Ah! cheers, yes that would be fantastic, thank you if you cant repair, please send anyway and i can have a go at the repair tooThought I had one, but the pdf is damaged. I'll see if there's a chance of repairing it...
Looks like the Sanyo LB1482M... The only data sheet I've seen is in Chinese (at least I think it's Chinese?) .What is the part number of the LED VU meter chip they use? I cannot read it on the schematic.
Cheers
Ian
Im getting over -16V out the 7915 reg - you are correct in the cap values 22uf wit two larger 2200uf caps too. i will swap them out as yes, sometimes hard to tell if they are failed unless tested as they dont always leak or bulge cheersI do think it's a really simple, standard supply, utilizing the common L7815, L7915 regulators. Most likely culprits are the capacitors. Try replacing the smaller ones (22uf I think) first. Use normal (not low-ESR) ones.
ah! that explains -16V so thats all ok!The 7815/7915 regulators are strapped with resistor dividers to raise voltage output to +/- 16V. How high does the -16V rail measure?
Those 22uF caps on the regulator outputs (C37/C38) should be at least 25V, not the 16V shown in the schematic.
In what way is the mixer operating improperly?
good to know! thank you And I know the owner of the mixer uses phantom power too so i will have a lookAfter glancing at the schemo, I see another "gotcha"....phantom resistors are only 0.25 Watt. Normally not an issue until a shorted mic cable is used. The power dissipation of the associated resistor(s) is over 0.33 Watts.
It's not just Mackie. I've seen it in many mixers/consoles....including Big Names. Not an issue, you say? Maybe not. But, I've seen more than a few "browned" resistors, especially in equipment that's been in service for awhile. For instance, in a studio, a dodgy cable can be left plugged in and sitting on the floor for weeks.
Bri
Thank youHere two original PDF of Mackie MS1202 mixer service manual and schematics.
Cheers HERB
thank youI do think it's a really simple, standard supply, utilizing the common L7815, L7915 regulators. Most likely culprits are the capacitors. Try replacing the smaller ones (22uf I think) first. Use normal (not low-ESR) ones.
thank youThere you go.
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