ZPA 0.5 control board

_Silverhorse_ · Post by **_Silverhorse_** » Fri Oct 26, 2007 11:28 am

Hello PG fanatics!

I have some questions for the tech guys on this wonderful phorum.
I'm a ZPA die-hard and have a ZPA0.5 with a PCB bord that has seen some better times, bought from Ebay last week to give it a better home. You can see that there are some big resistors cooked. I have seen allot of (abused) ZPA's who have this same issue.

Why is it that these resistors are so damn hot (I guess current limiting resistors ??)and is there a solution for my other ZPA's to protect the PCB board’s coming black?

Post by **stipud** » Fri Oct 26, 2007 11:57 am

Wow! That looks like it got pretty warm.

Welcome to the Phorum

Post by **Francious70** » Fri Oct 26, 2007 12:21 pm

Welcome to the phorum mang. I'm sorry, but I do't have an answer for your question.

1moreamp · Post by **1moreamp** » Fri Oct 26, 2007 2:20 pm

That appears to be the +&-16 volt regulator board, and opto feedback for the safety circuits. You really need to rework the entire board by replacing all of the caps, and and defective components.
I would replace all the solder join ts with new solder and i would use silver solder for heat issues.
I would also look into mounting all the power devices higher up off the board to increase the physical distance from the FR-4 board material. < alos use hook bends in the leads of the power devices to give them some locking into the circuit board, if you elevate>
Also repair the burnt trace I see in the corner.
The power resistors are going to get hot this is inevitable by design, but if you distance the devices from the board a bit it will help some.

All the solder is shot on that card, and I do mean all of the solder joints. The power resistors leads have oxidized so you will either need to sand them with scotch-brite or fine grit sandpaper just to get solder to adhere to the joint and wire again.

The flashed trace worries me as there was a severe condition that caused that.
I would try and rework everything on that card just to get it back to spec. As for the heat damaged FR-4 material, I would use a dremel and make sure there is no conductive pathways between the traces with lite buffing and possibly some minor trenching into the surface.

It might be better if you called Phil at PG and asked for a replacement board at this point, due to the huge amount of labor this is going to take. They may still have a few of these in stock all ready stuffed with parts.

PM me if you need more help....C

rolandk · Post by **rolandk** » Fri Oct 26, 2007 2:47 pm

Welcome to the phorum! Thats a very early circuit board. Shortly after the ZPA's were released there was an update which involved changing some resistor values to prevent the heat stress that you see.

If you want to fix it yourself then let me know and I'll give you the details.

Thanks, Roland (PG Engineering Tech)

_Silverhorse_ · Post by **_Silverhorse_** » Sat Oct 27, 2007 4:33 am

Thank you all for the warm welcome!

Cecil, you have very good eyes. There is indeed a burnt trace in the corner, that’s why one fan doesn’t work any more. I hope when this is fixed, the fan will be working again. I will follow your advice.

Roland, thank you also for the support and yes I like to fix the board myself that is for me much more satisfying than plug in a new one. I will PM you with my E mail address so you can give me the info.

When the board is finished photographs will follow but it will take a while (ordering the components and silver solder,…)

Thank you all,
Peter

Post by **smgreen20** » Sat Oct 27, 2007 1:16 pm

Silverhorse- Welcome.

I applaud your taste. Please do take care of those ZPAs. If I had the cash flow, I'd buy as many as I could. For now all I have is a 0.3 and a 0.5 both in white.

Please do so on the follow up.

I know I speak for all of us that we'd like to see the after work.

1moreamp · Post by **1moreamp** » Sat Oct 27, 2007 9:33 pm

rolandk wrote:Welcome to the phorum! Thats a very early circuit board. Shortly after the ZPA's were released there was an update which involved changing some resistor values to prevent the heat stress that you see.

If you want to fix it yourself then let me know and I'll give you the details.

Thanks, Roland (PG Engineering Tech)

THX RolandK

C

_Silverhorse_ · Post by **_Silverhorse_** » Sun Oct 28, 2007 8:09 am

Silverhorse- Welcome.

I applaud your taste. Please do take care of those ZPAs. If I had the cash flow, I'd buy as many as I could. For now all I have is a 0.3 and a 0.5 both in white.

Please do so on the follow up.

I know I speak for all of us that we'd like to see the after work.

One day I'll build my dream system and let you all know. This system will be like the engineers of the Zeropoint series had in mind when they designed these incredible amps. For now I have 2 black ZPA0.3 V2 amps and 2 black ZPA0.5 V1 amps in new condition, a 3th one I need to fix.

Also waiting on the shelf are:

- 130 HO PG alternator
- 2 Brax 2 Farad capacitor
- one Cyclone (new)
- black EQ232 with TBA2
- ZPX2
- 3 X-over cards for ZPA amps
- 2 Boston Acoutic 8.5 subs and one set 6.5

but need more stuff when funds permit...
the 3th ZPA0.5 that I’m gone repair now will be for daily use, not for my dream system.