Pioneer HM82 - No power

[idledk]

Hi, I'm having a Pioneer which doesn't turn on any more, and have found the SMPS to be the problem, but with my somewhat limited smps knowledge I can't find the problem.

Purchased the full service manual, and have attached the smps diagram.

230volt mains.
I measure 325vdc on C805.
On IC821 I measure 21.5 volt on VCC so this should mean that its above startup voltage.
3.1volt on feedback. and I get 3.3volt on the 3.3volt output from the transformer (after d223 and d224)

+22 and +15 volt is however dead, so I suspect IC823 is dead, but before I rush out and purchase a new I just wanted to check with the experts if I have missed something.....

Unfortunate I don't have a scope :-(

[Longbow]

Re: Pioneer HM82 - No power

Interesting design - not your usual approach. I'm not familiar with the symbol they use marked 'B' but assume it is a ferrite bead. IC823 drives the 3.3v winding as well as the main winding. The IC is regulating the 3.3v as it should, so the IC is working in my opinion. You really do need a scope to see if the 3.3v is clean (to see if the filter caps are ok). Also R824 and R825 are critical and should be measured carefully. Check the 4 parts connected to the main winding as best you can and also look for cracked traces.

Is there really ZERO volts on the +15 and +22v?

[idledk]

Re: Pioneer HM82 - No power

Yes, B is a small ferrite bead, about the size of a ½watt resistor.

Actuallu, now that I measures again:
53.2 volt dc on +15 volt output. Must have remembered wrong.
+22 output at zero volts.

[Longbow]

Re: Pioneer HM82 - No power

First, let's assume you have done as much as possible with the meter. Please use the secondary ground to measure secondary voltages! It isn't likely that you would see +55v on a +15 volt line. Steady on.

We also assume that you have disconnected the load on the +15 and +22v, and confirmed that the rectifiers check OK, and filter capacitors are not shorted, especially C221, C222.

Any new information?

[Stegtir]

Re: Pioneer HM82 - No power

I have Pioneer Np01 which uses the same smps.

Found the 2 rectifiers ss315 shorted on the secondary which I have replaced. Still nothing, secondary side is completely lifeless. C805 has 320dc so were good there. C823 has nothing across it do ive replaced that but still no joy. Startup resistor measures fine out of circuit.

Can anyone offer what to check next?

[R_J]

Re: Pioneer HM82 - No power

Which 2 rectifiers were shorted?, were they the ones on the 3.3 volt output? If it was, ic251 or the optocoupler could have been damaged.
On the primary side, have you checked R824,R825. What voltage do you have on pin7 of ic821, if it is 0 , R823 could be open, D824 could be shorted or most likely the ic821 is bad, I would also replace C823.

[Stegtir]

Re: Pioneer HM82 - No power

Hi thanks for quick reply.

D222 and D226 were originally shorted. 0vdc on pin 7. D824 test fine . Ill check R833, 4, and 5,they are smd which will be a pain.

[Stegtir]

Re: Pioneer HM82 - No power

So R823 is ok, R824 and R825 seem to have gone high. Would this be cause of the rectifiers going short or as a result. What role do they play in the Smps? I'll try and find some replacements and see if we come back on line

[R_J]

Re: Pioneer HM82 - No power

If R824 and R825 are open (high res.) then IC821 is bad. What is the resistance between pins 4 or 5 and pin 3, if it is low the mosfet inside the is is shorted for sure
the resistors are on the CS (current sense) pin of the ic to monitor the current through the mosfet, but if the mosfet shorts the resistors being low ohm will go open.
I suspect the rectifiers shorted which would put a lot of load on the power supply, blowing the ic.
You should check and make sure nothing is shorted that is connected to that +15 volt line just in case

[Stegtir]

Re: Pioneer HM82 - No power

Hi,

No shorts on ic pins so hopefully its ok, they are cheap enough anyway. Ive ordered some resistors so I'll update when they arrive next week.

Thanks again!

[Stegtir]

Re: Pioneer HM82 - No power

Hi again,

Replaced the current sense resistors and still no joy.

There is 0v on vcc line still. I've checked everything back to the transformer and all components are fine.

I don't understand why?

[R_J]

Re: Pioneer HM82 - No power

What is the voltage on pin 5? Did you replace the ic?

[Stegtir]

Re: Pioneer HM82 - No power

Hi,

Thanks for the assistance.

I have 320v on both drain pins. I haven't replaced the ic yet. When does the vcc come live? I thought if there is nothing there then the ic isn't being powered?

[R_J]

Re: Pioneer HM82 - No power

Grind the top off the ic and see if the startup cell is working? see pdf page 3 in post #9

[Stegtir]

Re: Pioneer HM82 - No power

Ill order a replacement ic ��

[Mr P]

Re: Pioneer HM82 - No power

Hi. I was wondering if swapping out that IC fixed the issue? I've bought one dead from a guy half way down the country (NZ). My thinking is it is a SMPS issue since the thing wont even power up. plan on taking the lid off tonight to have a looksie.
Cheers....

[znjamznjam]

Re: Pioneer HM82 - No power

Hy Guys

Is IC replacement (ICE3BR0665J) enough for working Power Supply?

Thanks in advance

[Andrew453]

Re: Pioneer HM82 - No power

Purchased the full service manual, and have attached the smps diagram.

Hi - please can you point me to where you purchased the service manual? Mine spontaneously powers itself off (only blue flashing light on the front left), but otherwise works perfectly so would like to fix it if possible.

[budm]

Re: Pioneer HM82 - No power

Free service manual.

[andrew1701]

Re: Pioneer HM82 - No power

Hi Andrew 543,

I have the same fault it runs for a day or two then switches off, very intermittent, it can last for days I have found the service manual at

we are not far apart, if I find the fault I will let you know and or repair your free of charge, there is a lot to digest, BR Andrew

I suspect a cap or a resistor going high.