Cary Audio SLA-70B amplifier


I have no schematics for my SLA-70B and Cary Audio no longer offer technical support on this very old [27 year old] amp.  The LED light on the front panel of my SLA-70B Signature Amp does not work [does not light up]. Upon my opening the bottom panel I noticed that the positive side of the LED was “just hanging in the air.  Also a resistor 100K 5W was totally blown up so I cannot take a reading of it at all.

[I don't know why I cannot include an illustration of the issue in question]

The negative of the LED is connected. The positive (orange wire) is just floating loose.  There is a resistor 100K 5W which is connected to GRD and the other side has blown up.

I do hope someone can allow me to upload an illustration. It will definitely help in solving this issue.
Thanks, richfrank

richfrank

Showing 9 responses by richfrank

Based on the pictorial I can see the connections, but I cannot determine the CORECT VALUES. The small (blow-up) resistor, is it actually 100K 5W ??  And the 2 that are parallel: are they RED/VIOLET/YELLOW  ??  I can't tell.

Do you know what are the correct values?
How you doing oldtimer, I mean oldhvymec. That's just the problem; I can't do a schematic; I cannot even send a photo because there is no place to upload a photo. And why I can't do a schematic? Because I don't know what goes connected to what.  We have a wire just "swinging in the breeze" that is loose, one end from the positive of the LED and the other end ??  Don't know where it goes!  I can see the high voltage wires B+ going into a 5-lug connector and soldered to lug #1. Lug #2 is empty.  At lug #1- it has also connected to it,  2 resistors in parallel bands RED-VIOLET-YELLOW 5W each which connect at the other end to lug #5.  Lug #2 is EMPTY.  Lug #3 is GRD. Lug#4 is EMPTY. At lug #3 is the resistor in question: 100K 5W ..... and the other end is BLOWN UP.  So what do I have? I have one leg of a resistor blown up and I have one side of the + wire of the LED in the air.
IF I HAD A SCHEMATIC  or a pictorial  I could easily see where they are to be connected. Right now I can only guess.  I am counting on your vast experience to show me.  Was that you that sent a link from the UK? Let me take a peak at it and see if I can solve it.
Hope to hear from you shortly.  I like your commentaries.
richfrank
Hey Oldhvymec..  I can see the pictorial,  finally!

BTW: Those pictorials also show the bias potentiometer  OUTSIDE of the chassic. My amp is so old that the bias is inside. I think that is a fabulous idea to be able to modify my old amp.  The pictorial is not that clear. Maybe we can blow it up some to see it clearer. 
Sr oldhvymec. With all due respect to someone that appears to know what the problem is and knows how to fix it ...... It does no good to give me a "hint". This is not a school atmosphere. I have a problem and I am going to the "forum" and am asking for help. I cannot solve this problem either thru Cary Audio or by getting into the amplifier to track the problem if I do not know values. I know what a resistor is, what a cap is, lugs, etc. but if I do not have a value attached to the resistor or cap in the schematic and have no voltage values, I am stuck. So please, if you know the answer, don't give me a hint or tell me to open a 6-pak, HELP ME FIND THE SOLUTION. If you want to charge me for your knowledge, let me know, but don't give me hints. I am not a kid!

Thanks for all your input and ideas. I'm sure they are all valuable. I have a few issues that may clarify some of my uncertainties. 1- I am 75 years "young" and cannot LIFT a 50 lb amplifier by myself; much less flip it over.  
2- Although I am a retired engineer, I have some difficulty following a pictorial or schematic when there are no values attached to them. It does  not help me to see a schematic drawing of the item in question if I do not have a voltage reading or description of the item in question.

3- Not having readings I cannot tell if the LED is burned out or damaged or shorted out or the voltage readings on either side of the resistors are good or not [regardless of resistor reading which seem OK].

4- Last but not least, I am retired living in Panama, Republic of Panama where the Panama Canal is and there are very few (I have not found one) "local TECH" that are EVEN WILLING to look at a wired amplifier. I am doubting that anyone under 40 years of age has EVER seen a point-to-point wiring.
As an example I asked: What size or voltage reading do I need to get the LED? Answer: Oh, don't worry about that. They're all the same. "Say What"?
So, what am I asking for? HELP. Help from someone knowledged enough to try to give me some decent advise.
My last question is: Is there a difference in the LED used? How do I check if it is shorted out?  The power fuse is blowing up so something is not going right.

Hello imhififa. Your "link" takes me to a page that is not inexistence. Looks like it is from Italy? Don't know, but I could not get it open. Sorry my friend.
Does anyone have any idea the type and voltage/amperage requirements are for the power LED in the Cary SL-70B amp?  I have changed the resistors in question, and when I plug in the amp, the power fuse 3 AMP SLOW BLOW ---> BLOWS UP.  I'm thinking the power LED may be shorted perhaps? But where do I get a new one? What is the model number? When I walk into a tech shop and ask for a Power LED what other info is needed to obtain the correct one?
Hello decooney. Great info. Sorry to say that Sound & Music are a retailer of home sound equipment and have decent technicians that know how to INSTALL these equipments. They do very little repair.
They're recommending someone else, but the truth of the matter is that it is most difficult to find someone who knows about point-to-point wiring. Everyone knows about chips and circuit boards and mother boards.  I will keep on trying.