ASR-10 not sampling / audio input issue

Synth Repair
1

Hi,

I have an issue with my ASR-10. The keyboard is functioning properly except when sampling. When i connect an audio source(line or mic, different switch positions, pot levels and audio levels), the keyboard OS doesn’t see the audio coming through. I say the OS because when in sampling mode i can see the audio level LEDs on the panel react properly to the injected audio signal but the VU meter on the display doesn’t move and when ENTER is pressed the keyboard sits WAITING for audio despite the fact the audio is present at the inputs.

When activating the monitor buttons(left and/or right), a crackling sound at a steady frequency is present and it double its frequency when i increase the sampling rate (for dry sampling) in the EFFECTs section. However, assigning/changing the effects doesn’t have an effect and i keep hearing that steady crackling. The effects section itself works 100% normal when playing the sounds loaded through disk. I also have eps-16 so i’m familier with the sampling setting hence it is not a setting issue.

The noise is present whether or not a source is connected to the keyboard.

When trying to sample the main output, the noise doesn’t come out but neither can i sample. It stays waiting.

I Did some troubleshooting with the oscilloscope and was able to see the clock and some data going out from the ADC chip. I’m suspecting it might be the ADC chip itself or some sort of syncing issue but as far as i can tell the buffer chips and flip-flops are good. Cable is good.

I’ve reached a dead block. Any thoughts ??

Thanks

2

Had a very similar issue on Emax II, replaced the ADC chip for $15 on eBay and sampling works good as new now.

1 Like
3

I agree with you. I suspect so but the ASR-10 ADC is rare and expensive (unless someone can advise a substitute) hence want to leave the replacement as my last option .i was hoping to see if there are other known components that might cause it to act like that.

BTW, what was the ADC you’ve used for the Emax ?

Thanks

4

It’s a CRYSTAL CS5326-KP for the stereo sampling version. The digital output on mine was completely dead so easier to debug.

Is it the Philips TDA1541a for the ASR-10?