Hifonics brz1700.1d straight to protection.

[rhempz01]

I have a hifonics that goes straight into protection. Immeadatlt after applying b+. No shorted outputs nor power supply fets. Drivers check ok in the power supply. I pulled the rectifiers and it Powers up now. Something in the output section. Is definitly causing the issue. A voltage regulator?

 

[rhempz01]

One of the small transistors on the output driver board doesn't check on diode test. Doesn't conduct across the two contacts. 1D Q6

 

[rhempz01]

One of the small transistors on the output driver board doesn't check on diode test. Doesn't conduct across the two contacts. 1D Q6. Does it matter which part I get mmbta42. Can someone tell me the exact part number so I can order them.

 

[bl4ckw1d0w]

I always replace the audio drivers in this amp regardless of how they test. Many times it solved my issue. I know they run hot from previous posts. Post the part number your trying to purchase.

Usually the difference in part number is just how they are packaged but if there are variations you can check the datasheet provided for the part listed. Some are cut tape, some come on a real, etc. Sometimes they even have a different pin assignment.

Check here. Hifonics BRZ1700.1D No Output

 

[Perry Babin]

Type 7 page of the tutorial.

 

[rhempz01]

Thanks. They all look virtually the same to me. One says high voltage but the datasheet are identical.. thanks perry, I'll go inside and look it up. I can't look at the tutorial in the shop.

 

[rhempz01]

I replaced all the drivers, removed and tested all the output transistors. Still the protection persists.

 

[bl4ckw1d0w]

Check the voltage regulators, check the green inductors near them as well they should read close to 5ohms.

I have had a few amps that those inductors read fine on the multimeter but the leg was broken off inside the casing so the connection must have been intermittent.

I know ive had one or 2 that needed tl072c on the driver board. I think the top one runs hot. Its been a while since i seen this board.

Check the bank of transistors in front of the audio driver board as well. I did have one shorted at one point. Might have been my fault but it did solve my protection issue.

Make sure your voltages are getting to the driver board and you don't have any pulled vias.

 

[Perry Babin]

It's rare that anything on the driver board fails other than two 1D transistors and rarely the top op-amp.

 

[rhempz01]

No pulled vias, before I changed the driver chips on the board it powered up OK without the output transistors. All my regulator voltages were good. I to have seen those small green inductors fail. I'll check the tl072. All the transistors in front of the board check OK in curcuit.

 

[rhempz01]

Im going to pull up the tuturiol tk verify the placement of the 1D, 2D transistors. I couldn't figure it out. Why the protection, I didn't have rail across my speaker terminals for a shorted output, yet it powered up with them?

 

[bl4ckw1d0w]

I think you can pull the driver board in this one and it will come out of protect if the issue is on the driver board? I wouldn't do it until you get confirmation this is ok.

 

[rhempz01]

I did and it does come out of protection. I changed all the drivers the tl072's the 220-330pf cap. Still the protection persists. It starts up fine and the relay will engage straight into protection.

 

[Perry Babin]

Is there DC on the output filter inductors before the relay between the time it powers up and the time the relay engages?

 

[rhempz01]

It was the overload protection curcuit. The Amp would power up without the rectifiers. I found a shorted 2sa1275. Replaced it and the Amp powered up normally.
It is drawing around 4amps of current.

 

[bl4ckw1d0w]

Where was the shorted component located I am curious.

 

[caraudioguy2100]

Not sure if that is an A1275 transistor but This one appears to be defective from the picture he posted .

 

[Perry Babin]

That's likely the DC offset protection. Look at the upper right corner of the attached diagram.