JVC HR-2200 help - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

8 Tracker · 21st May 2014, 11:52 am

Ian: yes, forgot to mention that fuse. It was wrapped in silver paper on the first machine! When I replaced it, it lasted for a while, then blew randomly again later. The third machine is now on its' third day of working without a fault. This is a record and I am hopeful it is now sorted.

I have some more circuit diagrams available if you need them.

Mark.

IanNVJ35 · 21st May 2014, 2:04 pm

If you find what causes this strange fault please do let me know. I've been going over the board very carefully but nothing seems to be damaged or short. I'm in two minds about desoldering the large IC and see what happens.

IanNVJ35 · 23rd May 2014, 11:34 pm

May I ask for some help? What trying to locate power transistor X3 on the front PCB with all the controls on it - but I can't seem to locate it on the diagram.

I have been replacing many leaking capacitors and now the mechanism is still apart from the head running constantly. X3 is getting red hot almost instantly - I'd love to know what it does.

Thanks for any help.

8 Tracker · 24th May 2014, 9:41 am

Here it is Ian, although this does not look like a power tranny. X2 is and is right next door.

I'd be very interested to know what caps you replaced, as I would like to get a second machine out of the three up and running if possible.

Mark.

IanNVJ35 · 24th May 2014, 2:10 pm

Thanks - and you are right - it is X2 (misread the PCB). Any suggestions on what it feeds?

Concerning the capacitors firstly go over the printed side of all boards with a magnifier. Look for corrosion - some capacitors look fine but sent a conductive corrosion through the solder joints. None of the yellow caps were faulty but small value black capacitors were faulty on most boards. C18, C2, C9, C7 on the front board C54 on the board below the head C48, C35, C77, C34 on the right hand board are just a few. All the black capacitors are suspect.

8 Tracker · 25th May 2014, 9:57 am

Ian,

X2 is the 10v supply regulator. Don't know everything it feeds, but it certainly supplies the processor on the audio/CPU board. Check the reset pin on the CPU (pin 7, IC4). It should be low after a short delay at switch on. If it remains high, the processor will be held in a permanant reset state. IC3 (bottom left on the circuit) is the reset pulse generator. C70 charges at turn-on and the op-amp output switches from high to low.

Also, check the transistor bridges that operate the two solenoids and the loading motor at the bottom of the circuit. One of them was short C-E on my board. This my well have been the cause of the blown fuse. I suspect that both arms of the bridge had been switched on together at some point.

Spurred on by your comments about the caps, I went back to my first machine and had a look at the processor. Sure enough, the reset pin was held high. C70 was the cause, it was leaking so badly that it would not charge up to a high enough level to switch the op-amp. When I changed it, the machine burst into life. I also changed all the black caps on that board. I see what you mean about them leaking.

Mark.

IanNVJ35 · 25th May 2014, 9:27 pm

Thanks - and my C70 was dried out too (missed that one). I now have a constantly spinning head and nothing else. The fuse isn't blowing any more but X2 gets hot so quickly (burning) I don't have time to fault find. As the machine really does need to be powered for me to do measurement I am at an impasse so sadly I will not be able to go any further with this one.

Glad you got yours going though - how's the picture quality?

8 Tracker · 26th May 2014, 5:44 pm

Don't give up just yet, Ian. Did you check the reset pin on the CPU and the transistors as per my last post? The 10v line only feeds the audio/CPU board, so the fault must be on there. Check X16-29 for C-E shorts. Also check the area around IC3 (bottom right on the drawing). I think this provides a pulse on switch-on to the two solenoids to ensure they are in the disengaged position. Particularly, check C61 around this area.

My first fixed machine (no.3) is giving good, reliable results now with pretty good picture quality. When I have time, I want to treat it to a full alignment. I will also go through and change all the black caps.

The other machine that is sort-of-working is really a hybrid of machines 1 and 2 now. It has the noisiest head drum I have ever heard. I am currently in the process of swapping them over. It has a strange fault in that when there is no tape in, the capstan works normally, but when I put a tape in, it stops and starts. This is a control problem as the voltage to the motor is intermittant. It was producing a picture of sorts before I removed the head drum.

