RCA-Magnecord 30/33 ? - UK Vintage Radio Repair and Restoration Discussion Forum

Levente · 2nd May 2018, 2:12 pm

Hey guys,

My new project is to get this beautiful machine back to life.

Its an RCA SRT-1 according to the label attached to it however, it is identical to Magnecord 30/33. It seems that the pream and the tape section is merged together unlike the Magnacord 30.

She has one 12AU7 and one 12AX7 and a Triad 32-B-8 transformer, a playback inout output in one old fashoned phono jack and two separate phono jack.

One LO and one HI.

Am I seeing this correctly that this has no output transformer or output amplifier? Only preamp at the input stage?

I can not find any schematic for this exact model, been searching for days...

If anyone recognize this or has info on this please let me know....i am trying to figure itout how to run this on a 15 Ohm speaker...

Thanks!

usradcoll1 · 3rd May 2018, 2:08 am

I'm in the US, but never had an exposure to this type equipment. It's considered to be a professional unit for a radio station or a similar type of an application.
There doesn't seem to be any output stage that can drive a speaker. An external amplifier would have to be used.
It's sad to see it was packed so poorly and it was damaged in shipment. It also appears that the rectifier valve is missing, probably a 6X4/EZ90. Also, the electrolytic capacitors would have to be remounted, before trying.
It looks like it's made for 120 volts, 60 cycles, so the speeds wont be proper.

Levente · 3rd May 2018, 2:16 am

hi,

thanks for the reply!

Yes, i have been on the web for weeks trying to find anything on this unit...only similar gear i found is the Magnecord M30.

Yes, you are right...there is the missing 6X4 rectufuer tube, until that arrives will not power it up...on 115V of course

Safety wise, there is one odd thing....there is an electrolytic cap 1000uF 15V and noticed, if all the tubes are in place, the +ve pin and also the -ve pin of that cap is somehow connected to the chassis...I have not seen anything lik it...is this normal in old gears?

usradcoll1 · 3rd May 2018, 4:33 pm

There probably isn't much in the line of repair information available on RCA's commercial equipment, as the only ones that had it was a specialty division of RCA service.
The 1000uf 15V cap is probably used in a LV DC source for the preamp heaters or the brake on the left motor.
Unfortunately, you'll have to reverse engineer the unit in lieu of the service manual.
BTW, was this unit from the US?

2nd May 2018, 2:12 pm	#1
Levente Hexode Join Date: Nov 2016 Location: Budapest, Hungary Posts: 386	RCA-Magnecord 30/33 ? Hey guys, My new project is to get this beautiful machine back to life. Its an RCA SRT-1 according to the label attached to it however, it is identical to Magnecord 30/33. It seems that the pream and the tape section is merged together unlike the Magnacord 30. She has one 12AU7 and one 12AX7 and a Triad 32-B-8 transformer, a playback inout output in one old fashoned phono jack and two separate phono jack. One LO and one HI. Am I seeing this correctly that this has no output transformer or output amplifier? Only preamp at the input stage? I can not find any schematic for this exact model, been searching for days... If anyone recognize this or has info on this please let me know....i am trying to figure itout how to run this on a 15 Ohm speaker... Thanks! Attached Thumbnails

3rd May 2018, 2:08 am	#2
usradcoll1 Heptode Join Date: Mar 2017 Location: Cedar Grove, Wisconsin, USA. Posts: 823	Re: RCA-Magnecord 30/33 ? I'm in the US, but never had an exposure to this type equipment. It's considered to be a professional unit for a radio station or a similar type of an application. There doesn't seem to be any output stage that can drive a speaker. An external amplifier would have to be used. It's sad to see it was packed so poorly and it was damaged in shipment. It also appears that the rectifier valve is missing, probably a 6X4/EZ90. Also, the electrolytic capacitors would have to be remounted, before trying. It looks like it's made for 120 volts, 60 cycles, so the speeds wont be proper.

3rd May 2018, 2:16 am	#3
Levente Hexode Join Date: Nov 2016 Location: Budapest, Hungary Posts: 386	Re: RCA-Magnecord 30/33 ? hi, thanks for the reply! Yes, i have been on the web for weeks trying to find anything on this unit...only similar gear i found is the Magnecord M30. Yes, you are right...there is the missing 6X4 rectufuer tube, until that arrives will not power it up...on 115V of course Safety wise, there is one odd thing....there is an electrolytic cap 1000uF 15V and noticed, if all the tubes are in place, the +ve pin and also the -ve pin of that cap is somehow connected to the chassis...I have not seen anything lik it...is this normal in old gears?

3rd May 2018, 4:33 pm	#4
usradcoll1 Heptode Join Date: Mar 2017 Location: Cedar Grove, Wisconsin, USA. Posts: 823	Re: RCA-Magnecord 30/33 ? There probably isn't much in the line of repair information available on RCA's commercial equipment, as the only ones that had it was a specialty division of RCA service. The 1000uf 15V cap is probably used in a LV DC source for the preamp heaters or the brake on the left motor. Unfortunately, you'll have to reverse engineer the unit in lieu of the service manual. BTW, was this unit from the US?