My Sony FH-100W has a TC-157W dual tape deck. Playback on both tape A and B player is great no issues. When recording to a tape (type1) or chrome on playback the left channel sounds great with correct level but the right channel can barely be heard. The right channel record level pot does not change it. I have looked over the board for any dry joints and checked there is good continuity from the amp to the connector on the back of the tape deck. The 13 pin plug, pin 9 is REC in right channel and 10 is rec in left channel. thanks
I can try to guide you in finding what the problem is, but I need a little bit more info as I'm not familiar with this unit and cannot find a service manual for it either. There are a couple of things I noticed: the unit is full logic, which means it doesn't have the typical REC/play slide switch. Given that the unit plays ok, I wouldn't consider the head to be a potential problem. 1. What do you mean by the right channel record level pot ? From what I can see there is no record level pot on this unit. Are you reffering to the internal trimpot ? 2. From what source are you recording on ? Does this happen independent of recording source ? 3. Do you have an oscilloscope ? If you can, provide some pictures of the internals.
Thanks for your reply. I have attached pics of the cassette recorder and the service manual (FH-110W is the same just with a digital tuner) The right channel rec in pot is located in the centre of the cassette recorder main board RV203 see the attached pic from the service manual. I have tried recording to tape from the radio unit and from Aux in from a cd player and from tape A to tape B with same result. I do not have a scope Correct I thought the same since the playback on tape B is fine for FWD and REV playback I thought the head was not the issue. The service manual is too large to upload so here is the link for the FH-110W https://freeservicemanuals.info/en/servicemanuals/viewmanual/Sony/FH110W/
Something that I immediately noticed in your picutres is corrosion on the PCB, possibly from leaked capacitors. Given your symptom, I would check the Automatic Gain Control amplifier (IC301 on the schematic) and its muting circuit first, as that is what sets the record level. There are some electrolytic capacitors in that circuit, so I would check those first. The signal goes into that AGC amp, then into the Dolby IC and REC EQ amp. The adjustment you have tried to make also affects the Dolby level on recording, so it's important that you set that correctly after repairing the problem.
Thanks I will change out the caps on the AGC amp section I only moved the recording level very slightly and moved it back to the same position after finding it made no difference.
Check to see if they are leaky first. The corrosion I see on the PCB is not on that area and it may not even be related to leaky capacitors. That's why I said it's a possibility, not a certainty. Given what you say now, that you only moved the rec level trimpot slightly, take into consideration that a tiny adjustment will not make an audible difference. I would mark its position with a marker and then turn it all the way up. Only then you can clearly see if it makes a difference or not. I would investigate further before changing any components, because you can end up changing capacitors without any result. ICs and transistors can also go bad. If you have at least a multimeter, I would proceed in the following way: generate a test signal (you can do that from a computer or digital audio player) of 1Khz, put the unit in record mode and measure the AC voltage: - at the input and output of AGC amp - at the input and output of Dolby amp - at the input and output of REC EQ amp
I can not see any cap leakage on the board. All caps look fine. In saying that I did replace the caps for the AGC amp I will try turning the RV203 all the way up. Will try the 1Khz tests thanks
The RV203 pot turned all the way up made a tiny tiny difference. The Left channel pot makes a big difference to the left channel as expected. Will try the 1Khz tests next.
Hi ... I downloaded the schematic ... and observing it I realized that it uses a relay to make the exchange from listen to record ..... Have you already checked it? That Relay is connected directly to the head ... if one of the contacts is dirty you may have the problem ... I enjoyed doing some copy and paste with the diagram to be clearer I am attaching a couple of photos ... . ... But in the end I took a closer look at your photos and noticed that just in the affected area there seems to be something between two pins of the head connector ... I hope all this can help you solve
Thanks for all your help with this ! So from the top diagram is that showing the relay in the playback or record state? Do you know what the relay connects to when its in record state? for Right and left channel? I was going to do a continuity test while recording I cleaned the CN303 pins you showed in the last pic with ISO and a toothbrush and they are now free of any flux. I have resoldered those pins and the relay pins too.
The relay is a double pole double throw one, so it has both channels into a single relay. I've marked on the PCB layout what is the one you are interested in. What I would measure instead is if there is any AC voltage drop across the relay's contacts, as there shouldn't be any when it's in closed position. Measuring the continuity in circuit may be thrown off by the presence of the bias signal. Just hope that your multimeter can measure AC signals of that frequency (it's in the range of 80-100Khz). @Silver965 Great job with the pictures ! I like it a lot how you explained it ! I really missed that relay, but that is likely to be the problem is in this unit.
Hello ... this relay grounded the recording output during listening ... during recording it grounded the audio preamplifier input ... On the diagram as it is drawn and in the listening phase ... photos that I put now and in the recording phase .... Check L203 -L103 and then C223-C123 ... or IC303 for now
The relay seems to be working fine as it moves when I press the REC button and back when I press stop. What should the values of L203 -L103 and then C223-C123 be? I do not see any cap leakage. I checked voltages for IC303 and all pins were correct voltages. while recording So does the right channel signal output from Pin 8 on IC303 then make its way to the head?
Yes in the recording phase ic303 sends audio to the head .. The output pins of ic303 are number 1 L channel and 7 R channel ... Since you have a working channel you could compare the values between one channel and another .... L203 measures the continuity and compare it with L103 ... if L203 is burnt the audio passes only from the capacitor C234 connected in parallel but it will be with a lower level I think .... if in that area everything is ok instead, move on to compare C223 with C123
ok thanks will check that Am I measuring AC or DC volts? Will be mV or volts? for L203 and L103? For the C123 and C223 should they be AC or DC volts ?
