Marshall Haze 40 Octal Socket - Parts Source

[mikeboone]

I have a Marshall Haze 40 that was victimized by a bad power tube. It apparently had some internal short that charred the hum balance resistors and really burned the tube socket.

I took the tubes out and applied power to see what was going on. All voltages were what I expected to see with no power tubes in, so no dead shorts or wierdness going. I put a pair of old, but know to be good, Sovteks in and the amp works.

I just need to clean her up and replace that tube socket but I can seem to find a source for that socket.

Do any of you super techs have a parts list with that part number and perhaps a source for it? It needs to be an exact replacement since the screws that hold the retainer clip also secure the PCB to the chassis.

Any help or direction would be great.

Mike

[Enzo]

a photo would help us know what you are looking at.

Guitar, Amplifier, and Korg Keyboard Parts | NATIONAL PARTS DISTRIBUTOR FOR KORG, VOX, BLACKSTAR. PARTS FOR FENDER, GIBSON, GRETSCH, HOFNER, SWR, GUILD, AND MUCH MORE would probably get it for you

A Antique Electronic Supply LLC probably has whatever it is, they have a large selection of sockets.

I'd be wagering it is a Belton socket.

[Enzo]

a photo would help us know what you are looking at.

Guitar, Amplifier, and Korg Keyboard Parts | NATIONAL PARTS DISTRIBUTOR FOR KORG, VOX, BLACKSTAR. PARTS FOR FENDER, GIBSON, GRETSCH, HOFNER, SWR, GUILD, AND MUCH MORE would probably get it for you

A Antique Electronic Supply LLC probably has whatever it is, they have a large selection of sockets.

I'd be wagering it is a Belton socket.

[mikeboone]

Thanks Enzo... The socket does appear to be a Belton. The pic form the top of the PCB shows that only 7 pins go through the board which is what I found confusing. I will check the sources you listed.

I added 1 more pic that better shows how the PCB only has 7 pins coming through... Odd, for me anyway.

Thanks again,
Mike

[Prairie Dawg]

Why not just clip the pin you don't need?

[Enzo]

Pin 6 is not needed.

[mikeboone]

Pin 6 is not needed.

Understood Enzo... Hopefully I can find a socket that has the insert for the screws and with the PCB pins that fit in so that the socket fits flush against the chassis.

This is why I don't usually take PCB amps but its for a good friend so... I like old stuff. Its harder to ferret out the problems but easier to work on.

I have worked on a few PCB amps but is usually those crappy Fender HR amps, just never had to change a PCB socket.

Another thing I don't like about this amp it is double sided with plated through holes. It's great for quality and stable solder joints but a pain to service.

[Enzo]

Look at those earlier resources, You should find the exact socket available, though you may have to lop off the unwanted pin.

[mikeboone]

The damage is far worse than I thought... Once inside, I discovered the heat lifted some solder traces. Also, one of the filter caps located directly adjacent to the socket, shows signs of heat damage lifting the traces there as well. Unfortunately on the cap, its a radial part and the damaged traces are located where the cap sits making it nearly impossible to replace the cap. I tired an axial cap mounted on end but there is not enough vertical clearance.

The socket was nearly impossible to get out with the plated through holes... I really dislike PCB construction.

I guess I can try to contact Marshall to see if they will sell me a populated main board. Do you know of a US based point of presence where I could make the inquiry?

Disgusted...

[Enzo]

If you can get the cap legs through the holes, you can always solder wires to them and from there to any point in the circuit. If the traces under the cap need to be intact for other reasons, then repair them or run wires in their absence, then mount the cap in place with a dab of glue and run wires to it. Lifted traces and pads may look dramatic, but usually you can just replace them with wires and get on with life. In fact, when I install a resistor or cap or something, I trim of the extra wire length, and save them in a jar. A nice collection of solid wire pieces. Then when I need an inch long hunk to bypass some trace break, there it is.

Circuit boards are like anything else, you need to learn to deal with them. Find a terminal strip on an old amp with five component leads through it. Each one wrapped all the way around as good practice demanded. Then all soldered. Now 40-50 years later you want to remove one of those components. Inevitably it will be the one whose wire is under the others. It will be a larger film cap running under several resistors. And its overall lead length will be an inch or two longer than your moern replacement part, so your new part won;t reach, and you'll have to splice on extender wire. Call that "easy?"

There are many ways to remove parts from boards. Some guys like braid, I hate braid. Especially on large areas of copper with a large part. It just sucks the heat away, and heating braid makes it worse.

You can use a vacuum solder sucker or station to melt the solder an remove it. Or you can remove the part and THEN clean the old solder away. Heat one leg of the cap and when melted, tilt the cap as far as it goes, even if a little, to pull that leg out of the hole some. Now heat the other leg and tilt it the other way. It ought to move a little further. Now go back to the first leg. This way you can seesaw the cap out of its holes, melting one at a time, each time getting the legs father out of the hole. Once out, refill the holes with fresh solder then suck the whole mess clean. That is one way

[mikeboone]

Thanks Enzo for the tips and for being the ever present voice of reason. All advise will be catalogues for future use.

I found some 22AWG solid wire (CAT5 cable) that I can strip the insulation from to use as replacement traces.

The last challenge is to get a tube socket with the "nuts" pressed into the screw holes. They secure the PCB to the chassis and hold the retainer clips. I did find a kit that you can "press in" some inserts in the same way that theses sockets are made. I could use that kit for other stuff too.

I was pretty cranked up when all this transpired. Thanks again for the advice and talking me off the ledge!!!

Mike