Yamaha 01V96v2 weak phones signal

[ThingWizard]

I just aquired a second hand 01V96V2 and it seems the phones signal level is very low, even when the pot is turned to max. I need to set the digital gain for the monitoring at +10dB to get anything close to normal.

Has anyone else with this mixer had the same experience? The same headphones work fine with all my other equipment. It seems like something is wrong with the headphone amp in the unit.

I got hold of the repair manual and I've been looking at the block schematics and the analog output specifications but I wasn't able to figure out how to measure the output level of the phones output to see if it's in spec.

From the block diagram it looks like if the problem is higher up in the monitoring chain it should affect the monitor output as well, but again I'm at a loss how to measure this correctly.

 

[Ike Zimbel]

Can you test the frequency response of the phones output? The most likely culprit is dried up capacitors in the headphone circuit.

 

[ThingWizard]

Can you test the frequency response of the phones output? The most likely culprit is dried up capacitors in the headphone circuit.

I might, if someone tells me how to do it What signal would I give it and how would I measure? My only experience measuring frequency response is using a mic and REW for room eq, but how would I measure the phones output?

 

[ThingWizard]

Maybe I should change these caps and see if it helps

 

[ThingWizard]

Further testing shows the whole monitoring section "weak" and unbalanced. I think there are lots of caps here that are not happy

 

[Ike Zimbel]

If it came from a commercial studio (or possibly a venue like a hockey arena) where it was powered on 24/7 for years, it's very likely that there are a lot of bad capacitors in it. Although Yamaha product is usually less susceptible to cap failure than other lines I've serviced, if it's been on for years, all bets are off.

 

[ThingWizard]

Hi Ike and thanx for the input,

There's a big change it has serious hours on it. I think I'll put it on the back burner for a while and save it for a rainy day. (My project pile is big enough as it is)

On a side note, I was looking at an Equivalent resistance meter to check caps even in circuit, is this something any of you have experience with? I was thinking what the easiest way would be to find faulty ones. (To avoid a Total Recall... Recap)

A new fault it has developed is IPDNS (intermittent partial display neglect syndrome), where the display looses half of it's graphics from time to time. Something with the contrast voltage apparently being driven by 2 different circuits left/right, and the left one fails sometimes. Cap to blame again I guess.

Good thing is the parts list in the repair manual is apparently done by Sheldon Cooper's Japanese cousin at Yamaha so it's meticulously documented.