ROWE AMI CD-100E Amp Driver Board

[TCW]

I have just replaced the set of power output transistors. I wanted to do a test on the Preamp and the driver boards with no load before I put the amp back in. On this amp it says to do the following yet there is no PHONO CARTRIDGE INPUT. There are two (2) RCA jacks for left and right CD Inputs. A four (4) pin Microphone Input. Any ideas on how to do this procedure? - Tom

Page 5-41 CD-100E Vol. 2 Sec 5

PREAMP OUTPUT

Short all five of the volume control pins located on amp. Press your finger against Pins 1 or 3 (outside
pins) labeled PHONO CARTRIDGE INPUT, and check for approximately 1 VAC at preamp output (Pins 3
or 5 of 13 pin connector to chassis Common). Replace the preamp board If voltage Is not present.

DRIVER BOARD
If voltage is present (from above) check the center pin of the output driver board for approximately 16
VAC. If voltage is not present, make sure your finger is pressed against the same outside pin with
respect to the channel that is being checked with the voltmeter.

[Ron Rich]

Hi Tom,
Obviously "it" lies ! Rowe eliminated the phono section of the amp, prior to that amp being made-- Which output boards are in that amp-- the ones with the bias control, or the ones with the LED non-settable bias ? Ron Rich

[TCW]

Its the 250 Watt 61024903 amp with a 61023703/23 preamp and the 40710105 driver boards with three LED's each.

[Ron Rich]

Hi Tom,
It's a later version then the writing, in your manual-- Ron Rich

[TCW]

So what your opinion is the procedure to check the 40710105 driver boards before I but a load on.

For example the 6-09931-02 Amp with it plugged in and running on the bench, with the 4-07101-03 driver boards I check voltages at the fuses. -36VDC on F1 and +36VDC on F2. Then I check the voltage on R29, it should be around 0.009 mV. This is the Idle Current of the associated power transistor. A reading of 0.9 mV for example would be a bad transistor on the driver board. A reading of .09 mV would be a leakey transistor. Beck I had one with 34 VDC that was a shorter transistor (Q5).

Tom

[Ron Rich]

Hi Tom,
I ainna never done tit that away-- I use the proceedure listed in the shop manual -- Ron Rich

[TCW]

Sorry, maybe I'm missing it then. What does the shop manual say about checking a 61024903 amp with a 61023703/23 preamp and the 40710105 driver boards with three LED's each?

I guess what I will try is:

1) PREAMP OUTPUT
Short all five of the volume control pins located on amp. Insert a pair of RCA jack cables (with male connections on both ends) in the left and right CD inputs. Press my fingers against the two center pins of the left and right channels, and check for approximately 1 VAC at preamp output (Pins 3 or 5 of 13 pin connector to chassis Common). Replace the preamp board If voltage Is not present.

2) DRIVER BOARD

If voltage is present (from above) check the center pin of the output driver board for approximately 16 VAC. If voltage is not present, make sure your finger is pressed against the same RCA center pin with respect to the channel that is being checked with the voltmeter.

[Ron Rich]

Tom,
Shop manual I have pre-dates the LED boards-- I just check for correct bias settings-- if the LED board will not achieve it, I fix the board--Ron Rich

[TCW]

As it turns out I need the wiring diagram for the 40710105 driver board. They are not to be found in the CD-100E & CD-100F shop manual.

I understand the 40710105 driver boards was used on the CD-100J Rowe LaserStar Saturn

[TCW]

40710105 driver boards. As far as I could tell everything checked OK, not the case though. R29, R30 & 31 were a blaze in about two seconds. This was the channel with no history of trouble. I would have expected the trouble from the other side. The fuses are the correct size, original and yet they held. Without the diagram I can only guess. I assume that if it was a shorted power transistor it would have taken the fuses. Terribly down about this. No spare driver board to swap in either save the other channel.

[TCW]

I simply cant seem to find any available information on the 40710105 driver boards. As I mention above R29, R30 & 31 were a blaze in about two seconds. I just checked the power transistors and three and a half out of four are open. As I was chasing around the web looking for any shred of information I might glean I was noticing that the other 61024903's looked different than mine for some reason. I finally figured it out.

The Amplifier Jumper Plug Assembly on my amp was apparently flipped around. I'm not sure what effect this may have had on my situation but it surly didn't help. I would think not the first time this has happened so any likely damage should be documented somewhere. Frankly I can't say I ever removed it but maybe I did at some point. Would this have caused all my problems and what if any damage may have occurred to the preamp then?

[TCW]

This list is from my own observations of my boards.

[Ken Layton]

I think the newest Rowe CD machine we had on our route was a "F". We only had one of that model and the title pages were always breaking. I have never encountered any of the Rowe amplifiers with the self adjusting bias driver boards. Your pictures and parts listing will certainly help others with those boards. Information about them is very sparse out there. Thanks for posting.

If I had to guess what your problem might be, it could be a leaky diode.

[TCW]

Thanks for sharing Ken,

I am all about sharing information so the more I find the better other interested folks will be. My interest is learning how to repair these boards at a component level but then I love to share with others what I have learned. Running into this "Amplifier Jumper Plug Assembly on my amp was apparently flipped around" had been a real embarrassment and a supper pain to discern what other damage was done besides the R29, R30 & R31 being burned up.

