IM-2715 Regulator Board HELP NEEDED!

[Robert Groh]

Sandy,

I spent a bit of time doing some research tonight and here are my comments/questions/recommendations:
1.  First I think you mean this is a IP-2715 (not an IM-2715).  

2.  Very simple circuit and you should be able to easily break the circuit into pieces to find out what is going down.  I suspect you either have bad capacitor(s) or one or more of the driver transistors are bad.  Could tell more if you could tell us what the symptoms are (.e.g. no output voltage, etc). But lets go with one we have.

Example trouble shooting process:
a)   Pull Q2 and put another power supply on Q2e (i.e. Q2's emitter - the base for the output pass elements). Put a light load on the IP-2715's output (e.g. enough to pull 30 mA at 12V, i.e. 390 ohms, 1W).  Set voltage on Q2e to 3V. Turn on the IP-2715.  You should see about 2.3V on the output (i.e. V(Q2e) - 0.7V or 3-0.7 = 2.3).  Increase V(Q2e) and the IP-2715 output should track with the 0.7V offset.

b)   If everything works, turn everything off - reinstall Q2 and pull Q1 - drive it's emitter with the external power supply  and repeat the process. Only diff - you should have about a 1.4V offset (i.e. 2 Vbe drops between Q2b and  the output. 

c).   If working, then back up one more stage and repeat.  Now you have a 3 base-emitter drop.

So I think you see where I am going with this.  Just break her down and find out where it doesn't work.  IC1 is nothing more than a regulated voltage source which drives (for current multiplication) 3 cascaded transistor amplifiers - all common collector.

By the way, the LM317 is apparently a good sub for IC1. There is a posting this forum (Jan. 30, 2001, Msg# 498 from Mike Miller that gives particulars.  I have data sheets, a schematic and parts info for the IP-2715 if you need info.

Hope this helps.

73
Bob Groh, WA2CKY




________________________________
From: "Alexander N. Gerli, Sr." <ac1y at NC.RR.COM>
To: HEATH at LISTS.TEMPE.GOV
Sent: Mon, January 11, 2010 3:06:36 PM
Subject: [HEATH-TEMPE] IM-2715 Regulator Board HELP NEEDED!

Hi, gang!

I have a basically working IM-2715 Battery Eliminator/PS, but its regulator
board is shot. I've tried to replace the pass transistor and regulator chip
to no avail. I am getting unregulated output of 18V from the transformer, so
I know that's all right.

I have an SB-104A with its HP-1144 PS and it occurs to me that the regulator
board for that PS is very similar to the one in the '2715, except that the
pass xstr in the HP-1144 is mounted onboard. Otherwise, according to the two
Manuals, they appear to be the same.

I want to save the '2715, but I need to fix (better, replace) its Regulator
Board. Can someone help me out? Seems that it would be nigh impossible to
find a spare original Regulator Board, so I could probably use one from an
HP-1144.

73,

Sandy AC1Y

Alexander N. (Sandy) Gerli, Sr.
4012 Bristol Road
Durham, NC  27707-5403
(919) 489-9638
CCA #AC96-00001

REAL radios glow in the dark!!!!


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