Fender Sidekick 35- transformer substitution

[foxtower]

Hi!

I have a Fender SK 35 Reverb with a bad power transformer. I'd like to substitute another center tapped 2 amp transformer, but can't seem to find out the voltage?

Another thread referred to the voltage for a SK- 65 as 24 volts... it may be the same, but I'm not sure.

Your help is appreciated!

[Enzo]

Did you contact Fender for a schematic?

Look at the main filter caps. Are they 35v rating? If so, then your power supp;lies are about 30vDC. The schematic for the Sidekick 35 Bass is 31v, I bet they are similar. Is your transformer part number 023054?

And ask Fender if those are still avaialable, then if so, any Fender dealer can order it.

A 31vDC supply would have about a 22VAC supply. So something in the 40-45VAC center tapped should work.

How did you determine it needed to be a "2 amp" transformer?

The 65 has higher voltages.

[foxtower]

Thanks Enzo!

Yes. it has 35v caps in the power supply, and according to the parts list (found here!) the transformer number is correct. I figure 2 amp because the fuse is 2 amp and the actual transformer is about the right weight for 2 amps.

I will try a fender dealer now that I have a part number... though usually old equipment isn't suported. We'll see!

Thanks again!

[Gokarna]

Hi,
I bought the same amp with a blown transformer and installed the one from a Sidekick Reverb 30. As I Remember, the voltage output 2 x 24 volts.

But be carefully, if the power transformer has blown, it is quiet likely, that something else in the circuit is wrong. And you don't want to ruin the brand new transformer again !

My amplifier workes some time and the failed again. I figured out, the a small transistor , 2SB560F (Q9 on the pcb) was charred, i changed it with a 2SB560E (little lower max. current gain [h(fe)]), the amp worked again and failed, now changed the transistor to a BC560, which is likely a substitute for the very hard to get 2SB560(F). I tested the amp for maximum 10 seconds it only make a very ugly hum/buzz. I found out, that the 2 big 0.5 Ohm / 5 W resistors get very hot (after just 10 sec).
Any suggestions ?


I also have a copy of the schematic here, but no scanner. I'll try to make a scan tommorow at work and post it then.

Best regards,

Till A / Germany

P.S.: BTW, i tried to get an original transformer from Fender/ Germany. They weren't interested at all. They didn't tell me: Oh, such and old (!) device, better trash it and buy anew one (from us), but that was what they wanted to bring to my mind. Service is still very bad compared to your country...

I hope, it'll help you.

[foxtower]

Thank you Gokarna!

I found a 24 volt center tapped USD $14 transformer from AllElectronics (my usual surplus supplier) that fit in with some new brackets and it works great!
The output is 12-0-12 to reach 24 volts.

I tend to think it might have been suffering from old age....

It has no thermal protection like the original, I don't use it that much but playing around so far nothing unusual has heated up. I could add some auto resetting thermal protectors if it does.

Resistors usually get hot after a while. I checked mine... no unusual heat! As to what is causing your problem... my repair skills are only adequate up to power supplies and obviously bad parts. Beyond that IF I have a schematic I can follow the voltage (volt meter) or signal (oscilloscope) and make a guess though I'm no expert!

No, service is no better here. Among my adventures was contacting a Fender repairman who wasn't interested....

Thanks again... now off to see if I can find any cool effects circuits to add to the Sidekick!

Originally Posted by Gokarna

Hi,
I bought the same amp with a blown transformer and installed the one from a Sidekick Reverb 30. As I Remember, the voltage output 2 x 24 volts.

But be carefully, if the power transformer has blown, it is quiet likely, that something else in the circuit is wrong. And you don't want to ruin the brand new transformer again !

I tested the amp for maximum 10 seconds it only make a very ugly hum/buzz. I found out, that the 2 big 0.5 Ohm / 5 W resistors get very hot (after just 10 sec).
Any suggestions ?


Till A / Germany

P.S.: BTW, i tried to get an original transformer from Fender/ Germany. They weren't interested at all. They didn't tell me: Oh, such and old (!) device, better trash it and buy anew one (from us), but that was what they wanted to bring to my mind. Service is still very bad compared to your country...

I hope, it'll help you.