Potentiometer swap out help

[Fivetide]

Hi I know this is low grade modding but I don't have very much experience with electronics, my potentiometer seems to have broken, its ok at a certain volume but then when I move it with either the remote control or by hand I get distortion and sometimes even one channel mutes. The amp in question is a PM-66SE, I've had it for over 20 years and love it. Orignally I had taken it to an engineer with the same problem about 10 years ago I thought he had swapped it out , looks more like he had fixed it some other way or it maybe they just tend to go on a regular basis.Anyway is there any pitfalls that I should look out for when replacing them, or tips to make my life easier? Thanks in advance. 🙂

 

[DF96]

Try squirting some switch cleaner into the pot, if you can find a hole in the casing. Turn the knob back and forth a few times. This will often work, if the problem is just dirt on the track.

 

[AndrewT]

make sure the amplifier is OFF while you insert liquids anywhere near it.
Make sure the liquids are fully evaporated before you switch ON.

Safer to unplug from the mains before you open up, or squirt anything.

 

[Fivetide]

Thanks for the replies , the external knob it self moves from side to side and the when I do that it the left speaker crackles.. any ideas ? I'll try the switch cleaner first though and I will unplug it 🙂 If you don't have anymore replies from me you know that I forgot lol

 

[KatieandDad]

If you have to replace it and can't get one to fit exactly, just fit it with the connections pointing away from the PCB and fit short jumpers to the PCB.

 

[DF96]

Crackles when you change the volume is a classic symptom of a dirty pot track. You can get switch cleaner from Maplin, RS or Farnell. Not cheap, but a can will last for decades unless you go into the professional repair business.

 

[KatieandDad]

Be careful with contact cleaner though. Some products actually dissolve the plastic that makes the pot track.

Now, this will age me. I used to disassemble faulty pots and clean the parts with a swab and some alcohol.

It certainly was better than relying upon the chemical properties of the cleaning fluid on their own.

 

[mickeymoose]

And while you in there: do the other pots and all switches. E

 

[DF96]

Yes, taking it apart and cleaning the old-fashioned way will always be best. You can see what state it is in. The trouble is that modern parts are not designed to be taken apart and reassembled.

I have never personally had a problem with switch cleaner, but I always use as little as possible and keep it only where it is needed. As it is a solvent, there is always the risk of it dissolving something it shouldn't.

 

[Fivetide]

Ive taken your advice or the consensus and will be popping to CPC in 10 mins for a can of 100005000 200ML - SERVISOL - AERO-KLENE 50, 200ML | CPC

An externally hosted image should be here but it was not working when we last tested it.

I'll do all the switches knobs buttons etc , give it a bit of a service 🙂 I think it deserves it after so many years of service , I'll post results.

 

[KatieandDad]

Dont use too much. I rely upon the physical action of the wipers to help in the cleaning rather than flooding it with fluid.

 

[Fivetide]

Oops flooded it 🙁 suppose more is less lol anyway I tightened the bolt on the front.. so it doesn't wobble anymore .. clean all the buttons and dials with switch cleaner and it works perfectly now I guess the loose bolt may have been letting in dirt over the years. Anyway thanks for all your help.. I think I'll look at some of the 66SE modding threads it may be good to replace some of the parts with new ones..

 

[Fivetide]

Cant tell you how much I love this amp even though I have it in my home office . Its sound awesome.. my set up is :
J River Audio Media Center 17 (FLAC) -- ASUS Xonar Essence STX Sound card -- Marantz PM-66SE --KEF Q10 -- all QED wires

I'll still sat here stunned just cleaning the switch has made a big difference to the quality.. how simple was that !! ?

 

[Fivetide]

So the first thing I am going to do is swap out

"REPLACED C801 C802 WITH 56V 22000uF SILMICS"

I Live in the UK and near to CPC in Preston Lancs, so if they have have the replacement it easy for me to pick them up.

But heres where the problem starts .. I search CPC and they have loads of 22000uf caps but none at 56v

example MAL210117223E3 - VISHAY BC COMPONENTS - CAPACITOR, 40V 22000UF | CPC

I suppose I'll have to search the internet for the right ones.. shame I was told vishay are very good caps

 

[Fivetide]

However I have found EEUFC1H102 - PANASONIC - CAPACITOR, 1000UF 50V | CPC

An externally hosted image should be here but it was not working when we last tested it.

For

• REPLACED C717 C718 C719 WITH 50V 1000uF BLACK GATE STD TYPE

So at least they have some things on the list lol
http://cpc.farnell.com/panasonic/eeufc1h102/capacitor-1000uf-50v/dp/CA05182

 

[Frank Berry]

You can replace the capacitors with 63 volt caps. It's not a good idea to replace a 56 volt cap with one which has a lower voltage rating. In a pinch, even a 100 volt cap would be fine.

 

[Fivetide]

You can replace the capacitors with 63 volt caps. It's not a good idea to replace a 56 volt cap with one which has a lower voltage rating. In a pinch, even a 100 volt cap would be fine.

Hi Frank thanks for that answer its what a needed to know , would these be overkill ? would they be an improvement because of the cost ?

MAL210119223E3 - VISHAY BC COMPONENTS - CAPACITOR, 100V 22000UF | CPC

 

[Fivetide]

Guess I need to learn how to search on the site I found these , much better price lol !
MAL205018222E3 - VISHAY BC COMPONENTS - CAPACITOR, 2200UF, 63V | CPC

An externally hosted image should be here but it was not working when we last tested it.

 

[Coconuts 500]

Contact cleaner is not necessary, just drain it in alcohol and move the pot for a while. Fixes most problems.

 

[AndrewT]

63Vdc capacitors and lower are relatively cheap.
75Vdc and higher are relatively expensive.

Use the lowest voltage rating >=35Vdc, that meets duty and specification.