8 July 2019

Pioneer DC-Z94

The nature of this work certainly brings some memory of my consumer electronics era. For your information I never work for Pioneer Authorized Center.
The DCZ-94 is a semi separate system from Pioneer. The basic package consist the Main amplification with built in twin cassette decks and a matching pair of speakers. Tuner, CD and TT player were sold separately I believe. 
 You can tell its 90s from the many buttons with firm boxy but stylish exterior. If I'm not mistaken this was also the time when many manufacturers began to put reverb/echo effects in Midi HiFi's, Borrowing ideas from THX, Dolby AC-3 technology trend of the time. On the other hand, I found old HiFis’ (70s, 80s and 90s) to be well designed compared to post 2000 toys
 The main problem of the DCZ was no power. I managed to get it to power up by luck. Then it went blank unable to be powered back. The standby light is active though. I hope it’s just dry joints at the power supply.
 The first thing I did was to clean the unit inside out, it’ll make it easier to look for dry joint, blown or leaked components, cracked board etc.

As I was blowing dust from the unit, the voltage selector cap fell off. The cap is part of a rotary switch assembly. In it are two leaf contact connecting the selected AC mains to the primary. The internal locking nib appears to be brittle and snapped off.
By now it’s obvious what the culprit is but without seeing an example, it’s hard to know which contact inside the switch goes where. There’s more wires going through the voltage selector heading to the primary as this is a global compatible model. I don’t think such a replacement part exist today.
 My attempt was to hardwire the mains bypassing the redundant voltage selector. I don’t think the owner will move to Japan or North America ever.
I began determining each primary input wire with a DMM to know which one is for 100, 120, 220 and 240VAC. I measured the winding resistance. Low ohms is for low voltage and vice-versa. I also used a step down transformer so I don't blow things up at first go.
The drive belts in the tape mechanism had melted. The left cassettes door/lid had broke at the rack and pinion side. I did emailed Hwee Seng Singapore inquiring whether they kept some old stock parts. It’s no longer available. No worries. The owner was fine with it as his father isn’t going to use it, further more it belongs to his father. His father just need it to work at least. I guess it has some sentimental value to the family. Looking back at the family youth when had he bought this. Fully understood this sir.
 As the unit was sent in with any audio source nor speaker, final testing was done using an external FM tuner and a pair of loaned speakers. That’s that and thank you for reading.

For other HiFi owner out there. If yours is fitted with this very same voltage rotary selector, you may want check it for any feel-able looseness. It will break one day.

Footnote – This used to be my core work until 1997. Anyone wishes to send similar gear for repair can be considered. Premium fees apply.

Thank you


bluesguy62 said...

Awesome troubleshooting and meticulous work. One of the reasons why you always have my deepest respect.

YusTech said...

Got to earn some ringgit sir. Expenses in or near capital is becoming crazy Cikgu. Hehe.

bluesguy62 said...

I agree with you. I'm facing a headache too especially when parts are priced in USD. Let us hope that we can survive this.