audio-talk

Thanks.
Another fail from Google !

Mark, I've got a also got few spares, if you need them.

Andrew

Thanks - another 8 would be handy for two more boards. Will you be at Owston ?

I bought 3 syringes of thermal grease ... no idea why, I can't see me getting through 1.

https://uk.rs-online.com/web/p/thermal- ... 3732323926

I'll bring the other 2 to Owston, anyone who can use them is welcome. Actually I wonder what other surplus I can dump on somebody, I mean I wonder who else might benefit from my treasure trove of goodies ...

IslandPink wrote: ↑Tue Jun 12, 2018 8:32 am Thanks - another 8 would be handy for two more boards. Will you be at Owston ?

Planning to be there.

Andrew

Those remaining are:

Neal : 4 x large
Michael L 2 x large

Neal are you planning on being at Owston?

thanks,

Andrew

Experimenting with something separate, my caps were all at my brothers so I used one of the 5600uF caps supplied with the DC boards. So THAT's what a blown capacitor looks (and smells) like.

No harm done and all valuable lessons. Andrew could you give me a link to the ones supplied please so I can check the datasheet and see where I went wrong ? I take it any 105degC 16v 5600uF cap will be fine ? I'll get some spares too.

This one ok ?

https://uk.rs-online.com/web/p/aluminiu ... s/7396800/

Hi Mick,

I wont' ask what happened. You really need Panasonic FR Series, high ripple, not cheap but worth it.

cheers,


Andrew

Thanks Andrew

Ok I've built all my boards for the new amp (4 small, 8 large) and am testing them now.

All good, but one board takes forever to reach the value. The others are all perhaps 20 seconds, but this one I timed (patiently) and recorded the values over a lengthy period. Aiming for 5v, after about 5 minutes it's at 4.78v, about 90 minutes later it gets to 5v. It seems to stabilise eventually.

Any clues where to look for issues?

UPDATE: when targeting 1.5v or 2.5v it's fine, just 5v it struggles with. Also the led is lit green, though not bright, whereas I can't tell the others are on.

RhythMick wrote: ↑Fri Aug 24, 2018 8:45 pm
UPDATE: when targeting 1.5v or 2.5v it's fine, just 5v it struggles with. Also the led is lit green, though not bright, whereas I can't tell the others are on.

Interesting. I can't offer the advice you need, but I remember quizzing Andrew and DavetB about how dim the green LED was on one of my boards when I had ( another) problem - we all agreed that it's barely visible in daylight - so if you have one brighter , maybe that is significant.

Yups, its used as a voltage ref IIRC, not an indicator as such.

No actually even targeting 2.5v it's slow to rise, just less noticeable. After about 10 minutes it gets to 2.44v. Temperature of both D44H11 & LD1085P are stable (around 44 & 54 deg C respectively, bolted to a 3mm copper sheet).

To be honest I could live with it, but I don't like things not being right.

Problem solved.

I realised the 2 boards I want happy with were the first board I built, and I'd never built a PCB before that. Sure enough there were some joints I was less than happy with. Reworked those and all is well.

I've now built 24 of these boards (16 large, 4 small) and I'd like to think I'm much better now. Think that proves it. All have been tested with resistors simulating 26, 71A & 45 heaters.

Thanks for the support and advice.