Hi all,
got micromega st3 salvaged by previous user - it had overheated trafos on DAC board with fried 1305 dac chips and output op-amps. Got dac chips replaced with 5$/pc from aliexpress, restored all op-amps, power etc. Got nice sound, clean output.
BUT - there's a strange option of double speed play - dunno why it is in CD player, but still. Once pushing x2 button, it plays on double speed just fine, but linear output distorted with pops and clicks and loud noisy sounds like... heavily scratched vinyl. Well, at normal speed it plays just fine, but on x2 - pops and clicks, however the original sound is also there.
Is it possible that I got counterfeit 1305 which are re-labelled something pin compatible but without x2? or something wrong with opamps?
no pops and clicks with spdif output to external dac on any speed.
got micromega st3 salvaged by previous user - it had overheated trafos on DAC board with fried 1305 dac chips and output op-amps. Got dac chips replaced with 5$/pc from aliexpress, restored all op-amps, power etc. Got nice sound, clean output.
BUT - there's a strange option of double speed play - dunno why it is in CD player, but still. Once pushing x2 button, it plays on double speed just fine, but linear output distorted with pops and clicks and loud noisy sounds like... heavily scratched vinyl. Well, at normal speed it plays just fine, but on x2 - pops and clicks, however the original sound is also there.
Is it possible that I got counterfeit 1305 which are re-labelled something pin compatible but without x2? or something wrong with opamps?
no pops and clicks with spdif output to external dac on any speed.
Do you have an oscilloscope?
Basically, you need to look at the signals going into the dac to see if they meet datasheet specifications. If the inputs are correct and the output is not correct, then you have a dac chip problem of some kind.
Basically, you need to look at the signals going into the dac to see if they meet datasheet specifications. If the inputs are correct and the output is not correct, then you have a dac chip problem of some kind.
Sure I have. Its tek 3052. But apparently, on single speed it plays just fine. It also plays fine on any speed with s/pdif output via external dac. Logically thinking it proves everything should be fine with input dac signals. I'll check for sure...
it was DSMB flag for 1305. The wire connection from servo board to the dac board was floating, so it do not get enough low or high. Done.
Interesting, that the consequences was only to observe at double speed.
BTW - to avoid getting fakes, I prefer follow method, if I need older DAC-IC's like PCM56, TDA1541, TDA1547, TDA1305 etc for replacement:
1) go to
CD-Player-DAC-Transport List
2) find out cheap cd player model with wanted DAC IC, e. g. TDA1305 by entering the type in the appropriate field and then activating the botton "Filter".
3) then buy a suitable model in used condition.
This has the advantage that I can find out clearly by exchanging the DAC-IC, whether it is defective resp. faulty or not. A second benefit is, that I am sure that I have no fake resp. counterfeit.
Last edited:
well, pretty smart, thanks. Now I have surplus of about 10 pcs of 1305 from different sellers, and all of them seems working just fine =)
By the way, if anyone is looking for Micromega eprom firmware, I made the dumps of v1.40 (old servo, older dacs), v2.41 (new servo, older dacs) and v3.22 (new servo, new dacs). And - I would be looking to have v1.98 and 3.41...