Recent Posts

1

Crack-a-two-a / Re: New developing issues

« Last post by drano81 on Today at 04:17:32 PM »

Thanks Doc! I watched this video again before rebuilding the circuit for that channel. I never found a broken wire, but it sounds as good as new now! I finally found time to install the stepped attenuator upgrade and I incredibly happy with the performance of this amp. Thank you Paul for nudging me in the direction of a bad connection.

While the C2A was down, I dusted off a non-bottlehead amp and there is simply no comparison. The C2A should really come packaged with HD800s haha. They are a great combo!

I guess the power cord will have to scratch the itch next…

2

MonAmour / Re: Oh NO! Left channel down!

« Last post by Paul Birkeland on Today at 03:55:53 PM »

I don't know who Sparkfun gets to make their parts, so maybe go with this instead:
https://www.mouser.com/ProductDetail/Texas-Instruments/LM431ACZ-NOPB?qs=QbsRYf82W3GYwUIvsPyMPw%3D%3D

3

MonAmour / Re: Oh NO! Left channel down!

« Last post by Ivan303 on Today at 03:32:39 PM »

One of these?

TL431

https://www.mouser.com/ProductDetail/SparkFun/COM-11078?qs=WyAARYrbSnbLnDtTAKoHfg%3D%3D&mgh=1

4

MonAmour / Re: Oh NO! Left channel down!

« Last post by Paul Birkeland on Today at 03:22:14 PM »

I would put a new 431 regulator on the B side and see what happens.  Also if you set your meter to beep for continuity, check each pair of legs on each transistor to be sure that none of them are shorted out.  It can be challenging (for me at least) to sort out whether the C4S is allowing the 5670 to draw too much current or if the 431 regulator has failed.  Based on your voltages, a shorted 431 regulator is very plausible, and they do fail from time to time.

5

MonAmour / Re: Oh NO! Left channel down!

« Last post by Ivan303 on Today at 03:16:40 PM »

Tube in:

x pad .777V

Pictures attached.

As there are no broken wires that I can see and it's been running perfectly for nearly a year then just up and died,  a failed component on the board maybe?

Thanks

6

MonAmour / Re: Oh NO! Left channel down!

« Last post by Paul Birkeland on Today at 03:09:29 PM »

5670 in.

7

General Discussion / Re: Need help for Upgrading new S.E.X with C4S

« Last post by chuotcon15 on Today at 02:45:42 PM »

Thanks for advising.
I will build it then asking again.

8

MonAmour / Re: Oh NO! Left channel down!

« Last post by Ivan303 on Today at 02:12:56 PM »

Tube in or tube out?

9

MonAmour / Re: Oh NO! Left channel down!

« Last post by Paul Birkeland on Today at 02:09:32 PM »

What voltage do you see on the X pad on the B side? It's next to bB. 

If you could post pictures of the top and bottom of the driver board, as well as the 9 pin socket wiring, there may be something we can see. 

10

MonAmour / Re: Oh NO! Left channel down!

« Last post by Ivan303 on Today at 02:05:54 PM »

Wire to OB removed.

Tube out

IB 412
KReg B 0V

Tube in

IB 116
KReg B 6mV

Thanks