I tested those points Dario. The -35v areas all measures good +/- a few 10ths of a volt. I am not getting a reading across D205 or any -14v on the -14.6v test pad. The positive voltage side all measures good +/-- a few 10ths of a volt.
Here are links to some pictures as requested Dario.
https://drive.google.com/file/d/0B_v6AlLmqoMHNnAzTHZwMTNjcnM/view?usp=drivesdk
https://drive.google.com/file/d/0B_v6AlLmqoMHOWJVNG5RVEFBdHc/view?usp=drivesdk
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Wait a minute, you said it's an older version board? Is it not the faulty series? A small extra jump wire was needed there..
No, it's not j1, the problem, but that the other channel is working seems to exclude this problem, true.
I'm on a mobile phone, not that easy the search, will get back later.
Ciao, george
I'm on a mobile phone, not that easy the search, will get back later.
Ciao, george
Ok, found the link. I was thinking of this old little problem:
As you see, resulted in a malfunction in the negative supply
But should be present on both boards.
http://www.diyaudio.com/forums/chip...on-build-thread-tutorial-203.html#post4181244
As you see, resulted in a malfunction in the negative supply
But should be present on both boards.
http://www.diyaudio.com/forums/chip...on-build-thread-tutorial-203.html#post4181244
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Looks like that's not my problem. I have Rev 1.02 boards from March 2013.
I tested for continuity on those pads just in case and they check out.
I noticed I am getting continuity between the -14.6 test pad and ground. I am also getting continuity between ground and the top pin of the LM317 when looking at the board bottom as shown in Darios voltage test picture.
I tested for continuity on those pads just in case and they check out.
I noticed I am getting continuity between the -14.6 test pad and ground. I am also getting continuity between ground and the top pin of the LM317 when looking at the board bottom as shown in Darios voltage test picture.
Depends on what continuity.. if it's zero ohm or close -then a solder blob, stray pcb 'finger' or the transistor gone;
If it's higher, then could be also the zener inverted?
If it's higher, then could be also the zener inverted?
Zener is properly oriented.
I am getting .008v to ground on that pin of the regulator.
So you are thinking T201 the BC640-16 has possibly gone bad? I will need to get more if that is the case. Think I am fresh out at the moment.
Thanks for the help thus far Joseph. I appreciate it very much.
I am getting .008v to ground on that pin of the regulator.
So you are thinking T201 the BC640-16 has possibly gone bad? I will need to get more if that is the case. Think I am fresh out at the moment.
Thanks for the help thus far Joseph. I appreciate it very much.
Last point: also a problem with the load (lm318 , pin 4) could short the regulator. Have a look also at that.
You can understand if it were the transistor; ripping it out should clean up the short.
A bd140 would do as well, if you don't have more bc640-16.. at least could have the amp going, until you re-order..
You can understand if it were the transistor; ripping it out should clean up the short.
A bd140 would do as well, if you don't have more bc640-16.. at least could have the amp going, until you re-order..
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I had a few BD140's laying around. Looks like that was it. T201 was bad.
Thanks for the assistance Joseph.
Thanks for the assistance Joseph.
Hello all,
Do you have some suggestions about wires (type, size,...) between RCA connectors and PCB and between speaker connectors and PCB?
Thank you!
Do you have some suggestions about wires (type, size,...) between RCA connectors and PCB and between speaker connectors and PCB?
Thank you!
Hello, i used:
- 24AWG 4n silver wires, insulated in Teflon and enclosed in a copper braid shield, from RCA to PCB;
- 14AWG LGC copper speaker cables (insulated but unshielded) from PCB to binding posts.
I used shielded signal cables because in my build they have to reach the center of the chassis for connecting to a rotary switch and to an attenuator, so they come close to AC power inlet and cables.
The result is great sounding!
I read somewhere that the RCA to PCB cable's copper shield should be grounded at one end only (RCA end?) - is this what you have done?
Thanks
Thanks
For output any AWG12 to AWG14 speaker cable will do but I suggest solid copper wire, preferably OCC and teflon insulated like Neotech SOCT (Available from PCX and HiFi Collective).
A good low cost alternative is VanDamme LC-OFC 268-503-000
For input a good quality twisted pair like the ones from Amtrans (HIFIC/PCX) or a miniature balanced OFC cable like Mogami W2944 console cable (available from eBay or pro audio stores).
The Mogami is much cheaper but still very good.
As always some care and time is needed to determine best orientation, if you don't trust cable directivity ignore this step.
Mmhh... it depends...
If you have a balanced shielded cable you can connect shield to signal ground on just one side (RCA side is a good candidate).
BUT if you're using a coaxial cable the shied is also the signal ground return and so it must be connected at both ends.
I connected copper shields directly to earth ground, via DENO choke (that actually acts like an earth ground star point).
Thanks Luca and Dario,
I use two cat5 wires (twisted) so that's my signal and ground return - I'm thinking that if I put a copper braided shield (around the cat5 wires) this will improve the shielding against possible interference. Guess it can't hurt to try.
I use two cat5 wires (twisted) so that's my signal and ground return - I'm thinking that if I put a copper braided shield (around the cat5 wires) this will improve the shielding against possible interference. Guess it can't hurt to try.