Hi there,
Sorry for posting this thread here, didn't know where to post it!Someone brought me a Numark DM1775A preamp/mixer with a few faults.I would like to know if there is any schematics available from Numark.I have been told that a schematic from dm1975 is equivelant.Any help????
Thanx in advance
Padelis
Sorry for posting this thread here, didn't know where to post it!Someone brought me a Numark DM1775A preamp/mixer with a few faults.I would like to know if there is any schematics available from Numark.I have been told that a schematic from dm1975 is equivelant.Any help????
Thanx in advance
Padelis
well ...more or less the same over here .... but still 1775 series was the most simple op amp design you ve ever seen .... at the time also numark products had by far better built quality ...
That means that beyond a few caps in the power supply and various pots that are going to be broken there is no chance that anything else is broken ...unless the unit is canibalized
If you have pot problems you may find them in the local srvice center in athens but at 16 euro each are simply out of the question ... so you may see some other alternatives like that FANOS shop in Athens that has just imported a very serious line of pots from ALPHA that is a manufacturer of almost ALPS quality ...
there is another option for pots also if you can find any there ...let me know how it works out
kind regards sakis
( i also have a schmatic of dm 900 which i think that will be the same or similar to all DMmodels as about topology and layout of parts ... if you like to have it email me )
That means that beyond a few caps in the power supply and various pots that are going to be broken there is no chance that anything else is broken ...unless the unit is canibalized
If you have pot problems you may find them in the local srvice center in athens but at 16 euro each are simply out of the question ... so you may see some other alternatives like that FANOS shop in Athens that has just imported a very serious line of pots from ALPHA that is a manufacturer of almost ALPS quality ...
there is another option for pots also if you can find any there ...let me know how it works out
kind regards sakis
( i also have a schmatic of dm 900 which i think that will be the same or similar to all DMmodels as about topology and layout of parts ... if you like to have it email me )
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numark op amp
Thanks Sakis, I didn't mean to pull your chain. The mixer in this thread http://www.diyaudio.com/forums/anal...t-little-mixer-today-velleman-promix-50s.html has got 4558 SIP op amps. 4558's are too noisy even for me. My thirty minute search has proved the velleman can't be updated to low noise ST33078 or JRC4560 op amps because ST and JRC don't make them in SIP. So, IF the Numark has SIP op amps, I don't want it to cut up for the gain blocks for my organ project. http://www.diyaudio.com/forums/analog-line-level/171910-gain-block-pcbs.html eserviceinfo.com doesn't have schematics on Numark either. It is tomorrow, at $35 used the Numark is probably sold already. I'm going to look at cutting up Ishida packing machine scale units for op amp gain blocks, I think, I have five of those cluttering up the carport. I updated a Herald Ra-88A mixer, I understand the circuit and upgraded it to 33078's and new caps already, but due to the ground plane everywhere blank on the pcb and that I'm using it for my turntable-radio hub, I don't want to cut it up. This belongs in analog line level forum if anybody wants to talk more, just the originator posted it in solid stateamplifiers.
Thanks Sakis, I didn't mean to pull your chain. The mixer in this thread http://www.diyaudio.com/forums/anal...t-little-mixer-today-velleman-promix-50s.html has got 4558 SIP op amps. 4558's are too noisy even for me. My thirty minute search has proved the velleman can't be updated to low noise ST33078 or JRC4560 op amps because ST and JRC don't make them in SIP. So, IF the Numark has SIP op amps, I don't want it to cut up for the gain blocks for my organ project. http://www.diyaudio.com/forums/analog-line-level/171910-gain-block-pcbs.html eserviceinfo.com doesn't have schematics on Numark either. It is tomorrow, at $35 used the Numark is probably sold already. I'm going to look at cutting up Ishida packing machine scale units for op amp gain blocks, I think, I have five of those cluttering up the carport. I updated a Herald Ra-88A mixer, I understand the circuit and upgraded it to 33078's and new caps already, but due to the ground plane everywhere blank on the pcb and that I'm using it for my turntable-radio hub, I don't want to cut it up. This belongs in analog line level forum if anybody wants to talk more, just the originator posted it in solid stateamplifiers.
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its an old leftover thread but keep this in mind ....like 5532 the same with 4558 not each and everyone available ion the market sounds the same ...
in some kinda hifi application such is a buffer (other than the IC hi end made) where the hart and soul of the project is just one ic then the diference from a 4558 of JRC and a 4558 od someone else is screaming ....
same with a 5532 often used as a first stage in amplifiers ... place there a Philips instead of a chinese crap and you will understand that are not the same ...
in some kinda hifi application such is a buffer (other than the IC hi end made) where the hart and soul of the project is just one ic then the diference from a 4558 of JRC and a 4558 od someone else is screaming ....
same with a 5532 often used as a first stage in amplifiers ... place there a Philips instead of a chinese crap and you will understand that are not the same ...
It has been a very long time since I had to fix one. As I do not know your level of expertise I may be going too basic.
If there are any input channel problems you can simply apply signal to a good one and compare the signal to the bad one.
Since you mentioned a few faults, let us assume the output is working. If both channels don't work check the power supplies and then change the dual op-amp.
That leaves the digital card and the possible need for slide pots. I would buy another one and steal parts from it as these units used are going for as low as $30.00 ea.
If you have trouble with the slide pots, sometimes you can take them apart, straighten the bent parts, relubricate the wiper and reassemble them.
If there are any input channel problems you can simply apply signal to a good one and compare the signal to the bad one.
Since you mentioned a few faults, let us assume the output is working. If both channels don't work check the power supplies and then change the dual op-amp.
That leaves the digital card and the possible need for slide pots. I would buy another one and steal parts from it as these units used are going for as low as $30.00 ea.
If you have trouble with the slide pots, sometimes you can take them apart, straighten the bent parts, relubricate the wiper and reassemble them.
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