Mark.

IanNVJ35 · 26th May 2014, 9:02 pm

Thanks Mark for the thoughts. I was not 100% sure what you meant by the transistor bridge - I did check the two trannies around where the solenoid and loading motor connects to the board - they were ok - is that what you meant? I did try to check the reset but the smell of burning transistor X2 stopped me before I have a chance. I may just let it burn whilst I do the check - it is replaceable I suppose. Nothing to lose really.

21st May 2014, 11:52 am	#21
8 Tracker Hexode Join Date: Jul 2009 Location: Mablethorpe, Lincolnshire, UK. Posts: 286	Re: JVC HR-2200 help Ian: yes, forgot to mention that fuse. It was wrapped in silver paper on the first machine! When I replaced it, it lasted for a while, then blew randomly again later. The third machine is now on its' third day of working without a fault. This is a record and I am hopeful it is now sorted. I have some more circuit diagrams available if you need them. Mark.

21st May 2014, 2:04 pm	#22
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: JVC HR-2200 help If you find what causes this strange fault please do let me know. I've been going over the board very carefully but nothing seems to be damaged or short. I'm in two minds about desoldering the large IC and see what happens.

23rd May 2014, 11:34 pm	#23
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: JVC HR-2200 help May I ask for some help? What trying to locate power transistor X3 on the front PCB with all the controls on it - but I can't seem to locate it on the diagram. I have been replacing many leaking capacitors and now the mechanism is still apart from the head running constantly. X3 is getting red hot almost instantly - I'd love to know what it does. Thanks for any help.

24th May 2014, 2:10 pm	#25
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: JVC HR-2200 help Thanks - and you are right - it is X2 (misread the PCB). Any suggestions on what it feeds? Concerning the capacitors firstly go over the printed side of all boards with a magnifier. Look for corrosion - some capacitors look fine but sent a conductive corrosion through the solder joints. None of the yellow caps were faulty but small value black capacitors were faulty on most boards. C18, C2, C9, C7 on the front board C54 on the board below the head C48, C35, C77, C34 on the right hand board are just a few. All the black capacitors are suspect.

25th May 2014, 9:27 pm	#27
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: JVC HR-2200 help Thanks - and my C70 was dried out too (missed that one). I now have a constantly spinning head and nothing else. The fuse isn't blowing any more but X2 gets hot so quickly (burning) I don't have time to fault find. As the machine really does need to be powered for me to do measurement I am at an impasse so sadly I will not be able to go any further with this one. Glad you got yours going though - how's the picture quality?

26th May 2014, 5:44 pm	#28
8 Tracker Hexode Join Date: Jul 2009 Location: Mablethorpe, Lincolnshire, UK. Posts: 286	Re: JVC HR-2200 help Don't give up just yet, Ian. Did you check the reset pin on the CPU and the transistors as per my last post? The 10v line only feeds the audio/CPU board, so the fault must be on there. Check X16-29 for C-E shorts. Also check the area around IC3 (bottom right on the drawing). I think this provides a pulse on switch-on to the two solenoids to ensure they are in the disengaged position. Particularly, check C61 around this area. My first fixed machine (no.3) is giving good, reliable results now with pretty good picture quality. When I have time, I want to treat it to a full alignment. I will also go through and change all the black caps. The other machine that is sort-of-working is really a hybrid of machines 1 and 2 now. It has the noisiest head drum I have ever heard. I am currently in the process of swapping them over. It has a strange fault in that when there is no tape in, the capstan works normally, but when I put a tape in, it stops and starts. This is a control problem as the voltage to the motor is intermittant. It was producing a picture of sorts before I removed the head drum. Mark.

26th May 2014, 9:02 pm	#29
IanNVJ35 Heptode Join Date: Mar 2010 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 846	Re: JVC HR-2200 help Thanks Mark for the thoughts. I was not 100% sure what you meant by the transistor bridge - I did check the two trannies around where the solenoid and loading motor connects to the board - they were ok - is that what you meant? I did try to check the reset but the smell of burning transistor X2 stopped me before I have a chance. I may just let it burn whilst I do the check - it is replaceable I suppose. Nothing to lose really.