marshall dsl 401

[DrGonz78]

I know I am probably way out here in left field... As I usually am Still I have to ask about the picture I see here... I mean pictures do funny things online and I mostly point out something obscured by the camera. However, something about that picture shows the traces have been scraped or something... Probably not the issue here but worth mentioning. It's the middle leg and follow the trace down. Sure you tested continuity on the trace but if there is a crack there would that cause issues when it is powered up? Just had to throw out this bone.

[g1]

Enzo: My concern about using the "official" Marshall pot was due to the extra connection for "screen D". I wasn't sure if this is some special tap that only the factory pot has.
That being said, the schematic shows the connection, but his pic of the board shows 1 pin not connecting to anything (unless double sided pcb), so it may not matter anyway.

[Valvehead]

I know I am probably way out here in left field... As I usually am Still I have to ask about the picture I see here... I mean pictures do funny things online and I mostly point out something obscured by the camera. However, something about that picture shows the traces have been scraped or something... Probably not the issue here but worth mentioning. It's the middle leg and follow the trace down. Sure you tested continuity on the trace but if there is a crack there would that cause issues when it is powered up? Just had to throw out this bone.

[ATTACH=CONFIG]23605[/ATTACH]

ha--i knew someone would see that ! i scratched it moving the end of that wire. I tested it--its ok.

[Valvehead]

ok, i will order a pot monday ...if i can find the exact one

[Enzo]

There is nothing special about the pot. Did you read the data sheet for the part I linked? It includes the taps. Page 2, right above the resistance table. The taps are the end pins.

On your schematic, if you look lower right page 1, you will find SCEEN D is nothing more than a small cap to ground. A little extra stability.
http://www.alliedelec.com/images/pro...S/70153365.pdf


Now that I look closer, are the two left end pins in your little photo soldered together? That doesn't seem right.

[Valvehead]

before i re-flowed it--i looked at those 2 end pins and they looked connected. HOWEVER--i can tell someone has re-flowed some joints on the board before I got it. SO-- maybe i will take another look and suck the solder away to be sure .

the Marshall pot is 11mm (in the link i posted) and the one you posted was 14mm , would that be enough not to fit correctly ? I will measure the pot i have tonight.

[g1]

The 2 pins soldered together go to the bias pot. Not sure if that would match up with the Allied pot.

[Enzo]

Which part number were you looking at at that Marshall parts site? I saw a bunch of 11mm pots, but I saw no dual pots. You need a 7-pin pot, all the ones in the link are 4-pin. Unless I missed one.

Get out a ruler. How wide is your master volume pot. I have to think since it has twice as many legs, it is wider than the rest of the pots. And if they are 11mm, then 14mm for this one sounds right.


Yes, your pinout and the Allied part are the same. This very amp is what I stock them for.

[Enzo]

ANother note: part sellers like the one you linked with the Marshall parts don't necessarily put all the parts they have on their web sites, they just put the most popular ones up. SO it is always a good idea to CONTACT them and ASK if they have the dual pot of DSL401 master volume available.

[g1]

the Marshall pot is 11mm (in the link i posted) and the one you posted was 14mm , would that be enough not to fit correctly ? I will measure the pot i have tonight.

That pot you linked is not a dual pot and will not work. The correct one is 14mm. Marshall® Dual-Pot, 2x A200K, PC Mount, D-Shaft - Marshall style and Pots,
If Enzo says the Allied pot is the same, then it will work.

[Enzo]

There you go, the exact part.


The Allied pot should work, but I understand having doubts and wanting the "real thing." That plus you'd have to come up with an order from Allied, they won't smile on just one pot. These amp part suppliers and tube stores often have other things you need to flesh out an order.

[Valvehead]

Its a bittersweet ending.......... got the pot today and installed it. My bias is now perfect---thanks guys !! yet... the amp has about a 1/2 watt of output. Jacks all good, got all my voltages, been over the joints 3 times, im guessing its the OT. My friend has the same amp so Im going to clip his trans in to confirm.

I did try the fx in/out. Preamp is fine.

That Peavey classic 30 ot is $124 .... ouch. I need to find a cheaper solution . wouldnt any 4- EL84 amp trans work ?

[Enzo]

Well, Classic 50 not 30 was the one I suggested, but that is more than I expected PV to charge. I think that does include shipping though, yes?

Yes, any quad EL84 to speaker transformer will work.

[DrGonz78]

Just found this one on a quick search... Hopefully shipping cost won't be too bad and it should be cheaper than the original quote you had.

ClassicTone # 40-18074, Marshall JCM900 & JCM2000 Style, 50W Laydown Output Transformer

[g1]

According to this : Output transformer:Marshall® 40W, DSL 401 - Output Transf. for Marshall
they use the same OT (4.5K) for the dsl401, JTM30 with 2x 5881 and the JTM/JCM60/600 with 2x EL34. I believe factory part # is TXOP-00012.
So this should be it: Transformer - Genuine Marshall, Output, 30 W, for JTM30 | Antique Electronic Supply
Much better price. You could check with them if it has the TXOP-00012 designation.