Hi All,

Recently bought a Bass Mark IV Series Head (export model - Australia) and love it - a bargain buy for a what seems like a really solid amp. Excellent condition overall. Had a couple of minor maintenance issues straight up: replaced the Din plug and socket for the automix footswitch due intermittent contact, also replaced the output jacks with some new switchcrafts as they were kind of loose and a bit intermittent too.

After reading some of the posts here, I contacted Peavey and they kindly emailed me full schematic and pcb layout files. Very helpful!

Have a couple of questions that someone may be able to help with as I'm a bit of a noob with solid state amp circuits. I've done a little bit of repair and mod work with the classic fender and marshall valve circuits over the years and mucked around with effects pedals here and there.

1. Everything is running sweet with this amp as it is. Should I bother with swapping out any or all of the electrolytic caps, given the amps age. Or just wait until something fails? Any other age related components I should be looking at?

2. Are there any highly recommended mods worth doing?

3. Have noticed that the high gain input jack is very occasionally intermittent. Is it worth cleaning and retensioning or just replace? Is it a standard item? Can Peavey supply and ship to Australia?

Thanks for any advice and assistance.

Evan in Brisbane, Australia.

The jacks are generic Switchcraft, and you should be able to find them where you are. usually they clean up, in my experience.

I never replace all the caps in something, "just because..." if they say the battery in your auto is a "five year" battery, would you replace it on the first day of year 6 even if it is working fine? if the amp works, it works.

These amps could easily run 40 years with nothing more than an occasional cleaning.

I've been a tech with a soldering iron in my hand for 20 years. He's right, replace caps one at a time. Old electrolytic caps usually leak from one end before they go South. Look for leakage and replace only the bad ones. Active components, like pre amp transistors and especially finals should be replace as pairs. Ruel of thumb, if it works, don't fix it!

Hi Guys,

Thanks for the responses. I'll open up the amp and have a look at the electros for any sign of leakage. If alls good, Ill just close it up and play the thing!

Cheers,

Evan

Your ears will generally tell you if your amp is working right.

Hi ive owned a MK iV since new when i bought it 85 ...its been a great bass...ive looked after it and its in great shape..the only thing electronic thats had to be replaced has been the on off switch ..which wore out a few years ago..i took into the Australian peavey distributors here in Sydney and they replaced it for me..only thing was the type of switch isnt made any more or in their spare parts ..so they replaced it with a similair current one ..type used on the 5150 amp i think..it sometimes gives a loud pop when switching off...but apparretnly this happens quite often with older model amps...mine says 1982 on the front

hope thats of some help

Leslie

Hi leslie,

Thanks for the response. Regarding the power switch, as far as i can tell, mine is original and my amp also makes a pop sound when turning off too. I wouldnt be worried about that. Mine sounds identical to yours. A mkIV series bass with 1982 on the front. sweet amp. Although I didnt buy mine new, the guy I bought it off still had the original receipt, warranty card and owners manuals. He even had the little 'Peavey - Made in the USA' hang tag with it! tops!

see ya

Evan