Need a new output transformer, checkmate 50!

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello all,
I am new to this forum, and am looking for some help.
I purchased a checkmate 50 amp a few years back, and stupidly ruined the output transformer...

anyways, im looking to replace it, and trying to figure out what to replace it with!

attached are pictures of my amp, and the schematic. any help would be great!

Thanks.

15943494_10208153739788572_918610534_o.jpg

15967060_10208153739148556_1581427349_o.jpg

15943058_10208153739188557_1546297973_o.jpg

teisco_checkmate_50.png
 
Trust me. I have squeezed 100 watts through a pair of 6L6GC's. They don't like it, and won't live long. Your amp makes about 50 watts, as do most other amps with a pair of 6L6GC's.

You need a transformer rated for 50 watts, 6600 ohms, and a secondary to match you speaker cabinet, usually 8 ohms. A Bandmaster replacement OPT will work, as will several others.
 

PRR

Member
Joined 2003
Paid Member
Let them think it is 100W.

(The "50" in the model is the price??)

50 Watts. Maybe 35, maybe 56, and on today's high wall voltages you may test-out 60W at high THD. Not 100W anything like a Sine.

It is a Japanese version of Fender.

I believe the core is smaller than many 2-6L6 Fenders. I would not over-buy this iron. The generic 40W and 50W Fender Replacements won't be exact right, but won't be wrong, and are about the lowest-price OTs around this power zone. Tubelab may be right that a 6.6K Bandmaster is more the right spirit than the 4K jobs for the Dick Dale inspired monsters.
 
I'd go with the Fender brand, and use a replacement for any Fender amp that has 2 6L6GT output tubes AND supplies the 8 ohm output winding. I usually buy them from Antique Electronics in AZ. Fenders are less expensive than Hammonds, which are relatively inexpensive. Fender trannies have proved themselves in the field for years. I doubt if anyone would hear a difference or see a reliability difference compared to the Mercuries. I'd also add a 20 ohm 5 watt resistor in series with a 100nF polyprop cap, across the output, at the output connector, so supersonic energy (above the audio frequency range) generated during clipping (overdrive) doesn't cause the output tranny to generate transients that go over 1000 volts, due to the rising impedance of the speaker at those frequencies (for reliability). If the secondary of the transformer is mis-matched (8 ohm tap driving 50 ohms for ex.), the tranny starts to operate as a spark coil. 8 ohm speakers are not 8 ohms at 50kHZ. I've fixed guitar amps where these high voltage transients caused arcing at the tube sockets. This can be the cause of a blown output tranny, blown tubes and their sockets and even potentially a blown speaker.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.