Bigguy2017

Perfection...

I had gigged one of these '79 - '82.

Great punchy tone.

Replace the jack socket - with a genuine Switchcraft (or a Pure-Tone) mono socket

Output Jacks – Northwest Guitars

Pure Tone Multi-Contact 1/4" Output Jack – Armstrong Music

Good for another twenty years...

Also, check the existing jack with another cable? It could be a duff jack plug.

Yes, certainly looks like some kind of Music Drive bass - the hooked 'Ric' horns are on the guitars too.

Headstock, tuners + truss rod cover are the same.

Music Drive (MD) Bass Guitar MCB 6200-f | #463741760 (worthpoint.com)

Same PuP and knob layout here

MD Music Drive Rare Mahogany Body Natural Bass Guitar - Made in Korea Circa 2000 | Reverb UK

Music Drive (MD) guitars and basses were made in Korea by Sumer Musical Instruments Company Limited, from around 2000

Also...

https://reverb.com/uk/item/77946719-metal-driver-md-bass-by-sumer-silver-burst-1999-samick-korea

They've got a Custom Shop now ... ?

::: MD Guitar ::: (mdcustomshop.com)

Your one looks like an MDB-610   https://mdcustomshop.com/kr/product/view.php?id=35&cate=19

2 hours ago, petetexas said:

Is there any milage in putting a soft start circuit ( the type used for electric drills , circular saws etc , that limits the initial switch on voltage , and gradually increases it ) in the

 

switch on cables in the amp ?

 

Dont know if this can be done , not enough knowledge , just a suggestion .

An NTC Thermistor in the supply line will do that

I go the other way (ooh vicar) and select a co-ordinated but contrasting coloured strap - this way I get to show off the guitar AND the strap 😉

This suggests the power amp section is AOK and the problem is in the preamp.

First stick a jack in/out in all the input and FX send return jack sockets - give them a squirt of contact cleaner.

If the opamps are socketed, give them a good push into the sockets.

Make certain you have a good working guitar cable...  😉

As usual, look for any bulged or leaky electrolytic caps...

Unplug/replug all the internal connectors inc HD3 (preamp / poweramp connections)

Also try unplugging the Reverb at HD1 and HD2.

If the opamps are socketed, give them a good push into the sockets.

Looking at the schematic it appears the preamp supply is Zenered down to +-15 VDC from the +-28 VDC power amp supply.

I'd have a good look at the +-15 VDC rails and their smoothing caps C36 C37 C300.

Put a 'scope on the +-28 VDC and +-15 VDC rails and look for hum. Obvs, if you have a 'scope (!) you look at the FX send and  trace the signal back to the input

Take it to a repairman....  😉

laney_hcm65r_sch.pdf

What sort of noise? Hum, hiss or crackles?

58 minutes ago, petetexas said:

The black square item , has only two tags connected to board , so it can't be a relay .

Have you a schematic of the Peavey T Max then ?

Pete

Looks like a film capacitor ? Can't see the part numbers.

There are a couple of pages in the manual showing this PCB with the 1K5 15W resistor, cap and fuse.

Peavey-T-Max-Bass-Schematics.pdf

42 minutes ago, sandy_r said:

 

Sheesh! ...are Peavey suggesting that this Amp has arced inside the Mains switch, at power on/off, for its whole life?!?  Is this regarded by them as a design feature?!?  Don't think it would have lasted a year of regular gigging & rehearsals!

 

Something else has failed, to cause any such arcing (if it exists) - needs a Tech (with more dedication than Peavey) to inspect and fix

 

 

 

100R and 0.1uF is pretty standard

Sounds like a nut/break angle issue. 

How many turns on the tuner post is the A string?

Making the max number of turns (three to four) will force the string to the bottom of the tuner post and may be enough to fix things... if not the nut slot may need some work.

Leaky DC blocking caps on the outputs?

Nice match for a blue JMJ Mustang

No, it's not right. They should be tapered - should be readily apparent, 'specially on a 1 degree shim.

See pics here  StewMac Neck Shims for Bass - StewMac

Lovely bass

Does the push / pull switch disconnect the power to the preamp or just switch it in / out of circuit?

Asking as the most likely reason for battery drain is continuous power to the preamp. 

It does have a 'stereo' output jack that switches the preamp on / off ?

First adjust truss rod to set neck to be straight, no relief.

With a straight edge check the whole neck is straight, including the upper frets over the body. 

 If there is a hump or ski jump, this can be lessened (a bit) by a fret level (if sufficient meat on the frets).

Otherwise it's off with the fretboard, level the neck and re-attach fretboard.

Lay straight edge on top of the frets and extend it to touch the bridge - ideally it should just lay on top of the bridge (not the saddle).

If it arrives more than a mm or so under this you need a neck reset. This is the most likely situation with an older instrument.

The present saddle could be lowered a little (maybe 1mm), but not more due to break angle.

As the 12th fret action is 4mm(?) you can only gain 0.5mm by shaving 1mm off the saddle, and that leaves the action at a high 3.5mm.

(Remember that 1mm lower at the 12th fret needs 2mm off the saddle).

Looks like it needs a neck reset.

For the buzzing check for a loose brace, top or back.

BTN Music ?

Bob Marley and The Waiters

The Ham

David Bogie

Pimply Red

Yes, as MD posted, there is virtually no break angle on the A - aim for three full winds or as much as possible down the post.

Depth of nut slots is decided by the first fret action, not by looks. Lowering the nut slots will give even less break angle.

2 hours ago, Burns-bass said:

Also looks like a Badass bridge which is a good upgrade!

Nah, on a Jazz that's a downgrade. IMHO Jazzes sound right with BBOT.

Yes, it looks like the lower bit is missing ?

(2) Warwick Tutorial: Replacing a Just-a-nut III - YouTube

UNLESS... it's a Sadowsky style one - they have a narrower lower part which is NOT visible from the sides

Sadowsky Just A Nut III 4 strengs 38,1 mm - gitarist.no

Surely that should be "Stick 20 quid or there abouts in an Alzheimer’s/ Dementia charity tin and I’ll forget to send them." 😉

Are you using an HPF on the Studio Live ? Put lots of cut below 35Hz - 50-Hz ish...

Could be lots of low frequency mush overloading the input.

Shawn Colvin tonight at The Queen's Hall Edinburgh