'65 Deluxe Reverb RI. Blown resitor.

[Chuck H]

I'm with you. You need to have a healthy respect for the voltages involved and not be scared of them. Think ahead about what part of the amp you are going to work in, where the high voltages are in that part and where other parts that have high voltages are that you won't be working in so as to keep your hand away from them. Know all the high voltage points and use only one hand to do the work. There is no reason to turn off the amp every time you work on it to take a reading if you know what you are doing and observe common sense. If I'm going to take multiple readings such as all B+ nodes and their corresponding pins on tube sockets, bias voltages, etc. it would take all day. On, off, on, off. Nope.

Indeed. The "professional" grade Fluke meters DO have registers for high voltages and currents. Yet they are sold with simple "proboscis on a wire" detectors for acquiring the knowledge they can reveal. Hmmm...

I do a couple of things for safety with these considerations. I actually DO clamp the ground lead for general voltage readings so that I can probe with one hand. And little mistakes like holding the chassis with one hand while probing with the other are a strict no no. In spite of being careful I was shocked badly once in my early ventures. It happened quite certainly because I had no real idea about proper safety. Thinking it only came down to being careful. That is a big mistake because mistakes happen. You really do need to think about, and align procedures with not even being able to complete a circuit path through your body. And I hope this opens up the discussion for any safety practices anyone wants to share.

[Randall]

Just to be the odd one out, I will say I ripped the guts out of my DRRI, and built it up on a turret board. I did not give a rats ass about that resistor. I just soldered in a 1/2 watt and called it good. It sounds great, no problems. Boom.

[Sea Chief]

All I have to add is the tech should not have been 'poking around' in the amp.

Turn it off, place a measurement lead, turn it on.

Poking is for amatuers.

This guy owns an established & successful amp-building Co, making very expensive (& excellent sounding) clones in UK. He's not an amateur- I wouldnt have taken it to an amateur to get an evaluation.

It was 5pm/ end of his day & he was doing it as a favour for me, basic few checks (via prodding a b &c) done & voltages, bias etc all checked within normal tolerances (tho 417v B+ with a 5U4GB I still think is too high.. why I took it to him.. & he concluded thats a touch high, but perfectly ok for a DR). Just as he was about to power off, we notice the red-plating. Then it took an hour of grumpings (what am i meant to do? I took a good amp in- I dont want to leave with it broken & not knowing how or what exactly is broken) and "what did WE do" (we? i wasnt even touching it..) etc etc.

Every pro tech I see probes one point to the next to the next, prodding away gently enough.. maybe just with less friday 6PM 'quick lets get this done' ham-fistedness thats all.

I had to keep schtum & apologise it caused a prob, & thank him for testing & trying to fix it, as I wasnt paying him for it- I was going to offer something after an evaluation, but how could I offer money when I take away an amp that's now broken that went in perfectly good. Once in the car Im thinking hang on thats a bit much.. Ive got to source/ find & fix myself.. as I see his tailights fade. Oh well. Sometimes you just -do- have to keep schtum don't you.

[Sea Chief]

Just to be the odd one out, I will say I ripped the guts out of my DRRI, and built it up on a turret board. I did not give a rats ass about that resistor. I just soldered in a 1/2 watt and called it good. It sounds great, no problems. Boom.

Sure, but the amps are slighty different. I must put back the RI component as it was if I dont have the knowledge to reason whether it can be bettered, or replaced with anything other than exactly what it was- simple as.