Auto power on problem with Paradigm PS1000

william13

Member
right! but so many places can short. A friend gave me an idea to disconnect the dc lines from the bridge rectifier to help isolate and I will do soon
 

william13

Member
Anyone out there who could tell me how to test the transformer for the Paradigm? I have it out of circuit at the moment
 

Yannick99

Member
Did you disconnect the dc line ? Short the relay, If you look schematic, you should have 80v between + and - from bridge rectifier.

You can also just remove the bridge rectifier. Short r184 and 185 (short the relay) and check for AC to the bridge input (transformer output). With no load fuse should be ok. If not, you will also know that something is wrong before bridge.
 

william13

Member
Can we take this step by step? (and thanks). I disconnected the dc line from the bridge and the fuse did not blow. (Essentially that removes the bridge) . Not sure I know now to short 184,185 ! I like your ideas!

I'm going to turn in. I'm excited to try these ideas. Thank you
 
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Yannick99

Member
Not sure I know now to short 184,185 ! I like your ideas!
Because r184 and 185 are to have a standby voltage. When music is detected, an op-amp turn on an optocoupleur (U17) and this one close a relay to bypass r184 and r185 to have full power on transformer.

So if you disconnect the dc or the bridge rectifier. You must bypass the relay RL1 by yourself. Put a wire over r184 and r185. Or put a wire between RL1 pin3, 4. Check the schematic you will understand
 

william13

Member
I get it. So when I disconnected the bridge rectifier earlier today (before this conversation) I did not bypass the relay. Nothing happened and now I understand why. I soldered the wires of the bridge back to the pcb. These wires were very hard to get back into the trace holes so I am not eager to disconnect the bridge again. Would I be able just to run the DMM across the dc wires and check for the -80 or given the probable short somewhere would that not be recommended? (and of course I will short the 184,185 to close the relay). On this unit I have a toggle that reads: off, auto-on, always on.
Wouldn't putting the toggle on always on close the relay for me?
 
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Yannick99

Member
Ok i thought it was connectors at the bridge. To test transformer with dmm. You will have a few ohm. Very few ohm. it's normal. But if you see 0,1 0,2 ohm it's maybe bad. Harder to test because transformer are coil with very low impedance. On secondary side you are suppose to have half ohm on center tap.

You can't check for the 80 v without disconnecting the load because the fuse will blow before you have time to mesure anything.
 

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william13

Member
On the primary side I am getting 1 ohm. Secondary with middle wire .5 ohm
Looks fine and smells fine. What do you think of that reading? Using a fluke dmm
So I am a little worried about primary reading because I know its rare to blow it.
 

Yannick99

Member
What do you think of that reading?

Looks fine to me. On secondary if you have 0,5 i imagine you have 1 ohm for the whole secondary coil ? transformer is probably fine. You have more luck to have a dead transistor, mosfet instead transformer.
 

william13

Member
I inspected all the mosfet visually and they look fine. I tested them for shorts in circuit. I compared left to right and essentially the readings matched up. (not sure if that means anything). Could a bad optocouper blow a fuse? I have another issue I want to run by you also. On the underside of my pcb there is a wire that runs to the fastener for the transformer. It came loose during work and I was a little unsure which of the 5 pins I need to attach it to. (actually I have it narrowed down to 2 pins) I can send a picture tonight. (BTW thanks for you help)
 

william13

Member
I am attaching two pictures to see if I made a soldering mistake here. The pictures show a 6 wire connector with 5 wires: 2 black, space, red, 2 yellow. for pins 1,2,3,4,5,6 respectively. Under the board there is a reinforcement wire that runs from pin #3 to the underside of ac neutral. This wire was found by me dangling from the underside of ac neutral and I thought it had been attached to pin 3 but since pin 3 has no connections to the transformer or anywhere else I am wondering if I soldered it to the wrong pin perhaps it should be connected to pin 2. I just want to be sure. This is not part of the


problem I have been having as it dislodged from its original connection as I was working on things

Addendum: I am 99% sure I should have attached wire to second pin!
 

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Yannick99

Member
short optocoupler doesn't blow fuse. there are resistor on each side so.

For you connector i dont realy know. I can't compare on my side my ps-1000 is't the same. The third pin was maybe for the 220v version. Often board are designed to fit with many model.

To test a mosfet, you check for a short with your dmm. But to realy test a mosfet you must unsolder the part and this is working
 
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william13

Member
Thank you for the video. I will be popping these out this weekend. In the past Mosfets have always been hard for me to remove because of there thick legs and the type of boards they have been soldered into. I ordered some chip quik solder to help. I will keep you informed. Thank you for the guidance
 

Yannick99

Member
I ordered some chip quik solder to help.

