Thurlby bench PSU

[Mjolinor]

I do have a few of these things bought new actually way back in the 1980s or possibly early 90s. I do blow them up regularly and never have any problems getting them going again without a manual.

However I just bought a used one with a "K1 module" attached to it. It is unfortunately a 30v 1a module and I could really do with having more current available. As far as I can tell there is no difference between the one amp and two amp versions but I can only find schematics for later models, not these that look like a spider laid them out inside. I am also unable to find any references to a "K1" module, neither instructions or service manual.

Does anyone know if their is a difference and if not how to increase the current. With the current limit pot maxed out I can get about 1.3 amps out of it. That pot seems to have been replaced with a 10 turn at some time, I am sure they do not come with one as standard, certainly none of my others have that.

[bd139]

The 2A versions have two layers of heatsink on the back and another two pass transistors. Don't push the 1A ones past 1.5A. Especially the old black and white ones which are made of poo. The older K1 module is a PL310 with a bunch of switching on the side AFAIK and not much more.

I would throw them all in the trash or ebay and get a late model PL320QMD or PL330QMD and just be done. They are architecturally better and very very difficult to blow up.

[Andy Watson]

Looks like the K module was only applied to the earlier models, the later models being triple output designs from the get-go. Try the attached - it mentions the K module. It also states that it was available in two varieties; K1 limited to 0.55A and K2 1.1A. You appear to already have the maxed-out version.

[Mjolinor]

Cheers for that. It is different from all the others I have found. Mine is the 0.55 amp version on the K module and 1 amp on the main supply.

[Mjolinor]

The 2A versions have two layers of heatsink on the back and another two pass transistors. Don't push the 1A ones past 1.5A. Especially the old black and white ones which are made of poo. The older K1 module is a PL310 with a bunch of switching on the side AFAIK and not much more.

I would throw them all in the trash or ebay and get a late model PL320QMD or PL330QMD and just be done. They are architecturally better and very very difficult to blow up.

I don't have several thousands £ available to replace these with newer ones and I only blow them up about one per year anyway so it isn't a problem, not like I do it every week.

[bd139]

Are you electroplating with them? That's the only time I've seen people use lots of them and blow them up. 

[Mjolinor]

Are you electroplating with them? That's the only time I've seen people use lots of them and blow them up. 

Charging liion cells mostly. Hundreds of them.

[bd139]

Ahh figures. That's what I use mine for mostly. That and SLAs