Revox A700 tension adjustment / Problems

[afunk]

Hallo,

Ich bin neu im Forum. Ich kaufte mir ein sehr schönes A700. Ich kann nicht scheinen, um die Spule Spannung einstellen. Ich habe die Trimmung Töpfe auf dem Sensor-Boards an die angegebene Spannung Arm der Höhe verstellt, sondern die Trimmung Töpfe interagieren, wo ich es in Ordnung, bilden den Anfang des Bandes bekommen können, aber am Ende die Versorgung Spannung so hoch, geht es Stände der Maschine . Em ich etwas falsch? Gibt es eine spezielle Methode? Gibt es eine Fehlfunktion des Bauteils?
Jede Hilfe wird gebeten.

Thank You,
Andrew Funk
USA

Casaandy@mac.com

Hello,

I'm new to the forum. I bought a very nice A700. I can't seem to adjust the reel tension. I've adjusted the trim pots on the sensor boards to the specified tension arm height, but the trim pots interact where I can get it okay form the beginning of the tape, but at the end the supply tension goes so high it stalls the machine. Em I doing something wrong? Is there a special method? Is there component failure?
Any help would be appreciated .

Thank You,
Andrew Funk
USA

[flyingdoc]

AW: Revox A700 tension adjustment / Problems

Hello Andrew,

cosmetically nice? Technically nice is the question.
The tape tension of the A700 was a problem till the latest versions of the A700.
So you should tell us the serial nr. of your A700 and if you you have any information about an update at a revox service station in the past.

There were four main revisions of the A700, units taken to the revox service in the past, were updated (here in germany for free).

The silicon dampers, when left in original condition, are most probably faulty.

Common to all other revox gear of that time, some electrolytic capacitors have fallen dry and trimmers are defective.

A very early A700 (serial <10000) is nowadays very expensive for a total revision.

[afunk]

Re: Revox A700 tension adjustment / Problems

Hi Herby,

Thanks for the reply!!! Just a quick history.
The machine in excellent condition and low hours as the heads show. I had a spare 1/4 track play head that JRF installed in the 4th position, had a switch and it works nicely. When i looked at the machine to purchase I noticed the pinch roller didn't have enough pressure to keep the speed constant, and the supply tension was very high. I increased the pinch roller pressure which helped but the reel tensions are incorrect.
If you know the upgrades or whats needed I'm a fairly competent tech and can upgrade the machine with the proper info. The machine serial # 019135.

Any help would be great. You can also email me directly @ casaandy@mac.com

Thank you again writing back.

Best Regards,
Andrew

[afunk]

Re: Revox A700 tension adjustment / Problems

Hallo wieder,
Die Ferien sind vorbei ausgecheckt die Maschine wieder. I sieht aus, als wenn es keine Start Spannung auf der Seite abzunehmen, wenn Sie die Taste spielen, öffnete ich die Maschine fanden die großen können Kappen sind undicht. gibt es 4 von ihnen in der Nähe der Aufwicklung Motor 1.5, 2x 3.5, 6uF. Das wird es sein, den Gedanken?

Hi Again,
Holidays are over checked out the machine again. I looks as if there is no start up tension on the takeup side when you press play, I opened the machine found the large can caps are leaking. there's 4 of them near the takeup motor 1.5 ,2x 3.5, 6uF. That must be it, any thoughts?

Thanks,
Andrew

Hi Herby,

Thanks for the reply!!! Just a quick history.
The machine in excellent condition and low hours as the heads show. I had a spare 1/4 track play head that JRF installed in the 4th position, had a switch and it works nicely. When i looked at the machine to purchase I noticed the pinch roller didn't have enough pressure to keep the speed constant, and the supply tension was very high. I increased the pinch roller pressure which helped but the reel tensions are incorrect.
If you know the upgrades or whats needed I'm a fairly competent tech and can upgrade the machine with the proper info. The machine serial # 019135.

Any help would be great. You can also email me directly @ casaandy@mac.com

Thank you again writing back.

Best Regards,
Andrew

[temi]

AW: Revox A700 tension adjustment / Problems

Hi afunk,

I am new to this forum too, but I am working on an A700 from a work mate. I have seen the large caps you mentioned, they work as phase shifter for the AC reel motors (a capacitor start and run motor). In Germany they are called "motor caps", there are 2 different types available, "starting caps" and "running caps". For the Revox motors, running caps are used. Here is a sample product information. C2/6,5µF and C3/1,5µf sit in the same can , if you do not use your A700 on 50Hz mains supply, you can omit C3/1,5µf for the supply and takeup motor. Just in case that you have problems to get the 1,5µf and 6,5µF in one can.

When I got the A700 from my work mate, the supply motor was spinning all time as soon as power was switched on. I found a shorted MJ411 transistor, replaced it by a MJ413 and the motor stopped running. Later I noticed that the new transistor was getting very hot and I wondered why. I loosened the brakes in stop mode and the supply reel again started spinning, but very slowly. I found another shorted transistor (Q18/BC 108B) at tape transport control board and now the supply reel does not spin in stop mode. But I still have problems with takeup tension in play mode.

kind regards, temi