This is so frustrating, I thought I'd share.
I have built the BOZ and got everything working fine. Then I took it apart to wire it nicer. My brother-in-law was coming today and I wanted him to hear it. I worked on it all yesterday and today. Then I tested the circuit tonight when everything was in place and it worked. Then all I did was put the lid on it and hook it up to my system and the fuse blew. By this time my brother in law has shown up, so I pop in one more fuse in and it blows (whats going on!). I then begin to debug it starting at the transformer and I think the tranny is blown. Its a plitron 300VA (30-0-30) and I am getting 45Vrms on one side and 100Vrms on the other (in series). Is this what one would expect from a blown transformer? Thanks
I have built the BOZ and got everything working fine. Then I took it apart to wire it nicer. My brother-in-law was coming today and I wanted him to hear it. I worked on it all yesterday and today. Then I tested the circuit tonight when everything was in place and it worked. Then all I did was put the lid on it and hook it up to my system and the fuse blew. By this time my brother in law has shown up, so I pop in one more fuse in and it blows (whats going on!). I then begin to debug it starting at the transformer and I think the tranny is blown. Its a plitron 300VA (30-0-30) and I am getting 45Vrms on one side and 100Vrms on the other (in series). Is this what one would expect from a blown transformer? Thanks
I am really sorry to read that you have met Mr. Demo Devil.
Please check for short circuits just behind the transformer.
Also a blown bridge rectifier could spoil everything.
Check for wiring mistakes.
Take your time, and I am shure you will solve the problem.
Regards
Please check for short circuits just behind the transformer.
Also a blown bridge rectifier could spoil everything.
Check for wiring mistakes.
Take your time, and I am shure you will solve the problem.
Regards
It is unusual to have a blown secondary in a power transformer. I suspect that you have a wiring error somewhere.
Jam
Jam
Hello Phill,
You should check rectifier diode bridge, zener diodes and 47.5 R
resistors in the power supply circuit.
Then check all transistors.
Also, check 22.1 R and 100 R resistors in BOZ main circuit.
It is very hard to damage the 300 VA transformer with BOZ.
It could do only damaged diode bridge.
Are you shure about the your voltage readings ?
Make shure to switch the multimeter to AC voltage.
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
You should check rectifier diode bridge, zener diodes and 47.5 R
resistors in the power supply circuit.
Then check all transistors.
Also, check 22.1 R and 100 R resistors in BOZ main circuit.
It is very hard to damage the 300 VA transformer with BOZ.
It could do only damaged diode bridge.
Are you shure about the your voltage readings ?
Make shure to switch the multimeter to AC voltage.
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
is that a torrid transformer?if so you may have formed a single secondry winding with the fixing bolt,puting the lid on completed the winding
Well, after a 2 hour drive and about 30min working on it I found the problem! It was, as mentioned by kristijan-k, the rectifier diodes and not the transformer. I had taken the project to my mothers and only brought a multimeter, so I could not really perform any diagnostics. The importance of a Variac should not be understated. I went home and got my variac and everything pretty much solved itself. The prob with the tranny was that I forgot to sand down one of the leads after I ripped it out.
One question about the rec diodes, I am using the specified diodes Pass gave. With the 300VA, 2200uF mod should I use higher current rec diodes? I am just wondering why this happened in the first place.
One question about the rec diodes, I am using the specified diodes Pass gave. With the 300VA, 2200uF mod should I use higher current rec diodes? I am just wondering why this happened in the first place.
Hello Phill,
The more powerfull diodes are not neccesary for this preamplifier.
The blown rectifier diodes were probably damaged by human error.
Check everything more than once when power up any circuit,
it will save you a lot's of time and nervs.
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
The more powerfull diodes are not neccesary for this preamplifier.
The blown rectifier diodes were probably damaged by human error.
Check everything more than once when power up any circuit,
it will save you a lot's of time and nervs.
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
In France we call this "L'effet Bonaldi"
Bonadi effect, by the name of our presentator for special technical thing. But in each try his material didn't work
Bonadi effect, by the name of our presentator for special technical thing. But in each try his material didn't work
Protecting transformers
I've no better idea than anyone else here about the problem is, but suggest the following for the future: put fuses between the secondaries and the bridge rectifier. If a bridge fails it may well fail short damaging the transformer. This may not be a common event but fuses and bridges are cheap while transformers are expensive. Not to mention that you can't run down to Radio Shack for an emergency replacement transformer before the in-laws arrive.
I've no better idea than anyone else here about the problem is, but suggest the following for the future: put fuses between the secondaries and the bridge rectifier. If a bridge fails it may well fail short damaging the transformer. This may not be a common event but fuses and bridges are cheap while transformers are expensive. Not to mention that you can't run down to Radio Shack for an emergency replacement transformer before the in-laws arrive.
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