Bigguy2017

I do not know the specifics of this amp but general principles apply...

Is this the same PJB model as attached .pdf schematic shows... ?

First check 15VDC and 12VDC supply rails are AOK - they both have internal fuses (as does the other 12VDC battery supply).

If you can unplug the power supply from the main board (plugin connectors?) will it power on now? Are all voltages present?

If all DC volts are AOK then there's a problem on the main board;

Look for burnt or discoloured components, leaking or swollen capacitors, bad solder joints or damaged PCB tracks. Have a sniff- any burnt electrics smell?

pjb_phil_jones_bass_briefcase_sch.pdf

I used to change them after about 2-3 months, but since I started using D'Addario NYXL 45105 jobs they last a lot longer - still not feeling a need to change them after a year.

They start out a little dull and don't get much duller.

Try a buffer pedal first in line

The BrightOnion Micro Buffer Pedal, TC Electronic Bonafide or Fender Level Set are all small, inexpensive boxes

I'd replace the truss rod nut.

Take the neck off, wind the nut fully out - you can cut a slot in it once it's proud of the wood.

Replace with a nice new nut with a smear of grease.

Is it a standard 3/16" allen key? If so it's a Fender #: 0038443000 nut

Power supply - plug it into an isolated supply or use a separate supply

Really nice - looks like a one piece body too...

Wow... looks brand new - nice colour too.

The Music Nomad one is excellent on bass and guitar tuners. Ball bearings baby... !

I have a friend who is a modeller - uses them for pilot's oxygen hoses and other details on planes and tanks.

Trouble is he only needs one set for a lifetime.... 😞

Threading elastic shock cord through tent poles

Another friend uses a bass string for holding knitting stiches - very technical...

A doubled over guitar 0.010" top E is good for blobbing wood glue into screw holes (scratch plates, strap buttons etc.) to make screws fit tight again

Unblocking gummed up glue spouts

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

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