Fender Hotrod Deville 212

[e_c_mccollum]

Where can I get the R3000 diodes used for spike protection in the output stage.

Any equivalents? The R3000's are hard for me to get.

Peavey told me about a 2000v version they use. Will it work?

The way I understand it you use a diode 2x's + 25% of the B+ voltage (485vdc). Why did fender use one so high?

[Enzo]

Why not?

The ones PV uses will work. The Fender ones are part number 029690001 and can be ordered through any Fender dealer.

[e_c_mccollum]

One r3000 diode is intermittent.

This is the second time the Amp has come to me as DOA.

The first time the bias circuitry had cold solders and thus affecting the bias voltage. The fuse blew and to keep the amp going, my customer installed a gum wrapper in the fuse holder.

This time cold beer spilled on one of the pwr tubes which cracked that tube.

The plate voltage varies on the driver tube. This is affecting the voltages througout the rest of the circuit. Driver tube tested okay.

The resistors on the tube board are being replaced and the coupling capacitors are being replaced by orange drops. Main pwr supply electrolytic caps check okay.

The amp has had circuit board defects and intermitent resistors in the past. His "jam room" doen'st have AC (hot in there) and it has affected the amp.

Peavey told me about diodes that they use #70402873. They are 2000v 250ma diodes. Gene Ford at Peavey told me there amps run similar to the fender (same tubes and voltages) and it should work fine. I wanted to make sure.

Upon using these diodes, will it offer more protection? Was Gene Ford right saying Fender over designed this amp?

[Mark Black]

The plate voltage varies on the driver tube. This is affecting the voltages througout the rest of the circuit. Driver tube tested okay.

Check the values of the plate resistors for the PI tube. Or better yet - just replace them with higher-wattage (I like 1W metal oxide) resistors. I've seen a few of the stock ones go completely open. Haven't seen the same problem on the other preamp tube plate resistors myself, but a preemptive replacement might do well there too...

[Enzo]

I agree, the PI plate loads in those amps do like to fail. And no I haven;t seen the preamp plate loads fail either.

I wouldn't worry about the level of engineering. Guys sit there and want a transient suppressor. One guy thinks Oh 2000 ought to do it, while the other guy thinks Oh 3000 ought to do it. Maybe one guy spec'd a marginal part once in the past, got in trouble, and now always leaves plenty of headroom.

It could also be a matter of vendors. The Fender guy might have to use certain vendors, and their HV diodes were the 3000.

It isn't always about the circuit.

[e_c_mccollum]

The connection on the circuit board for one of the plate load resistors for the driver circuit just lifted enough to cause problems. His circuit board is falling apart but it can be repaired. He will be using a fan now....finally.

Good idea to fuse the high voltage ciruit? If yes, what amperage and fuseholder do you recommend since this is high voltage.

I know the Marshall's fuse the output tranformer B+ but I am interested in the complete high voltage ciruit. You never know.

Another thing, this amp uses .1uf 630v coupling caps on the ouptut of the 12ax7 driver. The orange drops have a rating of 600v. Will it work? I don't see why it won't.