General Electric RP-1590-A Stereo

Page 2 of 4 Previous  1, 2, 3, 4  Next

Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Thu Dec 25, 2014 1:06 pm

Additional tinkering has found a couple of fairly interesting faults. I say tinkering because this instrument has made me feel about as incompetent as anything I have worked on lately. The first fact I found out is that this thing may be afflicted with the malady of wanting to lift its traces at the most inopportune time. And that the speakers will work without the wing speakers attached. This thing has been a real pain at times.

I pulled the wing speaker female plugs (jacks) out and looked at them well. There is a really thin plastic washer between the two halves of the jack. One of these was broken. The effect was to short out the plug, rendering the left channel weak. I cut a new washer out of a piece of plastic drinking cup. That took care of that problem. I cleaned the plugs and jacks up really well, using an old Prevox brush and contact cleaner. Then I gave them a squirt of WD-40 just for grins. This put the instrument in good operating condition. I played my three records again, both sides and then retired the instrument for the evening.

The owner of the stereo called this morning, and I offered him a phone demonstration of his stereo. I powered it up and the turntable turned, but no music. I found the only tube lit was the rectifier. Since the red pilot light is across the filament tap of the power transformer, that makes the transformer good. The three amplifier tubes were dead as a hammer. No filaments. I pulled the tubes and found continuity on the filaments. Now I get to pull that chassis again, after I got everything back in the cabinet (!) and find out why I have no filaments to the amplifier tubes. This will make the third trace that I have had to repair. I sure hope this is not a trend.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Thu Dec 25, 2014 2:04 pm

It just wants lovin'.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Ragwire on Thu Dec 25, 2014 9:07 pm

Wildcat445 wrote:You guys may be getting sick of this project, but I am having a ball!...
WC

Oh no. It gets more interesting, actually.
avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Thu Dec 25, 2014 9:29 pm

I have read about the horrible PCB boards encountered in some GE equipment.  I have not personally experienced this until now.  Every time I fix one trace, another one fails.  I have considered the possibility of an undetected short of some kind, but have tentatively dismissed this possibility.  It seems that if I had a short, the instrument would not run well for two or three hours.  It fails when it is repowered after being allowed to cool off.  The only option I have at this point is to hard wire the chassis sufficiently to eliminate the traces failing.  The plate, screen, cathode and filament circuits at least.  I will evaluate the signal circuits to see how they act when I am done.  If this stereo were not a family heirloom, I would have trash canned the project by now as simply not worth the effort.  I can test and replace drifted resistors and may even replace the coupling caps while I am there.  This may turn out to be a labor of love, rather than one making any economic sense.

Since this is unchartered territory for me, I need some advice. First, should I use different colored wire for the various circuits, or would it be considered a "professional" repair if I used one color wire throughout? The PCB traces are all the same color and they will still be there for troubleshooting purposes. Also, where can I find some solid strand hookup wire? All I have found is stranded. 20 gauge should work, I would think. I have made spot repairs on PCB's but have never totally hardwired one.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Thu Dec 25, 2014 10:42 pm

RadioDaze has solid wire in 22 gauge.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Thu Dec 25, 2014 11:15 pm

Auto part stores carry solid wire in smaller gauges that work relatively well.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Thu Dec 25, 2014 11:27 pm

I never thought of an auto parts store, 75. Thanks.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Fri Dec 26, 2014 8:06 pm

This thing is gonna give me more gray hair than I already have! Rolling Eyes

I hope I can explain this properly so you guys can follow what I am doing.

I have no filaments lit on the 12AX7 and both 7189's. The rectifier lights. I have B+. I have screen and plate voltage. Just no filaments on the amplifier tubes. These filaments and the red pilot light are powered by a 12 volt (nominal) tap on the power transformer. The red pilot light works. There is a green wire from the power transformer for 12 volts + and a green with black tracer wire from the power transformer for the common. On the physical trace on the PCB, the common from the pilot light goes to the three tubes before it gets to chassis negative, the trace of which is behind the bolts that hold the PCB to a metal bracket. The positive to the three tubes runs off the same trace as the positive to the light. If I check for voltage across pins 4 & 5 on the three tubes, I get nothing. If I check from positive of any of the tubes to the common rail, I get voltage. This crazy thing should work. A resistance check on this circuit shows continuity across the tubes, the common is good, and the positive circuit shows continuity. Yet I have dead filaments. I do not have a set of jumper wires here. I may stop by RS on my way home from work and get a set. The positive trace from where the light junctions the filaments to the first 7189 has got to be open, even though it checks good. The trace that I repaired on the screen circuit checked the same way. It had continuity, but I still had no screen voltage. I am going to jumper from the positive on the light to the first 7189 and see what happens. The traces on this board all look good. This problem may be a fluke, so I won't have to totally rewire this chassis. BTW, the positive for the pilot light is right next to the place I repaired the screen supply wire. I wonder if I caused this condition myself somehow.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Fri Dec 26, 2014 9:12 pm

