President Jakson - no power Tx

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Lopez
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President Jakson - no power Tx

Post by Lopez » 19 Oct 2017, 13:48

hi guys
I have this radio and that was broken, the final transistor blow and i replace the original MRF477 for 2SC1969 but now don't have Tx anyway. The radio appear work fine but no power Tx

Radio Make and Model: President Jackson
PCB Number: PB042
PLL Number: MC145106P
Test gear available: only a multumeter
Symptoms: No power TX

What is working: It lights up and Rx fine, i guess...

anyone can help me?
were i looking for the problem?

can i check any voltages?

Thanks
Fábio

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Re: President Jakson - no power Tx

Post by 14CS06 » 20 Oct 2017, 10:54

Hello

Replace the original MRF477 for 2SC1969

Please look at this link

http://spectrum26.pagesperso-orange.fr/


Image

Image

http://spectrum26.pagesperso-orange.fr/ ... 20477.docx

1. VERIFICATION AND REPLACEMENT MRF 477 GRID and JACKSON Rest Current Adjustment
1) Verify that your transistor driver type 2SC 2166 is not HS because it is rather fragile and it would be stupid to replace a MRF 477 for nothing
For this you have several solutions, check the presence of the HF on its collector with an RF probe or check its junctions with a simple ohmmeter (not very reliable).

2) If your driver is OK we continue (no need to go further if you are not sure!).
3) The destruction of the PA transistor on a JACKSON often leads to the destruction of other components (remember that the PA works in class A = that is linear).
4) Before replacing it, check the following points:
5) Verify the adjustable resistance VR9 (100 ohms) = SOUVENT COUPEE
- Check resistance R237 (10 ohms) = OFTEN CUT
- Check capacitor C183 (10 PF)
- Check capacitor C184 (270 PF)
- Check the special diode (gauge) that is glued to the MRF477 and replace it if necessary with a 1N4148 (this is not the ideal but you have no choice because for a particular find a temperature sensor c ' is almost impossible).
Now you have the choice or hand over the original MRF 477 if you have the chance to own a replacement (unfilled to date or at a price approaching the price of the TX!).
The other solution is to put a transistor 2SC 1969 in its place:
Much has been written about this as the crossing of the paws; no need if you follow my advice!
WARNING VERY IMPORTANT (it has never been said on other sites!).
Please put an isolation mica behind your 2SC 1969.
Why ?
Simply because the old transistor had its transmitter (center tab) connected to the radiator = no risk because a class A transmitter is connected to the ground of the TX. Here are the two micas insulators (washer & rectangle):

The new (2SC 1969) has its collector (center tab) connected to the radiator = now the collector (powered by the + 12 volts) is connected to the chassis (you now understand the IMPORTANCE of the insulation of that -this ).

The transistor is fixed and its insulation checked to ohmmeter one can continue!
On my two attached photos I put POINTS of colors on the legs of the different transistors and on the welding points on the printed circuit board:

GREEN = BASE
BLUE = TRANSMITTER
RED = COLLECTOR

Just weld the legs of the 2SC1969 on the right colors and you will soon understand that it is not necessary to cross the legs of it because the manufacturer has provided a transmitter output (blue) in the center and left of its platinum printed!
Now (contrary to some people's assertions) the rest currents of the DRIVER and the PA must be adjusted.
To do this switch to channel 19 in USB mode
MIC gain to ZERO = significant.
Remove the PA / DRIVER power supply unit (the small copper bridge in front of the output stages).
Connect an ammeter between TP8 and TP6 set VR10 (left) to obtain a current of 80 MA.
Connect an ammeter between TP8 and TP7 set VR9 (right) to obtain a current of 35 MA (PA quiescent current).
These average values ​​can be refined if you have an oscilloscope to visualize the output signal:
These settings are made in BLU carrier (especially do not speak in the microphone during the tests!).
IF IMPOSSIBLE to have this range of settings = VALUE MUCH TOO HIGH (style over 500 MA) is that you have either the diode plated on the transistor roasted or the adjustable potentiometer RV9 value 100 ohms out of use because track cut!
Replace the power supply unit is switched to AM mode with mic / gain at max.
Set the AM power by VR11 to 8 Watts max for a 2SC1969 otherwise overruling.
Same as BLU on modulation tip (whistle) set with VR8 the power at 20 W PEP max.
Set VR12 for 92% AM modulation rate
The FM deviation (modulation rate) is set by VR4.
Calibrate your S / Meter in transmission with VR7 (red zone limit).
If OK the alignment is continued:
Check the potentiometer CARRIER VR5 = set it to have the least possible emission in BLU (without micro signal of course) = in principle it is in the middle of its travel.
This potentiometer is at the center of the TX (width direction) and just behind the integrated circuit IC3.
I give you the exact text of the manufacturer for this setting.
Adjusting the carrier on Jackson (CARRIER)
Set VR5 to achieve minimal carrier wave unmodulation for USB and LSB modes

