trying to repair a Tesoro Vaquero.

[ejudasf]

Hello all.

Found a used and abused Vaquero on the marketplace for $80.00. I didn't notice it was missing the GB knob in the pic, so I talked him down to $40.00. He handed me a bag of replacement knobs and the GB pot with both nuts and washers.

At first turn on, without the GB in place, it just put out a solid beep. Re-installed the GB pot and after fiddling with it, on-off-on-off, it started to work in DISC mode. Switched to ALL-METAL, and it works. The GB feels a little janky with 'detents'. It's supposed to be smooth. I have ordered a new one from Mouser. I measured the resistance across the range, and it seemed to be good.

Here's the weird part. It won't detect a high conductive target in min DISC mode. It will beep on a nickel with the DISC at max. So the phase is way off. I don't see a way to adjust anything, as there aren't any tiny pots inside. I found a spot where one could go, but it doesn't look like it has been removed.

The sensitivity and DISC level pots have a built in switch. I have ordered a pair of those as well.

I see a total of 5 caps that can easily be replaced. I could do that.

I almost forgot. It came with an 8x11 DD coil. The DC resistance for pins 1&3 measure 4.9 ohms. GOOD. Pins 2&4 measure 100 ohms. Not sure if that is okay.

I was hoping to see a gutshot of another Vaquero, and also a DC resistance reading of another 8x11 DD coil.

Any suggestions, questions, and comments are welcome to get this machine back to tip top.

I know 1 person, who lives about an hour away, that owns a Vaquero. I think I will have to call him up to try his coil on my machine, after the cap replacement.

Thanks for any help.

[Carl-NC]

I get 4Ω and 60Ω. Are you sure you have the right GB pot value? Is it ground balanced?

[Qiaozhi]

This might be the Tesoro Vaquero schematic.
The GB pot is shown as 50k.

[ejudasf]

Thanks guys, for asking questions so quick.

The GB pot is the original pot. 50k and 3.75 turns. I have a new one coming in.

The ground balancing does work. It's not as drastic as my Bandito at extreme NEG. At extreme POS, they seem to be about the same.

I was kinda thinking that the coil might be 'out of whack', since it's measuring 100 ohms on pins 2&4. My first Tejon coil measured 5.1 and 65 ohms. This was back in the 90's. I kept notes on stuff like that.

I'll look over the schematic and hope that I can find my buddy to borrow his coil for a quick test. I really am leaning towards the coil being bad.

Thanks again guys.

[Aleks85]

Hi amigo, the link contains all the information I have about Tesoro sensors.
https://drive.google.com/drive/folde...-RpY51ftprIp0N

[ejudasf]

Hi amigo, the link contains all the information I have about Tesoro sensors.
https://drive.google.com/drive/folde...-RpY51ftprIp0N

Thanks Aleks85 for sharing that info with me. Your notes look like mine, except I still have mine in a notebook.

I must come to the realization that the coil I have is the culprit for the failure.

What's 40 ohms between friends? Just enough to cause havoc.

Tomorrow I should get all the parts I ordered from Mouser. It will have new pots and electrolytic caps.

The schematic that Qiaozhi shared, helped for verification of the caps. I think it might be a different version though. It does not match up 100%. I will try to mark the differences between my machine and the schematic.

I shall report back next week.

ed

[Carl-NC]

Most detectors are not especially sensitive to RX coil resistance. In the case of the Vaquero, a 100Ω shift will cause about a 0.16° phase error which is probably unnoticeable. However, it could be symptomatic of something else. I almost always recommend trying another coil when a detector is acting up, it's the weakest element in the circuit.

[kt315]

this is all i have.

[ejudasf]

Thanks for the images kt315. I see that there is an added cap on mine, touching the 8 o'clock position of the circle.

I did receive my parts in, so I will replace them and the GB pot. Everything else looks good.

BRB

ed

[ejudasf]

Small fun update.

Electrolytic caps and GB pot have been replaced.

I did order a couple of 100k w/switch pots as well. Mouser sent 10k. Oh well. I don't have to change those since the OEM ones do measure correct.

Since the coil does measure 100 ohms on the Rx side, pins 2&4 of the connector, I tried to fool the machine by placing a 180 ohm resistor across the pins. The Disc 'acts' a little more true. It detects a quarter. But the threshold is non existent.

I'll just wait to test with a friend's coil and/or till I get a chance to buy a replacement coil.

Thanks for ya'lls input on this matter.