Is this acceptable?

[vwdude]

So I got a great deal on a blown ZPA0.5. I am restoring it with Elna caps and new transistors. Problem was, it was missing the plexi. I went to a local plastic place and I am having them custom cut me a piece of tinted 1/4" plexi to correct dimensions. it will have all polished edges and they are drilling the screw holes. I am also going to have a gold vinyl sticker cut in the correct logo/size.

I am just wondering if this is acceptable in the eyes of the true aficionados? Ideally I would get an OEM piece, but I couldnt locate any.

also, what do you guys think this amp could be sold for? I plan to sell it on ebay once done, unless it is preferred to keep it "in the family" and try to sell it on here first.

just looking for thoughts. BTW I am an electrical engineer, and I am working with a professional sound engineer on this. We plan to do this as a side job if we can get amps for a good price. we might do repair work as well if this one turns out as good as we expect.

[zeropoint0.5]

the plexi is not a important thing.... a blown up amp can be repaired.....

everybody who knows the zpa's know they have a fragile powersupply.......

I would buy a blown up zpa.... i will not buy a "repaired amp by somebody else",

cause the only thing you have to do is to clean up the mess other people made.....

damaged traces/via's, not the right components......

If you repair it to use yourself, fine.....

If you don't know what you are doing, it is smarter to not touch the board at all.....

the people who can do this succesfully you can count on you're own hand......

Personally i hate "repaired amps by a stranger......" i leave them aside.....


anyway good luck with "winning some money on it ".......

[vwdude]

i understand your reserves about someone else doing a repair. i personally dont trust other peoples' work either, and i am not proven yet. i assure you that i have many years of experience in this.

also, the initial goal was not to "win money". I have been looking for a good pair of zpa0.5s for some time. i gave up and bought a mcintosh amp. i then came across this amp and decided that it deserves a better life than in the garbage.

oh, and it might be pertinent to explain what i do for a living. i work on medical equipment. i do the same thing that im doing on this amp, except if i screw up at work people can die.

[Kirghiz]

Personally, since I don't have the skills to repair an amp myself, I would be just the opposite of the above. Honestly, I probably wouldn't delve into vintage gear at all for that reason, and haven't to this point, but if I were going to, I would be looking for something that has been restored. I would also be looking for some sort of guarantee from the person that did the restoration. That said, guaranteeing car audio gear is a double edged sword because people are stupid and can blow up a perfectly good amp in 5 seconds flat if they don't know what they're doing.

As far as the plexiglass goes, I'd want it to be as close to original as possible, but that is a small thing compared to the above and having a durable, working, restore job on the product that buyer's would have confidence in. In terms of business upside, there are probably more lucrative hobbies one can have. Even a fully restored mint condition amp isn't going to be selling for what it retailed for unless it is something that is super rare like an MS2250 or something like that. I tend to think that if you came out making enough profit against the cost of the amp and cost to repair, and you came out with a reasonable "by the hour wage" to account for the time that you invested as your profit, you've done pretty well. That easier said than done too though.

[ttocs]

do what makes you happy with the glass. Seen some people on here that have added led strips under the glass to light up the inside of the amp for a different look and I think its cool. Don't let yourself be restricted to what PG made because remember back then if you wanted them to paint on hot pink with neon green letter, they were cool with that.

[trickyricky]

Laser cut/etch the logo on the plexiglass.

[vwdude]

Thanks guys. You have been very helpful.

honestly, these amps are not anything magical. They are basic circuit boards with standard off the shelf components. With good soldering skills and smart planning, these can be repaired. "the people who can do this succesfully you can count on you're own hand......":roll: its not rocket science.

That said, I am only replacing the power supply caps and the blown transistors. There are still 100s of other components on the boards that could go bad eventually. They shouldnt assuming that the amp is properly installed and not abused, and none of the caps that I install are bad.

Honestly, im not worried about the electronics. I am paid quite well in my normal job because I am good at what I do. I was more concerned to get everyones opinion on going with a new plexi versus using OEM stuff...showing my attention to detail on this restoration.

If this were for my car i would use my creative intuition, but since I plan to sell this, I want to do whats best overall and let the new owner modify it how they feel fit.

laser cutting and etching the plexi would be very cost prohibitive. The plexi is getting cut and polished by a professional plastic place, and they are willing to make more if people have a want/need. I am paying decent money for it because i am getting tinted plexi.

