Resonant Power Technology

6041-1100-03

A18

Although I was unable to diagnose the problem, when I took the power supply module to Resonate Power Technology in Milpitas, California they were able to repair it very quickly. This repair was around 1999 or 2000.

Block Diagram

RPT6041.DWF
To view this file you need to use the free WHIP! plug in from Autodesk.

115/230 to 300 VDC

It takes in the 115 or 230 volts and converts it into 300 VDC.  This is done in the input side clam shell of the dual clam shell power supply.  Because there is no mains frequency transformer the power supply appears to be DC open when the line cord is tested with an ohm meter.
There is 318 VDC going to the output half of the supply indicating that the first half is OK.

300 VDC Switch to -12

All the outputs are supposed to operate with no load with no more than a 5 % increase in output voltage.  When J2 is disconnected, removing all loads, the -12 Volt supply seems to work OK.

300 VDC Switch to +24

The +24 VDC supply has no output.  Since it feeds the +5 and +12 outputs they are also dead.
Q3 is extremely hot.  It is marked
BUZ71A
PH
8630
G  D  S
The schematic shows it as
Q3
71A
It is the switch that drives T2 through D4 (4937).  The source is connected to ground.  The Gate is driven from a 7556 dual timer.  The Drain is connected to the +24 VDC output.  T2 drives the gates of Q1 & Q2 (IRF840R) which are the main +24 VDC switches to T1.  U2 is a 723 high quality linear power supply chip.  U1 (LM139 op amp), U2 and U3 are feed from the Sheet 2/6 portion of the supply that includes the -12 volt supply.

U2 (723) has a 5.1 V zener connected from pn 7 (V-) to pin 2 (ILIM) and with the chip out of it's socket the voltage is about 5.5 VDC, but with the chip installed it's about 1.8 VDC.  Maybe the 723 is dead?

+24 VDC Linear to +5 VDC

+24 VDC Linear to +12 VDC

Dead RCS-5A

The RCS-5A receiver is totally dead.

 
 
There is a 17(f) pin socket MS connector {A18-J2] and a 5(m) pin MS connector [A18-J1] to the right of this image.

A18-J1

Pin #
Cable
P.S.
A
  
230 Input
B
Switched Line hot
115 Input
C
Switched Line neut
Common
D
Line Ground
Chassis Grnd
E
  NC  NC

A18-J2

There are 6 outputs from the power supply
 
Pin #
P.S.
 Set Voltage
A
24 Gnd Fan
B
+ 24 V Fan
+24.2 +/- 0.1
C
+ 12 V to MB
12.2 +/- 0.05
D
+ 12 V to CRT
12.2 +/- 0.05
E
Pwr Fail Out
F
- 12 V to MB
-12.1 +/-0.05
G
Gnd (-12 MB)
H
+ 5 V to Synth
+5.2 +/-0.05
J
+ 5 V to MB
+5.2 +/-0.05
K
 + 5 V to MB
+5.2 +/-0.05
L
CB Trip -
M
CB Trip +
N
12 V Gnd to CRT&MB
P
Gnd to 
CRT&MB
R
Synth Gnd
S
Gnd to MB
T
Gnd to MB


Across the top are Test Points for:
 
External Name
Internal Name
Result
GND
    
Pwr Det
    
- 12 VDC
  
-4
+ 24 VDC
J3
near 0
+ 12 VDC
J2
near 0
+ 5 VDC
J1
near 02..

There are 4 cables leading from the first clam shell.
The 12-pins at the top right are P2.

The dual 12-pin (24 total( verticle in the center is P4.

One cable goes to the 3-pin molex connector P3 (along bottom edge of this view and has the two wires carrying the 300 Volts DC from the first half.
 
IC
P/N
Function
U1
LM139J
  
U2
LM723CJ
  
U3
ICM7556MJD
  
U11
TL594IJ
+ 5 VDC
U12
TL594IJ
+ 12 VDC
U13
LM139J
  
U18
LM139J
  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


The Input side has a metal box holding J1 and J2, the 300 Volt DC supply and some of the output voltage supplies.

This box contains U14, U15, U16 and U17.

The Yellow transformer along the right wall is T12 which is driven from U17
 
IC
P/N
Function
U14
LM139J
  
U15
LM139J
  
U16
601-4 Opto Isol
Pwr Fail Out
U17
CS2842A
Oscillator

Test Points

 
Label
Description
P2  Open
300R
318 VDC
+300
318 VDC Rtn
U17-7
118 VAC
+12HK
1.5 VDC
+57 VDC
HKR
1.5 VDC Return
+32HK
+11
+87 VDC

If all the boards are removed from the motherboard ( A9, A10, A11, A12, and A13) and all the power connectors are removed from A4, A5, A6 and A7 then the -12 VDC output can be adjusted and appears OK.  If any of the boards is connected the voltage drops from -12 to around -8 and with all connected the voltage drops to around -4 VDC.  Transformer T12 is driven from Q42 which is driven from U17 (Cherry Semiconductor CS-2842A).  With the power supply outupt connector (J2) disconnected the frequency from U17 #7 to "300R" is about 7 kHz and with J2 connected (all loads applied) about 13 Hz.  The dsata sheet for the CS-2842A indicates for Rt=649 Ohms and Ct= 15 nF the frequency should be about 76 kHz.  Vcc at U17 #7 is about 10.95 with J2 connected and with J2 disconnected the voltage varies from 10 to 13 VDC.  Pin 8 Vref should be 5.0 VDC but it is around 2 volts.  I think that U17 is bad.
U17 was not the problem.
 

Q3 is extreamly hot.
Q3 the BUZ71A, U2 the LM723CN and U3 the NE556 are all available form ST Microelectronics in San Jose.

Possible inventions:

US4009430: Antiparallel commutated inverter  Feb. 22, 1977 / April 14, 1975   issued/filed
US3925633: Circuit for controlling power flow from a high frequency energy source to a plurality of high frequency loads  Dec. 9, 1975 / Sept. 6, 1974
US3652874: CIRCUIT FOR CONTROLLING THE CONDUCTION OF A SWITCHING DEVICE  March 28, 1972 / July 30, 1970
 
back to Brooke's RCS-5, home page