Hafler DH-200/220 Mods

Does anyone know how to get vinyl transfer letters made for an amp logo? See attached mockup done on my computer. (Not perfect, but close enough for my needs) My case needs repainting and I would like to get a fresh new look for the logo as well. If I can find an affordable source, I'd be willing to get a larger quantity and make them available to other members who want to do the same.

Q2. - my fins are a bit faded and scratched, any recommendations to refresh the black anodized finish? I've read that painting aluminum is difficult and reduces the heat dissipation properties of the anodized metal.

Thanks! - Sixto.
hafler logo mockup.jpg
 
Hi

I do not know of a source for transfer lettering but if an emblem would work I have seen whole front/back panels being done using the pcb fab. Member “bonsai” has done it on his phono xltra preamp. Black solder mask, gold plated holes/pads and white silkscreen for the graphics.
You would specify your pcb thickness which can be very thin. They do edge plating too so that would look cool done with gold plating. It is possible to not need any silkscreen if plating is done in gold. There is also aluminum core pcbs to but the solder mask is usually white for led usage have to look into that.
I think they only accept Gerber data for pcb fab so that’s a matter of doing a graphics file conversion or import into pcb software to generate a Gerber file.
At one time we had a local print shop make transfer graphics on adhesive backed transparent plastic.
I hated doing transfer lettering, never could get it straight :)
As for fins, you could use a permanent ink felt marker, but it leaves a somewhat noticeable mark. If you do all that’s visible might make it look better.
 
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I found a source for some NOS 2SJ48/2SK133. (Or alternatively) 2SJ50/2SK135. My Hafler DH220 has 2SJ49/2SK134.
Assuming I can get either matched pairs, or individual spares that match the VGS of my existing transistors, would using either of these in combination with existing cause issues like added offset or distortion?

The only difference. I can spot on the data sheets is the max drain/source voltage 120v for 48/134, 140v for my 49/134 and 160v for 50/135. Seeing that rail voltage is around 70v, and I’m don’t intentionally push the amps to clipping…Would either of these be a suitable replacement (individually or in pairs) if one of my power transistors goes poof in the future, and is one spec better than the other? Furthermore, would there be any issues from one channel to the other if the replacement transistors were used on only one channel?

P.S, I’m aware of the Exicon option, but they are different enough, that I don’t think they would work as individual replacements…

Thanks! Sixto.
 

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"Does anyone know how to get vinyl transfer letters made for an amp logo?"

This unit and software seems plausible for anything you may want...

Cricut Explore 3 - 2X Faster DIY Cutting Machine for all Crafts, Matless Cutting with Smart Materials, Cuts 100+ Materials, Bluetooth Connectivity, Compatible with iOS, Android, Windows & Mac, Mint $289

Possible vendor:
https://www.amazon.com/Cricut-Explo...l+printer+machine&qid=1699227286&sr=8-11&th=1

HTH,
David
 
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Thank you David, the price seems right, I just need to dig deeper into the specs to make sure it can do the small letters I’m looking for… I found a few shops online, but they all said my font size was too small for their machines. They required 2mm line thickness min, and I’m looking for 1mm.
Sixto.
 
Be very careful buying EOL parts on the internet
Read Bob's write up on matching mosfets. Matching insures current sharing for paralleled devices. DH-200/220 does not use a ballast resistor.
https://www.cordellaudio.com/poweramp/DH-220C_MOSFET.shtml
You want as a minimum a mosfet Vds or bjt Vce breakdown V of no less than 2xVpk or your total rail +/-70 = 140V
Do not mix up devices, use same devices in parallel and their complements
Exicon are fine replacements, although the TO-3 is EOL
 
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