A little XBOSOZ help

Pathmark · 15th May 2007, 01:46 AM

So I powered up PSU boards for xbosoz kit and measured +9 and 0 right before I started to see smoke!

I tried the second board same thing, not sure what to start checking to confirm PSU boards.

Before hooking up the boards I checked power supply was +70 and -28. Any suggestions would be great.

Thanks,
Pathmark

Netlist · 15th May 2007, 07:23 AM

Pathmark,
Could you provide a link to the schematic?

/Hugo

BobEllis · 15th May 2007, 10:02 AM

The PSU was working properly by itself and then smoked when you connected the XBOSOZ, correct? I'll venture a guess that you got at least some of the 1000 uf caps in backwards on the XBOSOZ. You'll probably need to replace the caps.

That or you fried your fets (check for very high to infinite resistance Source to Drain in either direction. If not, they need replacing). Handle them carefully - a little static on the gate is all you need to fry them.

Pathmark · 15th May 2007, 11:57 AM

Sorry if not enough details. The boards are twisted pear audio based on Terry (metalman) schematic.

The xbosoz boards were not attached I was simply checking the PSU rails. Again on power-up the measured +9 and 0 (+ and - rails respectively) and then some smoke.

Pathmark

BobEllis · 15th May 2007, 12:12 PM

I'd still guess a reversed cap somewhere or a solder bridge. Did you trim the component leads or could something have bent over and shorted.

I know where to find the schematic, but a link here would be handy.

Pathmark · 15th May 2007, 01:13 PM

Schematic for xbosoz psu

jupiterjune · 16th May 2007, 12:47 AM

Pathmark-

Are you using two transformers?

I did not look up the Twisted pear wiring diagram, but the ps diagram you posted looks the same (as far as trafo wiring goes) as Nelson's original article.

When I first hooked up my BOSOZ ps, I tried to use a single transformer. I believe I had it wired wrong, which caused the magic smoke to quickly exit the bridges.

JJ

Pathmark · 16th May 2007, 01:09 AM

Yes using two transformers for 30-0-30 for positive and 12-0-12 for negative, same avel as posted in forum.

I have posted on the xbosoz thread as it seems to have more replies. My issue is only with the positive rail on both boards! I only get 4.5V and then smoke.

Pathmark

Babowana · 16th May 2007, 01:18 AM

Check if zeners are put to the right direction.
Check the MOSFET's pins are correctly connected.

jupiterjune · 17th May 2007, 12:37 AM

Pathmark-

I would check those wimpy little 4004's to see if they are blown.

Also, if you have an unregulated power supply laying around, you can use it to check the regulated portion of the circuit past the diodes. A lower voltage PS, say +- 20 volts is better for this. (after doublechecking to see everything is installed correctly, of course.)
Just connect ground to ground, V+ to the junction between R1 and C1, and V- to the junction between R2 and C2. Your regulated voltage out will app. 3 to 4 volts less than your unregulated voltage.

JJ

15th May 2007, 01:46 AM	#1
Pathmark diyAudio Member Join Date: Jan 2007	A little XBOSOZ help So I powered up PSU boards for xbosoz kit and measured +9 and 0 right before I started to see smoke! I tried the second board same thing, not sure what to start checking to confirm PSU boards. Before hooking up the boards I checked power supply was +70 and -28. Any suggestions would be great. Thanks, Pathmark

15th May 2007, 11:57 AM	#4
Pathmark diyAudio Member Join Date: Jan 2007	More details Sorry if not enough details. The boards are twisted pear audio based on Terry (metalman) schematic. The xbosoz boards were not attached I was simply checking the PSU rails. Again on power-up the measured +9 and 0 (+ and - rails respectively) and then some smoke. Pathmark

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15th May 2007, 07:23 AM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	Pathmark, Could you provide a link to the schematic? /Hugo

15th May 2007, 10:02 AM	#3
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	The PSU was working properly by itself and then smoked when you connected the XBOSOZ, correct? I'll venture a guess that you got at least some of the 1000 uf caps in backwards on the XBOSOZ. You'll probably need to replace the caps. That or you fried your fets (check for very high to infinite resistance Source to Drain in either direction. If not, they need replacing). Handle them carefully - a little static on the gate is all you need to fry them.

15th May 2007, 12:12 PM	#5
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	I'd still guess a reversed cap somewhere or a solder bridge. Did you trim the component leads or could something have bent over and shorted. I know where to find the schematic, but a link here would be handy.

16th May 2007, 12:47 AM	#7
jupiterjune diyAudio Member Join Date: Nov 2006	Pathmark- Are you using two transformers? I did not look up the Twisted pear wiring diagram, but the ps diagram you posted looks the same (as far as trafo wiring goes) as Nelson's original article. When I first hooked up my BOSOZ ps, I tried to use a single transformer. I believe I had it wired wrong, which caused the magic smoke to quickly exit the bridges. JJ

16th May 2007, 01:09 AM	#8
Pathmark diyAudio Member Join Date: Jan 2007	Yes using two transformers for 30-0-30 for positive and 12-0-12 for negative, same avel as posted in forum. I have posted on the xbosoz thread as it seems to have more replies. My issue is only with the positive rail on both boards! I only get 4.5V and then smoke. Pathmark

16th May 2007, 01:18 AM	#9
Babowana Formerly "jh6you". R.I.P. Join Date: Jul 2006	Check if zeners are put to the right direction. Check the MOSFET's pins are correctly connected.

17th May 2007, 12:37 AM	#10
jupiterjune diyAudio Member Join Date: Nov 2006	Pathmark- I would check those wimpy little 4004's to see if they are blown. Also, if you have an unregulated power supply laying around, you can use it to check the regulated portion of the circuit past the diodes. A lower voltage PS, say +- 20 volts is better for this. (after doublechecking to see everything is installed correctly, of course.) Just connect ground to ground, V+ to the junction between R1 and C1, and V- to the junction between R2 and C2. Your regulated voltage out will app. 3 to 4 volts less than your unregulated voltage. JJ

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