[Kruemelix]

I tried another PSU board and exactly the same thing happens. Around +30V between +30/GND and +10V between -30/GND. Seems as I soldered something wrong. Can I post some HiRes pics of the PSU board? Perhaps someone here can see the failure as I am still thinking having done nothing wrong...

Thomas

 

[Kruemelix]

another thing: the right OPA541 is getting way too hot on both boards

 

[DaKi][er]

Quote:

Originally Posted by Kruemelix another thing: the right OPA541 is getting way too hot on both boards

Most certainly sounds like you killed the -ve output opamp, check that none of the capacitors near it haven’t blown, the tantalums really like to go short circuit when they die.

Also the way it works is the -ve opamp takes its input signal voltage from the +ve opamp and inverts it for its output, so trace that back as well and check the 2 10K resistors as if there is something wrong there and the input is open circuit it will kill it too

The psu circuit is very temperamental, anything wrong at all on it will nearly always end in catastrophic failure, check everything twice over

 

[DigiPete]

Quote:

Originally Posted by Kruemelix another thing: the right OPA541 is getting way too hot on both boards

Hmmm, check your LM338 inputs/outputs to make sure they are correct.

Try posting also on Headwize in the Dynahi PSU DIY section.

 

[DaKi][er]

BUMP!

Quote:

Originally Posted by DaKi][er OK, I’ve been slowly working on a dynahi, after being given all the parts for 2 and a half of them and completed one that had a busted psu from kenny12 and all I had to do was to get one working for a friend of his which was no problems after getting some more opa541's for the psu and a little more care in the construction and testing than kenney12. So with all the other parts left I got enough to make a balanced dynahi and have decided to go nuts on it and do it all perfect from the start. I got a psu board all soldered up and outputting a nice +/-30.000V after hand selecting resistors to get a perfect output. Now onto the amp, I’ve been measuring the gain of the transistors but I’m a little unsure on what the ideal transistor values for what spot. So here is a list of what I’ve got and I’m after some recommendations on what transistors to use where. 2sa1145 *snip* 2sc2705 *snip* 2sc3421 *snip* 2sa1358 *snip* 223.2

 

[dip16amp]

2sa1145 164, 164.1, 165.1
2sc2705 178.12, 178.3, 180.2
2sc3421 149.3, 150, 150.3, 150.5
2sa1358 196, 196, 196.65, 197

2sa1145 169.3, 169.4, 169.45
2sc2705 180.3, 180.6, 180.7
2sc3421 158, 158.7, 159.3, 161.5
2sa1358 197.4, 198.1, 198.75, 198.8

2sa1145 172.3, 172.5, 173.4
2sc2705 181.35, 182.55, 182.8
2sc3421 161.9, 162.3, 163, 164
2sa1358 199.65, 200.1, 200.5, 200.5

2sa1145 173.7, 174, 174.5
2sc2705 183.5, 183.55, 183.7
2sc3421 166.9, 167.8, 168.6, 169
2sa1358 201.1, 201.8, 202, 202.75

 

[DaKi][er]

Makes sense, Thanks for that

 

[rsaavedra]

I'm rebuilding an enclosure for my Dynahi, in fact two separate enclosures, one for the power supply, another for the amp.

Using a 7ft balanced shielded microphone cable to bring the electricity (+, -, and ground) from the power supply box to the amp boards box.

The + and - wires in this cable are 22 AWG, ground will travel through the shield mesh. Does this sound like a good choice of a cable to bring the DC power (+/-30v, 2A) to the dynahi boards?

 

[Pars]

I would probably opt for either larger gauge or more runs. Also, I would not use any type of audio connector for this that a user could mistake for an input/output. Something like Amp 97 series, etc. circular connectors would be good. Amb has done this and recommended a connector for it.

 

[rsaavedra]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif I would probably opt for either larger gauge or more runs. Also, I would not use any type of audio connector for this that a user could mistake for an input/output. Something like Amp 97 series, etc. circular connectors would be good. Amb has done this and recommended a connector for it.

The balanced connectors wouldn't be a problem for me, this would be the only balanced cable I have at home, at least so far. Yet I certainly see your point though, a balanced cable running DC power would be very destructive if plugged into the connectors of a legitimate balanced component. Quite risky. I will have to find another use for this balanced cable

Thanks Pars!

 

[DigiPete]

Quote:

Originally Posted by rsaavedra /img/forum/go_quote.gif The balanced connectors wouldn't be a problem for me, this would be the only balanced cable I have at home, at least so far. Yet I certainly see your point though, a balanced cable running DC power would be very destructive if plugged into the connectors of a legitimate balanced component. Quite risky. I will have to find another use for this balanced cable Thanks Pars!

I'm using 12g power cable wire from home depot and 20-amp plugs/sockets (sideways pins vs. the standard vertical pins on 120v household plugs).

 

[flecom]

i would look at CPC connectors... or maybe SpeakON connectors would be good since they are designed with large conductors in mind, and they are locking too... other usual suspects could be used also, such as DIN connectors... im also a fan of radio mic connectors... switchcraft has the three pin version... but i have seen them start at 2 pins and work their way up to i think 8 pins dont remember

ex

http://www.switchcraft.com/products/connectors-53a.html

 

[n_maher]

Quote:

Originally Posted by flecom /img/forum/go_quote.gif i would look at CPC connectors... or maybe SpeakON connectors would be good since they are designed with large conductors in mind, and they are locking too...

I would go one step further and use the Neutrik PowerCon connectors. They have three dedicated terminals which would be useful for this application and they are a "one-way" plug meaning that you can't get it wrong. You could use the Speakon connectors but you would have to find the 4-channel version as i think the one's most commonly found are two conductor, or at least the ones that I used for. I also like to make sure that none of the connectors used on my amps duplicated on that amp. So for the Dynahi I'd use a standard IEC receptacle for the AC input and then use a Powercon setup for the umbilical between the PS and Amp.

rsaavedra, here's the back panel of my PPA which used a Powercon for the AC connector and Speakon hardware for the umbilical cord.

 

[j4cbo]

Cases are expensive!

I'm looking for a good enclosure for my Dynahi (potentially to be upgraded to a Dynamite in the future). The HiFi2000 "Pesante Dissipante" and DIY Enclosures 1712HS both look really nice, but they're insanely expesnive - $150-$200 after shipping. I could stretch that much, but I'd have to put everything in one case rather than two, and apparently that's much preferable from a noise and interference point of view.

Are there any nice-looking, not-overly-expensive, heatsinkable cases out there?

 

[Pars]

look here