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Author Topic: Princeton Chorus SS Board Advice Needed  (Read 1389 times)

MurphyPeoples

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Princeton Chorus SS Board Advice Needed
« on: January 07, 2017, 08:18:43 AM »

Hello. This is my first post to SSGuitar. I purchased a Fender Princeton Chorus for my 16yo daughter. It's great, but boy is the Volume Control knob on Input 1 touchy!
It will go from Normal volume to 10 as you dial up or down the sound. If you fiddle with the knob back or forth, you can get it back to normal. I'm pretty handy with electronics, and I've gone ahead and pulled
the board out. I plan on checking all the suspect soldier joints and reflowing them. And cleaning out all the pots with D5.

Any other hints you might provide will be greatly appreciated! I've posted a pic of the board. Looks like it was pulled and tested in '98? Also, did the 9836 caps originally have hot glue melted between them for shock absorption?
If not, this has been done too. (I had planned on doing that lol)
Thanks again. Warmest regards,
Murphy
« Last Edit: January 07, 2017, 01:21:38 PM by MurphyPeoples »
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MurphyPeoples

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Re: Princeton Chorus Advice Needed
« Reply #1 on: January 07, 2017, 08:23:54 AM »

Here's a shot of the right side of the board also.
Murph
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MurphyPeoples

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Re: Princeton Chorus Advice Needed
« Reply #2 on: January 07, 2017, 01:21:13 PM »

Well, I'm beginning to think that my problem is actually in the input jack. Inspecting the underside of the board, I noticed that there was flux still located
all around the #1 input jack. Plus, on second look, the jack is completely different brand the all the others. Using a 1/4" plug, it fits "okay" but not as tight as #2. Plus the #1 input is slightly smaller and doesn't fit in line symmetrically with all the other jacks on the board. It actually sits about 1/8" lower towards the board than all the others. The soldier connections might have been cracked when the board was threaded back into the housing from it sitting lower than OEM. This just screams to me... replace me!

So I'm going to order a few 1/4" fender 9 pin jacks. "A few" because the #2 input - though OEM - is missing a chrome ring just inside the female connection. As you can see... this is all new to me! LOL.
But I've been repairing Electromechanical Pinball Machines for years, so this seems pretty straight forward. I'll replace both main input jacks.

Any suggestions on where to order Fender SS electronics? I'd like to deal with someone you folks would recommend. Again, thanks in advance.
Murphy
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galaxiex

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Re: Princeton Chorus SS Board Advice Needed
« Reply #3 on: January 07, 2017, 01:47:40 PM »

Yup, those notorious Fender input jacks...

Very much a weak point on many "modern" Fender amps.

You might consider replacing them with "proper" panel mount Switchcraft jacks as detailed here...

http://hotroddiy.com/howtoarticles.php

Scroll down and click on "Replacing Damaged Jacks"

This is for the Fender Hot Rod Deluxe and is an older article,
but I bet it's very similar, if not exactly like, the Princeton input jack setup.

HTH

Sorry, I don't have any suggestions where to buy the original jacks,
tho they should be available many places...

Edit; Oooops, sorry, you have 9 pin jacks and the HRDX uses 5 pin.
Still... it might be possible to replace your jacks with better panel mount type.
Would need more research to determine that.
Got schematic?
« Last Edit: January 07, 2017, 02:02:28 PM by galaxiex »
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DrGonz78

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Re: Princeton Chorus SS Board Advice Needed
« Reply #4 on: January 07, 2017, 04:21:12 PM »

If your in the USA then I would look at this place for buying the jacks...
https://www.guitar-parts.com/catalog/fender-amp-jack-pc-mount-0

Another one is here...
http://darrenriley.com/store/fender-stereo-amp-jack-0990913000/

From what I gather the original Part# is 0031570000 or 0025931000. As it states on the DarrenRiley site "Fender part# 0990913000  (same as 0031570000 ,  0025931000)"
« Last Edit: January 07, 2017, 04:22:23 PM by DrGonz78 »
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MurphyPeoples

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Re: Princeton Chorus SS Board Advice Needed
« Reply #5 on: January 07, 2017, 05:03:19 PM »

Thanks guys! Yes, I'm in the USA. I haven't found the schematic yet, only for the Princeton Chorus "DSP" (What does DSP mean?) - and looking at that schematic the DSP board is different.
Thanks for the leads on inputs! I'll get some on order. I appreciate the replies!
Murphy
Clinton, SC
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galaxiex

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Re: Princeton Chorus SS Board Advice Needed
« Reply #6 on: January 07, 2017, 05:18:51 PM »

Digital Signal Processor

The DSP amp has digital effects built in.
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MurphyPeoples

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Re: Princeton Chorus SS Board Advice Needed
« Reply #7 on: January 07, 2017, 05:22:10 PM »

Digital Signal Processor

The DSP amp has digital effects built in.

Oooookay. : ) That makes perfect sense! lol
Thanks.
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Enzo

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Re: Princeton Chorus SS Board Advice Needed
« Reply #8 on: January 07, 2017, 06:47:01 PM »

I recommend against putting metal Switchcraft jacks in there.  First, they will not have the auxilliary switching the Fender jacks do.  Second, they will not adhere to the original grounding scheme.    The real jacks will last a long time if one simply respects them.  I have replaced many of them, yes, but think of the thousands of those amps that did NOT need new jacks.

