Audiosource Amp one/A

Nicholas_23

Hey guys , got this amp for nothing , literally , so I figured Id take a crack at it. The thing powers on but there is no output to the speakers. The board looks good from the top and shows no signs of burns or blowouts. Any ideas of what to look at next?

dcibel

The obvious would be the fuses, the DC power supply voltages on each rail, and the output relay. If all that is good, then send a sine wave through the input, and trace it through the circuit with a scope to see where it is lost, which will get you near the damaged components very quickly. On the cheap, a cellphone headphone jack can be used as a signal gen, and a computer soundcard can be used as a scope.

Silver1omo

https://makezine.com/projects/sound-card-oscilloscope/
Now I want to test this...

dcibel

Soundcards can make very effective scopes within their bandwidth limitations. Just need attenuators to bring the measured signal within the 1v or so limits of the card input.

You could even remove the input caps on your card and provide external DC coupling switch.

Silver1omo

That page provides a simple attenuator circuit and a link for a scope software. 

Tom_S

There was a thread on PETT about modding the Amp 100. Someone had asked about an AMP One/A that was intermittent in that thread. It turned out to be the relay was bad. 

rjj45

Got a little DSO138 a couple of months ago. Lots of fun and useful 
https://www.aliexpress.com/item/DSO138-2-4-TFT-Pocket-size-Digital-Oscilloscope-Kit-DIY-Parts-Handheld-Acrylic-DIY-Case-Cover/32637684820.html?spm=2114.search0104.3.46.642c16f4l1Mdh7&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10130_10068_10324_10547_10342_10325_10546_10343_10340_10548_10341_10545_10696_10084_10083_10618_10307_10869_10868_10059_100031_10103_10624_10623_10622_10621_10620,searchweb201603_16,ppcSwitch_5&algo_expid=34e6263d-4b01-4e2d-9484-dfc60e8766b5-6&algo_pvid=34e6263d-4b01-4e2d-9484-dfc60e8766b5&transAbTest=ae803_2&priceBeautifyAB=0

S7910

Tom_S said:

There was a thread on PETT about modding the Amp 100. Someone had asked about an AMP One/A that was intermittent in that thread. It turned out to be the relay was bad. 

Found it. http://techtalk.parts-express.com/forum/tech-talk-forum/56976-how-to-turn-your-audiosource-amp-100-into-a-real-amp-paying-it-forward

Nicholas_23

Thanks for the links and info guys. I went ahead and ordered a new relay . 6 bucks shipped . It was cheap enough to try . Hoping I got the right relay

dynamo

Are your PS caps domed or is that just the pic making them look like that? If they are, they may be worth replacing too.

Nicholas_23

dynamo said:

Are your PS caps domed or is that just the pic making them look like that? If they are, they may be worth replacing too.

Dust and lighting , I just brushed off the caps to verify and theyre good. 

Nicholas_23

I was able to replace the relay , still no audio output. On the plus side , I can now hear the power supply charge up when turning it on, so back to the drawing board. 

Nicholas_23

Curious , is the a way to test the Toshiba C5198's that are in this amp? I have a LCR and a DMM