No Sound Se/30 Reloaded board

[iantm]

I just received a serviced reloaded board. At first it didn't boot — I got the stock VRAM Simasima — but I found some of the chips weren't properly seated and tried stock ROM shifted in the socket slightly for better contact.

It boots! But no sound.

I am going to work with what I know / am capable of doing, as methodical as I can be: Plug in headphone to see if I get sound at all. Continue to play with the chip seating. So far, it's only sound. SCSI works, ROM/RAM swapped a few times, but none of the latter matters here I don't think because if it was the issue I wouldn't get to the desktop.

I don't think it's a major issue with chips as the components were working prior to the transfer, but since I didn't do the transfer myself and don't have ton of diagnostic tools it's difficult for me to say.

Any other advice — for what to try, or what diagnostic tools might be useful in this situation outside of a multimeter would be helpful. Hopefully it doesn't mean I need an oscillator or something else really expensive. I'll also check out CayMac's videos

OR maybe: What, besides a SE/30 extension cable would be beneficial in running the board outside of the chassis? I think part my issue here is that I'm running a video card from the PDS slot; I'll switch to a Mac without that so make that easier.

I'm thinking jumper wires from the speaker -> board might be all I need once I can get the board out of the chassis?

 

[finkmac]

considering it's booting, it's probably something in the amplifier circuit... all you really need to diagnose that is a multimeter.

when you say no sound... do you mean no sound from the speaker? if you plug in headphones, do you hear sound?

 

[iantm]

Good news is the headphones register clear sound and startup chime, so I think the problem is much narrower and might be physically connected to the jack. I'll fuss with that and/or swap with a spare.

 

[finkmac]

there's a microswitch in the headphone jack that mutes the speaker when headphones are connected... sounds like it's screwy. I'd just swap it for a spare.

 

[iantm]

I noticed this on the backside. Are the contacts supposed to be bare? Since I didn’t do the transfer I have no idea.

 

[croissantking]

I noticed this on the backside. Are the contacts supposed to be bare? Since I didn’t do the transfer I have no idea.

Yes they are - they’re just there for testing purposes in case you want to test the onboard sound without a headphone jack installed.

 

[iantm]

Does that mean to solder a speaker directly to those contacts?

I went through the trouble of swapping in a different headphone jack thinking it was something bad about the connections inside, but I still don't get any sound out of the speaker— reliably. For a moment sound through the speaker was scratchy, then it went away after a restart, which suggests it's something intermittent and physical, but I'm struggling to figure out what it is.

I don't think it's the speaker because a different logic board plays sound perfectly. I don't understand what could be off about the reloaded board to cause this.

 

[finkmac]

beep out the audio circuit. verify that sound is actually reaching the speaker when there's nothing plugged in, etc

 

[Callan]

The headphone jack feeds back to a tl071 and 2 transistor (amp). These are located rght below the vram / above the sony chips. As finkmac said, I'd check connectivity from the headphone jack to the op amp and make sure your parts test good.

 

[iantm]

I’ll study the schematics more and learn better what I’m actually trying to do. I admit I don’t understand any of it yet.

I bridged those contacts but still get no speaker output and sound from the headphones, which is confusing. I really thought that would do something.

I’ve got my multimeter out but I’m not really certain what I’m doing. Yet.

 

[iantm]

verify that sound is actually reaching the speaker

Hmm. I get nothing from the continuity meter on the J11 pins. The signal is reaching the speaker contacts from the 1001 resistors output, but after that I’m at a loss.

 

[SpocksBeer]

Is the speaker good? Should be somewhere around 55 to 64 ohms (my working ones usually measure 58ohms).

 

[iantm]

the speaker worked perfectly with a different board. I tried coaxing a Sunday with bodge wires but nothing was consistent. I can’t seem to figure out why no signal is reaching J11.