The new "My Ref" Rev C thread

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troystg

troystg

Member
Joined 2004
gainphile said:
Hello.... if the sound is harsh, most likely its the speakers :).

I've built my GCs with so-so "non-quality" caps, R, etc. point-to-point and have not touched them since :D

The whole system sound just marvelous .. 2 days for building the GC, but took me almost 2 years to work on the speakers :smash:
Click to expand...


Except for these aren't really gainclones... ;)
 
M

madisonears

Member
Joined 2007
Can anyone please help me diagnose a non-working amp? No relay click, and no LED other than a brief flash after amp is turned off for a few seconds.

I don't know anything about troubleshooting, but it seems all voltages are correct except one: I get 29 volts at C14, not 24. Resistor values are all right on spec.

Peace,
Tom E
 
ClaveFremen

ClaveFremen

Member
Joined 2005
inserra.it
Paid Member
gainphile said:
Hello.... if the sound is harsh, most likely its the speakers :).

I've built my GCs with so-so "non-quality" caps, R, etc. point-to-point and have not touched them since :D

The whole system sound just marvelous .. 2 days for building the GC, but took me almost 2 years to work on the speakers :smash:
Click to expand...

gainphile said:



oh.. well, at least we know the problem then :D
Click to expand...

Hi Gainphile,

it's not exactly so.

Also my Gainclone was harsh, and it was due to capacitors (both PS and bypasses)...

http://www.diyaudio.com/forums/showthread.php?s=&threadid=136359

Probably your "non-quality" caps were good for the gainclone ;)
 
troystg

troystg

Member
Joined 2004
pinkfloyd4ever said:
Hey guys could you please check my power connections before I fire this baby up? I am using a light bulb tester but I'm still nervous...this is my first time wiring a transformer & I really don't want to fry anything. I'm using an Antek 2225 if that matters

primaries

secondaries

secondaries to board
Click to expand...


Yep, looks good from the pictures, but the light bulb circuit was not shown.

I would suggest you mount those terminal strips to something <card board, wood, plexi>. They will be live @ 120 VAC on one set and 25 VDC on the other. No good if they move or twist around.

And as Atilla says, exposed live metal is never good.

In you final iteration I do hope you crimp on terminals and not wrap wire under the terminals.

And just so you don't think I am being negative, it looks like you have some VERY nice parts <trafo, enclosure, etc..> and I bet it will be a very solid, good sounding amp when you are finished.
 
B

bluegti

Member
Joined 2004
Re: Troubleshooting... where do I start

bluegti said:
I got all parts soldered and checked joints. Seems ok.

I turned on the amp using "Poor Man's Variac". No bright bulbs so there are no apparent shorts.

The LED lights up.

But... no sound. There is a slight click coming from the board about 2 seconds after I turn the amp on. But no hum, buzz, etc. I checked my preamp, cd player and speakers with another amp and everything works so it must be the amp.

Not sure where to start - I've never had an amp not work the first time. I guess this is a learning experience. Are there voltages I should be checking, etc?

Thanks for your help.
Click to expand...

I know the source is good because I swapped amps, and everything worked. I swapped back and the Rev C didn't work. I did some reading in this thread and saw some recommendations for checking voltages and resistances.

I got 0 Resistance between the following points and PGND:

+C3 = 0R
-C8 = 0R
-C6 = 0R
+C11 = 0R
+C1 = 0R
-C2 = 0R

This was a little unexpected because I thought that all the negative sides of the caps would be going to ground, but I triple checked against the silk screen and I have them installed correctly so I'm guessing that some positive sides and some negative sides of the caps are grounded.

I got the following voltages (voltages in parenthesis were recommended in earlier post):

-C3 -36.3V (-32.5)
+C8 +36.4V (+32.5)
+C6 +11.72V (+12)
-C11 - 11.83V (-12)
-C1 -36.3V (-32.5)
+C2 36.5V (+32.5)
+C14 +16.73 (+24)

So it seems I'm in the ballpark. I would think I would get some sound. Any suggestions of what to check next?

P.S. 1997 VR6, although I was hit head on while sitting at a stop light by a drunk driver coming down the wrong side of a divided roadway. Everyone was ok but bluegti RIP.
 
troystg

troystg

Member
Joined 2004
It appears that your voltages are at least 4 volts off on most and a BIG 8 volts on C14.

