Vestax PMC-05 Pro II... not working, thought I'd give it a go as a pet project

[Finnish_Fox]

So, I have an old Vestax PMC-05 Pro II in my closet... thing hasn't worked in years. Was thinking about trying to get it back into operation, mostly to teach myself how to work with electronics. (READ - if it works great, but I won't be devastated if I can't get it done).

Any tips on how/where to start diagnosing the problem?

Obviously...

- Pull it out, check for power
- Check inputs/outputs functionality <- I want to say there was an issue with this, but I haven't looked at the thing in 4 years or something.

[Estacy]

do any lights work? are there any signs of it powering up? what isnt working? is it not letting sound trough or doesnt it power up at all?

[purex like soap]

plug it in and fire it up.

[Finnish_Fox]

plug it in and fire it up.

Yah, covered that part in my post above. Anything specific I should look for (...as in being absent)?

[Finnish_Fox]

do any lights work? are there any signs of it powering up? what isnt working? is it not letting sound trough or doesnt it power up at all?

Cheers. I'll take a look tonight if I can find the ac adapter.

I don't know shit about electronics... just how to use them.

[djpenguin]

Cheers. I'll take a look tonight if I can find the ac adapter.

I don't know shit about electronics... just how to use them.

You've got a huge task in front of you. The very first step is to turn it on and see if you can get it to operate as normal. Try every feature/function. Make a list of anything that does not operate normally. Then come back here and post your list.

[Finnish_Fox]

You've got a huge task in front of you. The very first step is to turn it on and see if you can get it to operate as normal. Try every feature/function. Make a list of anything that does not operate normally. Then come back here and post your list.

Cheers. I figure learning anything worth knowing isn't going to be easy. As I said before, it'd be a huge accomplishment to DIY. Electronics always interested me and it bothers me that I know how to fix very little other than computers (and not the electronics themselves).

[Johbremat]

A multimeter is a great tool for helping you learn and diagnose. It's a handheld unit with two cables, each ending in a single prong. At its simplest, you place the prongs along a know electrical path to complete the circuit, and can obtain a reading (or none, if the circuit remains open).

As you locate direct paths and those interrupted by components (such as capacitors) you may be able to determine if there's a fault. At this point - let's say a cap is blown - you can take the next by testing your ability to solder.

[Finnish_Fox]

A multimeter is a great tool for helping you learn and diagnose. It's a handheld unit with two cables, each ending in a single prong. At its simplest, you place the prongs along a know electrical path to complete the circuit, and can obtain a reading (or none, if the circuit remains open).
As you locate direct paths and those interrupted by components (such as capacitors) you may be able to determine if there's a fault. At this point - let's say a cap is blown - you can take the next by testing your ability to solder.

Surprisingly, I actually have one despite the little I do know.

[Finnish_Fox]

So, I got the unit it out and was able to test it for about 15 minutes last night before passing out on the couch. Note - I could not find a goddam RCA-RCA cable so I used an RCA-1/4" and plugged it into my KRKs (TRS input) just for the purposes of the test. Not sure if some of the interference came from unbalanced-balanced issues.

Have had a chance to only test the left channel on a limited basis.

Turned it on - power light does not work but the gain meter between the channel lit up so I could see it powered.
- Have to keep master volume very low, lots of distortion/interference coming through. Lots of humming.

Plugged in CDJ into phono/line inputs of left channel:
- On phono, sound with A LOT of distortion comes through. From my limited testing, it appeared there was a lot of bleeding in the crossfader as well. (Left channel very loud and distorted, level had to be kept low. Crossfader to the right, what was playing in left channel was very low in volume.)
- Meter appeared to max out no matter what.

What worked:
- Crossfader Reverse

Hardware broken:
- Left channel transform (phono/line) switch. Literally the lever broke off but I can still change positions between the two inputs on that channel.

[g-sep]

Whenever you plug a CDJ in, you have to set it to Line. Phono amplifies the signal and is only used for turntables :tup:
That's probably why it was maxed out.

[Finnish_Fox]

Whenever you plug a CDJ in, you have to set it to Line. Phono amplifies the signal and is only used for turntables :tup:
That's probably why it was maxed out.

