9090 rhythmic dropouts??

Boobtubeman

Sleeps with tv parts
Hehehe best way i could describe it... :D

Basicly, as described in my previous thread, im trying to restore the family 9090 that has finaly come home but suffered some in-law hands inside.. Protection issue is resolved, onto the next issue...

Turns out, the radio and pre-sections were dead due to a failure in tr1-3 on the power board.. I used NTE289 on tr 1 and 3. I used NTE152 on tr2..

Upon power up, i was greeted with music however, the sound would cut in and out. I hooked a meter to pin15 and noticed the power level was dropping off a few volts every second in rhythm (like a turn signal on a car)

Seems to be only in this power area as nothing else (lights, amp,protection relay) is affected... Power supplied from D01 is steady.

Are my new transistors suspect???

SR
 
Well your not out of the woods yet… personally I never cared for NTE subs… so if nothing else a caution flag there. Lets play confirm the volts.
F-2546
The positive side C-02 is_______? And does that bounce?
The junction of R-04 R-05 is _______? ( does that bounce ) ?

The 36V output of F-2546 goes to the EQ 2541( first ) so you might want to have loudness and all EQ out AND F-2543 master vol, bal & Mic pre PLUS F-2543 has a sub regulator to step the 36V to 33V to feed F-2544 ( tone control circuit ) AND to the silly F-2431 step down reg for FM ( which is a known failure point )..

So it's a crap shoot…. Does the unit do it at idle?
 
As per the schematic....
TR-01 TR-03 2SC1211 ( C,D ) NPN
TR-02 2SD313 (C,D,E ) NPN TO-220 E-C-B from front
I do not have a cross for those on file...
 
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c02+ is 43v drops to 42 on bounce.....

If you mean the common rail r04-r05 share, its bouncing 13v-15v.....

Pin 15 24v-26v bounces..

output on D01 is 50v tiny to no bounce..

I did some poking around the tr1 and tr3 and the bounce is quite pronounced..

If you mean idle as in like AUX no input, it sounds like a heartbeat so much i pulled the rings to PRE and MAIN just so the amp wouldnt get the surged audio signal. Amp quiets after pulled off PREamp

Volts continue to flux in idle and Music from FM...

Starting to suspect the NTE stuff especially tr1 and 3.. Unless i have a bad cap in that area..

SR
 
And you need to be +36 volts on 15

and ( if I understand you ) the range is +24 ~+26..... which is more than 10 volts outta range of spec...

Do the NTE devices feel hot?
 
Hehehe well i didnt know what ya meant by junction and idle... :D

Tr2 feels a bit hot.... 1 and 3 dont feel hot....

SR
 
I used those NTE parts to fix my 9090. 289A instead of 289 though. Works great. I can't say they aren't junk, but they are better than whatever was in there! Lol. It was what my local electronic shop recommended as subs. My preamp wasn't getting power either. Anyhow, just wanted to say those parts worked for me. Now, I wouldn't use NTE for main output transistors lol. I understand their reputation. Good luck!
 
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Yep, looks like this one is gonna be on ME...

FRYS only had 289.. looks like 289A is the one i should have used. thought they were the same, THEYRE NOT... 289A handles more power...

Guess im gonna have to order them from somewhere...

Well...... Back to the gutter...... :(

SR
 
Hehehehe whoops indeed... My local FRYS only sells the whole numbers, No A,B,C
I remember going back to that aisle twice and looking. I used tube logic towards transistor purchasing... They are pretty much the same transistor EXCEPT the 289 A has a higher power rating...

On the upside, aside from the voltage bounce, ITS ALIVE!! :D

Perhaps even better when the right ones show up.. :thmbsp:

SR
 
NTE is like ACME. You do a cross reference search for 25 different transistors and the same part # comes up. Sometimes you can get away with it , especially in the power supply but that's about it- how can 1 transistor cover all the gains, frequencies , pinouts and voltages of 25 different transistors? It simply cannot.
 
A lot better replacement parts are OnSemi and Fairchild. Available @ Mouser.

2sd313 use MJE15032G or KSC2703 (onsemi and fairchild)

2sc1211 use KSP05 or MPSA05 (both Fairchild)
 
Larry THANKS just added this to my X file !
I will drag out my closet queen 9090… soon great info…
BK maybe boobtube likes that anvil drop on head like Wiley Coyote
 
Cant say im a fan of anvils... Used to be 7 tv shops here, ALL ARE GONE... RS used to have a warehouse/store with a knowledgeable employee... CLOSED.. Small shop in mall still open Cashier doesnt know S**T!!..

LAST RESORT: Drive 22+ miles to a FRYS who only stocks ACME... Havent bought transistors in 10 yrs never knew NTE was bad... till NOW...

But hey, i gave it a shot......

SR
 
Boobtubeman... get set up with Digikay or Mouser... only takes a minute, get quality parts.. EZ online ordering, cheaper than RS or Fry's.. if you chat with em they will assist you with parts substutitions or just general info.. ship as fast or as slow as you want..
It's ALL good...
 
Yep, gonna have to do that.. Just sad these places here are gone... The disposable age has arrived... Interactive assistance is almost dead these days...

Used to order caps from Justradios and he'd take my list and make the necessary, subs, nowadays, he just refers me to the order form and helps not at all... Gonna have to check out these places... :)

SR
 
My 9090 is a Hanger Queen. The amp board is toast. I have my Weller WLC-100 station set to 4 or 5 and the G.D. traces ALL lifted and broke off. WTF? Crappiest board I've ever worked on. I tried to bridge with scrap cap leads, but small stuff like that ain't fun having to wear 10X magnifiers just to see what I'm doing.

So I either sell the damned thing for parts and hope I get what i paid for it, or get a good working board, and new outputs (2 are blown now due to the board before I got it).

It's a pretty looking unit, but Damn, Sansui could have designed a board with better traces. My 2000 has better, heavier traces! Hell, the phono board on my 1000A beats the 9090 all to hell.

Larry

Larry
 
Yeah this one had the tracks lift on tr1 and 3. Now i need to re- do those 2 transistors again... UGH....

SR
 
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