Are the PC traces uncoated so you could possibly do a reflow? If you use a relatively narrow tip and flux the trace, that can eliminate any trace fractures. We get them on equipment as new as 10 years old. The boards are acid etched and it makes the copper brittle and it can hairline fracture with any torsion. A reflow is one of the anyway jobs I do on old pc boards in need of repair.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Guest on Fri Dec 26, 2014 10:02 pm

If you want some 24ga solid wire, I can send you some or get some scrap from any telephone guy. I always use it to jump bad traces.

Guest
Guest


Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Fri Dec 26, 2014 11:49 pm

75, I appreciate you suggestion. I wonder if my hands are steady enough anymore for me to be able to do that. I think what is happening, somewhat confirmed by what you just pointed out, is that the trace may LOOK fine, but it is actually hairline fractured. It apparently shows continuity, but will not pass current. AND, I can't see exactly WHERE it is fractured. The wires from the transformer go thru two small holes in the board. There is another small hole where the pilot wires go thru the board. There is a blob of solder that covers the tips of these two wires, with the trace to the tubes flowing from there. The break must surely be immediately following the last little hole with the wire for the pilot light. You think if I heated this area I could reflow the trace? I've never done that before. I always just run a wire around the defective trace and move on. I am taking lots of time on this, I realize, but I am trying to learn something as I go. MR MEZ, I may take you up on your generous offer. I'll keep you informed of progress. I think you both.

I have some old telephone cords around here someplace. Would the wire from a phone cord be large enough to work for this? I never thought of that stuff.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Fri Dec 26, 2014 11:56 pm

If you should want to do a reflow, I strongly advise you to use flux. It will make the job so much easier and you will spend less time on the trace reducing the chance of a lift. Hopefully they would have some at the shack.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sat Dec 27, 2014 12:08 am

If I decide to try a reflow, do I just run my iron down the trace? Do I put the flux on the trace first then heat, or put the flux on the iron, or what procedure do you recommend?

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sat Dec 27, 2014 3:12 am

Make sure it's clean, usually a brush off with 91% iso alcohol will do, then apply the flux to the trace, then put a bit of solder, enough for a good plate and run the tip of the iron between the eyelets, just putting a coat of solder across the length, make sure it wets well.  If there any bad fractures, sometimes the crack will show through.  Make an L shape of solid wire and bridge the crack with the bottom bit and cut the vertical leaving the bottom horizontal bit to bridge the crack.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sat Dec 27, 2014 5:17 pm

Not that I claim to know what I am doing, but I am going to try and evaluate my chances of success on this thing. I don't want to have as much time in this project as I do in one of my Magnavoxes, but this instrument seriously needs help. Perhaps rewiring it is the soundest decision. I appreciate your input, 75. Whatever I decide to do, I only want to do it once.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sat Dec 27, 2014 5:19 pm

I give it good odds.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sat Dec 27, 2014 5:51 pm

I started out working on the kitchen island, but now I have record player parts all over the kitchen. I have gotten onto people in the past for working in horrible conditions, and here I am doing it myself. How complicated can a record player be?, I asked myself when I started. Pretty damned aggravating at times, is the correct answer. And that is no excuse to try to work on something without the proper tools. I figured a needle and some caps and maybe go thru the changer and I would be done. It just hasn't worked out like that. And no good deed goes unpunished. Heck, I'm not griping, per se. I appreciate the opportunity to feel stupid and learn something. And the faith that at least you, 75 and Don have in me. Maybe this stereo does not like Conway Twitty. Perhaps I should test it with a different record. Very Happy

