Sinmarc power transfomer R2280 replacement needed

[mikeydee77]

Never heard of this make before but apparently popular during the Franco era of Spain. Sinmarc copied Marshall and Fender and it looks pretty well made. Combination of PCB and hard wiring. All looks pretty good to me.

This one in front of me is a Fender twin essentially but unfortunately this one in front of me has a blown mains transfomer so I am looking for a replacement. The amp has 6 pre amp tubes, a magic eye VU meter and a quad of 6L6. From the schematic attached. the transformer is 0-380, 0-60 3.15-0-3.15 (power tubes) and 6.3 (pre amp tubes). I am in the UK so looking for something that is readily available here.

Any idea what the reason is for the two heater windings?

As this is essentially a Fender twin clone that is where I started looking at the Hammond replacements and they seem to be 5.5A on a 6.3v winding.

My calcs for the filament current are: 4 x 6L6 @ 0.9A + 6 ECC8n @ 0.3A + 0.27 (magic eye) = 5.7A would appreciate any comments on that - like what degree of safety margin I neded to be aiming for.

[J M Fahey]

Yes, the Hammond one should fit perfectly.

2 caveats:

1) search for a somewhat lower high voltage winding, modern tubes vcan not stand +525V +V , don't even try it.

Some 320VAC will be more in line with modern tubes, meaning some 450VDC unloaded, some 420/430 loaded.

2) that amplifier was modded for EL34 , which were available in Spain (Philips/Miniwatt) while 6L6 were expensive American imports.

You may use them or original Fender 6L6 which today are easier to find, of course bias them properly, they need different voltage (around -52V 6L6 ; around -38V EL34 are classic values) .

They were very well made, the idea for a Pro was to buy one (expensive) and then use it for many years.

There are two heater windings, probably a larger (thicker wire) one for power tubes, a smaller (thinner) one for preamp tubes.

Of course, if you get a PT with a single "large" 6.3V winding use it for all tubes, check Fender Twin schematic and layout for ideas.

The magic eye Vu Meter is just a gimmick, but doesn't hurt

Post a couple pictures

By the way, "Sinmarc(a)" means "No brand" .

I guess in the old days some Spanish Guitar player said "I bought a new amp" and when buddies asked "Is it a Fender/Marshall?" he answered "no, es un amplificador sin marca" (which practically needs no translation )

FWIW Franco's high tariff local industry protection had many good effects, one of them was sparking (out of sheer need) the creation of speaker factories "as good as JBL" to supply national cinema and Pro audio needs, such as DAS and Beyma ... what Soundmen buy today when they need "a JBL like the old ones" , go figure.

[Mick Bailey]

I've seen a few amps with dual heater windings. My theory is that maybe it's intended to reduce hum by splitting the heavy power tube load from the lighter and more sensitive power tubes. I don't think it makes a lot of difference in practice.

The Spanish versions of European brands are quite interesting and their version of the Land Rover was (in my view) more advanced than the British original and well-regarded. I had a Spanish Ford Escort and it was the best car I've ever owned. Their Ducati motorcycle built by Mototrans had some problems with certain models due to poor materials, though.

EDIT; JMF's suggestion of lowering the voltage is a good one. I have a Traynor that eats EL34s due to the high B+ and nothing in modern production lasts very long.

[mikeydee77]

I've seen a few amps with dual heater windings. My theory is that maybe it's intended to reduce hum by splitting the heavy power tube load from the lighter and more sensitive power tubes. I don't think it makes a lot of difference in practice.

The Spanish versions of European brands are quite interesting and their version of the Land Rover was (in my view) more advanced than the British original and well-regarded. I had a Spanish Ford Escort and it was the best car I've ever owned. Their Ducati motorcycle built by Mototrans had some problems with certain models due to poor materials, though.

EDIT; JMF's suggestion of lowering the voltage is a good one. I have a Traynor that eats EL34s due to the high B+ and nothing in modern production lasts very long.

Cheers Mick. 20 odd years ago I lived in Madrid for a while repairing PC which were new kids on the block at the time. Santana are the Spanish Land Rovers made under license out there and they were absolutely everywhere. They would need to be good as Spanish off-road conditions can be pretty tough.

[mikeydee77]

Thanks for the advice.

Yes you are right there are two heater runs one thick and one thin. Actually The amp is filled with fine striped wires which makes it look very distinctive. I will get some pics up later on.


Cheers, Mike

[mikeydee77]

Heres some pics

[Mick Bailey]

I haven't seen too many amps with the surface-mount style boards - last one was a 1980s Sundown. This used to be a common construction method with TVs in the 60s. Certainly makes component replacement easier if everything can be done from one side.

[mikeydee77]

I haven't seen too many amps with the surface-mount style boards - last one was a 1980s Sundown. This used to be a common construction method with TVs in the 60s. Certainly makes component replacement easier if everything can be done from one side.

Surface mount for the over 40s

[Pedro Vecino]

Much work. Beware of Ero capacitors that remain (currently tend toward short). This amp uses a excessive high voltage aggravated by the mains voltage. They were designed for 220V and in U.K. are 240V. Better, use a power transformer with a lower voltage, but if you use EL34, more fun in this amp.