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Sometimes you just have to improvise

Watthour

Watthour

Electron Rancher - JS3600
Subscriber
An otherwise decent condition SX-780 crossed my bench and had serious water damage. Boards soaped, de-fluxed, and brushed, transformer repaired, mechanical devices cleaned and lubed, caps replaced, offset and idle checked (can't set idle, but it's 28mA or so), and tuner realigned to actually receive, reject, and discriminate, it was time to deal with the case. This was obviously wet and delaminating, and the glue joints at the top panel had let go.

SX-780CaseSides01.jpg



Since finding 16mm seven-ply veneer sheets is about impossible in the U.S. I had to fabricate some. It ended up being 9-ply so I hope no one notices, but it finished up after surface sanding about 0.012" thinner than the original. By the time it gets that Korean plastic wood decal it should be pretty close:

SX-780CaseSides02.jpg


Has anyone ever seen replacement case parts for these? I'd hat to have to go through this again for another one since this took me several hours.
 
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When I did my 790 I used solid 1x8 Oak for the side pieces, and cut it down to length and width. Reused the top piece, sanded, stained, oiled the whole thing.

Took a couple hours like you said.

Larry
 
How do you plan to tackle the top?

Looking forward to after pics.
 
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About like this:

SX-780Case01.jpg


I'm not concerned with the excess glue since the Korean Vinyl Walnut will cover it all (tomorrow, maybe).
 
Cool, so it appears the top edges are flush?

I've done one, just a lowely SX450. Trying to cut around the vents seemed nearly impossible, so I veneered the whole top.

To provide ventilation I dremeled many holes (carefully) in the back plate. Ghetto, but worked just as well.

Curious to see how you handle this, looks like you're off to a good start.
 

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Looks like a decent start. It something that should be patterned for future restores. The vinyl crap is for the birds. I think if it is stained right it could look like the case of say a 980.
 
The top is inset about 0.050 compared to the sides, and the metal grille is flush with the top. The original was that way (patterned after two other 780s) and the original cover was woodgrained vinyl, so that's what it is getting. I don't think that stain on mahogany/birch plywood ever looks right. I used the plywood because it is smooth and stable in thin sections, not for appearance. I could have gone with hardwood in single pieces since my planer will do 15" widths. Maybe on a more deserving unit.

Camino - I have it in CAD.
 
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Watthour said:
The top is inset about 0.050 compared to the sides, and the metal grille is flush with the top. The original was that way (patterned after two other 780s) and the original cover was woodgrained vinyl, so that's what it is getting. I don't think that stain on mahogany/birch plywood ever looks right. I used the plywood because it is smooth and stable in thin sections, not for appearance. I could have gone with hardwood in single pieces since my planer will do 15" widths. Maybe on a more deserving unit.

Camino - I have it in CAD.
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I dont know. i think i would try the hardwood approach. I mean it is a Pioneer. I am biased I guess. I think Pioneer messed up when they went with the vinyl stuff. It would be a very interesting piece with the hardwood and a one of a kind. I do understand the originality of going with the vinyl stuff. If mine wasnt in such good shape I think I would try.
 
I'm looking forward to seeing what the replacement vinyl looks like. You're going to clean and paint the grille too, right?
 
The replacement vinyl is embossed grained (for texture like the OEM) and is supposed to be walnut, but it doesn't look like any walnut I've ever worked with. Then again, the original vinyl on the other Pioneers I have doesn't look like walnut either.

SX-780Top11.jpg


Yes, I will lift, sand, and paint the grille semi-gloss black like OEM before gluing it into place. It's not perfect, but a far cry from how it arrived:

SX-780Top09.jpg
 
Wow. I thought my 580 looked like it went through a flood. This one make mine look like a light rain on a sunny afternoon!

Just out of curiosity....what are you using to clean the boards?
 
