Nahash5150

Today is the 50 year anniversary of the Wreck of the Edmund Fitzgerald. Something I learned just today after watching a documentary - this recording was not a first take, it was the first time the band had ever played it. They tried recording more sessions but none were as good as this one, so this is what we have today. The only take, first time ever played by these guys! btw - it is still unknown how the ship went down.

Then we need to go to amplifier repair 101, especially after finding shorted pre-drivers. Check these resistors since you didn't mention them: R154, 156 43R FR VAS HR emitter R146, 144 10R signal coupling R168, 170 10R FR HR low current R172, 174 10R signal coupling R196, 198 22R, 27R CMR bias Deviations more than 10% are BAD PARTS.

The new RC4136Ns at Mouser are drop in. However using a socket on these chips does not present the problem in the C1. Special care is needed when replacing the op amps in a C1. It's very easy to lift the pads or break traces. As for whether you need to change one or not depends on what the problem is. If you don't have the knowledge and the equipment to assess what's causing the issue then changing the op amp can be a reasonable next step, provided you have good workmanship, but of course there's no guarantee this will solve the problem. 'Popping' is normally caused by a difference in voltage from one circuit to the next. The op amp could have a slight DC offset, there could be a bad solder joint somewhere, the switch itself could be really noisy even after cleaning, etc. If you could see the frequency response of the filter this would make everything so much easier. Because if it's working correctly then a little bit of noise is not a big deal because it's not like you stand there and play with the switch while you're listening to music. The more often you use the switch then the cleaner it will become. They are slide contact switches so they clean themselves the more often they are used. Convenient!

Hello, That's definitely not normal, and not the kind of anomaly the 'thump fix' was designed to correct. One could swap the input board connectors between left and right to see if the problem is in the input section or in the amp stage. I have a suspicion it's the muting circuit in the input board.

Welcome! It needs a restore. Those amps have a lot of problems due to age/use and it's best to stop using it until you get it restored, otherwise there could be smoke. The crackling is indicative of more trouble ahead. It needs more than a recap and I highly recommend Nelion Audio (us!) because we know what we're doing and we stand behind our work.

As others have said, that switch should be inaudible when activated or not. It rolls off frequencies lower than about 10Hz (these are so low we can't hear them, but the speakers can still respond to them) , which protects your speakers from 'rumble' generated from turn tables. However, if you use speakers which utilize sound ports for better bass response, it's a good idea to keep that filter active since vented cabinets tend to 'run away' from infrasonic signals which might be present in any media, and overextend the woofer, leading to damage. There are no less than 8 versions of the M-1.5(t) !!!

Hello! I just installed one for a VTCC last week. They are $600 installed. You'll need to also buy 6 tubes - 4x 6922's and 2x 12AX7's. No one who has ever used one of these has gone back to using an external. This phono board is AMAZING. Those are Telefunken Black Diamond 6922's and Eletro-Harmonix gold pin 12AX7's. The 12AX7's are for the subsonic filter, so they don't need to be uber expensive tubes there.

The bias should stay between 50mA and 150mA at idle after 10 minutes of warm up. If you've chosen your sweet spot, say 90mA (because that's mine), then it shouldn't change. If it does by more than a few mA, then it could indicate a problem, especially if it won't adjust properly or keeps falling out of your sweet spot. We aren't taking over the warranty. We are just willing to service these units and do our best to support them, unofficially, because right now, there is no official support. I'm sorry I don't know the exact origin of the trouble. I just know that it seems to be related to time, nothing else.

For those experiencing issues with the bias setting on the RAM285, the issue is likely with the burn-in effect of the circuit and transformer winding that powers the bias circuit. Many Bob Carver Corp amplifiers experience this trouble. Common complaints are: - The bias does not adjust high enough. - The bias does not adjust low enough. - The meter is not working. Unfortunately, there is no DIY fix for this. The RAM285 has extremely unfriendly serviceability. The PCB hides most components and is multilayered. Reworking the circuit board requires technical experience and proper tools. Moreover, the trouble has common causes but it may also be related to other less common troubles, so the amplifier should be fully tested to verify what the real trouble is. Please inquire with us to get your RAM285 serviced if it is experiencing any trouble.

I used Krud Kutter - The Must for Rust solution

A received a Hafler DH-220 to fix along with an extensive upgrade kit. It came with a USB drive with docs and pics. A well put together project. The unit was in dire need of service. Old, crusty, and very dirty. Top of unit: Near power switch and primary fuse: Taken apart: I removed most of the screws and derusted them, then cleaned and derusted the chassis, heat sinks and other various parts. It was a load of work! But it cleaned up pretty good. All new amp driver boards that had to be stuffed by hand. Crazy! New speaker binding posts and RCA jacks as well. It looks so much better now though: Sorry - forgot to snap a picture of it all put together. But here's an internet one:

We can do that... C-4000 C-1

Problem: Main reservoir capacitors venting Solution: Full restoration! The main reservoir capacitors on the 5ch and 7ch models have reached their end of their usable life. They will boil, and vent - possibly causing permanent damage to surrounding circuit boards. Electrolytic fluids are corrosive. Furthermore, if these large main capacitors fail, they can damage the power supply by shorting to ground on one side, in a normally balanced supply. In most cases, the main fuse will blow from the failing capacitor, but there is no guarantee.

Problem: Severe burning of the PCB around regulator circuits on dual channel boards that can lead to permanent damage Solution: Full restoration! The regulator circuits need to be rebuilt and modified to prevent future burning. Without service, these amps can be become UNUSUABLE.

Make sure the power transformer is as secure as possible. Tighten the 4 large screws on the bottom of the chassis until they are snug. If the transformer still feels loose, pop the top and tape some cardboard over the transformer top, just enough to fit under the metal cover. Or this can happen: