Fender stage 160 amp blowing fuses

[elebish]

http://www.schematicsunlimited.com/f/fender/fender-stage-100-160-guitar-amplifier-schematic
Use the diagram on the bottom left that applies to your input voltage. Hope this helps! Ed.

 

[kemjet]

Thanks Ed for help now i have complete schematic & wiring guide, i already tested & found defective parts that causes huge hum sound, 1N5353B (16v)zener diode & 82 ohms resistor..Thanks for sharing..

 

[elebish]

Thanks Ed for help now i have complete schematic & wiring guide, i already tested & found defective parts that causes huge hum sound, 1N5353B (16v)zener diode & 82 ohms resistor..Thanks for sharing..

Glad I could help. Zeners are difficult to test with unit turned off. Typically .6--.7 Volts forward bias with diode checker ohm meter. Isolation and substitution are good techniques to use when troubleshooting if possible.

 

[kemjet]

Again i have problem with Fender Stage 160 after i trouble shoot i found that Zener Diode 1N5353B 5W (16V) is defective but here in my country there is no available 5watts zener diode only 1 watt is available, is there any recommended solution for this? i attached the schematic.

 

[kellys_eye]

You could fit the LM317/LM337 with the appropriate resistors chosen to give the exact output voltage or fit an 7815/7915 pair with diodes in the ground leg to bump the output to 16V.

 

[duke37]

I doubt if the difference between 15 and 16V will be important.

A powerful; zener can be made by using a smaller zener feeding the base of a large transistor (2N3055). The regulated voltage will be about a volt higher than the zener.

It is not clear whether the zeners are to produce a regulated voltage or to clip high voltage transients. Do the voltages just feed a few op-amps?

 

[kemjet]

for reference i attached the Fender Stage 160 schematic.. we can see here the low voltage supply section & the load.

 

[elebish]

I suspect that being where the diodes are placed, that they are to keep the voltages in the neg and pos legs of bridge output to + and -16 vdc and to suppress transients. I don't see a varistor at the 230 vac input, placed after the on/off switch. Install a varistor (MOV) across output of the power switch. See web sight: http://www.electronics-tutorials.ws/resistor/varistor.html
Ed.

 

[elebish]

I suspect that being where the diodes are placed, that they are to keep the voltages in the neg and pos legs of bridge output to + and -16 vdc and to suppress transients. I don't see a varistor at the 230 vac input, placed after the on/off switch. Install a varistor (MOV) across output of the power switch. See web sight: http://www.electronics-tutorials.ws/resistor/varistor.html
Ed.

You may not need those 2 zeners if you place a MOV at ac input.

 

[kellys_eye]

You DO need the zeners - they regulate the supply for the op-amps in the filters and pre-amp circuitry. An MOV will make zero difference to the way the system works and removing the zeners will blow all your ICs to bits.....

5W zeners aren't unusual but if you can't get them locally then the alternative use of fixed voltage regulators (the 7815/7915 will work perfectly and without the added diode I mentioned) should be easy enough to source.

 

[elebish]

You DO need the zeners - they regulate the supply for the op-amps in the filters and pre-amp circuitry. An MOV will make zero difference to the way the system works and removing the zeners will blow all your ICs to bits.....

5W zeners aren't unusual but if you can't get them locally then the alternative use of fixed voltage regulators (the 7815/7915 will work perfectly and without the added diode I mentioned) should be easy enough to source.

The use of the zeners depends on what the unregulated voltages are. You are right about the MOV not changing the normal operation of the 16 volt circuits. I would still install the MOV, since transients at the 230 input would introduce transients every where in the amp. Try this substitute from MCM Electronics: http://www.mcmelectronics.com/product/1N5353