Want to replace pots and jacks on used Fender M-80 - advice?

[joel_ostrom]

I recently bought an old used Fender M-80 from a friend at college. It sounds fantastic, but its worn and battered. I'm really wanting to do some fix up work on it to get it running well again.

One thing that's most annoying is the crackly pots. Any of them that you turn (EQ especially) you get a lot of crackles and pops in the amp. I have a schematic and manual from the amp from the actual Fender website, but i need to order the pots first. I'm thinking of going with mojotone.com

also, i'd really like to swap out the input jacks (not very sturdy) for something hardy. The input jacks on this amp are plastic 9 pin PC mount pots, is there any way to install a standard switchcraft all metal input jack and simply route the signal to the proper traces on the PC board?

appreciate any advice you can give me.

[Firestorm]

I have no idea what kind of pots are in there: if they're panel mount, you have plenty of options, but if they're PC mount you have to get exactly the right ones. As to the input jacks, nine pins sounds like more than a straight input situation, more like channel switching or something similar. Might be difficult to implement with conventional jacks. If the jack is actually worn out, exact replacements are available, but if you just want a more solid jack, I'd have to see a schematic to see what you can do.

[joel_ostrom]

they're PCB mounted bracket/snapin type pots. the values are as follows:

15A50K
15A2K
B50K
30C100K
30C50K

i'm kinda new to electronic component language, unfamiliar with the values "30C" and "B" and such.

they look like these:

[IMG:500:408]http://www.tubesandmore.com/cemirror/in ... -250KA.GIF[/img]

i'll attach a copy of the schematic for you to see how the input jacks work.
thanks for your help!

Fender M-80 Series Layout & Schematic.pdf

[Lynxtrap]

You could try contact spray on the pots.

[Gibsonman63]

If you spray out the pots, order some DeOxit to do it with. I believe those pots are available at Antique Electronic Supply. You will have the least amount of grief if you go back with with exact replacements and treat the amp gently. Upgraded pots will probably have a larger diameter back, so space may be an issue. The input jack that you have is probably plastic and isolated from the chassis. You will need to keep that in mind if you upgrade it. There are probably extra solder points on the input jack for strength, not extra conductors.

If it were mine, I would try spraying the pots first, just wait until you have the right stuff to do it with because your entire signal passes through some of them.

[M Fowler]

I picked up a neglected Randall RG-100 Classic solid state head cheap thinking I could use the chassis and cab.

After I used DeOxit on the noisy pots it functioned normal and so far I have not stripped the amp since it works so well. I would give that a try first before replacing the pots.

Mark

[Firestorm]

they're PCB mounted bracket/snapin type pots. the values are as follows:

15A50K
15A2K
B50K
30C100K
30C50K

i'm kinda new to electronic component language, unfamiliar with the values "30C" and "B" and such.

i'll attach a copy of the schematic for you to see how the input jacks work.

The input jacks are stereo shorting types. All nine pins are used, so there's really nothing to be done except replace the jack IF it wears out. Antique Electronics has those. Unfortunately, their supply of snap in pots is limited so they don't have all the values your amp uses. To find some of the oddball ones (like the 2K and the 50K C taper) you should check Angela Instruments http://angela.com/potsforguitarsandampl ... spx?page=2 and Music Parts Guru http://www.musicpartsguru.com/thumbnail.asp?cid=27

But do try cleaning the pots first with Caig Deoxit Fader Lube. Cleaning the pots is non-trivial since the open side is down towards the board. Good luck.

[paddy]

9 Pin jacks can be found here.

http://bustedgear.com/part_jack_input.html

Cheers.
Paddy