gallien krueger MB150S

[pontiacpete]

This amp came to me because of an intermittent cutting off problem. The friend who owns this amp had already taken it to 2 repairs guys and the problem still persisted. It plays great but on occasion the sound would cut out completely and then come back. The LED power on indicator remains on when the sound cuts out. So far I've reflowed all the solder joints on the 1st PCB of the power amp. This did not solve the problem. That didn't surprise me, being that the amp still is powered up when it's cut out. Speaker wires seem stable and secure. There are 3 PCBs in this amp and they are connected together with connector plugs. I've found it very difficult to work on this amp in general because of the way the 2 of the PCBs are attached to the top of the cabinet and the PT is mounted inside the speaker cab. (As I'm writing this I'm thinking of other ways to deal with this problem)Aaaanywaay, my latest theory is that its the connector cables. Has anyone come across this type of issue with these or similar amps?
Now I've tried using silicone to stabilize the connectors and also I wrapped the whole on connector with a wire tie and so far it's not cutting out.
Is there a better way of making these connectors more stable,(if in fact this is the problem)? I keep asking myself if I should just change them out all together.
thanks
pete

[Dave Curtis, dB AudioTech]

Have you treated the connector contacts with D5 or some other contact treatment?

[pontiacpete]

I will, now that you've mentioned it. Dumb of me not to have thought of doing that on my own.
thanks!
pete

[Enzo]

Does this have the switching power supply module? (As opposed to a largeg conventioal powr transformer and filter caps.)

If so, there are a couple rectifiers in TO220 packages. They look like transistors of voltage regulators or something except only two legs. get under each leg and pull upwards a bit, see if any legs are broken off right at the body but still touching most of the time.

The broke off legs allow the amp to function, but it only takes a little vibration or thermal expansion to open the connection. I have replaced as ton of those.

[pontiacpete]

It has the regular style, square shaped transformer mounted on the top inside panel of the speaker cabinet. I believe it's not a switch power supply module. I'm thinking this becauuuse(and I'm pretty embarrassed to admit this but...)in my attempt to reflow the 1st small board of the PS I disconnected the TX and the made a fatal error wiring it back in, uuugh. That was a $105 f**k up on my part. However in my conversations with Lani at GK she was talking about this switching PS. It's the older tx or older version of the MB150S. I waited over a month for the regular ole square TX. OH WELL, Live and learn.
Besides thinking i'm a fool, what else do you think could be causing this problem?

regards
pete

[Dave Curtis, dB AudioTech]

I will, now that you've mentioned it. Dumb of me not to have thought of doing that on my own.
thanks!
pete

I actually expected you to say you'd done that already. It's one of the first things I do on any amp. Clean and treat *all* contacting points; and although it doesn't apply here, use only Caig GxL (ProGold) to treat tube pins; it's rated for the heat. Quite often, reported crackles and intermittants are non-existant when I fire it up.

[pontiacpete]

Thanks Dave,

I don't have the Pro Gold. Will get some.
Are there any issues with getting it on PCBs or the transistors?

[Enzo]

No.