Didn't have a turntable on hand and wanted to test the input... did not know it amplified the signal and that makes a lot more sense. I'll check the line inputs at lunch.

Cheers.

[djpenguin]

So, I got the unit it out and was able to test it for about 15 minutes last night before passing out on the couch. Note - I could not find a goddam RCA-RCA cable so I used an RCA-1/4" and plugged it into my KRKs (TRS input) just for the purposes of the test. Not sure if some of the interference came from unbalanced-balanced issues.

Highly unlikely if the cable run was less than six feet and not crossing any high voltage lines.


Have had a chance to only test the left channel on a limited basis.

Turned it on - power light does not work but the gain meter between the channel lit up so I could see it powered.
- Have to keep master volume very low, lots of distortion/interference coming through. Lots of humming.

-Replace power indicator LED, possibly associated resistor too
-Please use you computer to record some of the interference/noise at a good volume, and post it here. The character of the noise will help to isolate where the problem is. Potential culprits: bad master potentiometer, leaking capacitors, cold solder joints, grounding problems


Plugged in CDJ into phono/line inputs of left channel:
- On phono, sound with A LOT of distortion comes through. From my limited testing, it appeared there was a lot of bleeding in the crossfader as well. (Left channel very loud and distorted, level had to be kept low. Crossfader to the right, what was playing in left channel was very low in volume.)
- Meter appeared to max out no matter what.

-Of course it was distorted and pegged the meter, you were feeding a -10dB signal into a -42dB input, and that's not even accounting for the RIAA equalization curve. How did the line-level input work? Any bleeding when using a line-level with the line input?


What worked:
- Crossfader Reverse

Hardware broken:
- Left channel transform (phono/line) switch. Literally the lever broke off but I can still change positions between the two inputs on that channel.

The Vestax part number for the switch is IS-05.

[Finnish_Fox]

Highly unlikely if the cable run was less than six feet and not crossing any high voltage lines.

Nope... 3 feet and crossing other audio lines maybe.


-Replace power indicator LED, possibly associated resistor too
-Please use you computer to record some of the interference/noise at a good volume, and post it here. The character of the noise will help to isolate where the problem is. Potential culprits: bad master potentiometer, leaking capacitors, cold solder joints, grounding problems

Can do. Think an on-board laptop mic (macbook pro) might work?


-Of course it was distorted and pegged the meter, you were feeding a -10dB signal into a -42dB input, and that's not even accounting for the RIAA equalization curve.

:eek:


How did the line-level input work? Any bleeding when using a line-level with the line input?

Going to have to check that again. I want to say I got nothing from the line, but it may have been that I had the level all the way down due to me being an idiot with the CDJ in the phono input.


The Vestax part number for the switch is IS-05.

Awesome. You rock. I'd rep you again if I could.

[djpenguin]

Can do. Think an on-board laptop mic (macbook pro) might work?

That should work fine.

[Finnish_Fox]

OK - another round of notes. I am checking the right channel as I am having problems toggling between line/phone on the left channel.

Good news -> good sound (despite distortion/interference) out of right line channel.

- a lot of distortion coming from the output, even with master and line levels all the way down.
- with CDJ -> line inputs, sound bleeds through if line/phono switch is set to phono.
- with CDJ -> line inputs and line/phono switch set to line, music plays but distortion is still present
- distortion flares up when using channel upfader, particularly when you hit the top

[Finnish_Fox]

Also, distortion remained after I turned OFF the mixer. Is this an issue with using an unbalanced output to a TRS input?

[djpenguin]

OK - another round of notes. I am checking the right channel as I am having problems toggling between line/phone on the left channel.

Good news -> good sound (despite distortion/interference) out of right line channel.

- a lot of distortion coming from the output, even with master and line levels all the way down.

Distortion, or noise? Is this different in character than the noise you heard on the master outputs earlier? Can you record whatever it is and post it?


- with CDJ -> line inputs, sound bleeds through if line/phono switch is set to phono.

