Little side project of mine over the last couple months. Found a 1988 vintage Ivie PC40 analyzer on eBay for $400 with preamp and microphone.
The preamp body is one of the hardest parts to find. If you have a PC40 can still buy new microphone capsules from ACO Pacific or B&K, but you need the specific Ivie IE-2P preamp body to go with it. Lot of PC40's fly across eBay for $900+ without the preamp body or a mic -- making it a pretty much worthless antique.
First time I powered it up it let out some smoke. One of the capacitors in the charging circuit went supernova and smoked out my living room. I had to remove the voltage regulator board and replace all the caps.
One of the known issues on these analyzers is that the battery packs go out over time. They also had an engineering change order issued to add an inline fuse into the pack to prevent issues if the pack grounds out to the chassis. I rebuilt the pack and am 100% certain I'll never be able to get that through a TSA scanner.
With the rebuilt rechargeable battery pack and the voltage regulator circuit repaired, I fired it up again. Worked great for about a minute and half before it started reading 160dB and smoked out again.
At first it looked like I overvoltaged the analog audio filter networks based on where the scorch marks were, even though the batteries read correct voltage and polarity before I turned it on. Then I found the real source of the problem -- a couple capacitors stuck to the bottom of upper PCB. They're not shown on any schematics and to the best that I can tell are not supposed to be there. Looks like someone aftermarketed these onto the bottom of the A/D chipset.
Snipped them out and tried again. Success!
I've since put it through a couple hours worth of use now and it seems very stable. Actually in better condition than the other several PC40's I've encountered in the last few years. All of the keys work reliably, the BASIC program hasn't lost its mind for any reason, and the preamp body doesn't fritz out in the 6-pin XLR mic jack. Microphone capsule is giving accurate results, which is a surprise because ordinarily over a 30-year stretch of time at one point or another someone's let the microphone bake in the trunk of their car or they've dropped it to the ground. Could be that someone's already replaced the capsule though.
The most surprising part is that the built-in printer has paper loaded in and still prints out measurement results. Takes a few minutes to print each result.
The preamp body is one of the hardest parts to find. If you have a PC40 can still buy new microphone capsules from ACO Pacific or B&K, but you need the specific Ivie IE-2P preamp body to go with it. Lot of PC40's fly across eBay for $900+ without the preamp body or a mic -- making it a pretty much worthless antique.
First time I powered it up it let out some smoke. One of the capacitors in the charging circuit went supernova and smoked out my living room. I had to remove the voltage regulator board and replace all the caps.
One of the known issues on these analyzers is that the battery packs go out over time. They also had an engineering change order issued to add an inline fuse into the pack to prevent issues if the pack grounds out to the chassis. I rebuilt the pack and am 100% certain I'll never be able to get that through a TSA scanner.
With the rebuilt rechargeable battery pack and the voltage regulator circuit repaired, I fired it up again. Worked great for about a minute and half before it started reading 160dB and smoked out again.
At first it looked like I overvoltaged the analog audio filter networks based on where the scorch marks were, even though the batteries read correct voltage and polarity before I turned it on. Then I found the real source of the problem -- a couple capacitors stuck to the bottom of upper PCB. They're not shown on any schematics and to the best that I can tell are not supposed to be there. Looks like someone aftermarketed these onto the bottom of the A/D chipset.
Snipped them out and tried again. Success!
I've since put it through a couple hours worth of use now and it seems very stable. Actually in better condition than the other several PC40's I've encountered in the last few years. All of the keys work reliably, the BASIC program hasn't lost its mind for any reason, and the preamp body doesn't fritz out in the 6-pin XLR mic jack. Microphone capsule is giving accurate results, which is a surprise because ordinarily over a 30-year stretch of time at one point or another someone's let the microphone bake in the trunk of their car or they've dropped it to the ground. Could be that someone's already replaced the capsule though.
The most surprising part is that the built-in printer has paper loaded in and still prints out measurement results. Takes a few minutes to print each result.
