Fender hot rod deluxe troubles

[Nay]

I was playing guitar with my buddy the other day and his amp just turned off suddenly and it will not turn back on. We checked the fuses to see if that was our trouble and the fuse seemed to be fine. We also tried putting some other fuses in just in case but that did not work either. Does anyone have any other ideas? I'm not really sure what else to check. Thanks

[Nay]

we replaced the fuse again to see what would happen and this time the amp did turn on. However, when the standby switch is flipped to on the fuse blows... maybe this will be a little more helpful

[Ch0jin]

Well I've not owned a HRDx, but when the same thing happened to my Peev it ended up being a dead power tube.

Fortunately for me the fuse protected everything else, so it was as simple as popping in two new 6L6's, a fuse, and rock on.

If your not amphetically inclined though I suggest taking it to a tech. If it IS a dead tube, it may have wasted some other components as well.

[Spudman]

Well I've not owned a HRDx, but when the same thing happened to my Peev it ended up being a dead power tube.




Exactly whatI was thinking. My HRDx died in exactly the same way. It was a power tube.

[Nay]

I was thinking it could be a tube too solely because I know my buddy has not replaced the tubes on that amp in a really long time. Why would a bad power tube cause the amp to keep blowing fuses though?

[Spudman]

I was thinking it could be a tube too solely because I know my buddy has not replaced the tubes on that amp in a really long time. Why would a bad power tube cause the amp to keep blowing fuses though?

Yes.

[jim p]

Aside from the tube if you lost the grid bias voltage this would also cause the power tubes to draw high current and hopefully just blow a fuse. If it is the power tubes you could take them out of the amp and see if it doesn’t blow a fuse then. As tubes age they can become soft meaning gas gets into the tube causing positive ions that will make the control grid go positive turning the tube on more, which will cause more ions and the current draw just keeps rising. On a fixed bias amplifier like this one there is no feedback to help offset rising grid voltage while with cathode bias the effect is not as bad but the tube can still get bad enough to go into the meltdown mode.

As far as replacement you will need to get a set of matched tubes and rebias the amplifier.

[Duff]

There is a history with the Hrdx of cold solder joints on the pcb. These presumably started happening when the mfg. process switched to the new lead free solder and the overseas technicians did not have the higher level of soldering skill to master working with the lead free solder; which is harder to work with, as a lot of us have found out, requiring higher temperature to melt the solder.

They weren't getting the solder and joint hot enough and cold solder joint were produced which did not adhere well to the surfaces being soldered and eventually they crack and the current gets messed up at the cold solder joint - causing excessive heat and burning out of part of the pcb and some of the components close to the burn point.

I had my new Hrdx taken in to the auth. Fender repair place and Fender paid to have the cold solder joints resoldered and the amp re tubed and biased. All covered under the warranty. This procedure is highly advisable if you have not had it done - having a qualified tech check and resolder any cold solder joints on the Hrdx.

To make this inherent situation worse, a lot of guys have their Hrdx's further hot rodded by having the bias "set hotter" to get a hotter sound. Some claiming that the factory bias is set to cool for optimum performance; so they have the bias set higher, causing more heat at the solder joints and intensifying an already shaky situation.

With this fact in mind, I would carefully examine the pcb and look for yellowed out areas or obviously burned areas on the pcb board itself. There are pictures of the burned spots on that kid's Hot Rod Deluxe website that is still up but not updated, last I knew. He explains the whole situation there.

I would imagine the newer Hrdx's have addressed the cold solder joint problem and trained their workers in the skills necessary to make a good solder joint using the new solder, but turnover of workers is probably a big factor and learning to solder properly is not simple with the new solder and many of the new workers might not be capable of learning how to solder correctly.

Therefore, I would suggest checking all of the solder joints and looking for cold solder joints or having a qualified tech check and repair them, BEFORE you get the short that blows the power tube/tubes.

This is just one possibility. As noted it could be the other way around where a tube blew catastrophically and took out other components. But it can just as easily be the other way around where the cold solder joint cracked and overheated and burned out the power tube.

According to a Fender tech I talked to the Hrdx components should be readily available to repair any failures; unlike many short run, lesser known amps for which the Asian components are no longer available, rendering them non fixable.

Good luck with the repair and I hope it's just a case of needing new power tubes and a standard biasing.