| Author | Message | ||
| Freddie Whitley (harleywizard) Username: harleywizard Registered: 03-2014 |
I've got an Rd-50, I have re-capped it, found a bad solder joint on the reverb pot, a bad Zener D9 replaced 12ax7 and both 6L6GC's,and IC 4, the reverb will sound ok at the lower end of the pot but as you roll into a higher setting it seems to go away. V2 gets much hotter than V3. I suspect the transister Q3 and I have some on order. Would I be correct in suspecting the 12AX7 also? | ||
| Freddie Whitley (harleywizard) Username: harleywizard Registered: 03-2014 |
This is my first post, I would truely appreciate any help anyone could give me with this problem.Thanks in advance Freddie | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
I'm NOT really familiar with the RD's that much but from past experience, I would look at other things first. If Q3 is one of the driver transistors(don't have the schem in front of me) I would look at that first, and maybe try cleaning the sockets too. Arcing connections COULD be a source of highr temps. Also, MAYBE you just have a crap tube. Are these tubes new? Reverb, are you sure it's not got the tank plugged in backwards? You might have to try subbing a tank or at least measure the DC resistance of the two transformers. Wait a minute. Q5 and 6 are the drivers. THEY might be overdriving the tubes. Really just a guess. Does it distort? MAYBE the 'verb pot is just trash? | ||
| Freddie Whitley (harleywizard) Username: harleywizard Registered: 03-2014 |
I have cleaned the sockets, and it does it with a different set of tubes also, I will change the pot and the driver transistors are where I suspect the trouble lies. I hope they will arrive tomorrow. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
When you measured the voltage on the bias resistors, what did you get? It should be 6.8 ohm 1 watt. Were they balanced? did the amp distort? | ||
| Freddie Whitley (harleywizard) Username: harleywizard Registered: 03-2014 |
on one I was getting 11.5 mv, the other I was getting 290mv when I first turned the amp on and climbed to over 310 when I turned it off in about 2 minutes. The other stayed steady with no signal in. I was getting some distortion last time I ran a guitar thru it. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Yeah, THAT'S the problem. Replace and see what you get then. They should be reasonably balanced. | ||
| Freddie Whitley (harleywizard) Username: harleywizard Registered: 03-2014 |
Many Thanks to you Mike! The Driver transistor was shot. I replaced them and it is getting 24mv across one resistor and 26 across the other. The tubes are doing like the should and when I played the guitar thru it sounds like it should! Thanks a load! This board means a lot to me! |
Tue, 03/25/2014 - 09:55
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