Bigguy2017

First, are you using a TRS cable? With just a TRS cable into the amp footswitch jack, try shorting T to S and R to S. This should give Toneprint on/off and Toneprint 1/2 switching as per diagram below Re Aux connection - how are you connecting from the phone? Out the phones socket (use a stereo minijack cable), or USB out the phone using a converter cable? Plug the minijack cable into the amp - touching the other plug end should give some buzz if working.

SOLVED: Zoom R16 factory reset - Zoom R16 Multitrack Recorder | Fixya

I'd pay money NOT to listen to this 😉

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

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?

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

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?

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

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.

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