The real jacks are easy enough to find.

They used to sell them loose, and they had the old part number.   Then they started packing them in poly bags with a cardboard peg hole top label, and they got a new part number for that packaging.
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MurphyPeoples

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Re: Princeton Chorus SS Board Advice Needed
« Reply #9 on: January 07, 2017, 07:06:41 PM »

I recommend against putting metal Switchcraft jacks in there.  First, they will not have the auxilliary switching the Fender jacks do.  Second, they will not adhere to the original grounding scheme.    The real jacks will last a long time if one simply respects them.  I have replaced many of them, yes, but think of the thousands of those amps that did NOT need new jacks.

The real jacks are easy enough to find.

They used to sell them loose, and they had the old part number.   Then they started packing them in poly bags with a cardboard peg hole top label, and they got a new part number for that packaging.

Thanks sir! It's interesting that I've found several websites with OEM Fender Jacks (#031570) for $6.95 and up. But then there's this site:
http://www.amprepairparts.com/fenderjacks.htm
And he sells 9 pin for $1.95 each. (6 packs for $9.95!) Has anyone bought from them before? I worry that "if it's too good to be true..."     ;)
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g1

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Re: Princeton Chorus SS Board Advice Needed
« Reply #10 on: January 08, 2017, 01:24:34 PM »

Yes, that is a reputable company.
See the note about not including the nut? 
I'm assuming they are getting the parts from Fender's supplier rather than from Fender themselves.  That and the fact that the nut is not included means a lower price.
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MurphyPeoples

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Re: Princeton Chorus SS Board Advice Needed
« Reply #11 on: January 10, 2017, 07:40:19 PM »

Yes, that is a reputable company.
See the note about not including the nut? 
I'm assuming they are getting the parts from Fender's supplier rather than from Fender themselves.  That and the fact that the nut is not included means a lower price.

Gosh. Those nuts are like a dime at Mouser Electronics. LOL.
I'm not new to electronics, but the Amp PCB parts are quite different than Pinball PCB.s  ;)

I've ordered quite a few and will post a follow up on quality once they arrive.

On another note... it took me nearly an entire hour getting the wrong #1 input jack (it was a low profile 9 pin - I think for a Hot Rod) off the darn board. Whoever hacked the board last used
enough soldier to sink a battleship. I'm not kidding. I had to take it very slow, and used around 12" of super wick copper before the jack would even begin to budge.

Thankfully didn't destroy a circuit in the process. My meter shows everything still connected. Whew!
Murph
« Last Edit: January 10, 2017, 07:41:52 PM by MurphyPeoples »
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g1

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Re: Princeton Chorus SS Board Advice Needed
« Reply #12 on: January 11, 2017, 02:23:54 PM »

  I realize the nut does not account for that kind of price difference.  :)
But it is an extra hassle if you don't have the original and have to source it separately.  For guys that are charging $1 per minute, it may not be worth it.
So mostly I just wanted to point that out for reference.  When those units were current, it was difficult to find that thread.  I suppose that is no longer true, but if those nuts from mouser are for metal jacks, they will not fit.
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Enzo

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Re: Princeton Chorus SS Board Advice Needed
« Reply #13 on: January 11, 2017, 03:55:37 PM »

When I used to buy them in bulk, I would get like 20 jacks in a bag, and then 20 pairs of nuts and washers.

Now fender sells them bagged up for point of sale.  Inside the bag is a jack, and a smaller ziplock with the nut and washer.   They don't come together.

Now when I order 20 of them, I debag them into a larger bag, and pile all the little nut sacks in ther too.  When I sell one, I grab a jack and a nut bag, and go to work.  I could just leave them individually bagged, but that fills my drawer with packaging, but it would be no less convenient to use.

So I don't think the nut has anything to do with the price.

Don't beat your head against a wall trying to rationalize a price.  If one company sells them at $6.95, and another $1.95, in both caes they make money, and in both cases it is all marketing.

In my shop, I sold those jacks for $4 each, as I did every kind of jack.  I bought the common small Jalco jacks by the hundred at 18 cents each, still asked $4.  I forget what Fender gets for those jacks wholesale, $1.35 maybe?  Their list price would then be $2.70.  Maybe it went up since my memory, what if they were to list for $3.48?  The $6.95 company could just buy them at retail, put an A markup on them and resell them at $6.95.  But then they could just as easily buy them from the other cheap source you listed, and resell tham at $6.95.  The head spins.

WHy do they charge $2.89 for a Coke at Applebees?  It costs them less than a nickel.
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MurphyPeoples

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Re: Princeton Chorus SS Board Advice Needed
« Reply #14 on: January 11, 2017, 06:23:06 PM »

I got both packs of the 4-pin and 9-pin today. They look exactly like the fender jacks with same quality, at least to the eye.
I'm soldiering it in over the weekend, and I'll let ya'll know how it sounds.

P.S. - I wish I had a shop like Enzo's was around here! LOL. Guitar Box stores have put all our small shops out of business over the last few years.
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