Pioneer's SA500 Blowing protection fuse

Post by **Nick** » Mon Jul 04, 2011 9:44 am

Apart from the 220v part, and the 30w part is possibly not enough.

Not that it matters, but what problem is this to solve? I thought you go th eamp working again?

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 2:27 pm

Yep I recapped the amp and its working great it's just when I was changing an interconnection cable I felt the amps case vibrating when switching it on from cold there is an internal thump from the TX
I used some rubber to try and damp out the vibrating which has helped .But the TX is marked 36-0-36 volts @0.6 amps when I metered it in circuit it comes out at 30.6 volts ac per winding
The amps working voltage is 42 volts DC which I get 41.6 volts DC it just when i replace the TX or have one made perhaps do i need a 36-0-36 volt or a 30-0-30 volt for 41.6 at the amp psu is just CRC

Mike H · Post by **Mike H** » Mon Jul 04, 2011 2:39 pm

I have no idea what "42V (36V)" on the diagram means, but to get 42V DC you need 30V AC r.m.s. Or in this case 30-0-30. Or can use a 0-15, 0-15 with a bridge rectifier. A toroidal from RS?

Unless the numbers in circles mean what the DC drops to at some continuous output power?

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 2:54 pm

Mike H wrote:I have no idea what "42V (36V)" on the diagram means, but to get 42V DC you need 30V AC r.m.s. Or in this case 30-0-30. Or can use a 0-15, 0-15 with a bridge rectifier. A toroidal from RS?

Unless the numbers in circles mean what the DC drops to at some continuous output power?

The 36 volts is with no input and the 42v is max input according to the schematic
I was just hoping to replace the TX with same voltage it's the TX in the amp that's confusing me as it is marked 36-0-36@0.6amps but tests on the meter @30.6-0-30.6 volts

Mike H · Post by **Mike H** » Mon Jul 04, 2011 3:39 pm

Yes it is confusing.

Well if it was 36VAC, then the B+ would be 51V, not 42V as written

So I would assume 30VAC is correct.

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 5:10 pm

Mike H wrote:Yes it is confusing.

Well if it was 36VAC, then the B+ would be 51V, not 42V as written

So I would assume 30VAC is correct.

Yep looks like it I just ran Duncan's psu and 30 volt does indeed come out at about 42volt DC
So how about one of these then as a direct replacement
http://www.rapidonline.com/sku/Electric ... 19/88-3824

Post by **Nick** » Mon Jul 04, 2011 5:45 pm

Yep, I think that would be fine. You loose the winding for the lamp though.

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 5:56 pm

Nick wrote:Yep, I think that would be fine. You loose the winding for the lamp though.

Thanks nick
Losing the lamp isn't a problem really I think replacing the TX is a good reason to improve the psu by making it an external and doubling the capacitance and maybe adding a choke any ideas on this

Post by **Nick** » Mon Jul 04, 2011 6:22 pm

Well, it would need to be a highesh current choke, but they are good at low voltages.

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 7:17 pm

Nick wrote:Well, it would need to be a highesh current choke, but they are good at low voltages.

Any suggestions on a suitable choke to use and where to get them

Post by **Nick** » Mon Jul 04, 2011 7:54 pm

What sort of current does the amp pull?

colin.hepburn · Post by **colin.hepburn** » Mon Jul 04, 2011 8:23 pm

Think it would be better to post the schematic as I may get it wrong again ah that hasn't worked image out of focus but think the amp is about 66mA and idle current of about 70mA

Mike H · Post by **Mike H** » Mon Jul 04, 2011 8:55 pm

You could run the lamp off one of the 30's if you use a 160R dropper resistor? Have to be >=4W though.

Or replace with a LED

colin.hepburn · Post by **colin.hepburn** » Tue Jul 05, 2011 4:25 pm

Yep may go with a LED just considering the idea of adding a choke to the psu CLC but Nick says it will require a high highest current choke according to the schematic total current is 66.5mA 60mA for the amp and 6.5 mA for the pre which is not used

cressy · Post by **cressy** » Tue Jul 05, 2011 9:24 pm

is it pulling 66 ma per channel (cant see the schematic on this phone) or total for stereo? there are plenty of chokes available that are rated for 100 plus ma that are reasonably cheap. try bluebell audio, speak to philip there and he'll be able to advise on this no problem. try the workshop number on the website first, hes usually there ime

audio-talk

Pioneer's SA500 Blowing protection fuse

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