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-   -   Trends ta-10 HELP ( another help thread ) (http://www.diyaudio.com/forums/class-d/104263-trends-ta-10-help-another-help-thread.html)

robert1325 27th June 2007 11:44 AM

Trends ta-10 HELP ( another help thread )
 
Hi,

My trends-ta10 has been out of working order for a month now and I'm sort of missing it's magic tone....

What I tried to do is install a better external volume pot ( PEC 50K) I rewired the RCA binding post directly to the volume pots input ( Unshielded , I know not good) and Grounded the pot to J4-LR . And the output of the pot is connected to J3-LR.

Here's a picture from M.Mardis site ( can remove if you want)

http://www.michael.mardis.com/trenda...ges/jumper.gif

Here's some shitty pics of my modding progress:

http://home.kabelfoon.nl/~ellruss/t-amp/P1010100.JPG
http://home.kabelfoon.nl/~ellruss/t-amp/P1010101.JPG
http://home.kabelfoon.nl/~ellruss/t-amp/P1010102.JPG
http://home.kabelfoon.nl/~ellruss/t-amp/P1010103.JPG

Black cable = center pot = J3 -LR = Output pot to input amp
Red cable = Right pot = J4-LR = Ground for pot
Copper cable= From RCA to Input pot ( Left pot)

When I switch it on, I get a hum and silence . Touching the pot makes the hum louder. and turning the volume up changes the volume of the hum. Oh yeah , the RCA posts are still grounded as they where before .

Some help would be greatly apreciated!

Robert

Pano 27th June 2007 12:37 PM

It's a little hard to tell, but I think you have the pot ground side connected to the wrong place. It should just go to ground, not J4.

The pot center pin should go to J3 - you seem to have that right. But you could also wire the input caps straight to the pot wiper. That would be the end of the cap that is now connected toward the rear of the amp. (3 hole row).

robert1325 27th June 2007 01:25 PM

Thanks!

OK, so I just did the ground thing as you sugested... The hum is gone except when I turn the volume up very high. ( this is normal , I had that before because of the obbligatoos)


But still there's this golden silence :('

My amp is dead? or is the pot connected the wrong way? I wired it the same as my alps blue pot... (worked fine)

Pano 27th June 2007 08:40 PM

If you have hum, the amp is not dead.
Try touching various parts of the signal path with your finger to get more hum.

Can you tell where the hum works and doesn't work? You might be able to trace the signal that way.

Do you have a portable CD palyer or radio with volume control? You could use that to inject signal into different spots in the signal path.

robert1325 28th June 2007 01:53 PM

Hi,

I tried touching the various wires and parts in the signal path...

The hum only gets louder when I touch the pot. I do get a slight tick when I touch the RCA posts . But it's not the same.

I was already using a portable radio with volume control , don't feel like getting a fright . I'm testing with some 4ohm speakers from a computer setup wich are not of any value for me. They worked ok on a vintage akai am-2600 amp so ... ( that amp is not very good either, problems with relais I think)

But since the hum only protudes when touching the pot I feel it must be the pot .:) Or should I try the signal injection method?

Thanks

Robert

Pano 28th June 2007 07:51 PM

Yeah, bypass the pot. Use the volume control of the radio to keep the signal low.

Just go in right at the caps. You should get signal that way.

Sjef 28th June 2007 09:29 PM

Quote:

OK, so I just did the ground thing as you sugested... The hum is gone except when I turn the volume up very high. ( this is normal , I had that before because of the obbligatoos)
This hum is not because of the Obliggato's it's because of the way the Obliggato's are implemented. When I look at your pictures I can imagine that this modded version only sounds worse than the unmodded version. The Trends is very sensible to shielding and proper wire/grounding layout, the stock version has some serious problems with it as well.

You might want to try to solder a ground wire to the housing of the Obliggato caps.

robert1325 28th June 2007 10:30 PM

I know it's the implentation :) Once the amp is working again I'll try grounding the obligatoos.

Despite the hum, the amp gained a lot in musicality with those caps. The amp went from a nice clean amp to a great musical /tube like amp.

Thanks for your tips, I'll try some more stuff tomorow.

robert1325 30th June 2007 12:32 PM

Got it working again! with the PEC volume pot.... Thanks for all your help!

Haven't hooked it up to my main speakers but out of the little full range test speakers the sound was very dynamic and smooth:)

Pano 30th June 2007 12:52 PM

Hey! No fair. :confused:

You are supposed to tell us what the trouble was. How did you fix it?


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