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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 11:58 am
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Yeah, that's what's trippin me out all accept U1 are reading proper voltage; which led me to the former hypothesis.

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PD


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 12:13 pm
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Hence my quandary. I think that the person that was using it put a fuse in the export slot and the US slot. Wouldn't that cause more voltage than it's rated for to pass through?

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PD


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 12:52 pm
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I would check voltages across zeners at power supply , CR56 (+16 V ) and CR57 (-16 V )

If this power supply is defective ALL of OP amp will have 12 V like U1A.

Or it is only U1A have the 12 volts ? In this case something wrong with U1A or any component feeding voltage ( to U1A ) include printed circuit board.

Those king of amp are realy tough to trouble shouting ; printed circuit with op amp....


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 1:00 pm
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If led LD2 do not glow , do you have 30 VAC at TP22 ?

No AC there or less than 30 V , the minus 16 Volts will be too low to all Op amp.

There are 2 fuse holder in this amp !!!! Import and export ? Where are they in the schematic ?


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 1:04 pm
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Ok I see the 2 fuse holder XF1. left corner , down

There no more voltage if you put fuse in each , they are in parallel , but could mean less protection for the amp in case of short.


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 1:11 pm
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IMO if LD2 do not glow you don't have 30 VAC at TP 22 AND you can't have -16 volts on ALL of OP amp . NOT only U1A

Be sure to check all OP amp voltage ; +16 V AND -16 V

If all OP amp have proper voltage except U1A , Led LD2 is defect or broken connexion same for U1A


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 1:12 pm
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Not possible to put two fuses in the same slot, the slot having a smaller inner and larger outer. As stratele52 pointed out, this wouldn't change the voltage anyway, only allow more current. The voltage is only changed with the transformer connections.

To be more clear, could you please indicate your voltage readings, not just "everything is reading proper"? Are you saying that you have the +/- 16 VDC at all other op amps' pins 4 and 8, and only read 12 VDC at U1 pins 4 and 8?

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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Sun Jul 07, 2013 1:32 pm
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shimmilou wrote:


To be more clear, could you please indicate your voltage readings, not just "everything is reading proper"? Are you saying that you have the +/- 16 VDC at all other op amps' pins 4 and 8, and only read 12 VDC at U1 pins 4 and 8?


+1


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Mon Jul 08, 2013 9:16 am
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shimmilou wrote:
Not possible to put two fuses in the same slot, the slot having a smaller inner and larger outer. As stratele52 pointed out, this wouldn't change the voltage anyway, only allow more current. The voltage is only changed with the transformer connections.

To be more clear, could you please indicate your voltage readings, not just "everything is reading proper"? Are you saying that you have the +/- 16 VDC at all other op amps' pins 4 and 8, and only read 12 VDC at U1 pins 4 and 8?



That's correct; I changed U1 again just to be sure. By the way, when I changed the OP Amps, I put in sockets. Thought I would add that so all info is known.

This is what has me befuddle; the readings and symptoms don't make any sense.

Thanks,

PD


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Mon Jul 08, 2013 9:25 am
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stratele52 wrote:
IMO if LD2 do not glow you don't have 30 VAC at TP 22 AND you can't have -16 volts on ALL of OP amp . NOT only U1A

Be sure to check all OP amp voltage ; +16 V AND -16 V

If all OP amp have proper voltage except U1A , Led LD2 is defect or broken connexion same for U1A



I've been thinking that perhaps there is a broken or cracked trace; so this is possibly the reason this is occurring and I will check it out. Seems that we're potentially making progress. :-)

Thanks,

PD


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Mon Jul 08, 2013 12:54 pm
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stratele52 wrote:
IMO if LD2 do not glow you don't have 30 VAC at TP 22 AND you can't have -16 volts on ALL of OP amp . NOT only U1A

Be sure to check all OP amp voltage ; +16 V AND -16 V

If all OP amp have proper voltage except U1A , Led LD2 is defect or broken connexion same for U1A


And what about TP22 , 30 VAC ?

We need some meat .... Some voltages reading . :wink:


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Post subject: Re: Roc Pro 1000 - No Sound, No LED's, but do get sound from
Posted: Mon Jul 08, 2013 1:25 pm
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+1 stratele52. We need as much info as possible.

DX7Man wrote:
...I've been thinking that perhaps there is a broken or cracked trace;...


I would look for bridged joints around your sockets, especially the U1 socket. Great idea to put in sockets, but sometimes a couple of joints get bridged that shouldn't be.

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