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Old 3rd March 2014, 04:57 AM   #2311
omishra is offline omishra  India
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Done my pearl-2 within new box and some letters on wooden faceplate.

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Old 3rd March 2014, 06:33 PM   #2312
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Default power issue solved

Hi y ALL, just for the record , I found removing C 24 stopped R30 frying and restored the negative voltage to - 24.1 volts no issues.

I took the sensible approach and built the PSU sides first. Including C24 on the Neg side, cold tests showed C24 behaves like a normal capacitor (you can see it charging up when on the ohm's/continuity function on the DVM)

The PCB has no shorts I can detect or see (cleaned it all with IPA alcohol as a precaution anyway) SNIFF SNIFF

anyone had this issue??

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Old 4th March 2014, 08:56 PM   #2313
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No problems with C24 in my Pearl. To make sure, check polarity again, + to gnd, - to R28.
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Old 4th March 2014, 09:59 PM   #2314
Itsmee is offline Itsmee  England
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Some 79xx regulators can go unstable with large values of capacitance on the output; try a quality brand with a 1 amp capability.
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Old 6th March 2014, 01:32 AM   #2315
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Default got that

hi boys,

Thanks Wellerman, all is well in terms of C24-- polarity correct etc , I have replaced the regulator, but will attempt to get a "name make" as it were , thanks itsmee--it seem all OK (for now!)

let ya know what happens when i power it all up (still anteing for a few "bits" to arrive!


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Old 10th March 2014, 06:16 PM   #2316
m2003br is offline m2003br  Brazil
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Default Problem with R30

Dear Johnny,

I think I know what is happening with your R30...
Being the 7915 a non-isolated specimem, the heatsink also become the "Input"
terminal of the regulator...
The only isolation between PCB ground plane and heatsink is the green mask.
When you touch the heatsink to change the IC or when you remove C24,
what happened is that some point of heatsink which was shortened to ground plane, suddenly become isolated.
Give a little spacing between both and your problem is definitely solved.

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Old 10th March 2014, 06:56 PM   #2317
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Default think you correct marcos

hi Marcos,

yes, I was think a similar thought(s) so I gave the heatsink(s) a "haircut" now they float in the air as it were with a nice little (air!) gap between the board and the heat sink, there has been no issues since.
(but I changed the -24v regulator as a precaution)

I have not powered it up yet though (waiting on some nice caps for the RIAA bit)

Thanks for you input sir, most helpful


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Old 17th March 2014, 12:34 AM   #2318
domyboy is offline domyboy  Scotland
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Hi Folks

So I built a Pearl 2 also. I'm getting some bad sound on the output. I took some readings and I have noted the voltages I have on the voltage schematic. the only voltage that appears to be wrong is the 12V between R16 and R17. Has anyone had this problem before?


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Old 17th March 2014, 01:57 AM   #2319
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What do you mean by "bad sound"? Can you adjust P1 for 0 volts on the test pad?
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Old 17th March 2014, 01:25 PM   #2320
6L6 is offline 6L6  United States
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If you can't adjust all the high voltage away with the pot, and you probably won't be able to, replace the ZVP3310.

Be extremely careful in handling, they are very static sensitive and easy to zap. It's not unusual at all to have killed one in construction, about half of the people building the Pearl 2 have done so.
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