Hot soft water, bar soap (Dial), and a stiff (cut short) China bristle brush to wash the boards, then a hot water rinse. I don't immerse them, but run the water over the boards. I use the wet brush to work up a nice lather and apply it to the wet board and components, brush the grime loose, then rinse. It's a little tough to clean thoroughly under the DIPs but a 1/2" wide brush gets it well enough. A few areas in this pig had something vile spilled into it before it took a shower and I had to use citrus cleaner to soften it and rinse it out. (The brown glue holding down the caps and heat sinks didn't get any less brown from the cleaning.) Obviously, the water doesn't help the switches and pots much, but at least it clears the dust and some residue in prep for the cleaner I use.

Of course, everything gets a thorough compressed air blast or three, and additional brushing and air under the tougher components to help dry out hidden areas. Then all the mechanicals get lubricated. The pot wipers and switch pivots are easy, but spindles on the pots and bearings/gear bushings in the tuner VC are toughest to lube. I use a bottle and tube with light oil (Tri-Flow Super Lube T) and load a syringe for the tight spots like the tuner. The tuner spindle and string guide rollers usually get a treatment, too. The interior looks like this after cleaning:

SX-780Top10.jpg



Oddly, this is a Korean built 780 but it doesn't have the Sanyo caps I expected to see.


This one was "extra special" since the transformer had been wet and laminations were rusting and loose. A little Xacto knife scraping, some 1200 grit wet-or-dry, and Glyptal with clamping until dry solved the transformer noise and rust. It's been running for several days straight without so much as a buzz.

As I mentioned above, it got some new electrolytics, new silicone grease, enlarged regulator heat sink, offset adjustment, and a tuner alignment. I may still want to replace the driver(s) for the relay since the protection holds on for about four seconds after power-up, but we'll see how she behaves for a few more weeks.
 
Watthour. Fantastic job. Don't worry about the 4 second "hold" on the protection. That's an acceptable length of time for them. Anything from 3-8 seconds in my experience with Pioneers in good or excellent shape is fine. If the relay is chattering or cycling then replace the driver transistor for the relay.

Larry
 
Yes, the Parts Express simulated walnut woodgrain vinyl is an Asian product, and might be very close to OEM. It looks almost as bad.

Larry - Thanks for the assurance. The relay doesn't chatter or drop at all, but seems to delay a little longer on initial engagement than the other two 780s I have. If 3-4 seconds is acceptable, I'll let it go for now.

There - Is it better in black?

SX-780Top12.jpg
 
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If you are really concerned about the relay time, change out the 33uf/16v cap (C317) next to the PA3004 chip. This controls the on/off timing of Q26 (2sc1384) thru the chip. They are located right behind the RELAY. You might shave 1/2 to 1 sec. off the "hold".

Read about it in the Service Manual, page 9.


Larry
 
Watthour said:
Yes, the Parts Express simulated walnut woodgrain vinyl is an Asian product, and might be very close to OEM. It looks almost as bad.
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Ah, I wondered whether that's what you meant. I've been thinking about getting a roll of that. I have an SX-750 and a PL-514 that I've recovered in walnut grain Contact Paper. It looks okay, no worse than the original, but it's pretty thin and quite susceptible to nicks and tears. I thought maybe the PE stuff would be an improvement, both in appearance and durability.

John
 
I have some generic woodgrain contact paper too, and the PE stuff is thicker. The contact paper (vinyl) is flat and the print is very poor quality, looking like it was done on a dot matrix printer. The PE vinyl has texture embossed in it and is a lot better quality print. You have to get within a few feet to see that it is not wood, whereas the contact paper is pretty obviously fake as soon as you turn the corner onto your street.

Check your PM.
 
Watthour said:
I have some generic woodgrain contact paper too, and the PE stuff is thicker. The contact paper (vinyl) is flat and the print is very poor quality, looking like it was done on a dot matrix printer. The PE vinyl has texture embossed in it and is a lot better quality print. You have to get within a few feet to see that it is not wood, whereas the contact paper is pretty obviously fake as soon as you turn the corner onto your street.

Check your PM.
Click to expand...

Thanks for the information. I agree with all you say about the Contact Paper. It's not the most attractive stuff in the world. Good to know that the PE stuff is significantly better.

(PM received & reply sent. Thanks!)

John
 
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