Phase 400 rebuild
- Thread starter Dchristie
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WOPL 400 update
So, thought you might like to see where I am with this project. Just finished putting in the 2nd row of output devices and tested the amp for voltages and bias . Everything showed within the proper ranges. So, I am halfway to having this complete with 2 more rows of outputs to go and then will need to add the LED board and final testing for electrical integrity.
While I can't say it has been easy, it has been a good learning experience for me and the White Oak parts are absolutely 1st class. Joe King and Mark Comer (with special emphasis on his instructional videos) have been great help as well as many of the rest of you ( Lee/etc) that I have personally messaged with questions. Thanks to you all .
So, while I am still not quite our of the woods, I can see the light at the other side and hopefully these final building stages will go as smoothly as the previous ones.
Will post a final pic once she (the red sticker in my amp was signed by Pam - hence the she reference) is completed.
Dean
So, thought you might like to see where I am with this project. Just finished putting in the 2nd row of output devices and tested the amp for voltages and bias . Everything showed within the proper ranges. So, I am halfway to having this complete with 2 more rows of outputs to go and then will need to add the LED board and final testing for electrical integrity.
While I can't say it has been easy, it has been a good learning experience for me and the White Oak parts are absolutely 1st class. Joe King and Mark Comer (with special emphasis on his instructional videos) have been great help as well as many of the rest of you ( Lee/etc) that I have personally messaged with questions. Thanks to you all .
So, while I am still not quite our of the woods, I can see the light at the other side and hopefully these final building stages will go as smoothly as the previous ones.
Will post a final pic once she (the red sticker in my amp was signed by Pam - hence the she reference) is completed.
Dean
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OH Sh- -T
Hi Lee, well, it went well until the last 2 transistors were inserted.
Got distracted and mixed up a NPN for a PNP. On power up noted the voltage was way off at half power and shut everything down and found the mistake.
So, can I just fix the problem by reversing the 2 transistors or have I really screwed everything up.
No noticeable issues with anything just the low voltage - can't believe I did this at this stage!
Thanks for your advice .
Dean
Hi Lee, well, it went well until the last 2 transistors were inserted.
Got distracted and mixed up a NPN for a PNP. On power up noted the voltage was way off at half power and shut everything down and found the mistake.
So, can I just fix the problem by reversing the 2 transistors or have I really screwed everything up.
No noticeable issues with anything just the low voltage - can't believe I did this at this stage!
Thanks for your advice .
Dean
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Lee, I was using my variac and DBT just as Mark did in his video.Noticed the 100 watt test bulb was on full and that is when I shut everythingdown. Saw, heard, or smelled nothing abnormal – just the low voltages on the rails athalf power . <o
> </o>
No fuses blew and the filter caps hardly charged . The misplaced transistors were the last 2 in the right channel.
Pico fuses are good and R 35 looks fine as well. I have another set of new NPN and PNP transistors- should I use these or reuse the originals.
This was the last test before normal power-up and setting of bias and putting music through her..
<o> </o>
Thanks<o></o>
<o> </o>
Dean<o></o>
> </o>No fuses blew and the filter caps hardly charged . The misplaced transistors were the last 2 in the right channel.
Pico fuses are good and R 35 looks fine as well. I have another set of new NPN and PNP transistors- should I use these or reuse the originals.
This was the last test before normal power-up and setting of bias and putting music through her..
<o
> </o>Thanks<o
></o><o
> </o>Dean<o
></o>
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Thanks Lee, I replaced the shorted outputs with new ones anyways as I bent the leads getting them out of the backplanes (they are in there pretty tight). I had new NPN/PNP transistors for my 2nd WOPL400 so being anal as I am, I felt I would sleep better with unabused outputs in the amp.
OK, after doing the above, everything checked out so I continued with the final testing phase and LED board wire-up. Ran it one more time through the dbt and then powered her up from normal AC. Let her sit for awhile, adjusted bias, checked DC offset and once again no signs of any problems.
