On Mon, 28 Jun 1999, Levente [iso-8859-1] Hársfalvi wrote: > > Ah. In that case it's likely that all OPL3s out there will be SMT, since > > the ones in the first SoundBlaster that used them were SMT. Unless anyone > > finds some standard 0.1 inch DIL versions, I will be unlikely ever to > > build the upgraded stereo version of the sound expander myself. > > W..why? OK, so I was a bit melodramatic - just annoyed at not being able to find 0.1 inch OPL3s even though the documentation I have states that they exist. > Well, it's a bit harder to make an SMT board, ...even soldering, > desoldering an SMT chip is horrible; but it's definitely possible. Once > I needed a 62256 Sram, so I removed one from a HDD (SMT, of course); > then placed the thingy to a DIL28 socket, soldered the pins to the > socket's pins by small wires, then applied some glue (epoxy) to fix > everything in its place. It still works ;-) It might come to that, yes... incidentally, that would get round the problem of the OPL3's different pinout - just solder the SMT pins to different IC socket pins :) > Guess designing the appropriate board is much like designing a THT one. > Well, producing the board and soldering the components into place is > much harder. Sorry - what is THT? > But you don't have to make everything with SMD's. Only the YMF chip is > involved, all others can still be normal THD's. The YAC512s will probably be SMD, or I could use YM3012s instead (not too sure about this). This is the DAC element of the new expander - the original used the YM3014B but that was for mono. Both devices are two channel stereo, so two would be needed for the full four channel support. > > Last night I succeeded in desoldering all the TTL logic chips on the > > board, sadly at the expense of the chips themselves, but never mind - I'll > > buy replacements today. I aim to have the schematic finished by next > > weekend. Putting in an OPL3 chip is simply a matter of deciding which > > address line to use for the chip's extra address pin (A1) and doubling or > > quadrupling the amount of DAC / op-amp circuitry. Apparently OPL3 has four > > channel sound output. > > I like this idea. The analogue upgrades are the messiest part - finding two channel DACs and adding the extra op-amp stages will make the board very messy. > That's just another thing besides this, I like FM sounds. The 4 operator FM in the OPL3 has 4 algorithms - there are 4 missing from the usual Yamaha DX21 set of 8. This should still allow some quite good sounds - almost up to the standard of the MSX FM expander thingy I have. Well, as I said I should have that schematic ready by the end of the week. Must get back to work now ;) Richard - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
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