[zeropoint0.5]

Thanks guys. You have been very helpful.

honestly, these amps are not anything magical. They are basic circuit boards with standard off the shelf components. With good soldering skills and smart planning, these can be repaired. "the people who can do this succesfully you can count on you're own hand......":roll: its not rocket science.

it seems you never heard a zpa play like it should.....then you would now how magical they are..... they are "the shit "

the problem is when somebody is going to repair it who don't know them, they going to put in "standard of the shelf components" to

replace the quality components with cheaper parts..... and then the shit begins.... i have multiple examples at home of it.......


I repeat, there are not much people who can do this succesfully.....

Do you have all the shematics ? to know witch components and exact value to use ??

Do you know how to adjust and set bias and dc offset back right ?? Very very important......

Do you know witch components to upgrade from a V1 to a V2 model ??

Indeed there are just a handful people who can desolder the vertikal daughter boards without ripping traces......

I will name you two of them...... Eric D and Valeks......


I'm going to buy another zpa amp in my country today. the only thing i will do is open it up and see if nobody has

repaired it yet or i see burned spots/components......

Just understand that the zpa's are complex amps,they play amazing but are not really reliable......

the more you have to heat up the same traces the more chance you have to damage them......

If you have to take out the wrong "new" components, that's already a third time you have to solder on it.......


I hope you're not upset with my post........and one advice...... if you have a zpa0.5 that plays good.....

keep it for yourself.......cause it's the best playing 12V amp i ever heard play (on speakers......)

[vwdude]

thanks for the info zeropoint.

I do know what components to use. I have done research, and I know the values needed. I am not removing the daughter boards as they are functioning properly.

I also know what you mean about improper repairs...the guy i bought it from had some hoaky guy try to repair it already and its completely botched. Luckily, the guy was so bad that he only tried to replace one transistor. He didnt find the other blown one or the fluid by the base of the power input caps. I ordered the correct caps and transistors and thats all I am replacing. I plan to use my o-scope and my bench test equipment to bias the channels.

Yes these amps are magical, but internally theres no pixy dust. I personally would love to run it in my car, but I have a Mcintosh on the way. I wont sell this 0.5 until I know that I am happy with the mac. I am, however, rebuilding this amp as if I were going to use it. Cosmetically it will look new, and internally I am running the ELNA caps as I understand they are an upgrade for this board. I was reading that the other caps do not need to be replaced unless they leak...which I am still investigating to make sure they are not.

[Eric D]

Be sure to replace the gate resistors when you replace the MOSFETs. The gate resistors generally take damage when any MOSFET fails.

I would not put ELNA caps in the power supply, they would not be any better than the stock caps. Using them in the signal path somewhere would be an improvement, but the power supply caps have so little to do with the SQ of the amp, it would just be a waste of resources.

Personally, if I bought an amp of eBay for example which had anything other than OEM brand caps in the power supply, I would remove them and put OEM back in. But, I am a PG collector, very few of my amps ever see use.

[trickyricky]

The suggested replacement for the "hf" series is the "fc". I just got my batch of fc, they look scary to me as they are also blue, but these have a gold stripe instead of silver. This is a suggested replacement by Panasonic....this would be consider oem....now.

[Kirghiz]

Yes these amps are magical, but internally theres no pixy dust.

Maybe not, but everyone knows that the output transistors are dipped in golden phoenix ashes before being soldered to the board. If you have to replace any of those transistors, they have to be sent to Hogwarts to be serviced by Dumbledore's phoenix before being installed in the amp.

[vwdude]

oh, and this amp is already V2.

So I am wasting money on those caps??? well they cant be returned so I might as well just use them.

All of the resistors tested out ok, but they can be replaced.

[Eric D]

If the resistors tested OK, then it is your call. I know I have replaced all the MOSFETs in amps before with gate resistors which tested fine, only to smoke a MOSFET upon power up. In these cases, replacement of the resistors and MOSFETs solved the issue.

Sometimes even the SG2525 PWM controller is damaged as well. Or in the case of some amp, they use a buffer transistor to drive the MOSFETs, instead if just the SG2525 on its own. These transistors often die as well.

A shorted MOSFET can sink a lot of current fast.

As for the caps, if you have them, use them. There is not much point in buying something different when you have usable parts in your hands.

[vwdude]

I am taking your advise, I am replacing ALL gate resistors, not just the ones on the bad MOSFETs. I think in the future (if I do any more), I will invest my money in replacing all MOSFETS and gate resistors, and not get the expensive caps on the power supply. Thanks for the info.

[zeropoint0.5]

I am taking your advise, I am replacing ALL gate resistors, not just the ones on the bad MOSFETs. I think in the future (if I do any more), I will invest my money in replacing all MOSFETS and gate resistors, and not get the expensive caps on the power supply. Thanks for the info.

now you get one of me....


http://be.mouser.com/ProductDetail/Inte ... bvXV2IM%3d

use these mosfets, the irfz48 , you need 16 for a zpa0.5, and make sure u use 330 ohm/1% metalfilm resistors as gate ones.....

and now it comes.... in most of the first versions, you will find 330 ohm gate resistors....

in some of the later versions and certainly the V2, you will find other type fet's , needing 33 ohm gate resistors.....

make sure you don't use irfz48 with 33 ohm gates, cause the resistors will burn..... and so will the fets.....

so..... with these irfz48 mosfet's, you will make a good and reliable upgrade of the power supply......

I've done 3 or 4 zpa's with them yet and with great results..... so here you get a golden tip......

[freshkryp69]

You want to use Panasonic "FC" series caps on the power supply, I use the 8200uf. and "HA" series for the rail caps, these are 10 or 12,000uf. Ive done several and they work fine and sound great as they should..

[vwdude]

Thanks for the help guys. I ordered the correct resistors already, but I was planning to replace the MOSFETs with what came originally. Are you saying that I should use the different MOSFETs?

I am now regretting that I spent $78 on those ELNA Caps. I am for sure not cheaping out on the components, and if I loose money on this amp then its ok, I want to make sure this amp gets the life it deserves.

[Eric D]

Thanks for the help guys. I ordered the correct resistors already, but I was planning to replace the MOSFETs with what came originally. Are you saying that I should use the different MOSFETs?

I am now regretting that I spent $78 on those ELNA Caps. I am for sure not cheaping out on the components, and if I loose money on this amp then its ok, I want to make sure this amp gets the life it deserves.

I would use the original type MOSFETs for replacement. Yes, you can go with better ones, but the problem is the ZPA does not have enough heatsink to make much use of any MOSFETs better than stock.

[vwdude]

I had been debating using the new MOSFETs, well I decided to order the upgraded ones. I am glad I had hesitated on ordering the resistors because I would have had to order all new ones again.

[vwdude]

So I got the upgraded mosfets and the ELNA caps came in finally. The 330 ohm resistors arrived, I had ordered 2 watt resistors but apparently the posts are too fat. When I ordered new resistors I ordered 1/4 watt ones. Will they work or should I get 1/2 watt resistors?

Btw I got the caps, mosfets and resistors off already. The previous repair done by some guy left lots of solder to clean up.

[vwdude]

I am adding to this as we started another discussion in my install thread and I thought it was more appropriate here.

So I tried to power up the amp. I connected the + and - to battery. I had previously said that I had a 50 amp fuse, turns out it was a 30 amp fuse. well, when I shorted the REM connection to 12 volts, the fans came on for about 1 second, then the fuse blew.

The suggestion was to open the amp again and look for pieces of wire that found their way inside via the fans. I removed all covers (including heat sinks) and i found a tiny piece of copper wire, but it was not shirting anything. Of course I removed it and verified that no others are floating around.

As I further disassembled the amp i discovered something that I previously missed. it looks like it needs to be repaired, but i wanted to know what you guys (the experts) think.



also, this looks like someone else has replaced this component, its doesnt look like factory solders, am I correct? doesnt look too bad other than their soldering skills.


and this was from the previous known repair that the guy i bought the amp from did. I know its REALLY ugly, but i didnt want to fruther damage the board by trying to clean it up. do I need to further clean it up?
before I replaced the MOSFET



btw here are all of the solder points for the caps i replaced:

[vwdude]

just an update...my DMM shows no continuity in either side of those lines. could that be what caused me to blow the fuse? I dont even know what that block does. never seen it before on any of the boards that ive worked on.

[biplaza]

any update ? this thread was interesting...

[ttocs]

the solder on the little blue piece doesn't look like it got hot enough to bond properly. I would start simple and just touch those spots with an iron and get the solder melted/bonded properly and see what happens.