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Hi guys
I have 2 problems, and need help.
1: Just finished building Placid BP, and when powering up, the three Leds on the one half side were glowing up with an orange colour. And the number 3 from the side died. I then measured the Ref voltage, and found it was way to high, 16.66 v to be correct, instead of 3.85 which is the correct voltage. The other side is just fine with green glowing Leds. I have check and double check soldering joints and that all parts are in their right places. Can anybody help?
2: Also build an Placid HD. I am not able to measure chunt. CCS is 475ma, and it works fine when playing. The heatsink close to the CCS measuring point get guite hot. Can`t hold my finger more than 3 sec before it`s to hot.
The other heatsink is not warm at all,almost no temperature at all. Is the Chunt reg dead ? Is it possible to run the Placid with a dead chunt reg ?
Will appreciate all the help I can get
Regards
Tommy
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Sry, don't have camera. But after I measured all resistors, it seems clear that R 7 A-B can be the problem. They measured way lover than 100K, around 60R. After rechecking the solder joints I found two very close to each other. I resolder them and are now waiting for replacement Resistors and Leds.
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SOLVED !!!
Stupid me,,,,one of the D1's where in the wrong direction. How do I check if it's broken ?
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If its the CLD you can put it in series with a 1R resistor and connect it to a 9V battery. You measure the rated current across the resistor then it is still good. :)
Or - you could just put it back in right way around and try it.
Likely if it died short it took out the LEDs with it.
I have never tried installing one backward so i am not sure if it would kill it. :)
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Thx Russ
I put it back on the pcb and it measured exactly the same as the other CLD's. 55ma. So I will give it a try later today. ( it took out 2 of the 3 led's when it was in the wrong direction)
It also measured 55ma, when not connected to the pcb.
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The CLD did survive my mistake and the Placid BP is working just fine.
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Good show. Glad you got it sorted.
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ha-ha
lucky for you I had the necessary parts
best
Leif
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Just finished Placid HD, and R-7 measure only 60K instead of 100K when mounted to the pcb. Desolder it and R-7 is ok. What can be wrong here ?
All other Resistors measure perfect according your parts list. Led's glowing fine and solder joints looks fine. What's wrong here ?
Russ or Brian ?
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Why do you think anything is wrong? Is the circuit working as expected?
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My bad Russ. The circuit is not working as expected. When ccs current is set to around 400-450ma and I then measure the shunt, the shunt value is almost the same. It seems for me that the Placid is shunting all it's css current. This happens with or without no load. Voltage is stabil 5.75 out. Ref V is 3.81. The BII is glowing and ready, but the very high shunt value concern me, and the one heatsink is very hot,ant the other one is cold.
As mention, all the other Resistors measure exactly as they should ( before and after soldering them to the pcb )
(Parden my bad scool english from the seventies)
Thx
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Originally Posted by: musicman  My bad Russ. The circuit is not working as expected. When ccs current is set to around 400-450ma and I then measure the shunt, the shunt value is almost the same. It seems for me that the Placid is shunting all it's css current. This happens with or without no load. Voltage is stabil 5.75 out. Ref V is 3.81. The BII is glowing and ready, but the very high shunt value concern me, and the one heatsink is very hot,ant the other one is cold.
As mention, all the other Resistors measure exactly as they should ( before and after soldering them to the pcb )
(Parden my bad scool english from the seventies)
Thx This is impossible. Are you measuring at the right test points ? CCS is measured across R1 (pos-pin from DMM at TP_VIN+ and neg-pin from DMM at TP_CCS+) - and shunt current is measured across R2 (pos-pin from DMM at TP_SHUNT+ and neg-pin from DMM at TP_OUT+) Edited by user Sunday, March 3, 2013 9:50:51 AM(UTC)
| Reason: Not specified
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Thx for reply avr300.
Yes I'm measuring from the right test points. I have build a Placid hd bp, and it works fine. Thats why I'm confused right now. The big question for me now is why R7 measure 60K and not 100K as it's supposed to. Off the board R7 measure 100K.
Thx
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It's no big question - you're measuring in circuit getting influence from the surrounding components. Try measuring the CCS and shunt current again (voltages across R1 and R2) and post the results. Edited by user Sunday, March 3, 2013 5:10:37 PM(UTC)
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Ok, here we go.
Vin and ccs across R1 is 400ma. Shunt across R2 is 400ma. This is without load. With load,the same result. Then I disconnect Placid for check of solder joints, and when connected and measured again, vin -ccs across (R1) 0.00ma , same result for shunt across(R2). The Placid sees to be dead, but the led's are glowing ok.,,,,,,,,,???
After connecting Placid to the trafoside the last time and power up, the fuse blow, so I think it's not worth taking the risk Anymore with this Placid.
Maybe it's best to use the lcdps that I've been using for the last two years without any prob at all. But I've read that the Placid 1.0 is a very low noise psu circuit and I thought I should give it a try to see if this will bring me another step to hifi-heaven.
The sound in my system is now very good, and I'm very impressed with the combo BII-Exa usb.
Thx
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Please take a pictures of the transistors, labels if possible. It is quite possible that this is a case of transistors installed in the wring spots.
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Oh, have no camera just now Brian. It was my son who take the pics and help me upload them. But I've checked and write down the transistor numbers. QN 1: F1A50AA J5200 QN 2: F1A07AA J 5200 All the other QN and QP transistors are in their right places. ( VR 1 and VR 2 are ok ) Thx Edited by user Wednesday, March 6, 2013 2:50:31 PM(UTC)
| Reason: Measuring mistake
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Measure the following:
AC voltage at the input
DC voltage at the large capacitor (under the board)
Do the voltage and shunt current pots function?
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