Ampeg B2 relay problem

[stevemcg]

I'm having a problem with my Ampeg B2 Combo where it occasionally will trip my house circuit breaker when I turn it on. After that, it will usually turn on but somtimes will not produce any sound (no audible relay click after power is applied). Other than that it plays fine. However, it's always seemed to have a problem preventing the turn on/off thumps. I'm thinking this all points to the relay circuitry. Any suggestions on what to look for when I open it up?

- Steve

[insp166]

I'm having a problem with my Ampeg B2 Combo where it occasionally will trip my house circuit breaker when I turn it on. After that, it will usually turn on but somtimes will not produce any sound (no audible relay click after power is applied). Other than that it plays fine. However, it's always seemed to have a problem preventing the turn on/off thumps. I'm thinking this all points to the relay circuitry. Any suggestions on what to look for when I open it up?

- Steve

How many of your house holds stuff is on that circuit
Like lights, refrigerator, televisions


MY TUBE AMP SITE

[stevemcg]

It's a 15 amp breaker that has nothing on it but porch lights, attic light, laundry room light. etc... all of which are turned off. I originally thought I had a problem with the wiring/breaker until I ran a test by running an extension cord to another outlet on another circuit and was able to replicate the problem there as well (another 15 amp breaker). I'm sure the problem is in the B2. It's always made a loud thump when turning it on & off, and I have had to discipline myself to turning the master volume all the way down beforehand in order to prevent it. Despite all of this the amp seems to work just fine. I just know that there'll come a day at a big gig where this problem will resurface at the most inopportune time.

- Steve

[izzybell2810]

It's a 15 amp breaker that has nothing on it but porch lights, attic light, laundry room light. etc... all of which are turned off. I originally thought I had a problem with the wiring/breaker until I ran a test by running an extension cord to another outlet on another circuit and was able to replicate the problem there as well (another 15 amp breaker). I'm sure the problem is in the B2. It's always made a loud thump when turning it on & off, and I have had to discipline myself to turning the master volume all the way down beforehand in order to prevent it. Despite all of this the amp seems to work just fine. I just know that there'll come a day at a big gig where this problem will resurface at the most inopportune time.

- Steve

Does the amp have a fixed power cord? Or is it a euro style socket and plug?
It's taking out a 15 amp MCB but not taking the fuse in the amp which will be lower than 15amp. Have you checked/swapped the power lead?

Dave.

[stevemcg]

The amp uses a conventional computer style power cord that plugs into the socket on the back of the chassis. The fuse is a 10 amp Slo-Blo. I used to have it all plugged into a power strip with it's own 15 amp circuit breaker, but it never tripped either. It doesn't do it all of the time, just occasionally.

If the relay were to stick in the closed position when I powered it off, would that account for the power surge the next time I turned it on? Normally the speakers are disconnected until the power is stabilized.

- Steve

[izzybell2810]

hi steve,

the reason I asked about the power lead is because the tripping is an intermittent prob. Are u sure there are no breaks in the power lead. When you say breaker do you mean an MCB or an RCD. The relay I would say is operated by a simple resistor capacitor timing circuit the resistor delays the charge of the cap which prevents the speaker relay from turning on for a couple of seconds.

Dave.

[stevemcg]

Pardon my ignorance, but I'm not sure I know the difference between an MCB and an RCD. It's just the typical 15A breaker you find on any home breaker panel (General Electric?) and not a GFI. But you do have a valid point about the power cord. I will swap that out just to eliminate that from the mix. But I don't think that would explain the other phenomenon (relay not engaging, anti-thump not working properly).

- Steve

[izzybell2810]

Pardon my ignorance, but I'm not sure I know the difference between an MCB and an RCD. It's just the typical 15A breaker you find on any home breaker panel (General Electric?) and not a GFI. But you do have a valid point about the power cord. I will swap that out just to eliminate that from the mix. But I don't think that would explain the other phenomenon (relay not engaging, anti-thump not working properly).

- Steve

An MCB is overcurrent protection and will allow a current upto it's value (In your case 15A) to flow all day long once it goes past it's rating it will trip and break the circuit. Think of it as the old type re-wirable fuse. An RCD is a residual current device and it detects earth faults, ie an appliance develops a fault and current is flowing to earth. The fault current flows via the supply companys earth provision back to the transformer, then back to your property via the phase conductor (live) and enters the RCD which detects the discrepency and cuts the supply. It cuts everything not just 1 circuit.

I don't think the 2 probs are connected Steve, have you got a schematic for the amp? I have 1 for a B2 svt 350 is this your amp?

[stevemcg]

Thanks for the clarification on the MCB & RCD. It's not the power cord... I swapped that out and it still tripped the breaker. Yes, I do believe I have the same schematic as the one you mentioned.