[BUILD] 1176 Rev A - Back to the beginning...

[Spencerleehorton]

Hi,

I am getting good signal waveform to C7 as soon as it hits the signal line amp I'm getting horrible waveform?
Could this be transformer based or does this sound like transistor? All voltages are as per schematic?
Wave form is good on WHT/BLK winding but not on BRN winding.
It seems when I go through the frequencies at about 10k to 15k the wave form drops by 1v per div.
This verifies what my ears are hearing with the top end being very dull.
I am going to get the transformer I've made tested and hopefully this is the problem but does anyone else have any suggestions?

Regards

Spence.

 

[Spencerleehorton]

Also would like conformation on what output transformer to use as I've just read that the Rev A doesn't use the UA-5002?

Regards

Spence.

 

[Spencerleehorton]

this is my Ohms for my windings on my did transformer

PRI winding A (BRN / BLK) = 109 ohms
PRI winding B (WHT/BLK) = 5.5 ohms
Sec winding C (BLU/RED) 182 ohms
Sec wind D (GREY/VIOLET) = 110 ohms (feedback winding)

I'm pretty sure I've either got it wired wrong or I need to wind a new transformer so I have the 1:1 winding 110ohms with the two windings in series at 182ohms then the feedback winding wound to 25:1.

Any help on this would be great.

Regards

Spence.

 

[Spencerleehorton]

well it seems in comparison to the info of the DC resistance of the other output transformers my GREY / VIOLET winding needs to be five times greater. this must be the reason i'm loosing the top end and why the waveform looks bad on the BRN winding as this is where it feeds back.
I will wind another with this new info.

regards

Spence.

 

[Spencerleehorton]

Hi,

with this other info i've now got it says that on a correct output transformer the WHT RED / WHT BLK winding is 1ohm?
this is very puzzling as Q6 would definitely over heat if it was that low resistance? it would need to above 100ohms surely?

regards

Spence.

 

[Spencerleehorton]

Could anyone verify the DCR of the WHT BLK / WHT RED windings please?

regards

Spence.

 

[Spencerleehorton]

Hi Anyone!!!

seems like im on my own within this thread, not a word from anyone about this!
Luckily i have sussed the problem and the transformer that i have wound does actually work a treat, just i had the windings round the wrong way.
Done full sweep with sinewave and nice and clean from 20hz to 20khz.
So my finding for this are:

PRI A = BLK / BRN = 110 ohm (2nd winding 1000 turns)
SEC A = RED / BLU = 110 ohm (3rd winding 1000 turns)
PRI B = WHT RED / WHT BLK = 5.5ohm (4th winding 11 turns)
SEC B = GREY / VIOLET = 182 ohm (1st winding 500 + 5th winding 500)

wound on EI-75

regards

Spence.

 

[Spencerleehorton]

As I feared Q6 getting hot due to Pri B winding not having high enough ohms!
This winding would have to be at least 110ohm then?
The 1 to 2 ohms would put Q6 into meltdown so this must be wrong.
Going to wind another version but with much higher DCR on the Pri B winding.

Spence.

 

[Spencerleehorton]

By my calculations the 25:1 feedback winding must be a misprint, I reckon it's 5:1, giving me this:

0.203mm X 2500 turns = 125 ohms wht blk / WHT red feedback winding PRI B
0.142mm x 250 turns = 28 ohm - SEC A ½
0.203mm x 500 turns = 50 ohms* for 600 ohm winding PRI A
0.203mm x 500 = 50 ohm for SEC B winding
0.142mm x 250 turns = 28 ohm B - SEC A ½


This all seems to be within 1-2% of other DCR figures , the feedback winding  could be

0.142mm x 2500 turns = 260 ohms for feedback winding PRI B but I know it only needs to around the 110 ohm mark to work properly and keep Q6 within safe working conditions.

 

[Spencerleehorton]

please, please , please could someone help me!!!

Im pulling my hair out here, this is the third output transformer ive wound and ive made sure ive got all the start and finishes labeled, i have hooked up as per schematic and i get nothing on output apart from must be high frequency? i cant hear it its too high!!!!

i have 3 x 50ohm (600ohm) windings and 1 x 117ohm winding, one 50ohm for PRI A, PRI B is the 117ohm winding, SEC A is a 50ohm winding and SEC B is a 50ohm winding.

I get good signal up until Line AMP, then its just all over the show!!!

Q6 now seems to be running warm rather than about to overheat!!! getting 0.59v across R32.

what am i missing? I just need to move on with this build, ive only ever got the REV A to sound like crap!!!!
i would really like to get the line amp working correctly , can anyone help please, pretty please with sugar ontop!!!!

regards

Spence.

 

[Spencerleehorton]

Going to replace Q6 and try this

3 X 600 ohm windings and 1 X tertiary winding 25:1

1200 for PRI A - 50 ohms 60 ohms - 0.203mm
600 for SEC A ½ - 28 ohms - 0.203mm
1200 for SEC B - 260 ohms - 0.102mm
600 for SEC A ½ - 28 ohms - 0.203mm
48 for tertiary - 2 ohms - 0.203mm


If anyone has any ideas I'm all ears, I'm getting quite lonely in here!!!

Regards

Spence.

 

[Spencerleehorton]

Question about the line amp for Rev A and Rev D, could a Rev D line amp work in a Rev A?

Spence.

 

[Potato Cakes]

The Rev A I've built have all been the Hairball kits with Ed's transformers. Unfortunately, I sold them all. I do have a stereo Rev D that could open up and check some voltages, but I don't know how different or helpful that would be.

Is there any reason why not use Ed's transformers to wrap this guy up? Just curious. I know it's frustrating to be stumped and helpful hints aren't forthcoming.

Thanks!

Paul

 

[Spencerleehorton]

Hi Paul,

Thanks for your help, should hopefully with your assistance be able to sort this now!!!
At least I'm learning loads about what to do with this circuit, would like to get a definitive yes or no on whether I could change the line amp from Rev A version to Rev D and what effect this would have.

Spence.

 

[Potato Cakes]

I sent you an email with the info requested. I hope it helps you sort it out. Let us know how you go.

Thanks!

Paul

 

[Spencerleehorton]

Hi Paul,
Yes thanks very much, this verifies what I thought about this txf, on my fourth revision now!
Hopefully this one should work well, big thanks to CJ for all his help.

Regards

Spence.

 

[Spencerleehorton]

i reckon even if i got an EA-5002 i would still be having problems!!! just cant figure it out whats wrong!!
zero set doesn't set over enough to the right, distorted waveform, im nearly there on giving up on this troublesome compressor.
absolutely stumped on how the WHT BLK / WHT RED winding can only have a DCR of 2ohm and it has R32 at 39ohm and Q6 doesnt overheat?
I have put R32 as 100ohm and changed R29 to 2Meg to reduce heat on Q6.
only thing i can think of now is that it is one of the capacitors that is damaged and producing the distortion?

C15 maybe?

Spence.

 

[Potato Cakes]

I'll double check those 2 windings again. If everything is in place and is not shorting/bridging anywhere, then I guess you have to go through each component at a time and see if one of them isn't indeed bad, which sucks.

Standby for double checking.

Thanks!

Paul

 

[hrby]

I started my build last week and I have run into issues with the Avel Lindberg y236106 Power transformer and getting the proper voltage readings on the pcb board and r87 and cr6.  So I have taken a step back to try to find where the issue is.  I am getting a 118V reading at the Iec plug...I have that running over to the switch where im getting a 118V reading on those pins.  with GR selected on the switch i am getting a reading of 118V on the pins where violate/blue and brown/gray.  So I know the power transformer is getting 118V into it.  Now on the secondary section I have the those wires disconnected from the pcb and I am testing the output voltage of the transformer.  When I put my common lead from the meter on red or orange wire and the red lead from the meter on the yellow or the back i should get an ac reading of 25 -30V...but I am getting a readings all over the place...should be simple right??? 
Could the power transformer  be bad??

 

[Potato Cakes]

Are you testing this with secondaries disconnected from the PCB? What are the ranges you are measuring that are all over the place? I'm not familiar with the quality of Avel transformers, but it's not impossible.
And of course, are your test leads good?

Thanks!

Paul