help needed with old detector

[keith777]

Hi guys.

i was wondering if anyone can give any information on this old detector. it was in a bit of a mess on the inside when i opened it as you can see from the photos. there was one component that had gone rusty. i went to unsold-er it to try and have a closer at it, but it fell apart in the process.
i was wondering. is it possible someone can make out what the part is that i need to replace it with.
also there is a battery holder for one 1.5v battery which need replacing as it is totally shot because of a battery been left in for a long time. this is no a problem. but there is also two battery terminals which looks like they would fit a standard square 9v battery, but the fitting are to dig to fit on plus you can not put both on together anyways. any ideas what voltage that will be running on?

thanks in advance guys.

[Koala]

I am on a little phone screen and it's hard to see the colours properly.

Its a resister


If it's orange black orange gold

30k at 5%

[WM6]

Citation from eBay:

"Manufactured by Young Electrionics, London, England.
Young's were bought out in 2013 by a military and defence technology company no user manual no longer available."

Resistor color code show 30k.

Maybe it is optical, but battery contacts seem a little big for regular 9V battery.
Other Young TR detector model (Fieldmaster) was supplied by 2x9V (18V?).

[kt315]

desolder the resistor, clear on edges and measure in those points.

[homefire]

Old BFO for sure. The caps I can see are only 10V so guessing it used 6 or 9V .

[keith777]

is that the resistor color code that i need. i have quit a few odds and sods of circuit boards laying about in the shed but non of that value on them. is there a 5 or 6 band etc resistor that i can use.

thanks for the help guys

[Davor]

Sure. Nowadays resistors are seldom 4 stripes 5% types, and are hell to read, so ask in a shop. It is always good to check the value with a meter before soldering it in.
But whatever ate through that resistor must have ruined PCB traces as well. Get ready for a big surprise there.

I'd say the battery terminal is supposed to be connected to a battery holder like this one:
https://cdn.solarbotics.com/products...1403.jpg?w=375
(I randomly picked this photo)
I can't say what voltage you need, but if there is a battery holder around you'll find out.

[keith777]

hi davor.
i checked the PCB traces. they were a bit powdery in some places but it rubbed off easy enough.
as for checking the value with a meter before soldering it in. i am lucky that i know how to do simple voltage checks with one.

[Polymer]

Hi Keith777,

Yes, that's the color code you need for a 30k resistor.

I find it hard to distinguish brown from orange in the photo.
Here are the combinations I can come up with for that resistor though:
brown black brown 100 ohms
brown black orange 10k ohms
orange black orange 30k ohms
orange black brown 300 ohms

As to the battery, since it seems vintage (like 60's or 70's) there are quite a few and
many oddball ones from that era with the type or connectors you have shown.

For example this (it won't be this one though):


Hopefully the battery you need might be 9 volts, but its maybe 6v or something in between.

How big is the space in the battery compartment? That might give us a clue more.

[Carl-NC]

Looks either brown-black-brown (100) or brown-black-orange (10k).

The battery snaps are more likely for an old obsolete battery like the PX19.

[Polymer]

I have just looked some more, being egged on by my childhood memories of oddball batteries.

This modern version might very well fit:
https://www.rapidonline.com/eveready...attery-18-0249

nostalgia batteries:

[Davor]

There is a 10V electrolyte capacitor on a main board, so I'd say it is safe to exclude anything beyond 9V. There are several possibilities, namely 4.5, 6, (7.5) and 9V. Considering the condition of the rig, powering it up should be attempted with a 50ohm resistor in series with a power supply. And start from 4.5 V. Just in case.

It should be possible to figure out the circuitry of the piggyback board the rusted resistor is on. It could be an amplifier or a voltage regulator. More photos are needed, and especially front and back side of a piggyback board. Whatever is written on the transistors and diodes is useful too. Also the wires - it is not possible from the photos so far to say which one goes where.

[keith777]

i forgot that there was a black clip holder next to the single 1.5v battery holder that i took off. i assume that this is the holder for the other battery.
the gap between the clip over connector measures 8mm and a regular 9v one measures 6mm.
i will take some more photos of the PCB etc in the morning.

[homefire]

As bad as that resistor looks my bet is it's still measurable. Only the Leads are toasted.

[kt315]

i did measure even a resistor that was fully burnt. trick is simple. delete a paint from whole resistor. accurately you must do. gently.
measure one whole part to edge of burn spot and another whole part - you get know approx the value. some additional info will give you also unburnt color belts.