I REPEAT that the replacement of a MRF 477 by a 2SC1969 greatly diminishes the performance of the TX (which can most can the least but not the opposite!)
This is especially true in BLU this remark!



1. VERIFICAÇÃO E SUBSTITUIÇÃO MRF 477 GRID e JACKSON Adjustment Current Adjustment
1) Verifique se o seu driver de transistor tipo 2SC 2166 não é HS porque é bastante frágil e seria estúpido substituir um MRF 477 por nada
Para isso, você possui várias soluções, verifique a presença da HF em seu coletor com uma sonda de RF ou verifique suas junções com um ohmímetro simples (não muito confiável).

2) Se o seu driver está OK, continuamos (não é necessário ir mais longe se não tiver certeza).
3) A destruição do transistor PA em um JACKSON geralmente leva à destruição de outros componentes (lembre-se de que o PA funciona na classe A = é linear).
4) Antes de substituí-lo, verifique os seguintes pontos:
5) Verifique a resistência ajustável VR9 (100 ohms) = COUPEE SOUVENTE
- Verificar a resistência R237 (10 ohms) = ESCURO CORTE
- Verifique o condensador C183 (10 PF)
- Verifique o condensador C184 (270 PF)
- Verifique o diodo especial (calibre) que é colado ao MRF477 e substitua-o, se necessário, por um 1N4148 (este não é o ideal, mas você não tem escolha porque, em particular, encontrar um sensor de temperatura c ' é quase impossível).
Agora você tem a escolha ou entrega o original MRF 477 se você tiver a chance de possuir uma substituição (não preenchida até a data ou a um preço aproximado do preço do TX!).
A outra solução é colocar um transistor 2SC 1969 em seu lugar:
Muito foi escrito sobre isso como o cruzamento das patas; não precisa se você seguir meu conselho!
AVISO MUITO IMPORTANTE (nunca foi dito em outros sites!).
Coloque uma mica de isolamento atrás do seu 2SC 1969.
Por quê?
Simplesmente porque o transistor antigo teve seu transmissor (guia central) conectado ao radiador = nenhum risco porque um transmissor de classe A está conectado ao solo do TX. Aqui estão os dois isoladores micas (lavador e retângulo):

O novo (2SC 1969) tem seu coletor (guia central) conectado ao radiador = agora o coletor (alimentado por + 12 volts) está conectado ao chassi (você agora entende a IMPORTÂNCIA do isolamento desse ).

O transistor é fixo e seu isolamento verificado para ohmímetro pode continuar!
Nas minhas duas fotos em anexo, coloquei PONTOS de cores nas pernas dos diferentes transistores e nos pontos de soldagem na placa de circuito impresso:

VERDE = BASE
AZUL = TRANSMISSOR
VERMELHO = COLECTOR

Basta soldar as pernas do 2SC1969 nas cores certas e logo entenderá que não é necessário atravessar as pernas porque o fabricante forneceu uma saída do transmissor (azul) no centro e À esquerda de sua platina impressa!
Agora (ao contrário das afirmações de algumas pessoas), as correntes de restrição do DRIVER e da PA devem ser ajustadas.
Para fazer isso, mude para o canal 19 no modo USB
Ganho de MIC para ZERO = significativo.
Remova a unidade de alimentação PA / DRIVER (a pequena ponte de cobre na frente dos estágios de saída).
Conecte um amperímetro entre TP8 e TP6 set VR10 (esquerda) para obter uma corrente de 80 MA.
Conecte um amperímetro entre TP8 e TP7, configure o VR9 (à direita) para obter uma corrente de 35 MA (corrente quiescente de PA).
Esses valores médios podem ser refinados se você tiver um osciloscópio para visualizar o sinal de saída:
Essas configurações são feitas no transportador BLU (especialmente não falam no microfone durante os testes!).
SE IMPOSSÍVEL ter essa gama de configurações = VALOR MUITO TOO ALTO (estilo superior a 500 MA) é que você tem o diodo chapeado no transistor assado ou o potenciômetro ajustável RV9 valor 100 ohms fora de uso porque corte de trilha!
Substituir a fonte de alimentação é trocado para modo AM com microfone / ganho no máximo.
Defina a potência AM por VR11 a 8 Watts max para um 2SC1969, de qualquer forma, anulando.
Igual ao BLU na ponta de modulação (apito) definido com VR8 a potência a 20 W PEP máx.
Definir VR12 para taxa de modulação de 92% AM
O desvio de FM (taxa de modulação) é definido pelo VR4.
Calibre seu S / Meter na transmissão com VR7 (limite de zona vermelha).
Se estiver bem, o alinhamento continuará:
Verifique o potenciômetro CARRIER VR5 = configure-o para ter a menor emissão possível em BLU (sem micro-sinal, é claro) = em princípio, está no meio de sua viagem.
Este potenciômetro está no centro do TX (direção da largura) e logo atrás do circuito integrado IC3.
Eu dou o texto exato do fabricante para esta configuração.
Ajustando o transportador em Jackson (CARRIER)
Configure o VR5 para conseguir a mínima modulação da onda do portador para modos USB e LSB

EU REPETIR que a substituição de um MRF 477 por um 2SC1969 diminui consideravelmente o desempenho do TX (o que pode ser o menor, mas não o oposto!)
Isto é especialmente verdadeiro em BLU esta observação!


@+
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Re: President Jakson - no power Tx

Post by cb4ever104 » 20 Oct 2017, 12:42

Lopez wrote:i replace the original MRF477 for 2SC1969 but now don't have Tx
As Claude has already said the 2SC1969 isn't a pin for pin replacement for the MRF477 . You need to modify the legs . Did you do that ? Also . You might find it hard to fault find on the output stage with just a multimeter . A scope would help a lot .

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Re: President Jakson - no power Tx

Post by dt307 » 20 Oct 2017, 12:58

I go a different way and its easy
Remove the two 560 caps and install a 2sc1945 15w -18w job done its a drop in.
I've also got a MOSFET in one of mine I did and that works great 35w
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Re: President Jakson - no power Tx

Post by Lopez » 20 Oct 2017, 13:40

hi, thanks for the help!!
cb4ever104 wrote:
Lopez wrote:i replace the original MRF477 for 2SC1969 but now don't have Tx
As Claude has already said the 2SC1969 isn't a pin for pin replacement for the MRF477 . You need to modify the legs . Did you do that ? Also . You might find it hard to fault find on the output stage with just a multimeter . A scope would help a lot .

Sammy

yes, i did that correction. The datasheet is my best friend in that decision :P

i'm check the tips of claude and i give a call. I suspect that 2sc2166 is burnt also, i go buying a new one and test it!

Can i align VR10 and VR9 with a multimeter or i need a old multimeter (that with needle)?