This isn't great, but it's not really something you want to deal with right away, because of the input level mismatches. Actually, it's probably a very good idea to stop putting line-level signal into phono inputs. It's not beneficial to the hardware.


- with CDJ -> line inputs and line/phono switch set to line, music plays but distortion is still present
- distortion flares up when using channel upfader, particularly when you hit the top

Okay, this "distortion" may be a dirty/damaged channel fader on this channel, especially if it's different than the noise you heard from the master output earlier. You're going to want to clean that fader, and if you do one, you may as well do them all. Mr. Smashy has a great Vestax fader cleaning tutorial here (http://www.djforums.com/forums/content.php?162-mr-smashy%92s-Guide-to-Fader-Maintenance).

[djpenguin]

Also, distortion remained after I turned OFF the mixer. Is this an issue with using an unbalanced output to a TRS input?

That sounds like leaky capacitors somewhere.

[Finnish_Fox]

Distortion, or noise? Is this different in character than the noise you heard on the master outputs earlier? Can you record whatever it is and post it?


Distorted noise? :shrug:

Sounds similar to a to having a guitar amp on, guitar cord in amp and touching it to metal in your guitar as your plug it in or to your hand. Not sure what that's called, sorry for the lack of description. That hummmmmmm sound.


This isn't great, but it's not really something you want to deal with right away, because of the input level mismatches. Actually, it's probably a very good idea to stop putting line-level signal into phono inputs. It's not beneficial to the hardware.

Let me clarify... I only put the CDJ into the left phono the once last night. What I meant right there is = with the CDJ plugged into the right-channel's line input and the line/phono selector was switched to phono (which should have resulted in silence), I could hear the music from the line input... so there is some sort of bleeding between the phono and line inputs on the right channel.


Okay, this "distortion" may be a dirty/damaged channel fader on this channel, especially if it's different than the noise you heard from the master output earlier. You're going to want to clean that fader, and if you do one, you may as well do them all. Mr. Smashy has a great Vestax fader cleaning tutorial here (http://www.djforums.com/forums/content.php?162-mr-smashy%92s-Guide-to-Fader-Maintenance).

OK - most of the "noise" is the sound described above, akin to a live guitar amp and cord being touched to the metal surrounding the connection on a guitar - just constant all the time. I am trying to find RCA-RCA because I think it may be the RCA-1/4 unbalanced I am running into the TRS input on my KRK.

It is a distinct "flare" of noise, I suppose slightly different.

I'll record it on my iphone 4s and see if that is good enough quality on YouTube or something.

[Finnish_Fox]

That sounds like leaky capacitors somewhere.

I see.

KRK with cord plugged into it, but nothing else - silence.
KRK with cord plugged into it, my hand touching connections - hum.
KRK with cord plugged into it, connected to mixer - very loud hum - regardless of if mixer is on/off, plugged into/not plugged into power source.

Could it be the RCA-1/4" cord? (I use it to go from my DJM-700 into a mono-input on my MOTU Ultralite - makes super crisp mixes. See my link below. :tup:)

[Finnish_Fox]

Oh, and thanks for the rep on that gun thread!

BTW - love the avatar. Huge Simpsons fan. Huge stoner.

[Finnish_Fox]

I see.

KRK with cord plugged into it, but nothing else - silence.
KRK with cord plugged into it, my hand touching connections - hum.
KRK with cord plugged into it, connected to mixer - very loud hum - regardless of if mixer is on/off, plugged into/not plugged into power source.

Could it be the RCA-1/4" cord? (I use it to go from my DJM-700 into a mono-input on my MOTU Ultralite - makes super crisp mixes. See my link below. :tup:)

I'm probably a moron. Wouldn't that actually be a grounding issue (like with the guitar example)?

[djpenguin]

I'm probably a moron. Wouldn't that actually be a grounding issue (like with the guitar example)?

Yeah, it sounds like that's what's happening.

I think the best course of action at this point is to record the needed noises, then take the mixer apart. When you have it apart, clean the faders and examine the circuit boards for any obviously bad components (burnt/blown resistors, bulging/leaking capacitors, cracked or broken ICs, physical damage to the PCB, etc.)