0.654V.

[NorfolkDaveUK]

Sorry Graham , I`ll try and remember that , thanks .

[julie_m]

Many multimeters have a transistor test function which measures hFE (aka gain). It requires inserting the transistor into a socket; it will accommodate PCB-mounting transistors with either the base or the collector in the middle (the pins are arranged E-C-B-E). There are two positions; one for NPN and one for PNP transistors. For power transistors, use short lengths of single-strand wire with crocodile clips on the transistor and the other end just bared and poked into the test socket.

Note that the hFE test should be done as well as, not instead of, the usual diode test. If you get a very low gain from a device that should have a much higher gain, make sure you have the collector and emitter leads in the right holes -- if you have them swapped over, it will behave sort-of-like a transistor but will exhibit very low gain.

[NorfolkDaveUK]

Thanks Julie , unfortunately mine doesnt have that feature , Its a fluke but an old one , (I dont want to change it because its bomb proof , literally , it came from the army tank unit ...lol) . Fluke 25 it is and I just love it , maybe I`ll get a component tester at some point , thanks for the info .

[NorfolkDaveUK]

OK so the 13005 didnt work at all but , someone gave me an original part so , I`ve put that in and ,...no difference . Still I have no speed change .

I`m finding this machine to be pretty complicated , there`s little power supplies all over the place

[Station X]

Did you test the "original" part before soldering it into the circuit?

Have you since tested it again to make sure that it hasn't been destroyed by a fault elsewhere in the circuit?

Can you post a bit more of the circuit please so that we can see how the diode bridge is fed.

[ms660]

The bridge input is fed from a 120v winding on the mains transformer via the motor winding and the play/FF,RW switch, on FF or RW the the motor receives the full 120 volts from the transformer, on playback the voltage across the motor is controlled by the transistor which in effect is connected in series with the motor in that function via the bridge diodes.

I tried to do a snippet circuit grab but failed hence my brief description above.

For a decent circuit description of the motor control look at the Sony TC-440 manual from vintageshifi site, the TC-458 manual can be got from there as well.

Lawrence.

[NorfolkDaveUK]

When I say "original" I mean NOS and yeah it tested good when i put it in and tests good now .

Here is the schematic.

[NorfolkDaveUK]

Thanks Lawrence . Much appreciated !

I assume the VIO / VIO is the 120v coming in .

[NorfolkDaveUK]

OK I just got the 440 manual . Thanks !

[8 Tracker]

Looking at post no.8, it looks like you've got no signal coming back from the speed sensor (pins 13 and 14 of the IC). It may be that your multimeter can't measure it. Can you put a scope on these two pins? If this signal is missing, the speed control circuit will run the motor flat out trying to get it up to the correct speed. Have you checked the motor as I advised?

Mark.

[NorfolkDaveUK]

I have mark , I had a look at the sensor and it seemed to be ok . I`ll check and see if there is a signal with the scope . The was 0v there and I believe there and it should be 1.8v so it does make sense its the sensor . I`ll have a look with the scope after tea but my meter should read it . Thanks again !

[NorfolkDaveUK]

Oh no actually , it pins 10 and 11 i`missing the voltage . 13 and 14 are a little but low though , should be 500 mV i think.

[Freya]

Are you aware of the faults these get with the capacitor/resistor arrays at position CP801 CP802 CP803 CP901 CP902.

The capacitors go short with visible blisters protruding from their sides, causing all sorts of speed and torque issues, this may not be your particular issue but worth checking as it is known.