Hi Zman!
It was going great until last night, a tiny solder bridge on the Yarra MB stopped me in my tracks 😱
Two working Melbourne’s turned into zero.
Troubleshooting and repair tonight 🙁
It was going great until last night, a tiny solder bridge on the Yarra MB stopped me in my tracks 😱
Two working Melbourne’s turned into zero.
Troubleshooting and repair tonight 🙁
Thanks Z,
I hope so too! You know how these situations can go, definitely need some Metallica background music for this one 😀
I hope so too! You know how these situations can go, definitely need some Metallica background music for this one 😀
I see that 2 resistors are mounted off the board on lugs, can this be done with the component legs instead of the lugs?
I have 2 boards built now less the 2 transistors and the 2 resistors on lugs. It looks like I need to read all the posts to find out why the lugs and what the gain is (4.7?).
You don’t need the lugs. Just insert directly into the holes/pads. The default gain is 15.6dB and is set by the (R118+R119)/R118 value of (5k6+33k)/5k6. If you want 30.6dB if gain use 1k for R118 etc. leave R119 at 33k.
Add some resistor lead clippings to the two test points to measure bias current though.
I think JP added feb lugs to allow easy de-soldering and exchanging of the gain resistor.
Add some resistor lead clippings to the two test points to measure bias current though.
I think JP added feb lugs to allow easy de-soldering and exchanging of the gain resistor.
Hi X,
The solder bridge was fixed quickly. The Melbourne’s were another story. I’ll give the short version though. After spending several hours checking/testing every component, the problem turned out to be faulty meter lead!!! The Melbs are all good 🙂
That’s great news to hear, Vunce. Sorry you were another victim to the bad wire Gremlin. That must be very frustrating - but hopefully a new page has been turned.
Does this build have gain? Is it the correct version for the Yarra?
1 more dumb Q, what is the part number for the heatsinks, I have some clip on ones but they are too large, TO126 right.
1 more dumb Q, what is the part number for the heatsinks, I have some clip on ones but they are too large, TO126 right.
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Default gain is 15.6dB. The gain is set by R119 and R118.
Gain = (R118+R119)/R118 leave R119 alone at 33k and adjust gain via R118.
Gain = (R118+R119)/R118 leave R119 alone at 33k and adjust gain via R118.
TY, I want the Yarra Pre to drive my M2x, hoping it will be a good match as my Mesmerize is unity gain and is really not enough, great sound though.
Hi batty, RS - Online here in OZ has the Fischer SK95-25-SA-220 heat sink in stock (their part number is 189-8319) and they are $3.77 AUD each incl. GST with 23 in stock for next day delivery. That is where I got mine from and are the same ones as shown in the original PCB build photo's.
With 15.6dB and 15.6dB of M2X, you have about 31dB overall which should be perfect for driving with a cellphone or usual RCA source.