Pioneer DC-Z92 Stereo Double Cassette Tape Deck Amplifier - Transformer problem

[JohnMcC]

Now on the circuit board (with the transformer removed)............... there is a resistance of about 10 ohms between Terminal 1 and Terminal 2 (primary side) because of the thicker wire link.

 

[Les Jones]

Hi John,
Measuring the resistance between secondary points 1 and 2 on the circuit board with the transformer removed should read infinity. Point 2 only goes to a short piece of track that is not connected to anything else. It would only be connected if the unit was configured for 220 volts. If that was the case the short link would be fitted and the longer link removed. With all the cables still connected to the board can you measure the resistnce between points 1 and 2 on the secondary side. These finish up being connected to the filaments on the display.

Les.

 

[JohnMcC]

Hi Les,

Measuring the resistance between secondary points 1 and 2 on the circuit board with the transformer removed should read infinity

Yes I agree, and it does read infinity

Point 2 only goes to a short piece of track that is not connected to anything else.

Correct...........now that I understand it is one or the other.......it makes sense. (Either 240vAc or 220vAc). Interestingly the short link must have been cut (when assembled), because there is a link soldered in there.

With all the cables still connected to the board can you measure the resistnce between points 1 and 2 on the secondary side. These finish up being connected to the filaments on the display.

Have just been and measured the resistance on the board across points 1 and 2 on the circuit board : Unfortunately it is open circuit, infinite resistance.
Does this mean that the filaments on the display have all blown ?

Thank you
John

 

[Les Jones]

Hi John,
It looks that way assuming that ALL of the interconnecing cables between boards are still connected. It thik there are two (Possibly more.) dispalys. I can see what looks like two bar graph displays on the schematic. You will know better as you have seen the unit. Before deciding they are definitely faulty I suggest measuring directly across the filament pins on the dispalys.

Les.

 

[JohnMcC]

Hi Les

It looks that way assuming that ALL of the interconnecing cables between boards are still connected.

Yes they are

It thik there are two (Possibly more.) dispalys

3..........please refer to photo

I can see what looks like two bar graph displays on the schematic

Correct..........equalizer

I suggest measuring directly across the filament pins on the dispalys

I have been and tried.............but I just do not know where to start.......It is a complex piece of kit with boards and wires everywhere. Cannot get to the displays.
Please see photos

Kind Regards,
John

 

[JohnMcC]

Hi Les & Spec,

I am delighted to be able to tell you that a friend of mine gave me a transformer which has output voltages fairly close to those of the original on my Pioneer Hifi.
He established from the service manual that the original transformer had the following characteristics :

Original transformer
Input voltage (Primary) : 240v AC
Output voltages (secondary) : 3v AC, 30v Ac, 14v AC


The replacement transformer :
Input voltage (Primary) : 240v AC
Output voltages (secondary) : 3.6v AC, 36v Ac, 9.2v AC
(This transformer is much larger in size than the original, so I was not worried about the wattage output)

Anyway I decided the voltages were close enough............so wired it up, and it all works !

Many thanks for your help again

Kind Regards,
John