I have been trying to solve a power transformer problem for what seems like forever. I changed the transformer in a Fender Supersonic 60 from 120V to 240V. The power in Thailand where I live is 220V. I installed a Hammond tranny. The problem is that the Hammond, like the Fender, has 3.75A/6.3V for the heaters. This is too low. The current draw is closer to 4.5A at minimum. Fender used the same tranny for the Hot Rod Deluxe which has fewer preamp tubes. Add to this the lower voltage and I get between 5 and 5.3V across pins 2 and 7. Tranny also gets hot. It seems I have two choices. I can use the existing transformer along with a 6.3V/5A filament transformer. This will give me the right voltage to the heaters but low plate voltage or I can install the Fender export Tranny which is 230V but again 6.3v/3.75A for the heaters. Any opinions or suggestions would be appreciated. I am far from an expert on this subject. Thanks.
Don´t overthink it, plus the reality is that 220V (which might even be lower at the actual wall outlet) will always be less than 230 or 240V, and you can´t change that.
I suggest you split your problem and address both hlves separately.
1) use the PT you have, either the original Fender one (best option because by definition it will work and fit there) or worst case the Hammond (which needs reforms) for HV only (and maybe Bias if t has that tap).
+V will be somewhat lower than expected, no big deal, you will n ot hear any difference.
2) add a properly rated 220:6.3V transformer.
If it has a 230V or 240V primary,secondary will *still* be slightly low, so best option would be to get a locally wound transformer which from the beginning was made for 220V mains.
FWIW I live in Argentina, also 220V mains, and that´s exactly what I do here.
I suggest you split your problem and address both hlves separately.
1) use the PT you have, either the original Fender one (best option because by definition it will work and fit there) or worst case the Hammond (which needs reforms) for HV only (and maybe Bias if t has that tap).
+V will be somewhat lower than expected, no big deal, you will n ot hear any difference.
2) add a properly rated 220:6.3V transformer.
If it has a 230V or 240V primary,secondary will *still* be slightly low, so best option would be to get a locally wound transformer which from the beginning was made for 220V mains.
FWIW I live in Argentina, also 220V mains, and that´s exactly what I do here.
JM,
Thanks for the reply. The original was 120V so I would have to buy the export model which is 230V but still not enough current for the heaters. Strange design from Fender. So far I haven't been able to find a 6.3v/5A 220V transformer. Edcor has a 230V. Should still give me a little over 6V. If I can't find one in 220 I will go with that.
Thanks for the reply. The original was 120V so I would have to buy the export model which is 230V but still not enough current for the heaters. Strange design from Fender. So far I haven't been able to find a 6.3v/5A 220V transformer. Edcor has a 230V. Should still give me a little over 6V. If I can't find one in 220 I will go with that.
Heater's voltage are ok within ±10% of its rated voltage, so don't worry if you use a 6V transformer in place of 6.3V.
Not much to add. The Edcor sounds good. I looked up the schematic and the Fender export has a 220V tap (white). You have some decent options to choose from.
Not sure where you pulled that spec from, definitely not from Fender which in any case would NOT have used an underspcified power transformer.
Plus the statistic fact that there are thousands of Supersonic 60 out there running happily with their Factory transformers.
Given what you say, I´d remount the original Fender transformer and use the amplifier with an external 220:120 V autotransformer, NOT a generic 220:110 one but a custom wound one which gives you trusted 120V.
You already spent a lot of money and have not solved the problem(s) yet so the trivial solution is to "move to USA 😉 " ..... not physically but by feeding the amp "USA mains".
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Specs
JM,
Here is a link to the transformer specs. It is the same part number as the Supersonic 60. Same current specs from Classic Tone and Hammond for this amp. Only Mercury has a higher current rating but they want over $200 for the tranny. By the time it got to me it would be closer to $350. As for the amps running happy with 3.75A imagine how happy they would be with 5A! I am already using a Variac. I want to sell the amp and want it functioning properly without external transformers. Thanks for the help.🙂
Transformer - Fender(R), Power, Hot Rod Deville | Antique Electronic Supply
JM,
Here is a link to the transformer specs. It is the same part number as the Supersonic 60. Same current specs from Classic Tone and Hammond for this amp. Only Mercury has a higher current rating but they want over $200 for the tranny. By the time it got to me it would be closer to $350. As for the amps running happy with 3.75A imagine how happy they would be with 5A! I am already using a Variac. I want to sell the amp and want it functioning properly without external transformers. Thanks for the help.🙂
Transformer - Fender(R), Power, Hot Rod Deville | Antique Electronic Supply
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Leadbelly,
Can you send me a link to those specs because on the schematic I have I only see a 230V or 240V tap. Thanks.