Can you measure the voltage of the secondaries? Should be ~24VAC +/- 2 volts.


With the voltage so low on C14 the relay is probably not engaging.


PS- Sorry about the GTi. I started car shopping for a 2.0T Audi A3 to replace the 1.8T Golf. My Toyota Tundra is a good truck, it's just not ME.
 
B

bluegti

Member
Joined 2004
I bought the transformer I am using from Uriah. According to him, it is 160VA 25V. There is no documentation or hookup information.

The transformer has 2 white leads (assumed they are the primaries) and 4 colored leads; red, black, yellow, and blue. I determined that the red/yellow leads were one wire and black/blue leads wires were the other wire by measuring when I got zero resistance on my ohm meter.

Here's how I hooked up the leads to the board:
  • yellow/blue wires together and connected them to PGND.
  • red wire to AC1
  • black wire to AC2

Here are the AC voltages I measured across the leads:
  • 26V between red and yellow/blue
  • 26V between black and yellow/blue

Here are the AC voltages I measured with one clip to chassis ground (I have not connected PGND to the chassis):
  • 31V between yellow/blue and chassis
  • 7V between red and chassis
  • 7V between black and chassis

I hope this helps. Please let me know if there are other measurements I should take, or if I should hook up my transformer differently.
 
troystg

troystg

Member
Joined 2004
Does your trafo look like this?:

http://picasaweb.google.com/troystg/Rev_C#5302725506012756242

EDIT:

If yours DOES look like that then you have the secondaries mixed up.

MINOR thing!!! Yeaaaaah!!!



red / yellow are a pair.
blue / black are a pair.

I tied the yellow and black together for the common tap.

red = hot = AC1
blue = hot = AC2
yel / blk = common = grnd


EDIT 2:

Mmmm... Coffee :D :clown: Morning everyone.. Happy hump day.
 
troystg

troystg

Member
Joined 2004
bluegti said:
Yep, that's what mine look like. I didn't think it mattered which end you used when making the common tap... I used the blue wire and you are using the black wire.

I will re-wire when I get home tonight and see how things work.
Click to expand...


It does not matter which end of the pair you use to tie to grnd / common.

But I did not see where you said you were going to use x1+x2 as a pair and y1+y2 as a pair.

Like I said, a picture clears it all up instantly.

:smash:
 
pinkfloyd4ever

pinkfloyd4ever

Member
Joined 2008
youtube.com/watch?v=dQw4w9WgXcQ
udailey said:
the light bulb is in SERIES with the hot line NOT parallel between the two.
maybe you have it right but if you have it parallel then it should light up no matter what. You want the hot line coming in and then going out of it. Neutral and ground are not connected to this lightbulb.
Uriah
Click to expand...
right that's how I have it http://picasaweb.google.com/lh/photo/p14mQrZ9mroZX6z0qmzUsA?feat=directlink but whenever I turn the switch on, the bulb lights

I don't get it.

I just checked everything (trafo, j-box that the bulb tester is mounted to, IEC/switch module, barrier block connections) for continuity with the DMM, and nothing showed a short
 
U

udailey

Member
Joined 2008
picasaweb.google.com/udailey/MyRef#
Lets go back to the secondaries.
http://picasaweb.google.com/kevin.gentsch/AudioStuff#5335057779527289490
Is it still wired like this or are the secondaries attached to nothing at all? I am not sure but maybe if you took a green and a blue that were in actuality one wire and connect them together the core might saturate causing current draw and lighting your bulb. I could be totally wrong on this but its all I can think of as your pics look right. Can you take a pic of the whole thing from start to end? One all encompassing pic.
Uriah
 
A

AndrewT

R.I.P.
Joined 2004
I don't like the metal junction box and the exposed mains screws under the bulb holder.
I see the Safety Earth connection in the bottom, good.

But what happens if one of those solid core wires breaks?
Which is the worst case seranrio?
What if the incoming earth wire breaks and springs up and touches one of those exposed Live screws?


This piece of equipment should get used a lot, It will get man/womanhandled, abused, thrown on the shelf, etc.
 
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