Rowe R-93 Amp Repair

I am looking for help with a Rowe 130W amplifier. The amp is out of a Rowe R-93 (45/CD Combo) jukebox. I get maximum volume on only the left channel. The problem does not change if I switch driver boards or transistor pairs. Swapping outputs at the plug results in the same problem but with the right channel on full so I know the speakers are wired properly. I swapped out an entire amplifier but did not connect the tonearm input. The box played normally until I plugged in the tonearm input. Now I have two amplifiers that play at maximum volume on just the left channel. I have a replacement tonearm, cartridge, and wiring but am not sure what was obviously taken out on the preamp.

The jumper and volume control are connected properly. The speakers have been attached to E3 until I get the volume problem under control. As I said, the sound from the CD player was fine until I connected the tonearm input. Removing the tonearm input after the fact did not alleviate the problem. Swapped out op amp chips, still no right channel.

Tried replacement tonearm with existing amp, music heard through left channel only, as expected. Reversed tonearm input, music still heard through left channel only, as hoped. Replaced preamp board with known working board, same problem – volume on full, no right channel. Strangest part to me is the loss of volume control. Any troubleshooting/repair suggestions?

Per chance--do you have the 13 pin jumper on "backwards" ???--Ron Rich

Ron Rich wrote:Per chance--do you have the 13 pin jumper on "backwards" ???--Ron Rich

I appreciate the suggestion as sometimes the obvious is overlooked, but not this time. I have also checked the balance control.

I noticed that the amp stays on even though no selection (45 or CD) is playing. Is there a mute signal for each channel?

Mono/Stereo switch has no effect.

Mute is accomplished with a two pin plug on the pre-amp board--underneath, of course, where you can't see it !
This "extends out" thru one of the mounted plugs on the amp chassis--look at the schemo, as I don't recall at this moment. It is "switched" by the "Mech Control" unit--internal triac. Ron Rich

The mute signal comes from the CCC board. If some one has swapped the amp or the CCC with an improper one, it can kill the circuit. Do you have the volume control pluged in properly and hooked up right? Its in the book.(like Ron Rich said)

Hello,

What is type number on your 130 watt Rowe Ami amp?
i.e. 6-09931-01 etc.

Regards
Alan Hood
AMI-MAN
UK

ami-man wrote:Hello,

What is type number on your 130 watt Rowe Ami amp?
i.e. 6-09931-01 etc.

Regards
Alan Hood
AMI-MAN
UK

It is a 6-09931-02.

Hello,

So we are talking about the same amp, the revision number is slightly higher.

Have you got the two pin mute connector connected to the pre-amp board?
Have you got the mute plug connected on the amp. It is a 6 pin molex plug, Station 2 on the wiring diagram.
With both of the above plugs connected the mute should work unless there is a problem with the the outer cam switch on the transfer motor or a faulty mechanism control board.

With regards to the volume control, I would make up a test lead using a 10k log pot connected to a 5 pin straight molex plug connect the wiper to pin 3 (ground) and connect pins 1 & 3 together and connect to one end of the pot.

I assume that your phono speakers are connected to the output package and the pink & purple are connected to E3 left and right and the black is connected to one of the E1's?

With regards to the 13 pin molex that connects the input to the output stages is there a link between pins 2 & 7? the other links are 1 to 3, 5 to 9 and 6 to 8.

Regards
Alan

Alan Hood
ami-man
UK

I assume that your phono speakers are connected to the output package and the pink & purple are connected to E3 left and right and the black is connected to one of the E1's? Correct

With regards to the 13 pin molex that connects the input to the output stages is there a link between pins 2 & 7? the other links are 1 to 3, 5 to 9 and 6 to 8. Yes

With regards to the volume control, I would make up a test lead using a 10k log pot connected to a 5 pin straight molex plug connect the wiper to pin 3 (ground) and connect pins 1 & 3 together and connect to one end of the pot. Should this be wiper to pin 3(ground) and pins 1 & 5 together and then to the potentiometer?

Prior to connecting the tonearm, the volume was controllable and present on both channels. I've been concentrating on the output being damaged, now I wonder if the problem is in the output or the input. My thinking still leads me to the preamp board.

ami-man wrote:
Have you got the two pin mute connector connected to the pre-amp board?
Have you got the mute plug connected on the amp. It is a 6 pin molex plug, Station 2 on the wiring diagram.
With both of the above plugs connected the mute should work unless there is a problem with the the outer cam switch on the transfer motor or a faulty mechanism control board.

Alan Hood
ami-man
UK

Have you got the two pin mute connector connected to the pre-amp board? Yes
Have you got the mute plug connected on the amp. It is a 6 pin molex plug, Station 2 on the wiring diagram. Yes
With both of the above plugs connected the mute should work unless there is a problem with the the outer cam switch on the transfer motor or a faulty mechanism control board. Swapped out mech control board. Continuity of N.C. and N.O. contacts functioning normally.

When the phonograph is engaged (no record playing), a hum is heard at full volume. After the switch cam is back in the home position, the hum disappears, but touching the needle creates audible sound in the speakers at full volume.

I have a Rowe 125 watt amplifier (6-07438-02) that I could try in my R-93, but the connectors are different. Anyone know if the preamp board (6-08552-01) can be swapped for the 6-07925-05 preamp used the the 130 watt amp (6-09931-02)? Or perhaps splice the proper connectors onto the existing harness? I want to get this box working but do not want to lose another amplifier in the process.

sdtm_glenn wrote:I have a Rowe 125 watt amplifier (6-07438-02) that I could try in my R-93, but the connectors are different. Anyone know if the preamp board (6-08552-01) can be swapped for the 6-07925-05 preamp used the the 130 watt amp (6-09931-02)? Or perhaps splice the proper connectors onto the existing harness? I want to get this box working but do not want to lose another amplifier in the process.

Just looked, no aux in for the CD player, only aux out. So much for that idea.

Hello,

Do you have access to a signal generator and a dual beam scope?

Regards
Alan Hood
ami-man
UK

ami-man wrote:Hello,

Do you have access to a signal generator and a dual beam scope?

Regards
Alan Hood
ami-man
UK

I'm afraid I don't have access to those tools at this time. I would like to know your line of thinking, though.