The here has no potted black box, only a bunch of TL and which don´t appear in the schematic I have (with the black box). Download Drawmer Drawmer mic pre & compressor ✅ Professional audio systems service manuals and repai information. Drawmer mic pre & : Full Text Matches – Check >> Voroshilov- jpg, , Schematic diagram OLDEST bulgarians doorphone.
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Started by tonebucket The Lab. Started by robinball The Lab.
Has anyone had any experience tech-ing one of these units? I’m seeing a lot of spurious signal output, even without the input being driven. I have the schematics and have been tracing through the unit, but haven’t found anything to lead me in the right direction.
Drawmer Electronics 1960 Mic-Pre/Tube Compressor User Manual
I’m getting the same issue in both channels, schematc it’s not like each channel is acting identically, which is interesting. Anyone have any info about the potted “VCA” module?
The first version of the potted VCA burned up and died pretty regularly. The first board layout was also different, and the current replacement VCA’s won’t fit it. That’s the only thing I’ve heard about, and experienced. Do you know the age, and have you contacted Drawmer? Some kind of control that’s intuitive, not complicated like a single knob” – Crusty “Back when everything sounde.
Hi, Not sure about age and haven’t contacted Drawmer as I got the unit second hand for very cheap I suppose that if it is schemtic VCA, getting assistance through Drawmer may be my only hope.
I find it interesting that both the channels have failed Now to contact Drawmer, thanks for your help. No chip VCA around how hearsay suggests it to be the case.
April schematc, Talk to Drawmer, in my experience they have been very helpfull. Tubefreak Member Netherlands Posts: Isn’t it a optical comp? Of so and if they used optocouplers for it, then those are suspicious as well. They are known to fail after some years. Btw, is yours the one that just sold shcematic ebay? From what I remember when trying to make qualified guesses to what the blackbox contained a very long time ago – I think it’s a vari-mu like differential long-tailed xrawmer, but with a semiconductor variable current source common to the cathodes in stead of controlling the grids like in “real” vari-mu.
What do you mean with OTA? Harpo Member Rahden, Germany Posts: A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
Drawmer Electronics –
Did one ch first and compared them Gar Gilles [ gtr amp builder ] while he was still alivehelped me build a gtr preamp design of his that controled gain from the cathodethat may have been too wide a range for a micpre but gtr would quickly get into overdrive. Had same problem with a unit i had to fix.
Re valved it and problem cured for a short while before fault reappeared. Checked the unit in situ and found that the sidechain wiring was open at the patchbay.
Download Drawmer 1960 docs – Professional audio systems service manuals and repai information
Rectified this and put more new tubes – problem solved! Check your wiring if using sidechain jacks.
If not – continuity check between sidechain tip and ring – if this isn’t showing low resistance clean the jack contacts or temp solder rdawmer the contacts and check.
I concluded that the sidechain return on the faulty unit was acting like an ariel and this was causing oscillations around the valve stages. Once the valves had schejatic stressed they needed replacing. This was a repair i did 4 to 5 years ago and the unit has been in daily use since then without problems. Hope this helps – the symptons seem to be identical to the unit i had to repair!
Drawmer – Manual
The non potted vca schematic is posted at the gmail site Obviously there are schmeatic more revisions than the potted and unpotted version. Make sure that the pots are solid. I have had many on the bench that had dirty pots.
And definitely recap if original caps! Some pots are between DC coupled opamps. Not drawmef good design practice with non-precision opamps and carbon pots. I swapped many TLs with low offset chips to adress that problem. Johan Member Sweden Posts: Johan on May 29, October 11, October 22, June 10, July 25, ,