Repairing a Drawmer DL231

[12dbLow]

Hi,

I'm trying to repair a Drawmer DL231 compressor. I'll post further information to ask for help when I gathered more measurements.

In short: Supply Rails OK /  Visually no broken parts / gain reduction on channel 1 reacts extremely slow, but it moves (Attack time over 30 sec, Release even slower) / audio passes through both channels without a problem.

For now: Does anyone have schematics? That would be a great help!

Best,
Adrian

 

[Tubetec]

I dont have schematics for any of the drawmers ,I do have one of the dual channel gates though ,and I did find some of the electrolytics had puffed up ,these units are maybe upto 30 years old ,so that might be a good place to start ,what I really love is these designs have stood the test of time and even to this day remain in production almost unchanged from the original ,definately well worth spending some time to get back into working condition .Chance emailing Drawmer ,they might just send you the service manual .

 

[buildafriend]

I don't have a schematic but you might want to ask them for the calibration procedure before digging too deep

 

[12dbLow]

Chance emailing Drawmer ,they might just send you the service manual .

Thanks for the advice. I mailed them.

 

[jensenmann]

It could be something as simple as a broken solderjoint at one leg of the attack pot. Give it a careful visual check or simply resolder all pots. Recapping won´t do no harm either.

 

[12dbLow]

They mailed me the calibration procedure. Thats pretty nice so far. Sadly they don't release the schematics "due to repeated copyright infringements"

It might take a week or two until I have time to continue this repair but I will post here again.

 

[Tubetec]

I did get a service manual for a 1960 off them before ,but had to pay for the previledge,this new trend of simply not supplying schematics under any circumstances is bad news ,and Ive a feeling it may fall on shady legal ground in certain jurisdictions as well.

 

[pucho812]

I did get a service manual for a 1960 off them before ,but had to pay for the previledge,this new trend of simply not supplying schematics under any circumstances is bad news ,and Ive a feeling it may fall on shady legal ground in certain jurisdictions as well.

I worked for a company that would not release schematics. The argument is they do not want people ripping off a design.  In the current climate of clones all over, it is a sound reason. Some companies will allow you to get a schematic if you are service personal and sign a NDA(non disclosure agreement). It basically says that you cannot disclose those schematics to anyone. 

 

[zamproject]

Hi

I got all data for my 301 some years ago, they first just send the calibration procedure, IIRC they say more or less the same as you for schemo.
I reply, I'm a tech... blabla... as perform studio maintenance... blabla (which is true but just my gear) and say that if there is a © problem about the circuit I'm ok to sign a NDA... I needed the schemo to fix it ...
I get back an email with the files without more question.

I really appreciate, Drawmer support is great even for long term discontinued product, you just have to talk a little.
I also understand small and independent company fighting to stay alive in this market, so maybe policy change and Drawmer won't release schemo anymore ?

Best
Zam

 

[12dbLow]

It could be something as simple as a broken solderjoint at one leg of the attack pot.

Doh... You're the man!  It actually was a broken attack pot. The solder joints were ok but internally it had no contact at all.

 

[Tubetec]

That was a hell of a good call by Jensmann , your as good as sorted 12db , I think there omeg pots in there from memory.

yeah Ive had to do the NDA a couple of times alright ,only company that steadfastly refused me was Fishmann,no matter what I said they wouldnt budge an inch ,understandable yes ,highly infuriating also though.

 

[12dbLow]

This unit has very strange corrosion at some points. (Maybe it was stored in a humid environment.) The pot pin was completely insulated from the resistive track due to corrosion of some sort. Also two resistors had some brown and blue efflorescence.

Anyway, now i've got the next problem. This pot seems to be very hard to find. I already searched every dealer that I could think of for now.

Pot: 22k log / shaft 4 x 15 mm / flattened at at the end / 16mm case

Drawmer has an online shop for parts (Nice!) but they don't have this one. I'll send another E-Mail but maybe you also have ideas...

 

[Tubetec]

Colin over at AML might be able to help ,
Heres a link to his 16mm pot selection ,
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_single_gang.html

22k log flat shaft he has ,maybe it will suit ,alternatively you might be able to clean up and rebuild the original

 

[jensenmann]

https://www.reichelt.de/4mm-Potis-mono/PO4M-LOG-22K/3/index.html?ACTION=3&LA=2&ARTICLE=88283&GROUPID=3133&artnr=PO4M-LOG+22K&trstct=pol_1

Maybe this can be made to fit.

 

[12dbLow]

Maybe this can be made to fit.

I already thought of that. It will be a bit fiddly to flatten of the edge at the right angle, so that the pot orientation is right. But anyway that seems to be the easiest option at the moment.

Danke

 

[jensenmann]

Aber gerne

Just for the record, here´s a thread with the link to schematics: https://groupdiy.com/index.php?topic=8944.0

 

[12dbLow]

Aber gerne

Just for the record, here´s a thread with the link to schematics: https://groupdiy.com/index.php?topic=8944.0

Thanks!!! Thats great.

Also for the record: Drawmer actually does seem to have the pots in their online store. I dismissed them at first because on the drawing the shaft looks much shorter than the one I have. The tech suppord told me they are right though.

 

[MistrFX]

Would you Please share the product code? Its for the 231 right?

Thank you
I am from the Netherlands.

 

[Ike Zimbel]

I have quite a few NOS Drawmer parts, including pots. I will have a look at what I have in 22K later today.

 

[TimG]

I have quite a few NOS Drawmer parts, including pots. I will have a look at what I have in 22K later today.

Hi Ike,
Let me know if you have a power transformer for a 221! I wasn’t clear if it would work with anything from the online store. Thanks!