ITT Pinto radio

[yoriro38]

Hi.

I have an ITT Pinto radio and I need help. There is no sound from the radio. Loudspeaker is OK, transformer is OK, but there is no sound.

Where must I look?

[Cobaltblue]

Hi and welcome to the forum

Just to confirm the radio's identity I have taken a picture from the Crackles web site (now sadly RIP).

Have you checked the earpiece socket (it mutes the speaker when the earpiece is inserted and the contacts get dirty).

Also check the on off switch and that there are no cracks (dry joint) on the pcb soldered joints.

Cheers

Mike T

[yoriro38]

Originally Posted by Cobaltblue

Hi and welcome to the forum

Just to confirm the Radios identity I have taken a picture from the Crackles web site (now sadly RIP).

Cheers

Mike T

Yes you are right, my radio is the same.

[Station X]

The circuit is available here:-

https://www.service-data.com/product...78/4013/m12978

[yoriro38]

I can repair tube radios but I don't have information transistor radios. The on off knob is OK but I don't know how to check earpiece socket, the socket has 4 wires.

[yoriro38]

Hi there.

My hobby is tubes radios and I have some information about it but I haven't information about transistor radios. I have looked transistor radios on internet pages and the earpiece socket may be faulty but I don't know how to check this socket and how to bypass this socket. This socket has 4 wires. Will I replace electrolytic capacitors?

[Station X]

A fault which causes a radio to be completely dead should be easy to find.

Check the battery/mains changeover switch. Use you meter to check that power is actually reaching the radio. Clean the contacts on the ear piece socket.

[Cobaltblue]

I have attached a snip of the circuit for the earpiece socket.

It looks like 2 of the wires will go to the same place on the sockets and this is the common connection.

so the output connection and the loudspeaker connection are the two you need to join together.

Cheers

Mike T

[yoriro38]

Headphone socket pictures

[yoriro38]

There are 3 wire ,white,brown , and yellow but the yellow have a shield and white wire.the yellow wire connect on pcb board.

[Station X]

Just clean or bridge the contacts surrounded in red. Have you checked the other points I suggested?

[yoriro38]

Dear Graham I will chek your suggestions but I don't undersand some points,
are there two switch in radio
1-battery-mains changeover switch
2-on-off switch
if there are two switch please write me ;I will measure which points on circuit.

[Station X]

There are two switches in the path supplying DC voltage to this radio.

1. The battery/mains switch is operated when you plug the mains cord or flex into the radio. When plugged in it switches between the battery and the internal mains power supply unit of the radio. I have coloured it red on the attached extract from the circuit.

2. The OFF/ON switch is operated when you turn on the radio. I have coloured it blue on the attached extract from the circuit. It supplies power to the radio from the internal battery or internal mains power supply unit depending on whether or not the power cord is inserted.

You need to use your test meter to prove continuity through these switches and check that power is reaching the radio.

A good initial check would be to check the voltage across C701 with the set connected to the mains supply. Expect to see approximately 9 Volts.

PS. Check the 315mA mains fuse for continuity.

[yoriro38]

Hi Graham I measured c701 between two legs and it is 12vdc

[Station X]

A bit high, but the PSU could be off load. What DC voltages are you measuring from the tags of the OFF/ON switch to chassis?

[yoriro38]

Hi Graham
I measured these two points(red marked) when the on- off switch open.perhaps the battery-mains switch may be faulty

[Station X]

You should have measure 12V on the top contact as it's connected to C701 and you've already measured 12V there.

What do you measure on the other tag, ie the wiper? If it's zero volts then clean or bridge the switch.

[yoriro38]

sory sory, I forget schema

[Station X]

OK.

So you're measuring 12V DC between the two red arrows.

Now check that the 12V is passing through the BATTERY/MAINS switch and the OFF/ON switch and is reaching Fe304 and Fe405.

[yoriro38]

Hi Graham
I found the problem , battery-mains switch was faulty. Just now the radio is working perfect but the speaker(1.5watt) no strong. Thanks for your help.