Marshall 5275 ss combo: no sounds when golng thru input jack, ok thru effects loop :(

[Led Hendriani]

Hello all!
I have had this amp for quite some time now and would like to finally sort it out.

A few years ago I replaced the push pull knob that was broken and still it does not work thru the front end.
I have very basic skills, but have repaired minor stuff before (mostly lucky!)

Don't know if I am accessing the full 75 watts thru the effects loop but i really want to hear what this baby can really do with the Marshall tone stack and master volume.... I have read that these sound awesome!

Is there any basic how to on this site that shows how to check everything step by step?

TIA for any help

[52 Bill]

Welcome to the place.

When you have a guitar plugged into the front and you listen to the noise at the speaker, does turning the tone or volume controls cause the hiss or noise to change character?

Do the channels switch correctly?

[Led Hendriani]

Welcome to the place.

When you have a guitar plugged into the front and you listen to the noise at the speaker, does turning the tone or volume controls cause the hiss or noise to change character?

Do the channels switch correctly?

From what I remember i do hear the different hi's and low's when turning the knobs. Don't remember whether it switches correctly..

I am out of town at my gf's right now and will verify tomorrow night both things you asked about.

[The Dude]

If you hear the noise level change, my first suspect would be that the input jack itself has cold/cracked solder joints.

[Led Hendriani]

I previously installed a new dual pot The dual pot is Gain/pull eq

There is nothing that changes when adjusting any of the knobs except the Master volume and treble knobs are really scratchy and that goes away when you turn them for a bit to clean it up.

I forgot that there is no level knob or shaft on the back under the label of DI.... Can't remember if it was a broken shaft or if it is missing the item that it controls entirely..... Will have to open it up.

Thanks!

[Led Hendriani]

The footswitch changes the channel light off and on.
I am pretty sure i already reflowed the solder at the jack...

[Led Hendriani]

There is not a jack or anything on the board that i can see that corresponds to the hole labelled "level"... At least not in-line of sight.

I see that i never completed the install of the dual pot... I went with a pot made for another Marshall that looked different from the original..... It has a white box attached with 4 legs that are not wired to anything.... At this moment I can't even recall why it needed to be switched out!

[Led Hendriani]

I think I changed it because it was a single not a dual pot... Like someone repaired it with the wrong type...

[Led Hendriani]

UPDATE

Took it to the Marshall amp guru near me...

Someone did a cheap attempt at a repair by putting the single pot on it and ran the wires from what was the 2nd part of the push pull pot through 2 new holes they put in the board to what it is not quite clear yet...
Also, someone cut out the D.I. level on the back and the guru said that is probably why the signal is not there until the effects loop...

Both are easy fixes but pricey when paying for expertise

Maybe a week and a half til I get her back... the anticipation is building!

Grateful that he is only on the other side of town instead of a few states away

[J M Fahey]

Hope you sort it, just the "guru" label scratches us the wrong way.
Couldn't you find a plain .... ummmmm ..... "tech" instead?

[Led Hendriani]

No disrespect intended....
The luthier that has helped me many a time also does minor amp work... when I asked him about this he let me know about the Marshall "guru" that could repair any Marshall

[Led Hendriani]

Finally got it back and it ROCKS!!!
He had to change out a chip and some other items and install a pot for the D.I. and repair some broken tracers...
Well worth the wait!