C-1010 blowing 2 fuses all times

pepepito · Jul 10, 2015

Hi All.

We finally recap the yamaha and we are waiting for the two big 22000uf caps ( backorder) and so we give it a try and we didn't get anything, power went on, connected the tuner , tested the inputs etc and nothing so we discharged the caps and start checking components and two of the 1A 250v fuses of the two Pink cables coming from the Transformer are blown so I got new ones and turn it on and nothing, checked the fuses again and they were blown again.

We are not experts but we are really good in following instructions

.

I was reading about the relays but dunno if is the same problem that those other threads so any help or ideas are welcome.

Thanks guys/girls.

clinic-audio · Jul 10, 2015

hello

I think you mean CA1010 ?

Disconnect secondary side of the power transformer and see if the fuse still burn out !

pepepito · Jul 10, 2015

clinic-audio said:
hello

I think you mean CA1010 ?

Disconnect secondary side of the power transformer and see if the fuse still burn out !

Yes CA-1010.

How do I do that ? I guess taking the fuses under the transformer ?

petehall347 · Jul 10, 2015

make sure c428 c427 are wired correctly

petehall347 · Jul 10, 2015

clinic-audio said:
hello

I think you mean CA1010 ?

Disconnect secondary side of the power transformer and see if the fuse still burn out !

secondary is disconnected right after the fuses blow

pepepito · Jul 10, 2015

petehall347 said:
make sure c428 c427 are wired correctly

Interestingly we where not sure about the Bipolar capacitor but those are not c427 or c428

The two C427 and c428 are 47uf 35v and they are new and correctly installed, they are polarized so it is easy to spot if they are wrongly installed.

The schematic I have is for version -0 of the power supply of the circuit board and I have version 1 but I don't know if there is a huge difference.

Thanks.

clinic-audio · Jul 10, 2015

:scratch2:

Seems to be a bad power transformer ....:scratch2:

pepepito · Jul 10, 2015

petehall347 said:
secondary is disconnected right after the fuses blow

I do understand that but from the transformer pink cables are directly connected to the track where those two fuses are and then I have some mica capacitors and 4 diodes I think so I don't understand what you mean with "after".

Sorry I'm not an expert on this so thank you for the patience.

pepepito · Jul 10, 2015

clinic-audio said:
:scratch2:

Seems to be a bad power transformer ....:scratch2:

is there replacement power transformer available ? or is this reparable ?

Thanks.

petehall347 · Jul 10, 2015

pink cables go the fuses as AC through the fuses then rectified to DC with d416 rectifier for the regulated supply that supplies B2 power rails ....c416 c417 in wrong way would also blow fuses ..
tell us the whole story about this unit ...like did it work at first ? has it always blown the fuses since you had it ?
what have you changed ?

avionic · Jul 10, 2015

pepepito said:
I do understand that but from the transformer pink cables are directly connected to the track where those two fuses are and then I have some mica capacitors and 4 diodes I think so I don't understand what you mean with "after".

Sorry I'm not an expert on this so thank you for the patience.

With the fuses removed.What if any AC voltage do you read across the two pink wires.Should be about 36 - 37 volts AC.

petehall347 · Jul 10, 2015

if the transformer was bad it would blow the fuse before it ...i think about 7 amps ... i am sure the transformer is not blowing these fuses ..
check AC voltages with those 1 amp fuses removed to prove this....edit echo wars just beat me to this bit ..

avionic · Jul 10, 2015

petehall347 said:
if the transformer was bad it would blow the fuse before it ...i think about 7 amps ... i am sure the transformer is not blowing these fuses ..
check AC voltages with those 1 amp fuses removed to prove this....edit echo wars just beat me to this bit ..

No he didn't. I did.

pepepito · Jul 10, 2015

avionic said:
With the fuses removed.What if any AC voltage do you read across the two pink wires.Should be about 36 - 37 volts AC.

I see 70Vac

pepepito · Jul 10, 2015

petehall347 said:
if the transformer was bad it would blow the fuse before it ...i think about 7 amps ... i am sure the transformer is not blowing these fuses ..
check AC voltages with those 1 amp fuses removed to prove this....edit echo wars just beat me to this bit ..

7A fuse still good, old fuse was repaired by someone with a wire I replaced it with the proper fuse

pepepito · Jul 10, 2015

petehall347 said:
pink cables go the fuses as AC through the fuses then rectified to DC with d416 rectifier for the regulated supply that supplies B2 power rails ....c416 c417 in wrong way would also blow fuses ..
tell us the whole story about this unit ...like did it work at first ? has it always blown the fuses since you had it ?
what have you changed ?

Unit was given to me in "working state" I remember tested it a while back and was working but every time you changed something it will make a noise like typical of when capacitors are dried or bad so I recap it then turn it on and this happened.

Doesn't matter if I set it to class A or not still blows the fuses as soon as you turn it on.

We changed every electrolytic capacitor on those old diodes execpt for the 22000 uf ones.

pepepito · Jul 10, 2015

petehall347 said:
pink cables go the fuses as AC through the fuses then rectified to DC with d416 rectifier for the regulated supply that supplies B2 power rails ....c416 c417 in wrong way would also blow fuses ..
tell us the whole story about this unit ...like did it work at first ? has it always blown the fuses since you had it ?
what have you changed ?

c416 and 417 are correctly installed too.

avionic · Jul 10, 2015

pepepito said:
I see 70Vac

OK that sounds about right. 70 VAC centertapped is 35-0-35. Theres nothing wrong with the transformer.

avionic · Jul 10, 2015

Next you need to check each diode in the D401 bridged rectifier. Preferably out of circuit.

pepepito · Jul 11, 2015

avionic said:
Next you need to check each diode in the D401 bridged rectifier. Preferably out of circuit.

A simple test with diodes still welded seems to suggest that they are all ok but tomorrow we will go and buy all and test each and swap if bad, I will keep you posted.

C-1010 blowing 2 fuses all times

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