I have been tinkering, trying to find a short or something that would cause all the PCB failures. I don't see a thing out of the ordinary other than the fact that I don't have any lit filaments in this amp chassis. This thing is like when you go out one morning and your car won't crank. You turn on the lights and they work. You reason the the starter must be bad, since the lights work. In reality, you have a bad battery. The lights take 20 amps and the starter takes 300 amps. The weak battery will supply 20 amps for the lights, but not 300 amps for the starter. That is the way running voltage on this PCB has been. I have voltage at times with the meter on the connection, but the break in the trace prevents enough current from flowing to light all three filaments. I have suffered with three lifted traces in about 3 hours of operation. I have to wonder about reliability down the road. I am not going to buy parts to amount to anything such as for the changer or any of that until I get the circuit board situation stabilized. That is my thinking at this point.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sat Dec 27, 2014 6:27 pm

The alarm systems I work with that uses the circuit boards that fracture easily also have battery charger and current/voltage monitoring boards. They will fail if anyone even thinks about them hard. An area with a high incidence of failure are the eyelet to connector joints, you may be having some of that where the tube bases are soldered to the board. After a while you get to sense where the failures are going to occur.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sat Dec 27, 2014 7:15 pm

What has been happening up to this point is that the failure seems to be not at the tube sockets, but at the power source.  The screen voltage problem occurred where the wire from the filter cap junctioned with the screen grid trace.  Both screens are connected to the same point.  I only lost one screen for some reason, though.  The failure (I think) with the filaments is at the point where the pilot light and filaments junction.  So you are right.  The problems appear to be at an eyelet or a junction.  I feel better that someone else has had this problem, and, in fact, it may be fairly common.  

75, do you think that this will be a recurring problem? Can I repair this breech and expect any type of reliability? I don't expect you to forecast the future. In your experience, can I expect more problems? Will I put this matter to rest by hardwiring the chassis?
WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sat Dec 27, 2014 7:20 pm

Just clean the joint well, flux it, give it a good reflow with a nice liquid looking surface, and clean it off afterward to check the joint. PC boards need hold no fear nor frustration.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by neali on Sat Dec 27, 2014 9:02 pm

75X11 wrote: PC boards need hold no fear nor frustration.

75, you ever work on a Predicta? Very Happy

neali
Member
Member

Number of posts : 184
Registration date : 2011-08-08

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sat Dec 27, 2014 10:08 pm

I won't try to diminish the difficulties of working on television chassis, but believe me, there is equipment I work on that looks like it was dug up at Gettysburg. They come from filthy damp deep underground recesses where the groundwater flows like artesian wells from the conduits that supply 13.8 kv to the transformers and rectifiers to provide 700v to run our electric train set. They put access control systems and fire alarms in these places and expect them to function like they were in an office building. Usually all I have is a tool bag and a butane soldering iron to do the rework with. I make decent money to do it, but it gets a bit trying at times. I've seen the internals on a couple of Predictas, and I would place that up there with lightning damage repair for it's recreational value. Smile
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by neali on Sun Dec 28, 2014 1:02 am

75, I am impressed, truly. Dealing with water is impossible, you have my eternal respect.

neali
Member
Member

Number of posts : 184
Registration date : 2011-08-08

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sun Dec 28, 2014 1:12 am

Wish I'd taken a camera to some of the sites. They're impressive.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 28, 2014 6:09 pm

I have taken pictures to chronicle my latest efforts. As soon as I get them downloaded to my PC, I'll post them here.

I have hardwired the filament circuit in the amplifier. The break was actually in the common leg of the filament circuit. The break was at the junction where the pilot light and tube filaments came together. I ran red wire to the positive terminals and a white wire to the common terminals. I have operating filaments and I have the stereo back. The motor mounts are so bad, I have to run the speed on 45 to play 33's, but I expected that. I'm lucky it turns at all. I found some two strand bell wire at HD for 24 cents a foot. I got ten feet, which gives me ten feet of red and ten feel of white wire. I got some flux, which definitely aids in soldering on PC boards. Thanks for that tip, 75. That saved me untold grief. I still may hardwire the entire chassis. That was a pretty straightforward operation. That may be Don't decision. I know he wants to keep everything as original as possible. I have caps ordered.

My next step is to order the necessary changer parts and dig into the changer.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Sponsored content


Sponsored content


Back to top Go down

Page 2 of 4 Previous  1, 2, 3, 4  Next

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum