varioprop 12s repair

[vari21]

hi dr depper, yes i agree with you the only ones available on ebay are BC547B but not BC547 which is 300mhz,and i think they are not the same.

 

[vari21]

anyway i ve already ordered 5pcs of philips bf199 1100mhz they comes from an old new stock please check this out

5pcs BF199 NPN transistor 25V 50mA 350mW TO-92 1100MHZ Philips | eBay

Les meilleures offres pour 5pcs BF199 NPN transistor 25V 50mA 350mW TO-92 1100MHZ Philips sont sur eBay ✓ Comparez les prix et les spécificités des produits neufs et d'occasion ✓ Pleins d'articles en livraison gratuite!

www.ebay.fr

 

[vari21]

hi dr pepper bc547b are available but not bc547 ,and i think they are not the same.
anyway i ve already ordered this please check this out.

5pcs BF199 NPN transistor 25V 50mA 350mW TO-92 1100MHZ Philips | eBay

Les meilleures offres pour 5pcs BF199 NPN transistor 25V 50mA 350mW TO-92 1100MHZ Philips sont sur eBay ✓ Comparez les prix et les spécificités des produits neufs et d'occasion ✓ Pleins d'articles en livraison gratuite!

www.ebay.fr

 

[Nigel Goodwin]

hi dr pepper bc547b are available but not bc547 ,and i think they are not the same.

The final letter ('b' in this case) simply signifies the gain range of the transistor 'b' is 200-450 and 'c' is 420-800.

When describing a transistor most people wouldn't specify the last letter, and a plain BC547 could have a gain from 200-800.

So same device, simply selected for gain.

 

[dr pepper]

I agree with nige.

 

[vari21]

i could nt find the bc 547 , bc547b only available and im sure are not the same.

 

[vari21]

thanks nigel in this case i have the 547B inside my box i will try it.
i ve ordered also the bf199 1100mhz from ebay it s a new old stock.

 

[vari21]

Finally it worked with 2N2222 , the emiter was nt soldered properly that s why.. relax for radio n1 .
but i have another varioprop12S same yellow one that i want also to repair the problem is i ve plugged by mistake the 12v battery in reverse polarity since then it stopped working , when i switch it on it turns on but nothing more, receiver not receiving anything.
surely one or more components are destroyed i dont know were to start investagating any idea thanks.

 

[Diver300]

Start by looking for burned components. If there are none, see if it is taking too much current. If it is taking too much current, or if any components are getting hot.

Reverse polarity could damage T102, T104, T110 and possibly the IC.

If it isn't taking too much current, and nothing is getting too hot, check the regulated supply between pins 14 and 7 of the IC. You should get around 5.5 V there.

Post your findings after that.

 

[dr pepper]

If the Ic is toast and it likely is if replacements are not available then its probably only good for parts.
You can make a simple rf probe from a cap, resistor and diode, if you have a digital multimeter then you can check if the transmitter actually transmits, and you have a means to check the rf probe as you have a working transmitter.

 

[Diver300]

The IC is a 74164. You could almost certainly use a 74LS164 instead, which is in stock at RS for £0.61. Cricklewood electronics have the 74164 for £2.50

I'm not sure if the IC would be damaged by reverse polarity to the whole circuit, as there is a regulator in the way.

 

[dr pepper]

Ok I didnt check that, I assumed again, it would be some special remote control chp.
I agree an Ls would probably work, might even be able to get an Act to work.

 

[vari21]

hi everyone ,the IC chip on my board is GZF1100 1YH7318UH , sorry guys i dont know the pineout of that chip. i ve checked with my l multimeter contuniuty mode and i ve noticed that the last pin is connected to the ground but i dont know were is located pin7.

 

[dr pepper]

Look at the chip with the notch or dimple in the top of the plastic case to the left, pin 1 is then bottom left.

 

[Diver300]

The circuit diagram that you posted has the IC labelled as a 74164. I have only done a brief check of the connections to the pins. The circuit would seem to work with the SN74164.

The SN74164 has been available since about 1975. I'm not sure if the exact IC is made any more, but the 74LS164 and the 74HC164 are, and either would probably work as a direct replacement.

The data sheet for the 74HC164 is here:- https://assets.nexperia.com/documents/data-sheet/74HC_HCT164.pdf Figure 5 shows the pinout.

 

[dr pepper]

Interesting design, it looks like the device is being used as an analog switch.

 

[vari21]

sorry about the circuit diagram of varioprop12S i ve posted ,my varioprop 12s has a different chip ,but im sure it can be replaced with 74164 IC since all other components of the circuit are similar but i could be wrong.

anyway i ve checked a voltage with my digital multimeter set on DC. black probe touching pin 7 red probbe touching pin 14 it reads 03.93 (when looking at the chip from the top red dot on the right hand side) pin 1 of the chip buttom left pin 7 buttom(ground) right pin 14 upper left.please correct me if im wrong.

 

[vari21]

just to give you an idea ,i took this picture from the internet but it is similar to my pcb.

 

[Nigel Goodwin]

Interesting design, it looks like the device is being used as an analog switch.

No, not as such - it's similar to reading a pot on a PIC without an ADC - you charge a capacitor and measure how long it takes to do so. In this case you're actually wanting timed pulses, so no 'measuring' involved, just the outputting of each pulse in turn. I recall a similar chip been used a number of decades ago in a magazine project for an RC system.

So it's essentially a simple ADC, created by waiting for a capacitor to charge to the switching threshold of the chip - so using LS or HC versions 'might' not work, as they probably have different threshold voltages?.

 

[vari21]

excuse me what type of capacitor should i use ,how to make that please do you have a diagram or something ,sorry my electronic level is low.