Search found 278 matches

by rjd2
Mon Nov 16, 2009 3:18 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: polysix problem: 74LS08's, or 8048?

UPDATE:

i found a few 74LS08's in another carcass. pulled them, and swapped around for IC's 30/31, and also tried IC25. basically same problem.

i have a few 8048's on order. however, is it a programmed IC? anywhere else would you focus your energies on a possible culprit?
by rjd2
Sun Nov 15, 2009 8:21 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: polysix problem: 74LS08's, or 8048?

so here's where i am at with this polysix(beside being a TOTAL glutton for punishment): -all of the manual functions work properly, save for the bleed issue at VCO MG MOD, which i am saving for last issue. -the programmer portion has some problems: 1-if a preset button is pushed, it "defaults" back ...
by rjd2
Thu Nov 12, 2009 2:22 pm
Forum: HELP!
Topic: EDIT: Polysix: TC5514 substitute?
Replies: 18
Views: 2397

Re: 8048 IC for Korg Polysix. 40-pin DIP: sub?

thanks. is the 8049 a drop-in replacement?
by rjd2
Thu Nov 12, 2009 4:03 am
Forum: HELP!
Topic: EDIT: Polysix: TC5514 substitute?
Replies: 18
Views: 2397

EDIT: Polysix: TC5514 substitute?

see below...
by rjd2
Tue Nov 10, 2009 4:20 pm
Forum: HELP!
Topic: Matrix 12 & CEM3372, CEM3374
Replies: 3
Views: 1028

Re: Matrix 12 & CEM3372, CEM3374

dont assume anything. i've seen opamps that are just south of VCO chips go south. w/ no scope, never would have found it. my suggestion: 1: MAKE ABSOLUTELY SURE you discharge any static in your hands. wristguard good, not critical IMO. 2: swap CEM chips from working to non-working voices. this will ...
by rjd2
Sat Nov 07, 2009 7:48 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: what diodes are in a polysix?

for Q1, by swapped, i meant replaced. it was a K30A; by bending the legs i was able to use an mp102. pinouts are different. yes, getting close! i think the constant reseating of the 8048 might have taken a toll on it. here's hoping, cause every single trace on its socket verifies. also, is there a t...
by rjd2
Sat Nov 07, 2009 1:47 am
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: what diodes are in a polysix?

ok, time to eat some crow: Q1 on KLM367 board swap seems to have BASICALLY solved it. i never would have guessed in a million years. this is the first time i've seen a transistor fail in the part of a circuit that basically looks brand new. cutoffres, you were totally right; thanks. the wierd part i...
by rjd2
Fri Nov 06, 2009 3:54 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: what diodes are in a polysix?

thanks, cutoffres. i dont think its the pot. i measured its impedance, its fine. i think it might be the DIODES that are south of the MG MOD switch. they arent giving me the same measurements across them at all. one reads .8M one way, OL the other. the other 1.8M one way, OL the other. they perform ...
by rjd2
Fri Nov 06, 2009 12:17 am
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: EDIT: what diodes are in a polysix?

EDIT: i am getting some funny impedance measurements across D6 and D7 at the output of the MG MOD 3 way switch. i want to try swapping them out. however, the schems dont show what value diode is used. i have 1n4148's and 4004's here, but i hate guessing. any geniuses know what i can use there? the r...
by rjd2
Fri Nov 06, 2009 12:13 am
Forum: HELP!
Topic: prophet 5 common problems
Replies: 11
Views: 1998

Re: prophet 5 common problems

REPLACING the PSU would be 10x harder than fixing the old one. as you have already switched it on with all the circuits connected, the odds you are JUST NOW going to fry any chips is low. im assuming the PSU is +/-15V and a +5V rail for LED's. i could be wrong. i do remember that it has a massive sc...
by rjd2
Wed Nov 04, 2009 2:46 am
Forum: HELP!
Topic: JUNO 6/60 LFO button: repairable or replaceable?
Replies: 3
Views: 243

Re: JUNO 6/60 LFO button: repairable or replaceable?

awesome, thanks!
by rjd2
Tue Nov 03, 2009 8:58 pm
Forum: HELP!
Topic: JUNO 6/60 LFO button: repairable or replaceable?
Replies: 3
Views: 243

JUNO 6/60 LFO button: repairable or replaceable?

hi folks, i have a disassembled switch of an LFO button on juno 6/60. it is apparently a rubber contact that connects the 2 internal pins. not working. tried cleaning. doesnt make any engineering sense to me, but i'll trust that it made an electrical contact in its heyday. is this replaceable or rep...
by rjd2
Thu Oct 29, 2009 8:29 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: just repaired Polysix. 1 problem still left. schem help?

thanks, cutoffres. i swapped IC21 for an LM13700; no change in behavior. q4 looks clean as a whistle. trying to diagnose logic problems with your eyes is the dumbest idea in the world; with that said, IC25 had a bit of corrosion on the legs, and it is one IC i didnt replace/socket. if this IC is res...
by rjd2
Thu Oct 29, 2009 4:14 pm
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

Re: just repaired Polysix. 1 problem still left. schem help?

yes, the MG wheel is completely down. it also exhibits this issue if the wheel assembly harness is unplugged. i figure its got to be related to the encoding of either the VCO/VCF/VCA mod switch, or the MG LEVEL pot. i can see where harnesses C06 and C11 come into the KLM367 board on the schem, but f...
by rjd2
Thu Oct 29, 2009 1:33 am
Forum: HELP!
Topic: EDIT: polysix problem: 74LS08's, or 8048?
Replies: 19
Views: 5032

EDIT: polysix problem: 74LS08's, or 8048?

hi folks, so i have been tackling a pretty beat korg polysix, and im almost done. the specs: KLM367 board: --------------------------- -new battery-of course -i have verified that every pin of IC's 30 and 31 of the KLM367 have continuity with the upper trace image i have. -R91 is now a 1418 diode, C...