Can you send me a link to those specs because on the schematic I have I only see a 230V or 240V tap. Thanks.
I'm looking at the same schematic as you. It looks like 220V between violet and white taps. If you look at the 100V example the white tap appears to buck 20V from 120V configuration. They don't show examples for 220V or 120V, but they are available for that transformer.
Leadbelly,
I think I understand but you have reached my limits on transformer knowledge. How would I wire it to for a 220V primary? The same as the 230V schematic except connecting white to P4 instead of white/black?
I think I understand but you have reached my limits on transformer knowledge. How would I wire it to for a 220V primary? The same as the 230V schematic except connecting white to P4 instead of white/black?
JM,
I am the guy in Thailand that has been trying to straighten out a transformer problem with a Fender Supersonic 60 for months. I put in a Hammond 290 VEX transformer to replace the stock 120V tranny. In your original message you stated that
"You pulled a HOT Supersonic transformer, meant to give hairy +485V +V and replaced it with a milder transformer, designed as a drop-in replacement for a Hot Rod Deville. So now expect HRD voltages, what else?".
The Hammond is rated for for 342V but doesn't that have to be multiplied by 1.41? In which case you get 482VDC very close to spec. FWIW Fender uses the same transformer in the Hot Rod DeVille as the Supersonic. What I don't understand is the 3.75A rating on the 6.3V Filament tap. The SS60 needs at least 4.3A if i am adding correctly. I am using a variac and have a 240V going to the primary side. I get only 2.1V on TP8. This should be 3.15V according to spec.I only 4.2V across pins 2 and 7 on both output tubes. This should obviously be 6.3V. I guess it is possible that the transformer is bad. I want to just order the Fender but I worry about the 3.75A rating. This is one of those cases where being in a small Thai town can be very frustrating. Any advice you can give would be greatly appreciated. gary
I am the guy in Thailand that has been trying to straighten out a transformer problem with a Fender Supersonic 60 for months. I put in a Hammond 290 VEX transformer to replace the stock 120V tranny. In your original message you stated that
"You pulled a HOT Supersonic transformer, meant to give hairy +485V +V and replaced it with a milder transformer, designed as a drop-in replacement for a Hot Rod Deville. So now expect HRD voltages, what else?".
The Hammond is rated for for 342V but doesn't that have to be multiplied by 1.41? In which case you get 482VDC very close to spec. FWIW Fender uses the same transformer in the Hot Rod DeVille as the Supersonic. What I don't understand is the 3.75A rating on the 6.3V Filament tap. The SS60 needs at least 4.3A if i am adding correctly. I am using a variac and have a 240V going to the primary side. I get only 2.1V on TP8. This should be 3.15V according to spec.I only 4.2V across pins 2 and 7 on both output tubes. This should obviously be 6.3V. I guess it is possible that the transformer is bad. I want to just order the Fender but I worry about the 3.75A rating. This is one of those cases where being in a small Thai town can be very frustrating. Any advice you can give would be greatly appreciated. gary
> at least 4.3A
Agree.
But I would not expect huge sag from this. It is only 14% on the winding and <10% on the overall power.
Can you source a separate heater transformer and fit it into the chassis?
Agree.
But I would not expect huge sag from this. It is only 14% on the winding and <10% on the overall power.
Can you source a separate heater transformer and fit it into the chassis?
You are confusing people. You have NOT shown that the correct Fender transformer for your amp has a latent defect at being spec'd for 3.75A. You are assuming it does because of that link to Angela Instruments for a transformer that does not mention YOUR amp model and says "EQUIVALENT", which means it is not a Fender part. Similar, the low voltage you are measuring is on your HAMMOND transformer, which I guess also was NOT listed as a replacement for your amp model. There is no monster here. Buy a stepup, buy a true Fender party, or buy something 3rd party with a heftier heater winding.
On the schematic for the Supersonic 60 the export transformer is listed as part #0041753000. This is the same "genuine fender" transformer that Angela and a few other sources sell. This has been confirmed by Fender. Fender will not give me any specs other than to confirm the number. I have asked. After doing more research I found that the Supersonic 60 head has two less 12a.7 tubes than the combo. This means the PT's current rating on the 6.3VAC tap is adequate for the head. Both the head and combo use the same PT again shown on the schematic. I guess Fender thought they could get away with the lower amperage on the combo. The only PT I can find that has a higher rating is from Mercury Magnetics and it goes for around $230. By the time it gets to Thailand it will cost half the price of the amp. I might get a separate 6,3V 6A transformer. I might just buy the Fender replacement.
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