Hifonics Zeus VII

[warpedhifi]

I have this Hifonics Zeus Series VII to fix, and the amp does not turn on? A little history, the amp was running great for 3 years. It does or did have an issue, when the amp was turned off, it would leak around 2 volts from the remote, which was enough to power on other amps. Then one day the amp was running fine, went into a store to get a few things, come back out, and the amp would not turn on?

The amp does not blow fuses, nothing looks bad on the inside, here are the readings on the TL594CN, and here are the pins and voltage:

1: .389
2: 4.64
3: .055
4: .036
5: 1.515
6: 3.509
7: .001
8: 12.67
9: 4.76
10: 4.75
11: 12.66
12: 12.19
13: 4.99
14: 4.99
15: 4.99
16: .001

The batt volts with amp hooked up is 12.70

Any ideas??? Thanks, in advance!

 

[Perry Babin]

The IC is producing output. What is the DC voltage on the gate leg of the power supply FETs?

Is there any sign of moisture/liquid around the base of any of the larger capacitors?

 

[warpedhifi]

All the caps look good, and in the power supply, we found one fet that is blown, but it is parallel with 5 others, the other side some of the fets at reading 7.5 volts instead of the 12.7 I tested with, while others in the same parallel read 12.7. So, will replace all 12 fets to be on the safe side.

The FETS are IRFz40, would it be a good idea to stay with them or change to a different model?? Thanks

 

[Perry Babin]

Does your 12v power supply have a variable output voltage?

Do you have an oscilloscope?

 

[warpedhifi]

The amp is being checked using a 12 volt battery in a vehicle, did not have access to a bench p/s at the time. But I should have the amp this coming weekend, so I can hook it up to my bench p/s. Yes I do have o-scope. Here are the pics of the power-supply in the zeus:

On the lower side, that does not have the blown fet, 2 of the six fets was reading around 7.5 on the center leg of the fets and they all should be reading B+ voltage.

 

[Perry Babin]

Without an adjustable power supply, it's going to be difficult to determine if the Z44s will work properly. Changing the gate resistors to a lower value (assuming that the originals are 220 ohms) will help but could cause other problems. 47 or 68 ohm gate resistors should be OK with the Z44s.

Try to locate a variable power supply.

The center legs of the FETs are directly connected to the primary transformer windings so if the DC voltage wasn't identical to the B+ voltage, you have a broken/bad connection.

 

[warpedhifi]

All the resistors are 220 ohms, most were reading ~220 ohms but some were reading in the low 100's and one was around 57 ohms. I am going to replace them and will stay with the z40's.

One last question, is there a difference between a IRFZ40 and a IRFZ40PBF? Mouser does not have the Z40's in stock, but they have the Z40PBF. If there is no difference I will order the PBF's.

Thanks for your help Perry!!!

 

[Perry Babin]

The lead free version (PBF) should be exactly the same.

 

[warpedhifi]

Update, Replaced all the Fets in the power supply, fixed a couple of broken traces in the power supply. All the gate resistors measured good, amp powered up normally, and plays great! Ready for another 20+ years of playing.

Thanks for your help Perry, Your repair tutorial was a great help on repairing the broken traces.

 

[brooklyn72]

Hello...my name is alex.

And iam looking for some one who could fix my zeus vll amp.the channels are burnt....I know theres a guy called steve....who can fix it....but I know u guys can too....can u call me and let me know if you csn do it..... phone number removed