Yeah i already tried chip quick. Works well but expensive at long run. Now i got a desolder gun. Best buy of my life lol

Good luck with your mosfet. Normally fuse are blowing when mosfet are dead short. If you find nothing, last thing to do before to abandon. Put a wire instead fuse, you will see and smell where the problem was. Buy better is to find the problem.
 

william13

Member
I missed a really good buy on ebay the other day for a vacuum desolder gun. Took my eyes off it.
So let me update you. I removed all 8 mosfets. Took a while but nothing destroyed in the process.
I moved that wire I was talking about because I had re-attached it wrong according to schmatic.
All Mosfets or bipolar jxn transistors BJT were tested. Each gave two readings in the 500 mv range. I did not try to charge them to test that. All tested ok so far. I disconnected the dc leads from the Bridge and hooked to DMM and put her on. Immediately there was a loud buzz that lasted 5-8 seconds and then a flash and there goes another fuse. (all mosfits out when this occurred.) The voltage reading went on and off so fast I missed it. So next I tried the light bulb in series current limiter trick. I put the unit on again and again a buzz. This time the fuse did not burn but a very loud continuous buzz like a door bell or something. It came from the near where the the cord plugs in

If I had to guess the relay has been converted to a buzzer. But why? I got a voltage reading in mid 60s through the light bulb so I know the transformer is not shorted but I did not see 80 v across the dc leads. If the relay is buzzing it means it is switching on an off real fast. Maybe this is blowing the fuse.
Thoughts?
 

Yannick99

Member
You have probably a problem on the auto on part. Tried to bypass it. Remove r186 and bypass r184 185. And retry with the bulb in series
 

william13

Member
Another thing I do not understand. If there was no audio signal how did the relays even get activated?
Maybe I should bypass the resistors to see if I can stop the buzzing!
You have probably a problem on the auto on part. Tried to bypass it. Remove r186 and bypass r184 185. And retry with the bulb in series
Is theauto on part the relay?
You have probably a problem on the auto on part. Tried to bypass it. Remove r186 and bypass r184 185. And retry with the bulb in series

I did exactly what you said:

removal of 186 with bypass of 185 an 184 stopped the buzz. Fuse did not blow even without lamp in series. DC voltage of bridge 68 instead of 80. My question is could the bridge have an issue reducing the voltage making the relay buzz?
 

Yannick99

Member
Another thing I do not understand. If there was no audio signal how did the relays even get activated?
Maybe I should bypass the resistors to see if I can stop the buzzing!
You right, without input the auto-on should be off.


Is theauto on part the relay?
Yes, when audio is detected C59 is fill-up and this turn on the optocoupler (u17) (throw the op-amp) When the sound isn't there. C59 become empty very slowly by R173 and after a while optocoupler (u17) turn off.

I know this because it's the same process on my ps-1000 and i looked that on oscilloscope.

DC voltage of bridge 68 instead of 80. My question is could the bridge have an issue reducing the voltage making the relay buzz?

You have maybe something here. As per datasheet you should have 80. Now yes maybe the bridge is defective or you pull too much current and this is lowering the output. Is the lamp was turning on ? If yes you maybe pull to much current. If not, it's maybe the bridge but it's hard to believe because when you do not have any load. If the bridge is broken on a side, You should have 80v anyway because you don't have any load. Or 68V it's maybe ok and the datasheet is wrong ?

the op-amp should work with +4 and -4v do you have this voltage. Check the lm324 datasheet for pinout.
 

william13

Member
Are you asking if I can deliver 4 v to a lead on op amp. I I think I have a variable power supply somewhere on my bench. Whats the process. The diode appear to be working on one side of the op amp. I guess I have to apply current to switch on the other side?
 

william13

Member
You right, without input the auto-on should be off.



Yes, when audio is detected C59 is fill-up and this turn on the optocoupler (u17) (throw the op-amp) When the sound isn't there. C59 become empty very slowly by R173 and after a while optocoupler (u17) turn off.

I know this because it's the same process on my ps-1000 and i looked that on oscilloscope.



You have maybe something here. As per datasheet you should have 80. Now yes maybe the bridge is defective or you pull too much current and this is lowering the output. Is the lamp was turning on ? If yes you maybe pull to much current. If not, it's maybe the bridge but it's hard to believe because when you do not have any load. If the bridge is broken on a side, You should have 80v anyway because you don't have any load. Or 68V it's maybe ok and the datasheet is wrong ?

the op-amp should work with +4 and -4v do you have this voltage. Check the lm324 datasheet for pinout.
What happens is this: With lamp in series, I turn on and the relay acts like a buzzer for about 5 seconds and the lamp glows dimly. After that the buzzing stops and lamp goes out but voltage remains 68v
Disconnecting the resister to the op amp and shorting the other two keeps the voltage at 68 and the relay of course sits quiet. I have an oscilloscope would this let me know if I am dealing with a half wave? I will try to figure out how to activate the op amp
 

Yannick99

Member
Are you asking if I can deliver 4 v to a lead on op amp. I I think I have a variable power supply somewhere on my bench. Whats the process. The diode appear to be working on one side of the op amp. I guess I have to apply current to switch on the other side?
No no, just check voltage if you have +-4 v. that's all
 

Yannick99

Member
What happens is this: With lamp in series, I turn on and the relay acts like a buzzer for about 5 seconds and the lamp glows dimly. After that the buzzing stops and lamp goes out but voltage remains 68v

ah, you had the lamp, the 68v with the lamp make sense. the 12v missing should be on the lamp. You was tellling me that the fuse was ok without lamp so i though it was directly
 
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william13

Member
I may have found something! There is a capacitor (C105) with a 22 uf rating but when I test it, it reads 800 uf! This connects to the relay. Wondering?
 

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