Distorted audio with new MacEffects Thunder PDS accelerator in an LC II

[jasa1063]

I just picked up a MacEffects Thunder PDS accelerator. With the accelerator installed the audio is distorted. Has anyone else had this problem with an LC II and a accelerator installed? If so, any known workarounds?

 

[Byrd]

Have you asked MacEffects yet? I’d do the usual troubleshooting, one stick known good ram, check PSU voltages, try a vanilla stock install of Mac OS 7.1

 

[jasa1063]

Have you asked MacEffects yet? I’d do the usual troubleshooting, one stick known good ram, check PSU voltages, try a vanilla stock install of Mac OS 7.1

The audio is works without the accelerator installed. The PSU is voltage also checks out. So at this point I can only think there is something with the accelerator causing the issue. I have contacted MacEffects to see what they have to say.

 

[just.in.time]

Potentially issue with RAM speed that isn’t an issue when running at factory speed?

 

[Phipli]

It's very unlikely to be RAM speed. The RAM runs on the bus, which hasn't changed speed.

Audio issues on accelerated Macs from the early 68k time period is common. Do you have the card's drivers installed? I know they often "work" without, but the drivers often patch issues like sound.

 

[ScutBoy]

Are you sure there's not a control panel or init for the accelerator? Very common that accelerators would throw off the timing for sound, and there were software fixes to address this.

 

[Phipli]

MicroMac Thunder Accelerator

See attached file. Remember it can't be expanded on a PC, or moved uncompressed on a PC formatted disk. Best to decompress it on the LC itself, or in an emulator if you know what you're doing regarding putting it straight onto a disk image for a SCSI2SD.

 

[Phipli]

Ah, I realise it says no software for the LC II, the extension is for the original LC. I misread it as no software for the ColorClassic.

 

[jasa1063]

The response I got back from MacEffects was that the issue is most likely due to issues with the sound chip at UB10. I checked that area with a 30x loupe and did not see any corrosion. They offered me a replacement accelerator or a refund, but I think it is something with the logic board at this point. If I power up the Mac LC II and the power it off an on again the sound is Ok. I can do any number of power cycles in succession after that and the sound is fine. Let it sit for 5 minutes and the issue comes back. I am just going to keep the accelerator and dig a little deeper with LC II logic board.

 

[Phipli]

The response I got back from MacEffects was that the issue is most likely due to issues with the sound chip at UB10. I checked that area with a 30x loupe and did not see any corrosion. They offered me a replacement accelerator or a refund, but I think it is something with the logic board at this point. If I power up the Mac LC II and the power it off an on again the sound is Ok. I can do any number of power cycles in succession after that and the sound is fine. Let it sit for 5 minutes and the issue comes back. I am just going to keep the accelerator and dig a little deeper with LC II logic board.

Is the LC II recapped? How did you clean it?

 

[jasa1063]

Is the LC II recapped? How did you clean it?

The LC II was recapped by the person I purchased it from. I haven't touched the logic board otherwise as all that was done already.