Roland Bolt-60 Needs Transformer

[CKuzGuitars]

I recently purchased a Roland Bolt-60 at an auction. It is in excellent cosmetic condition but the first time I fired it up there was a burning smell then it just shut down. No power at all. The fuse is fine, there is voltage going to the transformer but nothing coming out at any of the connections. The transformer model is 022-147. Anyone have info on a replacement? Thanks!

[glebert]

Was the amp listed as working? Did you try to get a refund?

[CKuzGuitars]

Thanks for responding but, that’s not the issue. I’m looking for a replacement transformer. It’s not an eBay thing, I knew what I was getting into and I already did very well with the items I purchased. Just seems like a waste to throw an almost new looking semi rare amp in the trash.

[glebert]

Got it. It seems unlikely to find another factory transformer, but you don't need a perfect match, just something close enough. According to the schematic you are looking to get 490V for the tube plates, -51V for bias (also gives 47V for the B1 voltage to preamp), and then the +/- 7V is created from the 6.3Vac heater supply. Those voltages shouldn't be a big deal to find something that will work. Then the other issue is size and form factor, since yours is a lay-down PT it might be a little more challenging to get something to fit, it may be you have to redrill some holes, open up the chassis cutout a bit, etc. If you are lucky the form factor is similar to a Fender where there will be lots of options, but Roland seems like they always liked to do their own thing.

One option would be to contact Heyboer transformers, one of their guys might be able to help find what you need.

Here's the schematic.
Roland-Bolt-60-Schematics.pdf

[The Dude]

When you measured secondary voltages, was that with secondary connections disconnected? If not, I would unhook secondary wires and retest the secondary output. It may be that there is a short external to the transformer.

[CKuzGuitars]

With everything except for the 120v input disconnected, there is no output at any connection.

[CKuzGuitars]

If I am reading the previous post and the specs on the transformer correctly, I am looking for 450v @ 250ma or possibly 490v according to Glebert. Cannot find anything on the Hammond spec sheets that matches and mercury’s website just plain old sucks unless you have one of the worlds most common amps. Checked monotone that uses heyboer and I don’t see anything close there either. So, I guess it’s going to be trash.

[Enzo]

I think glebert was saying your B+ supply would be 490vDC, which suggests to me the transformer needs to provide about 350vAC.

[CKuzGuitars]

Enzo, so, I’m a guitar repair tech. Not an amp guy but I’m pretty handy with a soldering iron and know basic amp safety. Would you be able to suggest a transformer that would meet my specs? Glebert did include a schematic and if you look at the photos, you will see there are markings on the transformer connections. I tried to find something that matched what is on the transformer but to no avail. Chuck

[Enzo]

Honestly I am not the guy for that. I am not familiar with the transformer product lines like many others here are.

[J M Fahey]

Beware Roland for some unknown reason sometimes rates transformers for the DC you will get, NOT the AC voltage.
Crazy, huh?

On cover itīs labelled 100 350 which I guess means "includes 100VAC winding (Japan Mains) , has 350VAC secondary"

Now secondary high voltage winding is labelled: "450V DC 0.25A", there is also a "55V DC 55V DC 0.2A" one.

But filaments are labelled 6.3V (AC?) although thev are also rectified to get +/-7VDC.

Crazy.