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PT for BE50Dlx

Hey folks!

I have a transformer I've set aside for my BE50Dlx build....It's a Heyboer, but it's not the one specified in the BOM. Would love to know if anyone thinks I would run into trouble using this one. HV Secondary seems like it's good for a 50w marshall style amp. The big question I have is the 14v yellow taps. Can I use that for the switching? I know if I spec the right voltage regulator, it can handle upwards of about 30v. But I know very little about switching schematics, in general. In the schematic, its showing a 12v and a 0V tap. However, the transformer I have has two 14v taps? wouldn't you need both sides of an AC feed to rectify to DC anyway? A little confused, and I hope Im explaining this correctly.

Thanks in advance,

Frank

Diagram is as follows:

3 answers0 replies

3 Comments

Andrea Antonello

Jun 08, 2023

Hello Frank, Andrea here.

Your transformer is ok! It's a notation issue, the tap can be represented as a 14V/14V or a 14V/0V, depending on the manufacturer of the transformer. It is the same thing.

Your 14VAC wires will go to the GBU8B (represented with red wires in the layout) and will then be rectified to 12VDC.

I have noticed that Heyboer doesn't have a bias tap. Are you using a separate transformer for the bias?

frankbenenati

Jun 09, 2023

Replying to

Hi Andrea,

Good catch. In my past builds (mostly 2204 style amps. See this for reference - https://mhuss.com/MyJCM/JCM800_2204.pdf), my bias current has been taken off of one of the high voltage taps and dropped with a 220k resistor. As a matter of fact, it looks like the BIAS circuit on you BE50 Dlx schematic matches the bias circuit on my 2204 exactly - even the 220K resistor (R38).

Instead of a separate transformer, couldn't I run a line to the standby switch and tap one of the main HV lines?

Thanks,

Frank

frankbenenati

Jun 09, 2023

Replying to

also thank you very much for confirming the transformer will work (in terms of the switching)!!