Homebrew Record Player. BSR UA6 deck and RS Components. Stereo Amplifier.

[DMcMahon]

The 2.45V choke voltage does not make any sense, suggest you measure the choke input and output wires individually wrt (with respect to) ground as suggested in post 117, this is a DC voltage.

I assume by motherboard you mean the amplifier board, this time you measured 8V, previously you measured 5.42V (which would have meant a large voltage drop), so either something is changing or being measured differently.

As previously stated the amplifier voltage of around 8V seems too low, so can you measure the AC voltage arriving at the bridge rectifier, i.e. measure across the 2 wires that go back to the mains transformer secondary output. As always please be very careful safety wise when doing live measurements.

As already suggested you may need to consider getting someone experienced to help you either on site or take the unit to someone, we are obviously going round in circles with no good short-term outcome looking likely.

David

[Bigears]

The problem Dave is I am not too sure how to test them, also by the motherboard I meant the PCB, so really I am not sure where to fix the testing cables to, that's my problem , whoever thanks' for the your time and advice. Regards Ken

[Bigears]

Its not worth taking it to someone to repair as it was only something I picked up from a flea market to work on to try and get some hands-on experience, I have learned one thing and that is the out let from the pick-up arm goes to the Volume control and not to the out put transformer Hower Dave thanks for your time and advice regards Ken

[Refugee]

It is no more complicated than measuring a battery with your volt meter.
You should be able to get used to using a meter pretty quickly with a handful of old disposable batteries.

[DMcMahon]

Ken you have successfully connected and measured several DC voltages already, so nothing really different.

For any DC voltage measurement the -ve (negative) lead of the test meter should always be connected to the -ve connection at the unit, in this case the black lead at the large capacitor. The -ve lead of the test meter would normally be black and the meter connection will be black and often called "COM" (common).

The red +ve (positive) lead of the test meter should be plugged into the red terminal on the meter identified as V (depending upon the meter there may also be other additional markings). So the red lead is the lead to connect to the various points that you want to measure, leaving the black meter lead on the black wire connection at the capacitor.

For DC voltage measurements you must switch the test meter (normally a rotary switch) to the DC voltage setting that is identified as V with 2 lines above, the top line being unbroken and the lower line broken into 3 segments.

Note - The -ve connection in a circuit may sometimes also be referred to as Ground/GRD (particularly if the line is earthed), 0V (zero volts), COM (common) etc.

For AC voltage measurement both the red and black leads have to be connected across the AC voltage source, so in your case the leads should be connected to the 2 terminals on the black REC 41A bridge rectifier that the 2 wires that connect back to the mains transformer secondary winding. The other 2 terminals on the REC 41A are the rectified DC voltage output. The test meter should be switched to AC voltage which normally is identified as V with a wavy line above it.

Meter references above are for modern Digital Multimeters (DMM), similar but slightly different for Digital Voltmeter (DVM) and analogue test meters. Note - digital multimeters are often referred to as DVMs.

David

[DMcMahon]

Post 82 indicated that if the original turntable cartridge, it could be an Acos Hi G.

This is an old crystal cartridge that potentially could be no good.

As per Post 119 would be good to confirm the actual cartridge fitted, it may well have type number stamped on the underside of the cartridge body.

David

[DMcMahon]

Originally Posted by Bigears

today I found a broken wire on the output transformer I did a repair now I hums and crackle from the speaker, please see picture regards Ken

Since this have you at any stage tried the turntable playing a record operation ?

David

[Bigears]

I just need to know where the Red and black wires go from the pick up are to the volume is the red live and the black earth ? on the pictures would that be right Dave ? regards Ken

[Bigears]

these are the pictures Dave

[DMcMahon]

So are the red and black wires with crocodile clips the wires that go to the amplifier PCB or are they meter test leads ?

Normally would expect red to be the live/signal and black to be the ground/low. But it depends on how the corresponding smaller wires are actually connected at the cartridge pins.

Check the back of the cartridge to see which colour wire is connected to which pin (try and get a photo) once again would expect red to be the live/signal pin.

The cartridge pins should have some sort of identification such as +/-, Hi/Lo, Signal/grd etc. While checking also try and find the cartridge make/model details.

The red/black wires connection at the volume control I think has already been well covered.

David

[DMcMahon]

Thinking back there was reference to a screened/co-axial cable for the pickup, the inner core is the live/signal connection and the screen/braid is the low/ground connection.

David

[DMcMahon]

Originally Posted by DMcMahon

The red/black wires connection at the volume control I think has already been well covered.

David

Should have read - The screened/co-ax cable connections at the volume control have already been well covered.

David

[Bigears]

The Black and red leads are test leads going from the pick-up arm to the volume switch , on the pick up are its red to red black to black, then the same test leads go to the volume switch I think black is earth, I just want confirmation before I solder them Dave

[ms660]

Originally Posted by Bigears

The Black and red leads are test leads going from the pick-up arm to the volume switch , on the pick up are its red to red black to black, then the same test leads go to the volume switch I think black is earth, I just want confirmation before I solder them Dave

By convention and the photo's Black is ground (earth if you like) and Red is signal.

Lawrence.

[Bigears]

I know how to measure voltage in batteries, I know how to test resistance, I know how to test the ohms in a speaker, just not really sure where to put the test probes when testing say the output of the rectifier, or the transformer, I know if testing AC has to be on the A of the multimeter V~

[DMcMahon]

It will be difficult for anyone not familiar with circuit diagrams/electrical schematics and the associated hardware.

David

[Refugee]

The rectifier is connected to the capacitor with solid wires. The two parts when connected together do the same job as a battery.
Someone has fitted a smoothing choke in an attempt to get rid of hum from the pickup wires passing through the deck metalwork.
It really needs a three core mains lead with the earth connected to the transformer core and the deck metal work and the choke removed so that the amplifier is powered directly from the capacitor.

[DMcMahon]

Originally Posted by Refugee

It really needs a three core mains lead with the earth connected to the transformer core and the deck metal work and the choke removed so that the amplifier is powered directly from the capacitor.

By transformer core should the earth be connected to the SCN (screen) terminal as shown in Post # 114 photo attachement # 1 or to the transformer metalwork or both ?

David

[Bigears]

thank you Lawrence. that's a big help regards Ken

[Bigears]

Hi all I have connected the red and black wires from the input arm to the volume and I am getting sound and music through the speaker, put its not good, most likely the problem is in the next two picture Ive just sent, I will clean them up later, however this has been a good leaning exercise for me , many thanks to, Dave, Lawrence, Graham and Edward regards Ken