New to the forum. I've joined in the hope that someone can help me figure out how to troubleshoot/repair the spring reverb on my HH Musician. The amp is in generally good condition. I've cleaned the pots, replaced the rotary switches, swapped the old 741 op-amps for NE5534 and replaced the PS capacitors for fresh ones. The 'Tone Correction' module still works fine and hasn't died on me yet.
However... I can't seem to figure out what is up with my spring reverb. The reverb still works but only if i pick very gently, if I strum a chord then I get this horrible blatty gated noise. There seems to be a problem with headroom in the signal.
Here are links to the schematics for the amp. there is not much to the reverb circuit assembly, I have replaced the opamps and can't see any loose connections or cold solder joints. The reverb tank itself looks to be fine, again no loose wires or connections.
http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier1of2.jpg (http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier1of2.jpg)
http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier2of2.jpg (http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier2of2.jpg)
Anyone have any ideas or come across a similar problem?
Quote from: ringworm on June 16, 2011, 11:32:23 AM
New to the forum. I've joined in the hope that someone can help me figure out how to troubleshoot/repair the spring reverb on my HH Musician. The amp is in generally good condition. I've cleaned the pots, replaced the rotary switches, swapped the old 741 op-amps for NE5534 and replaced the PS capacitors for fresh ones. The 'Tone Correction' module still works fine and hasn't died on me yet.
However... I can't seem to figure out what is up with my spring reverb. The reverb still works but only if i pick very gently, if I strum a chord then I get this horrible blatty gated noise. There seems to be a problem with headroom in the signal.
Here are links to the schematics for the amp. there is not much to the reverb circuit assembly, I have replaced the opamps and can't see any loose connections or cold solder joints. The reverb tank itself looks to be fine, again no loose wires or connections.
http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier1of2.jpg (http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier1of2.jpg)
http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier2of2.jpg (http://i197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier2of2.jpg)
Anyone have any ideas or come across a similar problem?
Can you tell if the spring tank is original? Sounds like it may have the wrong tank in it.
Yeah, the tank's original. When I first got it from a friend the reverb worked but the main amplifier channel didn't work, when I replaced the op-amps the main channel worked but the reverb had gone bad. The LM741s and NE5534 are identical except that the NE5534 can take a few volts more, making it less likely to get overloaded. I've gone back over my soldering twice now and see no bad joints.
Quote from: ringworm on June 16, 2011, 01:08:52 PM
Yeah, the tank's original. When I first got it from a friend the reverb worked but the main amplifier channel didn't work, when I replaced the op-amps the main channel worked but the reverb had gone bad. The LM741s and NE5534 are identical except that the NE5534 can take a few volts more, making it less likely to get overloaded. I've gone back over my soldering twice now and see no bad joints.
Sounds like something happened during the repair. Maybe a short in the line into the reverb tank?
It must be but I just can't see the fault and I've gone over it a number of times with a magnifying glass and torch. I have the original 741's still and some other new stock ones. My soldering iron died the other day so once I get that replaced I'll maybe socket the IC's and start swapping them around to see if there is an issue with the parts.
Quote from: ringworm on June 17, 2011, 04:36:49 AM
It must be but I just can't see the fault and I've gone over it a number of times with a magnifying glass and torch. I have the original 741's still and some other new stock ones. My soldering iron died the other day so once I get that replaced I'll maybe socket the IC's and start swapping them around to see if there is an issue with the parts.
That's probably the best idea yet. Could very well be a faulty IC.
Unless I'm mistaken and that often happens ???
a uA741 and an NE5534 are worlds apart and in some circumstances may not work.
I would be doing some testing long before I just swapped parts like that.
I can't see the schematic clear enough but I'd put back the 741 for the Reverb driver at least and if the problem still exists then go looking for bad joins between the tank wires.
Socketing opamps is not always a good idea as it just makes more potential points of failure.
Phil.
You are not mistaken!
Swapped the 5534s back to 741s (no sockets) and the reverb has sprung back to life! The pinouts are only slightly different, not sure why the 5534s work in the amplifier circuits but not in the reverb circuit... scratches head.
Anyway, all is working as it should and sounding good.
Thanks for the pointers.
Glad you got it working again.
All I can say is that *great* equipment was built around 741's for ages and needlessly substituting them with "better" ones often does not improve the sound.
Good Engineers design *within* the devices limitations.
Problems appear when you want them to do what they were never designed for.