Re: [Harp-L] Amp troubleshooting

[MARK BURNESS <markwjburness@xxxxxxxxxxxxxx>]

With the amp disconnected from the wall, pull out the rectifier tube & power tubes, fit a new AC fuse (a fried looking fuse is a fried fuse, also check whether the amp has an internal B+ fuse - DRAIN CAPS BEFORE HANDLING THE B+ FUSE, you don't need to drain caps to handle the main AC fuse, just be sure to unplug amp from the wall) . 
 
Plug the amp into the wall AC & power up. Does the pilot stay on without the fuse blowing? If so, power down & refit the rectifier tube...power up, all good? If so, it looks like a power tube failure. If not, suspect the rectifier & replace. 
 
If the fuse keeps blowing without power tubes & rectifier, take the amp to a tech.
 
HG30 & H35 are both cathode biased so you can't fit one power tube at a time to find the culprit if just one has failed - fit a pair of known good power tubes (amp is "self biasing" no need for adjustments to bias), power up, what happens?
 
 


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From: Ross Macdonald <pdxharpdog@xxxxxxxxxxx>
To: List harp-l <harp-l@xxxxxxxxxx> 
Sent: Wednesday, 7 August 2013, 5:00
Subject: [Harp-L] Amp troubleshooting


Hey list, I have a harpgear 30 amp that quit mid tune at a gig last weekend. No buzz, no hum just nothing. It wasn't the power supply from the venue. Took it home and tried the next day to plug it in and turn it on.  The power indicator light came on very briefly and then went off. Took a look at the fuse and the fuse looks a bit fried but intact. 

Any ideas, I am not good with tube electronics and have a heavy gigging schedule coming up.  Have sent Brian an email to ask his opinion on course of action, but hoping its simple like the fuse because I only gig through this amp. 

Thanks in advance for any help or advice.

Ross MacDonald 

Sent from my iPad