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What is on your workbench right now?

Rick Sykora

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Shielding of signal cables, not only twisting.
Thanks, was pondering that too but do not have any on hand. That closer coil is not moving so the board is going to have to go somewhere else.

Nobody really will care other than me. Mounting externally will have other compromises, so getting out some Flexseal tape and mounting board diagonally. Will likely remove the big terminal block too. The wiring will keep the board from moving much and the outputs are protected. Knew it was going to be a tight fit but want to stop fiddling with this amp and start using it!
 
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Rick Sykora

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May add a couple of tie wraps to better secure, but this solved the problem...

D31D0819-E0C8-487F-BBCB-B2743F125251.jpeg

Please forgive the crappy screenshot using my iPad camera, but was getting late.
 

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tomchr

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Mounting brackets like the Keystone P/N 4332 (available from Mouser) could be helpful. They'd allow you to mount the board perpendicular to the bottom.

Tom
 

Rick Sykora

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Mounting brackets like the Keystone P/N 4332 (available from Mouser) could be helpful. They'd allow you to mount the board perpendicular to the bottom.

Tom
Thanks Tom! Would love to do that, but the board is a few millimeters too tall to fit.
 

Rick Sykora

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Back in action! :D

ECD6230B-C5CD-4AF7-843D-E45B67E84BDC.jpeg
 

Hipocrates

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Audiolab M-DAC in dire need of some service./QUOTE]

Man those lelon caps are terrible... I have one of those with the same problem some where....I totally forgot about it.
I forgot to add that is a well documented capacitor plague on some those units. (it have like 150 of them)
 
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solderdude

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HE560 that should have an intermittent driver.. doesn't do that here... pilots error ?
 

sabristol

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1 (3).jpeg

On the bench right now is a 1979 Rotel RX-300 receiver.
Classic problem: blown rectifier diode due to faulty electrolytic(s). Got it working and halfway through a recap this afternoon. Sounds ok. I'll give it an alignment next, even though the FM receiver seems sensitive enough as is.
2 (1).jpeg

I've also got the matching Rotel RD-300 cassette deck on the bench, well actually it's underneath it now and making it's way towards the bin / eBay. It has all sorts on mechanical things wrong with it (e.g. belts aged, return spring snapped, retaining clip broken, foggy VU meters) so have sort of given up and of the mind it's likely to be BER.
 

Rick Sykora

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A member's Purifi EVAL-1…

021AD627-6622-4078-A848-AC38C96C5F24.jpeg

Turns out R92 and R99 were blown on power supply, so would not power up…

BD36693A-22DE-4B35-9F65-BEE499D08285.jpeg
 
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pma

pma

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Thread Starter #297
Turns out R92 and R99 were blown on power supply, so would not power up…
Interesting ....
Mechanical or overcurrent damage? SMD resistors have issues if the PCB bends. I think we cannot expect >30 years lifetime from current amplifiers. I am with @restorer-john in this.
 

MakeMineVinyl

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Interesting ....
Mechanical or overcurrent damage? SMD resistors have issues if the PCB bends. I think we cannot expect >30 years lifetime from current amplifiers. I am with @restorer-john in this.
Low value resistors are commonly used as fuses (although we typically use 10 ohm), so there might be some other problem lurking.
 

Rick Sykora

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Interesting ....
Mechanical or overcurrent damage? SMD resistors have issues if the PCB bends. I think we cannot expect >30 years lifetime from current amplifiers. I am with @restorer-john in this.
pretty sure it was overcurrent as these pcbs are mounted on thick aluminum, but not my amp so cannot be sure.
 

sabristol

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On the bench.... just about finished the repair and refurbishment of a 1980 NAD 3030 "New Acoustic Dimension Stereophonic Amplifier" (!)
.
Bench - 1.jpeg

Main problem was the 2N3055/MJ2955 output transistors as distortion in the right channel prematurely increased with power output, albeit within OEM spec. The original transistors were dated 79/80 although the 3055 in the distorting channel had previously been replaced with an RS branded item dated 82.

NAD 3030 Power vs THD - Before Service.png

After a full Nichicon recap, transistors and service:
NAD 3030 Power vs THD - After Service.png

1622370208541.png

NAD 3030 Frequency Response - After Service.png

The one thing I'm not happy with yet is the Phono stage, as it seems particularly noisy. It's based on BC549, BC559, BC556 and BC546.
1622371466675.png
 
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