Only thing left to do is run music through her and hopefully she will sing. Regarding the dbt, as a novice with little formal training in electronics, the theory behind this device makes sense but you never truly appreciate these things until they actually prevent a catastrophe in actual use. Such is the case here (assuming PAM is not damaged and plays music which I still have to verify). It was only when I noticed for the 1st time that the 100 watt bulb was full on that something just wasn't right as it was not on during the testing of the previous 3 rows of transistors. And then when I measured such low voltages in the B+ and B- rails and also in the filter caps, I really knew that something major was amiss. The fact that it looks like the dbt "saved my bacon" really emphasizes how important these simple devices are when doing these projects and the fact that I was both unfortunate and fortunate at the same time to see a dbt in action is a real learning experience.
So, I will give a final report later today on the health of PAM but she looks good to go at present.
Dean( QUOTE=laatsch55;170320]If no fuses went, I don't think you stressed the outputs enough NOT to use...[/QUOTE]
OK, after doing the above, everything checked out so I continued with the final testing phase and LED board wire-up. Ran it one more time through the dbt and then powered her up from normal AC. Let her sit for awhile, adjusted bias, checked DC offset and once again no signs of any problems.
Only thing left to do is run music through her and hopefully she will sing. Regarding the dbt, as a novice with little formal training in electronics, the theory behind this device makes sense but you never truly appreciate these things until they actually prevent a catastrophe in actual use. Such is the case here (assuming PAM is not damaged and plays music which I still have to verify). It was only when I noticed for the 1st time that the 100 watt bulb was full on that something just wasn't right as it was not on during the testing of the previous 3 rows of transistors. And then when I measured such low voltages in the B+ and B- rails and also in the filter caps, I really knew that something major was amiss. The fact that it looks like the dbt "saved my bacon" really emphasizes how important these simple devices are when doing these projects and the fact that I was both unfortunate and fortunate at the same time to see a dbt in action is a real learning experience.
So, I will give a final report later today on the health of PAM but she looks good to go at present.
Dean( QUOTE=laatsch55;170320]If no fuses went, I don't think you stressed the outputs enough NOT to use...[/QUOTE]
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Ok, just hooked PAM up to my restored Citation 17 preamp and Dynaco A35 speakers and she is singing sweetly. Looks like I avoided the repair blight ( thank you DBT) so I feel fortunate.
Thanks to all who provided guidance and to Dennis for steering me to this Phase Linear site in the 1st place.[
Dean
QUOTE=laatsch55;170349]Amen Dean..
..the best is yet to come. Wait till you hear that sweetie!![/QUOTE]
Thanks to all who provided guidance and to Dennis for steering me to this Phase Linear site in the 1st place.[
Dean
QUOTE=laatsch55;170349]Amen Dean..
..the best is yet to come. Wait till you hear that sweetie!![/QUOTE]
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Magnetic Pick Up Tool
One of the major difficulties I had with the whole WOPL400 rebuild was the task of inserting the output transistors into their respective positions on the backplanes. Mark had warned about this task on his video but I had no idea how frustrating this could be. For some reason, I had only a little difficulty getting the first 14 devices to seat correctly but then I ran into the 2 outputs from Hell. Those last 2 took me hrs to finally coax into their inserts and it was the problems I had with these last 2 specific transistors that eventually led to my mix up and my inserting each into the wrong column and the resultant short that nearly caused me to blow a blood vessel. So, upon mentioning this to Joe, he indicated that some of you experts have a neat tool that takes the pain out of this part of the rebuild called a magnetic pick up tool. He was also kind enough to send me a photo of this miracle tool and I ordered one on the spot from Sears. So could one of you who have experience with such a tool provide some insight on exactly what is the proper technique when inserting output transistors into WO backplanes using the magnetic pick up tool ?
One of the major difficulties I had with the whole WOPL400 rebuild was the task of inserting the output transistors into their respective positions on the backplanes. Mark had warned about this task on his video but I had no idea how frustrating this could be. For some reason, I had only a little difficulty getting the first 14 devices to seat correctly but then I ran into the 2 outputs from Hell. Those last 2 took me hrs to finally coax into their inserts and it was the problems I had with these last 2 specific transistors that eventually led to my mix up and my inserting each into the wrong column and the resultant short that nearly caused me to blow a blood vessel. So, upon mentioning this to Joe, he indicated that some of you experts have a neat tool that takes the pain out of this part of the rebuild called a magnetic pick up tool. He was also kind enough to send me a photo of this miracle tool and I ordered one on the spot from Sears. So could one of you who have experience with such a tool provide some insight on exactly what is the proper technique when inserting output transistors into WO backplanes using the magnetic pick up tool ?