Hifonics Olympus VII

[mike49504]

Perry,

Do you or does anyone know the value of theese resistors??

As you can tell they are badly burnt

 

[Perry Babin]

Probably 2.7 ohms.

 

[mike49504]

Wondering if you know why theese things smoked ?? Is there a common problem or someone abused the amp?

 

[Perry Babin]

It's generally due to abuse but it can happen if there is an open shield ground in the amp or head unit.

 

[1moreamp]

It's generally due to abuse but it can happen if there is an open shield ground in the amp or head unit.

I agree abuse. I have replaced hundreds of these resistors over the years. 2.7 ohms 2 watt, you can try 5 watt for durability reasons.

These like to toast up like this on extreme clipping situation like trunk bass. The open ground Perry mentioned would have ground loop noise so bad you would not be able to listen to it for more then 10 seconds without shutting it off. Unless the amp was connected to subs in a trunk where all you could hear would be muffled bass rattling the vehicle. Some folks will listen to anything you know...lol

 

[gisewhcs]

I saw those resistors burnt to ashes in several ZED-Amps from that era.
Most of them failed because of open signal grounds.

Nearly always the the ground pin was broken directly at the PCB, probably a manufacturing fault at those cinch connectors.
Check that by bending/twisting the connector a bit, because sometimes there was no open ground when I had the amp disassembled on my bench,
but reassembled with the sideplates on it, signal ground read open.

 

[mike49504]

I have a problem still with this amp if the board is out of the sink its idles perfect.

As soom as i put the board back into the sink and clamp stuff down it draws current. I have the insulator paper in place and its in good condition.

And when i was trying to figure out why i bump 1 of the side plated and it started sparking.

Any ides on whats causing this?

 

[Perry Babin]

With the transistors tightly clamped to the heatsink, check for continuity from the center leg of the power semiconductors to the heatsink. They should all read OL.

 

[mike49504]

From the center leg of the 2sc2061's to the chasis of the amp reads a direct short.

 

[Perry Babin]

The 2061 in the power supply?

 

[mike49504]

Yes the 2061 Is in the power supply section in front of the fets.

Out of the board they test fine when in the board and board in sink they test shorted from middle leg to chasis of amp

 

[Perry Babin]

Are you reading ~0 ohms?

The center leg is likely connected to ground by a resistor of ~47 ohms.

 

[mike49504]

From center leg of 2sc2061 to the heatsink 0 ohms

 

[Perry Babin]

That's connected to the gate resistors. Many of the traces probably pass along of where the board meets the sink. Do you see any areas where they could be making contact?

 

[mike49504]

Ill look on the board . I also overlooked this before but one of the mylar caps is missing in the power supply section (c9) has been removed by someone.

 

[gisewhcs]

Was this cap connected in series with an 24Ohm R to prim. ground?
And do you have a second pair in this configuration?
Then it's likely a 0,01µF 100V.

 

[janikphoto]

I used to have the olympus VII and loved it to death back in the day. I had two, and each time they were stolen... I miss those amps! I still have the plug connectors in a box somewhere. Sorry for highjacking your thread, but I had to give a shout out to such a wonderful old school amp.