sa-7500ii dead

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frankwood

Active Member

• Feb 12, 2015

• #1

hi everybody, i have a big trouble with my pioneer today. i turn on the power switch and...nothing. no power ligth, no sound, no click from the relay. i checked all three fuses(one 5amp and two 1amp) a??nd that's ok. i have my tranfo working since it gave me the output voltages. so here i am don't know what to do next?

 

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frankwood

Active Member

• Feb 12, 2015

• #2

need help! don't want to crush it. and don't have money to just take it to the shop.is there a common trouble on these? if my transfo work, what makes that i have nothing's working?

 

jheu02

AK Subscriber

Subscriber

• Feb 12, 2015

• #3

Are you sure the fuses check good? Continuity test them.

 

Ths364

Super Member

• Feb 12, 2015

• #4

If you can check the transformer, you can check the rectifier output after you've verified the fuses. Check with the meter set to DC volts.

 

jheu02

AK Subscriber

Subscriber

• Feb 13, 2015

• #5

I'd also check the power switch itself to see if the contacs are any good. Have any deOxit?

 

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frankwood

Active Member

• Feb 13, 2015

• #6

Ths364 said:

If you can check the transformer, you can check the rectifier output after you've verified the fuses. Check with the meter set to DC volts.

Click to expand...

ok good, so i'll try to locate the rectifier circuit. if i understand well, there is no other way; i must follow the alimentation untill i stop somewhere? soory for my limited skills but i really want to save this one and no money for that....(p.s.the three fuses are good).thanks

 

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frankwood

Active Member

• Feb 23, 2015

• #7

well, i'm still stock. as i said before the transfo works and all the fuses too. don't know what to do next. near the two big caps , i see four diodes maybe it's the rectifier circuit? don't know how to test it any input could be appreciated

 

Copa1934

My ears are bleeding

Subscriber

• Feb 27, 2015

• #8

frankwood said:

well, i'm still stock. as i said before the transfo works and all the fuses too. don't know what to do next. near the two big caps , i see four diodes maybe it's the rectifier circuit? don't know how to test it any input could be appreciated

Click to expand...

Lurking. Have a 7500II that quit on me. Sounds very similar to mine.

 

petehall347

the brandy coffee man

• Feb 27, 2015

• #9

if you can see the terminals on the large filter capacitors you could measure voltage across
each one .

 

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frankwood

Active Member

• Mar 3, 2015

• #10

petehall347 said:

if you can see the terminals on the large filter capacitors you could measure voltage across
each one .

Click to expand...

ok, so it could be a filter capacitor issue?i'll check it soon and come back. thanks a lot. what should be the voltage on those? the same voltage as the transfo out?

 

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frankwood

Active Member

• Mar 4, 2015

• #11

so i checked tension at each filetr capacitors and it gave me 0 volt. ac or dc.maybe normal? all four big diodes seems working properly.
p.s. i let the power on like 2 or 3 minutes to do my checks and it begun to smell burning. so i turn it off. since i have no voltage that goes to the amplification section, it must be at the power supply no? tanks

 

jheu02

AK Subscriber

Subscriber

• Mar 4, 2015

• #12

If you don't have a dim bulb tester, remove the output transistors before you do any further testing or powering on. Search DBT or dim bulb tester to see how to make one. It's a current limit protection...invaluable for repairing vintage equipment. You should also make sure you have the service manual prior to doing work. That would answer your voltage questions.