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Re: President Jakson - no power Tx

Post by Lopez » 20 Oct 2017, 13:47

dt307 wrote:I go a different way and its easy
Remove the two 560 caps and install a 2sc1945 15w -18w job done its a drop in.
I've also got a MOSFET in one of mine I did and that works great 35w

what mod i need to make to that? in future maybe i need to do that because the 2sc1969 is dificult to buy here...

you are talking to replace mrf477 with the IRF520 mosfet? did you have a "tutorial" to i looking for? if so, i keeping it in safe place for the future if you give to me!!

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Re: President Jakson - no power Tx

Post by Lopez » 20 Oct 2017, 13:49

thanks claude to the help and the tips...i check everything and come back later

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Re: President Jakson - no power Tx

Post by dt307 » 20 Oct 2017, 14:23

if you insist on doing the 1969 conversion
a good high res pic of the rear solder side of the pcb most mrf477 ive seen go short and take out the supply track
voltage readings on rx and tx of the
pre driver
driver
final
this will get sammy ,me and any one else all on the same page
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Re: President Jakson - no power Tx

Post by dt307 » 20 Oct 2017, 22:10

Lopez wrote:
dt307 wrote:I go a different way and its easy
Remove the two 560 caps and install a 2sc1945 15w -18w job done its a drop in.
I've also got a MOSFET in one of mine I did and that works great 35w

what mod i need to make to that? in future maybe i need to do that because the 2sc1969 is dificult to buy here...

you are talking to replace mrf477 with the IRF520 mosfet? did you have a "tutorial" to i looking for? if so, i keeping it in safe place for the future if you give to me!!

the 2sc1945 is by far the easy way, remove the caps check all your voltages are correct,drop the 1945 in check the bias and set the power level close the bonnet.

if you search here i know some one posted a guide but if you cant find anything i will do one but it wont be till next week

but will be a lot more simple if i send you a ekl369fn bias part and a fqp13n10 fet
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Re: President Jakson - no power Tx

Post by dt307 » 20 Oct 2017, 22:12

but i would like to see the voltages i asked for before you continue and some pics as to whats been done m8

there is no point trying to convert to mosfet if you have problem caused by the 477 going south as a 1969 will work if installed correct

whats been posted by claude and others is all you need to get it working with a 1969
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Re: President Jakson - no power Tx

Post by Black Spirit » 20 Oct 2017, 22:35

Hope you didnt throw the 477 away because to me it looks like the 477 may have been good and 2166 was actually at fault, Also check the bias diodes are still good.

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Re: President Jakson - no power Tx

Post by dt307 » 21 Oct 2017, 01:58

Black Spirit wrote:Hope you didnt throw the 477 away because to me it looks like the 477 may have been good and 2166 was actually at fault, Also check the bias diodes are still good.
that would be funny .....i presumed he checked the driver and diodes out and was good as he been given all the info needed to check them
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Re: President Jakson - no power Tx

Post by dt307 » 21 Oct 2017, 02:14

Lopez ...........let me crystal clear and basic as possible . "1. VERIFICATION AND REPLACEMENT MRF 477 GRID and JACKSON Rest Current Adjustment
1) Verify that your transistor driver type 2SC 2166 is not HS because it is rather fragile and it would be stupid to replace a MRF 477 for nothing" do you understand this and how to perform this test? this was the first thing was asked of you to do and is very valid and WILL tell you exactly which transistor/s are faulty.
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Re: President Jakson - no power Tx

Post by Lopez » 26 Oct 2017, 23:01

sorry for the delay...

yes i check the 2166 and the measurement is a litle bit strange. I order a new one to replace.

The MRF477, the radio don't have the original transistor and i don't know what was in the place because the other tecnician erase the chip...
I didnt take any measurements yet because dont have the 2166.
Tomorrow i will post the pictures og the radio now, before change the chips.


Thanks for all help guys

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Re: President Jakson - no power Tx

Post by Lopez » 26 Oct 2017, 23:06

Black Spirit wrote:Hope you didnt throw the 477 away because to me it looks like the 477 may have been good and 2166 was actually at fault, Also check the bias diodes are still good.

don't throw away but the arent the mrf477, is another chip but i don't see what because the other tech erase the chip!!! :thumbdown: :thumbdown:

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