As you say

May 15, 2021 19:20:46 GMT Ken Layton said:

Information about them is very sparse out there. 

I wish I could get my hands on the “Shop” manual instead of just the service manuals. My hope is that they would contain "Test Point" data for each board to pinpoint component failures. Maybe they have some common repair scenarios or narratives with tips.

Please check out my other post regarding "ROWE AMI R-92B Amp 6-09931-02". I'm trying to repair my 4-07101-03 driver boards. Notice the voltage differences at R29 on both left and right channels below, Right -34.88VDC, Left -15.5mVDC. 

I would love to know your thoughts on this on that post.

May 9, 2021 18:09:42 GMT TCW said:

It looks like both driver boards need some attention.

Has the 4-07101-03 driver boards. I checked the voltages at the fuses. -36VDC on F1 and +36VDC on F2. Then I check the voltage on R29, it should be around 0.009.

Right Chanel
F1 -36.14VDC
F2 +37.34VDC
R29 -34.88VDC

Left Chanel
F1 -37.2VDC
F2 +37.3VDC
R29 -15.5mVDC

Looks like I will need to come up with some real world part numbers (Not ROWE AMI numbers listed below) for the Diodes and transistors. Help please?

COMPONENT LIST FOR AMPLIFIER BOARD 4-07101-03
C1 CAPACITOR    MONOLITHIC   CERAMIC    .1 Mfd          70020649
C2 CAPACITOR    MONOLITHIC   CERAMIC 220 Pf             70028606
C3 CAPACITOR    ELECTROLYTIC                 47 Mfd 35V    70023012
C4 CAPACITOR    ELECTROLYTIC                2.2 Mfd 58V    70023805
C5 CAPACITOR    MONOLITHIC   CERAMIC    .1 Mfd          70028649
C6 CAPACITOR    ELECTROLYTIC                 15 Mfd 50V    70023009
C7 CAPACITOR    MONOLITHIC   CERAMIC  .01 Pf             70028636
C8 CAPACITOR    MONOLITHIC   CERAMIC 100 Pf             70020601
C9 CAPACITOR    ELECTROLYTIC                22 Mfd 35V     70025810
C10 CAPACITOR  ELECTROLYTIC                22 Mfd 35V     70025810
C11 CAPACITOR  MONOLITHIC   CERAMIC 220 Pf             70028606
C12 CAPACITOR  MONOLITHIC   CERAMIC .01 Pf              70028636
C13 CAPACITOR  ELECTROLYTIC                47 Mfd 35V     70023812
C14 CAPACITOR  MONOLITHIC   CERAMIC 470 Pf             70020612
C15 CAPACITOR  MYLAR                           .10 Mfd           70024002
CRl-CR2 DIODE - SILICON                                              70035002
CR3 DIODE - ZENER 10V                                                70035514
CR4 NOT USED
CR5-CR12 DIODE - SILICON                                           70035005
CR13 NOT USED
CR14-CR15 DIODE - ZENER 5.1V                                    70055527
F1-F2 FUSE - 5 AMP 70072010
P1-P2 WAFER - POLARIZED (4 CKT)                                70075004
P3 WAFER - POLARIZED (5 CKT)                                     70075005
P4 WAFER - NON-POLARIZED (4 CKT)                             70074904
Q1 NOT USED
Q2 NOT USED
Q3 TRANSISTOR DUAL (NPN)  2N2920 60v 0.03A - 78      70030301
Q4-Q6 TRANSISTOR (PNP)      ITT A 56 940                     70030104
Q7-Q9 TRANSISTOR (NPN)      MPS A 0 6                         70030008

[TCW]

There is a circuit board between each set pf the transistors with three diodes and all three are open. Parts manual refers to them as 40863101, Circuit Board Assembly - Bias Diode With Wires (seeing how I have the 40710105 driver boards, I half wonder if I need these? Pictured below.). Anyone have an idea what the spec is on these diodes? The black one is a is a 1N4157, a "three junction "stabistor" type diode, also referred to as a Forward Reference Diode or Forward Regulating Diode, Spec sheet attached. I need to find an equivalent. UPDATE: Patrick Glasser, Electronics Technician @ Digi-Key Electronics suggests part number 2156-1N5821-ND as a possible alternative. Also I have seen others in the amplifier world use CMXSTB300 multi-chip silicon diodes by soldering on legs to the device and using them axial position. CMXSTB300 Data sheet my.centralsemi.com/datasheets/CMXSTB200_SERIES.PDF Yet others have found NTE replacement NTE177.  www.nteinc.com/specs/100to199/pdf/nte177.pdf

As for the other two. The one on the right is a 1N4148, a High Speed Switching Diode AKA.

The one on the bottom, there are no markings on the device. All I can say is that the one I have that is still good, I get readings in both directions when I have it in the ohms setting. 9.92KΩ in one direction and 9.56 KΩ in the other. I'm going to need help identifying this one. UPDATE: Positive Thermistor,  P-10 k, 10%. I purchased NTC Thermistors Resistors MF58 3950B 10K Ohm Glass Sealed.



A beetr one can be found at 
www.digitroncorp.com/getmedia/824DFFAE-F11A-451C-A8DF-65A92EFB02A5/1N4156-2c-1N4157-2c-1N4453-2c-1N4829-2c-1N4830-2c-1N5179-2c-MPD100-MPD400A.aspx?ext=.pdf