Why Is Everyone Wanting To Jackup The Voltage On Some White’s

[Tony]

Time to read some of the extensive battery threads on 18650 custom battery setups. 
Im sure Steve will post some links. But essentially, no one is using AA lithium’s to achieve this extra voltage.

[GB_Amateur]

9 hours ago, Coastie59 said:

How are you getting 14.48 v from eight  1.5 AA lithiums?

I think this is a misunderstanding, or at least an unrealistic expectation for disposable lithium AA's.  Here is a plot in the Energizer 91 datasheet which shows that when brand new, the voltage is upwards of 1.7 V but it falls off quickly:

[havingstl]

I've read a lot of those thread but never can quite get a clear picture of voltage an original TDI pulse scan can handle.

[Steve Herschbach]

https://www.detectorprospector.com/forums/topic/3534-minelab-coil-on-whites-tdi/?do=findComment&comment=39321

Up to 18V is mentioned but the consensus seems to be that 16V is the “safer” maximum. But any boost at all is at your own risk.

[Geotech]

11 hours ago, havingstl said:

I've read a lot of those thread but never can quite get a clear picture of voltage an original TDI pulse scan can handle.

The limitation is the LM386 audio amp. There is a 12V version and an 18V version; White's should have used the 18V one, if not then even 14.4V is pushing it. However, there are also a couple of 16V caps on  the audio stage so anything over 16V is probably not doing them any good.

[Steve Herschbach]

Just a loosely related side note. There were a lot of TDI detectors that got replaced by White’s under warranty. How do I know this? White’s often simply replaced detectors that had a warranty issue instead of repairing them immediately. I’m not sure why, but that is what they did. These units were repaired at some point, and then offered to dealers at discount as “factory refurbished” with a full warranty.

I took advantage of this as a dealer for a couple purposes. I had full warranty refurbished models I could sell you for quite a bit less than my competition. I also could circumvent White’s dealer advertising restrictions by advertising these as “used” detectors. Nearly all of these looked exactly like a new detector in a box, with the exception of a blue slip explaining they were factory refurbished.

Long story short is White’s had an endless supply of these detectors. I probably sold more refurbs than new TDI detectors, as I never had anyone balk at saving $200-$300 dollars and still getting a full warranty. My theory is they actually were more reliable than a normal new unit, as they had been looked over quite well before getting that blue slip.

I tell this tale only in that it made me wonder why so many of these detector were returned to White’s. The TDI generated a lot of heat. And I speculated that perhaps the failures were related to component failures in the amp system. I don’t know for sure, but I just want people to know that boosting the voltage is not entirely without risk. The detector is not bulletproof. With the White’s factory closing their doors, getting repairs done could develop into an issue, especially if parts shortages develop.

[GB_Amateur]

2 hours ago, Steve Herschbach said:

There were a lot of TDI detectors that got replaced by White’s under warranty.

....

Do your observations apply to all TDI models or just the small box (SL)?

[Geotech]

After the first 200, the TDI used an Atmel micro that had a tendency to randomly lock up. When you turn on the TDI it would just squall. A lot of units were shipped and the problem didn't show up until after some usage. I found a nearly pin-compatible PIC micro, rewrote the code, and we had a drop-in replacement. Until I got that done we swapped out a lot of units. Sometimes more than once. The SL started out with the PIC so it never had the problem. I was never able to figure out why the Atmel locked up.

[havingstl]

3 hours ago, Geotech said:

After the first 200, the TDI used an Atmel micro that had a tendency to randomly lock up. When you turn on the TDI it would just squall. A lot of units were shipped and the problem didn't show up until after some usage. I found a nearly pin-compatible PIC micro, rewrote the code, and we had a drop-in replacement. Until I got that done we swapped out a lot of units. Sometimes more than once. The SL started out with the PIC so it never had the problem. I was never able to figure out why the Atmel locked up.

Would the unit lock up permanently or after enough resets it would operate again?

[Geotech]

19 minutes ago, havingstl said:

Would the unit lock up permanently or after enough resets it would operate again?

With most units flipping the power switch a few times would usually get it to kick on. Some, though, would lock up every time.