Marshall Valvestate 8080 question

jdbwales

Recently got one of these for nothing and I’m fixing it up (replaced pots, cleaned connections etc) - it’s a stunning practice and grab and go amp, fair play.  

 My issue with it at the moment is that I need the fx loop to stay at the 0db setting rather than the -20db as I have the fx at 100% all the time.

The latching micro switch that changes between these two settings is damaged and doesn’t work properly - realistically I’ll never need the -20db setting, so if I was to desolder and remove the switch from the circuit entirely, would that leave it permanently on the 0db setting (normally the switch is on the ‘in’ position for 0db) or just cock things up mightily? I can always order and fit a replacement switch, but would removing it entirely save me the bother and run the loop permanently at 0db? 

Cheers!

Keefy

The schematic is easily available as a pdf. As far as I can tell, you just need to hardwire the fx send to the junction of R17 and R18, and make sure the junction of R43 and R20 is not connected to earth.

jdbwales

Sounds easy enough and thanks for the reply - is there an idiot proof way to do this? @ICBM ; have you done this at all? Sorry to tag you in, it’s just that you know, well, everything.   

Keefy

My best tip is to take photos and make sketches as you go, also use a meter to check what is connected to what. If it all goes tits-up you then stand a better chance of getting it back to how it was.

ICBM

jdbwales said:

Sounds easy enough and thanks for the reply - is there an idiot proof way to do this? @ICBM ; have you done this at all? Sorry to tag you in, it’s just that you know, well, everything.   

lol

Actually my advice would be to replace the switch properly - it’s not difficult and you need to have the amp apart to hardwire it anyway. It’s not impossible that one day you will want to put a pedal in the loop which won’t take 0dB.

If you can’t find the right type online, Marshall are very helpful with parts, and failing that I may have one - PM me if you can’t get one elsewhere.

jdbwales

Thanks both, sounds fair enough - I’ve bought 2 switches from eBay that seem to be correct so they’re coming this week, are these the right ones? 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F253172887770

Will just install a new switch if so!