You didn't say what failed other than the power supply FETs. I don't generally recommend replacing parts blindly.
I guess that was my point.. If I need to remove the parts any way to test them, I thought I would order replacement parts for the ones that are more likely to need replacing. More a matter of not having to place multiple orders for parts being that shipping is the biggest expense.
The next step in troubleshooting would be to replace what I know is broken, then try to power it up with limited current as to not blow it up again. That is the current plan.. If I can have the parts I need on hand, that will save time and money.
The next step in troubleshooting would be to replace what I know is broken, then try to power it up with limited current as to not blow it up again. That is the current plan.. If I can have the parts I need on hand, that will save time and money.
You can check for shorted output transistors while they're in the board. You can replace them all if you'd like (even if none are shorted).
What is the value of the gate resistors? If they're 470 ohms, I'd order 100 ohm resistors in case you need to replace them (of the 470s don't control the gates of the FETs well enough).
What is the value of the gate resistors? If they're 470 ohms, I'd order 100 ohm resistors in case you need to replace them (of the 470s don't control the gates of the FETs well enough).
I checked the output transistors in circuit, and none seem to have a dead short. I could see the capacitors charge/discharge on the meter so I guess that is a good sign that they are OK.
Would you suggest I change the gate resistors even if I use the Z34 replacement part? If I am going to do that, I might as well go for the Z44, or even the Z46 or Z48? What is your opinion on that?
Currently the gate resistors are 680 Ohm. I measured one of them to confirm it was 680, and it was..
Would you suggest I change the gate resistors even if I use the Z34 replacement part? If I am going to do that, I might as well go for the Z44, or even the Z46 or Z48? What is your opinion on that?
Currently the gate resistors are 680 Ohm. I measured one of them to confirm it was 680, and it was..
I understand. What advantage, or improvement will the 100 Ohm resistors give me?
Any idea what wattage those are?
If I am changing the resistors anyway, what is my best option for replacement FET?
Thanks.
Any idea what wattage those are?
If I am changing the resistors anyway, what is my best option for replacement FET?
Thanks.
The resistors are 1/4w.
100 ohm and IRFZ44s should work well.
If the resistor value is too high, it won't allow the drive circuit to properly control the FETs. This will lead to overheating and premature failure.
100 ohm and IRFZ44s should work well.
If the resistor value is too high, it won't allow the drive circuit to properly control the FETs. This will lead to overheating and premature failure.
ok. so the plan is to check all of the output transistors again, order some parts and see what happens.
Thanks!
Thanks!
Put all the new parts in, and the magic smoke all came out already... <sigh>. Put it aside for a while out of frustration, but looking for any new advice..
Maybe it is worth while to just send it out for repair? Any place in NJ work on them?
Maybe it is worth while to just send it out for repair? Any place in NJ work on them?
7 years later, and I pulled this thing out of the draw...
With fresh eyes, I noticed that last time I was working on it, one of the heat sink insulators on the last 2N6487 had shifted, and likely shorted to the heat sink. Looking around visually, I could see that one of the new Z44's had blown. Confirmed with a meter, it was bad- and the rest all seemed OK.
I replaced the bad Z44, fixed the insulator, and tested with the cover on. Nothing at all happened. No indication it would come on at all. I guess that is better than blowing up more parts!
Anyway, still searching for a schematic to this thing... and welcome any advice.
With fresh eyes, I noticed that last time I was working on it, one of the heat sink insulators on the last 2N6487 had shifted, and likely shorted to the heat sink. Looking around visually, I could see that one of the new Z44's had blown. Confirmed with a meter, it was bad- and the rest all seemed OK.
I replaced the bad Z44, fixed the insulator, and tested with the cover on. Nothing at all happened. No indication it would come on at all. I guess that is better than blowing up more parts!
Anyway, still searching for a schematic to this thing... and welcome any advice.
The following may be similar to the power supply control circuit:
http://www.bcae1.com/temp/ppipc420002.swf
http://www.bcae1.com/temp/ppipc420002.swf
I am having trouble opening this file. Happen to have a PDF version of the schematic?
Just looking at the parts on the board, I am assuming the SG3525 is supposed to be driving the power supply, but not clear if the bank of Z44's are driven directly? or through something else? There are some Op-Amps on the board in that neighborhood but unclear if they are part of the power supply or audio section.
My assumption is when the Z44 blew, it took something else with it.
It's all I have. It's a common file type. Try a different browser.
Follow the traces between the output of the driver IC and the FETs to see if there are drivers.
Follow the traces between the output of the driver IC and the FETs to see if there are drivers.
Why did you order it from china? It's a common IC that's available from most any electronics component distributor.
Not looking to sell it. I have a few other PPI units of the same vintage. this broken one was running the sub's. I have a Infinity RSA250 now in it's place, but when this is fixed I will swap it back... That said, everything I own is for sale- if it is worth more to you than it is to me. 😛
Because I am a cheapskate? LOL... Is there a problem with the Chinese parts? I figure they are all from China anyway..
When I initially attach the power supply, there is a spark- but I think that is the capacitors charging up. Putting 12V on the remote turn on lead does nothing. No lights, no increase current draw. Guessing at this point one of the transistors in the trigger line may be bad? Considering how it failed, that does not make much sense.. Still hoping I can find a schematic for this thing.
There are MANY counterfeit ICs coming from the far east. MANY! Ebay is just about as bad. You have a really good chance of getting dodgy semiconductors.
There are ICs produced there but are in authorized plants where standards are met. Those are the ones you get from authorized distributors like Mouser or Digikey.
If the voltage goes to 12v on pins 13/15 when remote is applied, post the DC voltage on all pins of the control IC. Copy and paste and fill in the blanks:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
There are ICs produced there but are in authorized plants where standards are met. Those are the ones you get from authorized distributors like Mouser or Digikey.
If the voltage goes to 12v on pins 13/15 when remote is applied, post the DC voltage on all pins of the control IC. Copy and paste and fill in the blanks:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16: