Bought a few ZPAs, interesting finds

[vwdude]

So anyone who follows ZPA amps probably saw the bunch that were on eBay a few weeks ago. I worked out a deal and bought them all. 3 from one buyer and 1 from another.

The 1 standalone amp was an easy fix. One of the 5w resistors had broken off. I replaced that, replaced the PS caps, and did a DC offset adjustment. Amp is in my car now and works perfectly. At some point I'll upgrade to v2, but I wanted to pull my white ZPA since someone was interested in it. (I won't reveal who it is, they can chime in if they want)

The other 3 consist of 2 0.5s with consecutive serial numbers and a 0.3 that's missing all screws and the side plastics. I have a parts amp that I can get them all from.

On one of the 0.5s I found a blown zener diode and a blown 5w resistor ( damn I should have ordered two rather than 1). The stated problem was that the left channel didn't work. This make sense wince there zener diode and resistor are both for the left side.



On the other amp, there's much more "work" that's been done that I now have to redo. The stated problem was that it works but stays on. I'll fix the below shown issues and see if that takes care of it. If not then I'll delve in further.

So someone took the liberty of "fixing" the power supply #2 board...



And I guess the PWM went out, but they didn't remove the power supply #1 board, so this was their solution...




Since I couldn't get a good shot of it, they cut the IC off and soldered the new one into the legs of the previous one.

So needless to say this one is getting upgraded to a v2 and I'll fix everything on both those boards. I tried to desolder the pins to remove the boards more easily but no-can-do, so I'll have to cut the pins to remove the boards. Board #1 is easy, #2 will be more time consuming unless anyone has any good pointers.

On the 0.3 I did a PS cap replacement. It needs rail caps and a v2 conversion. Otherwise it's just really dirty but I think it works. The rest of the power supply looks good, the transistors all look decent (one or two might be a little sketch and I might replace them just for the sake of making it look right) but it's all about getting the missing screws into this one.

Btw, here's all 4 amps during replacement of PS caps, some worse than others...
S/n 455


S/n 456


S/n 612


S/n 365

[vwdude]

The skins are out this week getting striped and re-powder coated for 3 of these amps plus a 0.3 that I restored a few months ago.

As for the terminal blocks, they were fixed for v2 so that they were not open on e side to allow wire through (and short stuff out), well I can't find anything that's currently made to replace them so I'm taking some that I already have to a machine shop to have a bunch made. Not sure what it will cost, but if it's cheaper to get a bunch then I might make extra in case anyone is interested.

[gfunk_nz]

nice, looks like you have a bit of work ahead with one amp.

[vwdude]

Yes I do, but it won't happen for a while. I need to finish up on the current projects that I'm working on. These amps are getting put away so I don't get distracted.

[gfunk_nz]

lol fair enough, I know that feeling all to well. Have you got a plan for all your ZPA's or was it a case of save them ending up completely trashed or binned?

[vwdude]

Not sure yet. I kind of want to have the spares. I'd realistically only need one of each model for my display/collection but I don't want to separate sequential serials.

[vwdude]

Well not much to update on these from a repair standpoint. I've been really busy with the whole house selling, house buying process and I've been trying to finish other projects before the move.

What I did get done is fresh powder coat, and if you've been reading my other threads, new plexi. These amps all had white logos so it was easy to get all amps done at the same time. I also had a distribution block re done as it had some rust.

Quick recap (so to speak since these have all be recapped) the two 0.5s have sequential serial numbers. One of the 0.3s came to me with no screws or plastic end pieces, and the other is featured in it's own thread because I got it from a member here, but it's lacking it's serial number. That last 0.3 is the only one that I've completely gone through and tested in this bunch.



Now that the cosmetics are done I'll start ordering parts and get them working again.

[vwdude]

Sorry to bring this back from the dead.

So I have a parts amp that's been sitting for a while. Today I removed the two power daughter boards and replaced all caps. One wouldnt come out without cutting the 90* pins so I replaced those as well on one of the boards (hence the red vs black spacers). All of the mini caps were upgraded to nichicon audio grade caps. I also changed the diode out to complete the v2 upgrade. Funny thing, someone previously changed some parts to v2 on the donor amp but didn't bother to recap it and they missed the diode. I also am planning to replace the PWM on the boards for each of these amps and adding in an IC socket. Since I'm removing these boards I'll be pissed if I find that one was bad after reinstalling the boards.

So the plan is to swap these into one of the amps, use those boards to do these same upgrades and swap that into the next one and so on.







Ugh I just ordered 10 fans for the v2 upgrades...$160 is crazy, but at least I got a deal for buying 10. Lol