Author Topic: QRV-08 hum  (Read 26524 times)

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Offline peranders

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Re: QRV-08 hum
« Reply #15 on: February 08, 2011, 06:10:45 AM »
You could check your supplier where you have go the transformer you use but Farnell has a type 1689063 which will work.
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Offline CapRock

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Re: QRV-08 hum
« Reply #16 on: February 09, 2011, 02:04:52 AM »
OK ill check my US supplier. here are the specs I will search for let me know if any of these are incorrect.
input voltage: 230VAC single primary
single secondary with 12 volt output
2.3 volt power rating

is that right? even though I'm on 115 the 230 input voltage will be ok. Im assuming that when I hit this transformer with 115 volts it will put out 24 volts instead of 12 right?

Offline CapRock

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Re: QRV-08 hum
« Reply #17 on: February 09, 2011, 03:02:06 AM »
is it a problem if the power rating is higher than 2.3V if all the other specs are correct?

Offline peranders

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Re: QRV-08 hum
« Reply #18 on: February 09, 2011, 06:21:42 AM »
If you put in 115 V into a 230 V transformer you will get half the output voltage. No problem to use use higher VA rating more than size.
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Offline CapRock

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Re: QRV-08 hum
« Reply #19 on: February 10, 2011, 02:10:15 AM »
OK I just want to be sure I order the right thing this time.  The one you sent me a link to is 230V input and 12volt output on a single secondary.  So for me that will be 115V input and 6 volt output on a single secondary.  Is that what I want? the schematic calls for a 230/2X15, so wouldnt I need a 230/2X30 transformer?  If you could just post the specs I should look for on input voltage, how many secondaries I need and what output voltage they should be I would have a better understanding of what to buy, thanks

Offline peranders

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Re: QRV-08 hum
« Reply #20 on: February 10, 2011, 10:15:58 AM »
Wrong of me.

Correct type for 230 VAC mains
1214583 230/2 x 12 V

1214591
This type will fit for you, 230/2x24V
http://se.farnell.com/myrra/44168/transformer-2-3va-230v-2-x-24v/dp/1214591
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Offline CapRock

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Re: QRV-08 hum
« Reply #21 on: February 24, 2011, 08:25:10 PM »
Hey Per,  My replacement transformers came in and I just installed them.  The voltages are still not right.  Even testing the secondaries of the transformers, I am getting wrong voltages.  It also just occurred to me that the power hits the varistor before going to the transformers.  Since I used the one you suggested in your bill of materials for 230VAC and I am on 115VAC will I need a different value varistor?  could that be the problem, if not what else can I do?  I am still getting LED's H2 and H3 to illuminate but the other 2 stay dark.   

Offline peranders

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Re: QRV-08 hum
« Reply #22 on: February 25, 2011, 10:59:46 AM »
The varistor is in parallel and now with perhaps a bit high value but it will not interfere for voltages under 250 VAC in. The varistor should be 150 Vor so.

How are your voltages right now? Can you give me some values? Anything hot?
/Per-Anders Sjöström, owner of this forum

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Offline CapRock

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Re: QRV-08 hum
« Reply #23 on: February 26, 2011, 01:12:17 AM »
ok here are a list of voltages for the transformers.  I have no idea why they would be outputting such different voltages.  All solder joints are solid.  let me know what I should do next.
input: 119
TR1 pin 1: .3v
TR1 PIN 5: 119
TR1 PIN 6: 5.6
TR1 PIN 7: 5.5
TR1 PIN 9: 0
TR1 PIN 10: 0

TR2 PIN 1: .3
TR2 PIN 5: 119
TR2 PIN 6: 21.3
TR2 PIN 7: 21.2
TR2 PIN 9: .3
TR2 PIN 10: .4

Offline peranders

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Re: QRV-08 hum
« Reply #24 on: February 27, 2011, 09:27:18 PM »
Can you measure across each secondary wings please?

Have you turned the rectifier bridges right?

What are your raw DC voltages?
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Offline CapRock

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Re: QRV-08 hum
« Reply #25 on: March 01, 2011, 01:57:44 AM »
hey per here are the results.  I resoldered the bridge rectifiers and now my voltages are even but no led's are illuminated

TR2:
across pins 6 and 7: 3.6v
across pins 9 and 10: 4.4v

TR1:
across pins 6 and 7: 3.6v
across pins 9 and 10: 4.4v

BR3: 2.1v
BR4: 2.8v
BR1: 2.1v
BR2: 2.9v

Offline peranders

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Re: QRV-08 hum
« Reply #26 on: March 01, 2011, 06:14:07 AM »
Did you switch over the voltmeter to DC when you measured the voltage across the rectifiers?

Voltage across R32, R33, E32, E33?
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Offline CapRock

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Re: QRV-08 hum
« Reply #27 on: March 01, 2011, 03:43:32 PM »
Yes I switched it to DC. and I measured across the positive and negative legs of each rectifier.  All of my rectifiers are mounted with the dc output legs (+/-) facing the large electrolytic caps, is this correct?  I will measure resistor voltages when I get back in town tomorrow evening. 

Offline CapRock

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Re: QRV-08 hum
« Reply #28 on: March 06, 2011, 10:07:37 PM »
Yes I switched it to DC. and I measured across the positive and negative legs of each rectifier.  All of my rectifiers are mounted with the dc output legs (+/-) facing the large electrolytic caps, is this correct?  I will measure resistor voltages when I get back in town tomorrow evening.

voltages posted below:
r32:  2.9v
r33:  2.1v
E32:  2.9v
E33:  2.1v

Offline peranders

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Re: QRV-08 hum
« Reply #29 on: March 06, 2011, 10:25:38 PM »
You have exactly the same problem in both channels. Are the electrolytic caps turned right? Anything hot?
/Per-Anders Sjöström, owner of this forum

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