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Old 1st October 2007, 03:10 PM   #1
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Default Powerpod 740 blowing fuses at powerup

I have a dead powerpod 740, brand new, that was returned to a store because it keeps popping fuses. This happens with all level zero'd out, not inputs. The fuses go off like firecrakers, and even shattered the glass!! I assume that there is an issue in the power amp section(s), but a schematic or service manual would really be of help isolating this. I noticed that zeoN_Rider seems to have access to these documents, But I can't email him because I'm a newbie (sigh). My email adress can handle pretty big files, so you could send the whole service manual.

Can anybody help?

p.s. I seem to have seen a few posts and comments about this the fuse popping DOA activity on the powerpods while surfing the net. Is there a generic issue that I should look at first? I'm electonically handy, but most my experience is digital vs audio gear.

Thanks a bunch for looking.
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Old 2nd October 2007, 01:42 PM   #2
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Default Powerpod is a 740 Deluxe model

Just realized that the Phonic Powerpod 740 I am working on is the Deluxe model. Still looking for schematic/service manual.


Thanks
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Old 2nd October 2007, 02:09 PM   #3
KP11520 is offline KP11520  United States
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Hi Shor,

The only thing I can recommend is don't keep replacing fuses and firing it up again. Sometimes this will allow components to fry just long enough before the fuse lets go. This happens especially after repeated attempts. Obviously something major is wrong and needs to be fixed before you try again and don't just remedy themselves after time. Sorry I don't ahve any more help to give but I don't want to see the problem get worse, I am just learning too!

Regards//Keith
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Old 2nd October 2007, 10:38 PM   #4
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Thanks, Keith, I appreciate the advice.

I actually have it narrowed down to the main power supply board. Looks like there are a pair of FETs (Q902 and Q905 according to the silk screen) that are cooked (dead shorts across all leads. This also showed up as a dead short across the + and - arms of a bridge recitifier (D913). After popping the FETS out, I now have some resistance, and I can apply power without popping the fuses. Of course nothing works yet, either. Tough doing this without a schematic or parts list, but I'm slogging along. I also found a resistor (albeit a small one) (R902) that had not been properly wave soldered to the board. The lead on the part let go and it was not connnected. Looks like it has something to do with the inductor side of the switching power supply.

From the notes on the silk screen it would appear that this power supply board is used interchangably in the powerpod 740 Deluxe and the powerpod 1062. Maybe somebody will have a schematic or service mnual that covers it. I tried the online place that was in one of the other posts, but they only have the service manual for the original Powerpod 740. I was able to get a service manual for my yamaha emx640 from them, so now I can take a look at why my reverb unit isn't working on that amp.

Alway something to keep me busy!

Later Mon.
Bill
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Old 3rd October 2007, 04:31 AM   #5
KP11520 is offline KP11520  United States
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Hi Bill,

Too bad you don't have the schematics to find the values on those FETs. The other thing you might look into is what happened upstream (closer to the power source) from those FETs to cause them to fry. Hopefully, it was the resistor (and it was upstream) not being connected properly that caused the meltdown

Maybe someone hooked up the wrong external P/S with higher voltage than it can take. I am just speculating.

If the FETs are cheap get extras in case the same problem happens again, but if that is the case, there is also definitely something else wrong! Good Luck!

Does Powerpod have a support web-site? Maybe if you email Tech support, they can tell you which FETs they are and may also sell them or tell you where they get them.

Look here, this might help: Phonic Powerpod 740 Deluxe

Regards//Keith

PS what do you play? I have a Taylor and a BC Rich Eagle Supreme (vintage late 70s).
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Old 3rd October 2007, 02:11 PM   #6
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I am primarily a singer, but I have around a dozen different guitars, none of which I play very well. (Quantity vs quality?) Most of them are cheaper knock-offs of classic styled guitars. I do have a nice Yamaha classical acoustic, along with several Galveston series acoustic and acoustic electrics. A Les Paul clone (Agile 2500), Strat clone, 335 clone, Johnson Telecaster (I'm still straightening this one out, it was unplayable from the dealer on ebay), Ovation knock-off (Applause) and electric bass (that I haven't learned to play yet) round out the rest of the collection. I also rescued two Yamaha rythm machines from Ebay and got them working, the rx5 and rx11. Last toy is a Tascam portastudio 4 track mixer/recorder that I salvaged from the dump! This of course doesn't include the various amps, pa speakers and mixers that are laying around.

As you can see, I like diversity, and I like salvaging broken stuff and putting it back on the road. Hopefully I'll be able to add the Powerpod 740 to my list of sucesses.

Thanks for asking.

Bill
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Old 3rd October 2007, 02:38 PM   #7
KP11520 is offline KP11520  United States
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Way to go!

Have you looked into Digidesign/Protools or Sonar yet? That is a whole project in itself!

Not sure where you live but there has to be a Sam Ash somewhere near you. Talk to them and ask them where they would send an out of warranty unit for a repair (hopefully not Phonic). Maybe that shop has the schematic and can help!

If that doesn't work maybe one of the Pro guys here can order the schematic for you and you can pay him (of course). You just have to find one nearby that will help you and hope that Phonic will sell the schematic to Pro shops.

Or call Phonic and ask to speak to repair and maybe the guy will at least give you the part numbers and alert you to any other potential problems (maybe this is a problem with this model). I saw one on Craigslist in Orange County (probably CA) that is for sale for $150 that supposedly looks brand new but doesn't power up. (He probably doesn't have a clue about the fuses).

Keep it up and when can we expect that first single?

Regards//Keith
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Old 5th October 2007, 02:02 PM   #8
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I want to thank Keith for going the extra mile on this one. While we weren't able to get the schematic, it turns out that this is a known issue, and Phonic has a kit with the parts that usually pop. I ordered the kit today, and it includes the two FETs I had already identified! I'll keep everyone posted on this. For information purposes, the number was 1(800) 430-7222, speak to David or Casey.

Later dudes.

Bill
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Old 9th October 2007, 08:06 PM   #9
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FYI - while still waiting for the parts from Phonic, just an FYI to let you know I was able to secure a service manual with diagrams and parts lists (no board layouts) from overseas. Don't know if it's my revision, but at least it matches what I am looking at. The FETs have a slightly different part number, so I assume I'm looking at an older rev of the same basic board.

Bill
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Old 12th October 2007, 04:49 PM   #10
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Semi-great news -

Got the kit from Phonic yesterday and installed the various components. The good news is that the unit is now powering up. It appears to be mostly functional, except that the monitor/main2 amp seems to be toasted. The 'limit' light on the front panel (and the one internally on the amp board) are both on solid, and the protection circuit is keeping both amps disconnected from the speakers.

The Monitor and Main line outputs are working OK however, as well as the effects unit. If I defeat the bad amp, the remaining amp appears to be driving the speakers correctly.

Now comes the hard part - troubleshooting the bad amplifier board!

Will keep you posted.

Bill
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